\JSouth American Fossils in Madagascar and India\j
\JWater Trapped In Earth As Crystals\j
\JBig Quakes May Be Gentler\j
\JGenome of Tuberculosis\j
\JGenome of a Spirochaete\j
\JGenome of an Archaebacterium\j
\JDog Genome Gets Closer\j
\JTubulin Unveiled\j
\JChicken Flu Virus Scare\j
\JWhy Red Wine is Good For The Heart\j
\JImmunoglobulin E a Killer?\j
\JGenetic Mutation Responsible For Allergies?\j
\JAsbestos Transformed\j
\JKyoto Environmental Conference Report\j
\JGlobal Warming Confirmed\j
\JAfrican Weather\j
\JCold Snap 8200 y.a.?\j
\JNew Toxin To Combat Insect Pests\j
\JPill To Combat Mosquitoes\j
\JGorilla Census\j
\JJapan Prize Results\j
\JTop Ten Scientific Breakthroughs (1997)\j
\JFirst Transgenic Cloned Sheep\j
\JPrion Chaperone Identified\j
\JSmall Comets in Doubt Again\j
\JMathilde Pictures Released\j
\JMartian Life Gets More Distant\j
\JRoyal Greenwich Observatory Closed\j
\JHigh X-Ray Bursts Detected Over Sweden\j
\JEnd of a Star\j
\JDeath of a Planet--Or Many Planets?\j
\JSwitzerland: The Gene Protection Initiative\j
\JGreen Tea Kills Cancer\j
\JPine Cone Intelligence\j
\JObituary for December 97\j
#
"Time Machines Get a Step Closer",14,0,0,0
(Jan '97)
Hendrik Casimir predicted the weak force between two plates in a vacuum which we now call the Casimir effect in 1948. Steven Lamoreaux at the Los Alamos National laboratory in New Mexico has just succeeded in measuring the force of the effect, using a torsion \Jpendulum\j. The result: a force within 5% of the predicted level was measured, a very good result indeed.
The importance of this is that any time machine that we can now predict will need to use two sets of plates experiencing the Casimir effect. But until we have a working time machine available to see what happens, the best we can say is that it is early days yet.
The Casimir effect is only measurable when two parallel plate are set up, just a fraction of a \Jmillimetre\j apart in a vacuum, and the result is that a weak force then operates to push them together. Empty space is not really empty, according to quantum theory. Instead, virtual photons are continually popping into existence and then disappearing again.
In the narrow gap between the plates, the only photons which can exist are those with wavelengths which are a equal to the gap distance divided by an integer. All other photons are excluded from the gap, and this means there are more photons pressing on the outside of the gap than on the inside, producing the force we call the Casimir effect. According to Lamoreaux, the force he measured, with a separation of just 0.75 micrometre, was about one billionth of a newton.
This is the third major breakthrough in physics that has been achieved with a torsion \Jpendulum\j, after a wait of almost two centuries. Charles \JCoulomb\j used a torsion \Jpendulum\j to measure the forces between electrical charges in 1785, and soon after, Henry Cavendish had used a similar device to measure the force of gravitation in 1798.
#
"New drugs",15,0,0,0
(Jan '97)
Scientists from Abbott Laboratories announced on January 17 at the 4th Conference on Retroviruses and Opportunistic Infections that they have begun clinical trials on a new anti-\JHIV\j drug, which is called ABT-378. They claim it is 10 times more potent than one of the most powerful AIDS drugs now on the market. Test tube studies of the drug, an inhibitor of the protease \Jenzyme\j that \JHIV\j uses to copy itself, suggest that the AIDS virus has an unusually difficult time developing resistance to it.
Epothilone A is produced by a myxobacterium and can be produced in comparatively large quantities by fermentation, shows promise as an anti-cancer treatment. Two groups of scientists are working on the synthesis and modification of the molecule.
#
"Humans Older Than Thought?",16,0,0,0
(Jan '97)
One way of defining humans is to call them "tool-making animals". Birds may use thorns, chimpanzees may use sticks, but only humans actually change and modify and make tools from other things, say most scientists.
On that basis, "made" tools are by definition the work of members of the \Jgenus\j \IHomo\i, but now there is evidence of Oldowan-style tools, reliably dated to 2.5 - 2.6 Myr (million years). The Oldowan Stone tool industry was named for 1.8-million-year-old (Myr) artifacts found near the bottom of Olduvai Gorge, \JTanzania\j. Later archaeological research in the Omo (\JEthiopia\j) and Turkana (\JKenya\j) also yielded stone tools dated to 2.3 Myr. Until the recent find, this seemed to fit with the earliest dates for bones and teeth which showed all the signs of coming from Homo, and so all was well.
These new occurrences are now securely dated between by several means, making the stone tools the oldest known artifacts from anywhere in the world. The artifacts are described as showing surprisingly sophisticated control of stone fracture mechanics, equivalent to much younger Oldowan assemblages.
So either \IHomo\i is older than we thought, or, as some scientists are now suggesting, the Oldowan tools were made by the robust Australopithecines, generally now referred to as \IParanthropus robustus\i and \IParanthropus boisei\i. If that is the case, then humans were not the only tool makers.
#
"Europa is Seismic",17,0,0,0
(Jan '97)
In a report released on January 17, NASA has announced that the \JGalileo\j images taken in December 1996 reveal ice-spewing volcanoes and the grinding and tearing of tectonic plates have reshaped the chaotic surface of Jupiter's frozen moon Europa. The images were captured when \JGalileo\j flew within just 692 kilometres (430 miles) of Europa, and while they do not show currently active ice volcanoes or geysers, they do reveal flows of material on the surface that probably originated from them.
Galileo imaging team member Dr. Ronald Greeley commented: "This is the first time we've seen actual ice flows on any of the moons of Jupiter." "These flows, as well as dark scarring on some of Europa's cracks and ridges, appear to be remnants of ice volcanoes or geysers."
As we indicated last month, signs of volcanism on Europa's surface make it more likely that there is warm liquid \Jwater\j, somewhere below the ice, \Jwater\j which may just support life. Said Greeley: "There are three main criteria to consider when you are looking for the possibility of life outside the Earth-the presence of \Jwater\j, organic compounds and adequate heat," said Dr Greeley. "Europa obviously has substantial \Jwater\j ice, and organic compounds are known to be prevalent in the \Jsolar system\j. The big question mark has been how much heat is generated in the interior."
"These new images demonstrate that there was enough heat to drive the flows on the surface. Europa thus has a high potential to meet the criteria for exobiology."
The icy crust of Europa shows signs of having been disrupted by the motion of tectonic plates, with different sorts of movement in different places. This is different from the pattern seen on the surface of Ganymede, leading scientists to speculate that these two moons may have different internal structures.
Galileo scientists will have a better chance to understand Europa's interior when the \Jspacecraft\j gathers gravity data on another fly-by next November. The gravity field is measured by tracking how the frequency of Galileo's radio signal changes as it flies past the moon. This was not possible during the recent fly-by because radio conditions were degraded as Jupiter passed behind the Sun from Earth's point of view.
After a swing past Jupiter, \JGalileo\j's next targeted fly-by will take it again past Europa as it passes within 587 kilometres (364 miles) on February 20.
#
"Moons Full of Life?",18,0,0,0
(Jan '97)
Possible planetary objects have now been discovered orbiting no less than nine different main-sequence stars. These companion objects, some of which might actually be brown dwarfs, all have a mass at least half that of Jupiter, and are unlikely to support Earth-like life: Jovian planets and brown dwarfs support neither a solid nor a liquid surface near which organisms might dwell.
Smaller rocky moons around these companions are another matter altogether, if the \Jplanet\j-moon system orbits the parent star within the so-called 'habitable zone', where life-supporting liquid \Jwater\j could be present. The companions to the stars 16 Cygni B and 47 Ursae Majoris might satisfy this criterion, say D M Williams, J F Kasting & R A Wade, in a letter to \INature\i this month.
Such a moon would need to be larger than 0.12 Earth masses, so as to retain a substantial and long-lasting \Jatmosphere\j, and would also need to possess a strong magnetic field in order to prevent its \Jatmosphere\j from being sputtered away by the constant bombardment of energetic ions from the \Jplanet\j's magnetosphere.
#
"Black Holes in Every Galaxy?",19,0,0,0
(Jan '97)
A Hubble Space \Jtelescope\j \Jcensus\j reveals that black holes are common in galaxies, according to a January 13 release on the \JInternet\j. Three black holes have been identified in three normal galaxies, and the team responsible suggests that nearly all galaxies may harbour supermassive black holes which once powered quasars which are now no longer active.
They took a \Jcensus\j of 27 nearby galaxies with NASA's \JHubble Space Telescope\j and the ground-based Canada-\JFrance\j-Hawaii Telescope (CFHT) on Mauna Kea, Hawaii, which are being used to conduct a spectroscopic and photometric survey of galaxies to find black holes which have consumed the mass of millions of Sun-like stars.
The key results are that:
ò Supermassive black holes are so common that nearly every large galaxy has one.
ò A black hole's mass is proportional to the mass of the host galaxy, so a galaxy twice as massive as another would have a black hole that is also twice as massive. This discovery suggests that the growth of the black hole is linked to the formation of the galaxy in which it is located.
ò The number and masses of the black holes found are consistent with what would have been required to power the quasars.
Two of the black holes weigh 50 million and 100 million solar masses, and they lie in the cores of galaxies NGC 3379 (also known as M105) and NGC 3377 respectively. These galaxies are both in the "Leo Spur," a nearby group of galaxies about 32 million light-years away and roughly in the direction of the Virgo cluster. Some 50 million light-years away, also in the Virgo cluster, NGC 4486B has a 500-million-solar-mass black hole. It is a small \Jsatellite\j of the very bright galaxy, M87 in the Virgo cluster. M87 has an active nucleus and is known to have a black hole of about two billion solar masses.
These new results suggest that smaller galaxies probably have lower-mass black holes, below Hubble's detection limit. The survey shows the black hole's mass is proportional to the host galaxy's mass. Now cosmologists will need to work on explaining why the black holes are so common, and why they seem to be proportional to the masses of the home galaxies.
The Hubble \Jtelescope\j's high resolution allowed the team to measure the velocities of stars orbiting the black hole. A sharp rise in velocity means that a great deal of matter is locked away in the galaxy's core, creating a powerful gravitational field that accelerates nearby stars.
The February 1997 servicing mission to the Hubble \Jtelescope\j will involve installing the Space \JTelescope\j Imaging Spectrograph. This spectrograph will greatly increase the efficiency of projects, such as this black hole \Jcensus\j, that require spectra of several nearby positions in a single object.
\BAnd in yet another galaxy . . .\b
The nucleus of the spiral galaxy NGC 1068 has always been obscured from direct observation by gas and dust. But radio images now suggest that it conceals a black hole of 10 to 20 million solar masses, and that the gas around it is swirling into the hole so rapidly that the nucleus is radiating at close to the theoretical limit, according to a report in \INature\i in early January, by Mitchell C. Begelman and Joss Bland-Hawthorn. Black holes, it seems, are all the go .
#
"Nobel Winners (1996)",20,0,0,0
The 1996 Nobel Prize Winners were named in October, too late to appear on the \JCD\j-ROM, and somehow were not listed in our December update. So here they are:
PEACE
Carlos Felipe Ximenes Belo and JosΘ Ramos-Horta "for their work towards a just and peaceful solution to the conflict in East \JTimor\j."
CHEMISTRY
Robert F. Curl, Jr., Sir Harold W. Kroto, and Richard E. Smalley "for their discovery of fullerenes."
PHYSICS
David M. Lee, Douglas D. Osheroff, and Robert C. Richardson "for their discovery of \Jsuperfluidity\j in \Jhelium\j-3."
ECONOMICS
James A. Mirrlees and William Vickrey "for their fundamental contributions to the economic theory of incentives under asymmetric information."
PHYSIOLOGY or MEDICINE
Peter C. Doherty and Rolf M. Zinkernagel "for their discoveries concerning the specificity of the cell mediated immune defence."
LITERATURE
Wislawa Szymborska "for poetry that with ironic precision allows the historical and biological context to come to light in fragments of human reality."
\BNobel Winners for Biology (1996)\b
Doherty and Zinkernagel's prize recognises research which they conducted when they worked together in the mid-1970s at the John Curtin School of Medical Research in \JCanberra\j, \JAustralia\j. Their research on animals showed that white blood cells (lymphocytes) must recognise both an invading virus and certain self molecules-the so-called major histocompatibility (MHC) antigens-in order to kill the virus-infected cells. This concept of simultaneous recognition of both self and foreign molecules formed the basis for a new understanding of the specificity of the cellular immune system.
Their research had an immediate and long-lasting effect on immunological and clinical research. Their findings on the specificity of the T-\Jlymphocyte\j-mediated immune response proved to be a fundamental advance in the understanding of how the immune system is able to recognise microorganisms other than viruses, and in the understanding of how the immune system reacts against certain kinds of self tissue. In late January, Doherty was named as "Australian of the Year".
#
"Mathematics Update",21,0,0,0
(Jan '97)
It happened in December, but news has only broken slowly about the discovery of another Mersenne prime, a type of number of special interest to people who care about number theory. They get their name from Marin Mersenne (1588-1648) who studied them. These numbers were known long before Mersenne, but he spent a great deal of time trying to find more of them.
Mersenne's name is now associated forever with numbers of the form 2\Un\u-1, and when such a number is found to be prime, it is called a Mersenne prime. When a number in this form is composite (that is, non-prime, having factors other than 1 and itself), it is just called a Mersenne number. The largest Mersenne prime so far known, the 35th found, is a number derived from n = 1398269, discovered in the Great \JInternet\j Mersenne Prime Search.
In the past, finding new Mersenne primes involved a great deal of time and effort, or a large computer, but now anybody can now join in adding to the list of Mersenne primes by contacting George Woltman's Great \JInternet\j Mersenne Prime Search at http://www.mersenne.org/prime.htm and reading what they find there.
#
"Obituaries for January 97",22,0,0,0
Clyde Tombaugh died on 17 January, 1997, at his home in Las Cruces. He was 90, but in the past year, attended lectures in a wheelchair fitted with oxygen tanks. Tombaugh will be remembered mainly as the astronomer who discovered Pluto in 1930, using a blink comparator. In the blink-comparator, a light would rapidly switch between pairs of photos, taken some time apart. This had the effect of making the stars look fixed, while against this background, a planetary body moving in its \Jorbit\j would appear to jump backwards and forwards, as the lights "blinked". On 18 February 1930, Tombaugh found the mystery planet, which the Lowell staff later called Pluto after the Greek god of the dimly lit underworld \JHades\j.
Tombaugh was self-taught, and spent much of his youth observing the sky. At the age of 22, he built a 9-inch \Jtelescope\j from old farm machinery and parts salvaged from his father's 1910 Buick. (When the Smithsonian asked Tombaugh, many years later, for his original \Jtelescope\j, he declined the request, saying that he was still using it!) When he sent drawings of Jupiter and Mars to the Lowell Observatory in Flagstaff, \JArizona\j, they offered him a job. Tombaugh helped search beyond Neptune for a "\JPlanet\j X," which astronomer Percival Lowell had predicted based on perturbations in Neptune's \Jorbit\j.
After finding Pluto, Tombaugh discovered six star clusters, two comets, hundreds of \Jasteroids\j, several dozen clusters of galaxies, and one supercluster. After helping test captured German \JV-2\j rockets in 1946 at White Sands Missile Range, he went to New Mexico State University, where he taught until 1973.
#
"Archaeological Finding in Beijing",23,0,0,0
(Jan '97)
Chinese scientists in \JBeijing\j have uncovered the first evidence of prehistoric human activity in what we now call \JBeijing\j. The discovery of stone tools and other artifacts, estimated to be around 20 000 years old, is likely to offer clues about how early human settlers populated the 300 000-square-\Jkilometre\j North China Plain.
Workers have spent the past month digging up pieces of flint, charred animal bone fragments, and charcoal from a 150-square-metre site in \JBeijing\j's main business district at the construction site for an office complex called Dongfang Square on Wangfujing Street. The people who left the remains were in the habit of roasting game and knew how to make and use stone implements for cutting and chopping. The Chinese are hailing it as a link to "Peking man", but there is still quite a sizeable gap to fill.
#
"Short Science Updates (Jan 1997)",24,0,0,0
In \JJapan\j, Yasuyuki Shirota of Hiroski University is trying a smaller form of \IJurassic Park\i: bringing a giant moa, \IDinornis giganteus\i, back to life. Shirota will be using DNA taken from a dead moa's \Jfemur\j, introducing the genes into chicken embryos. He hopes to find some of the homeobox genes that should be present in the DNA, and to use these to generate a moa-like chicken.
In \JAthens\j, archaeologists report that they have discovered the remains of the \JLyceum\j, the school opened by Aristotle.
NASA saw the top stories of 1996 as: "Did Mars Once Harbor Life?", a story we have already covered, "Shannon Lucid Sets U. S. Space Flight Record", referring to her 181 days on board the Russian Mir craft, "A New Wave of Martian Exploration Begins", about the successful launches of the Mars Pathfinder and Mars Global Surveyor missions, "\JGalileo\j Unveils Jupiter and its Moons", (described above), "\JHubble Space Telescope\j Continues to Amaze Astronomers", referring to the discovery that old stars go egg-shaped, as well as finding images of galaxies under construction and stars in their death throes, "Next Generation Launch Vehicle Chosen for Development", announcing the X-33 test vehicle, a one-half scale version of the planned Reusable Launch Vehicle. This model is to have had fifteen flights by the end of December 1999. Called "VentureStar," the vehicle will launch vertically like a rocket and land horizontally like an aeroplane.
Wheat was in the news as January ended. An article in \IBioScience\i by David Pimentel showed the \Jwater\j needs to grow a \Jkilogram\j of a number of crops. You need 500 litres (500 kg), to grow 1 kg of potatoes, and wheat and \Jalfalfa\j both require 900 litres, rice demands 1910 litres, soya beans 2000 litres, a single \Jkilogram\j of chicken uses up 3500 litres, but the same amount of beef required 100 000 litres of \Jwater\j, mainly to grow the crops to feed the \Jcattle\j. In the fairly dry environment of the Mir space station, NASA \Jastronaut\j John Blaha harvested some space wheat, but there was no seed. Maybe they didn't give it enough \Jwater\j? Meanwhile, the US Air Force has been looking for a gentle way of stripping paint from Stealth bombers when they need a new coat of paint. The answer, they say, is to use pure starch, extracted from wheat.
Russia's main component in the International Space Station, the service module, is now some eight months behind schedule. Without this module, the whole space station will be unable to function.
And even more serious, the Trojan swarm, a large population of \Jasteroids\j, possibly bigger than the asteroid belt orbits the Sun out near the orbit of Jupiter. A new study of the swarm's orbits suggests that the orbits are not indefinitely stable and that more than 200 'escaped' Trojans over 1 km in diameter are already roaming the \JSolar System\j, a few of them on Earth-crossing orbits. Reminding us of the Cretaceous-Tertiary impactor, we have to wonder if any of these are coming our way. Another January report suggests that the asteroid belt we see today is a mere remnant of what was once out there, so perhaps the worst is over.
#
"Green Cells For a Greener Australia?",25,0,0,0
(Jan '97)
Australia is one of the worst offenders when it comes to carbon dioxide emissions. It has a first world demand for \Jenergy\j, no nuclear power, limited hydroelectric power, and places little reliance on oil as a fuel for its electricity generation, using the country's abundant \Jcoal\j supplies instead. Successive Australian federal governments have so far done very little beyond the level of \Jrhetoric\j about the problem.
Coal produces more CO\D2\d per joule when it is burnt than \Jhydrocarbons\j such as oil and \Jnatural gas\j. These fuels produce some of their \Jenergy\j from the \Joxidation\j of the \Jhydrogen\j in the \Jhydrocarbons\j, yielding harmless \Jwater\j vapour, while \Jcoal\j yields almost nothing but CO\D2\d. So as countries around the world start doing their bit to reduce greenhouse gases, \JAustralia\j's poor record and lack of action is looked at more and more harshly.
Alternative \Jenergy\j sources have long been used in small amounts in \JAustralia\j, but the areas of high tidal range are far from the main cities, and so are the most windy areas. Rainfall is generally too low for any increase in hydroelectric power, and \JAustralia\j's old mountains are too low in any case to provide the sorts of levels needed. And while \JAustralia\j has abundant uranium deposits, there is a general public reaction against nuclear power. That leaves just one major resource that \JAustralia\j has in abundance: sunlight.
The problem has been a lack of efficient solar cells, but now that task is coming under control. Situated partly in the tropics, any Australian developments are likely also to be of immediate use across much of the third world, so some of the recent breakthroughs from the international team at the University of \JNew South Wales\j look very exciting.
The need is for a large, efficient, cheap, cell which has a low maintenance demand. It has to use cheap materials in small amounts, it needs to be made in large units so connection costs are reduced, and it has to be efficient so that a good \Jenergy\j yield is delivered.
The University of \JNew South Wales\j in Sydney has drawn together interested researchers from all around the world, working on a number of promising directions at the same time, under the leadership of Professor Martin Green, who developed the first "Green cells" some years ago. The workers are trying to improve the performance of photovoltaic cells to get them closer to the limits of performance, put thin films of silicon on cheap materials while maintaining performance, and also develop the hardware that is needed to use the cells in practical environments.
#
"Photovoltaic Cell--What is it?",26,0,0,0
(Jan '97)
This can be the subject of some mind-bending \Jmathematics\j, or it can be kept simple, and slightly less precise. This is the fuzzy version for beginners, and is really only an approximation, even for silicon cells. A photovoltaic cell (as it is described here) is a semiconductor device, made of silicon which has been carefully purified, and then equally carefully unpurified with selected impurities. Some of the silicon is "doped" with atoms which leave "holes" for electrons to fit into ("p-type"), some is doped with atoms which supply extra electrons ("n-type"). Neither form of silicon is electrically charged, but the additional electrons and "holes" are essential to the operation of a semiconductor like this.
The two types of silicon are combined to make a diode, a device which typically passes electrical current in one direction only. Electrons in the flat thin diode that we call a photovoltaic cell are "excited", or given \Jenergy\j by light shining on the cell, so that they "jump" to a higher \Jenergy\j level, and can then move across the gap or junction between the two types of silicon. The UNSW researchers have also tried adding a second doped surface below, producing a "bifacial design" which delivers even more power-it has, they say, limited but novel applications.
There are other materials which could be used as well, but these seem all to have been eliminated, either as laboratory curiosities, not able to compete, either on grounds of efficiency or cost, or on account of the dangerous nature of the materials used in the cells. Some, like cadmium telluride, show some promise, but cadmium and tellurium are not nice substances to work with, so while there are large-scale manufacturing efforts on cadmium telluride and copper indium selenide thin film cells, the future looks like being largely a silicon one.
\BImproving performance\b
The obvious first step to getting better results is to increase the surface area of the cell. You can do this either by increasing the size of the cell, or by reducing the shadows that fall across the surface of the cell.
One of the nastier problems about these cells is that you need metal conductors to gather up the electrons and carry them away, and metals do not pass light through. Not, that is, if the metal is thick enough to carry any significant current, and that means the cells begin to defeat their own purpose. The UNSW team have got around this by cutting grooves into the surface of the cells with a \Jlaser\j, and laying the metal strip on its edge. This simple step has raised efficiency (the amount of light converted to electricity) from 15% to 20%.
Already a BP Solar commercial plant in \JSpain\j is producing cells equivalent to 2 megawatts a year. These are commercial cells produced in commercial quantities, but even these have efficiencies of up to 17.5%. Other licensees include Solarex in the USA, Samsung in Korea, Central Electronics Laboratories in India and Deutsche Aerospace in \JGermany\j.
\BCheaper materials\b
The biggest cost in making silicon cells is making the very pure silicon. But while a solar cell is typically around 200-500 micrometres thick, more than 90% of the output comes from the top 15-20 micrometres. So it makes good sense to try laying down a thin film of the expensive material on some cheaper surface, while (hopefully) maintaining the efficiency. This last requirement has been made just a little bit harder, by trying at the same time to reduce the degree of purity in the silicon, thus making the material cheaper still.
Silicon comes in a number of forms. Monocrystalline silicon is expensive, and has to be sawn, but it offers a very high efficiency. Polycrystalline silicon also has to be sawn, but it is cheaper, being cut from cast ingots of silicon. The cells made from this material are slightly less efficient, and they still need to be thick. Amorphous silicon is grown as a thin film, but it lacks the crystalline structure, so the holes and electrons are more likely to recombine before they can be usefully collected, thus wasting the \Jenergy\j used to separate them and reducing the overall efficiency of the cell.
The present direction of the UNSW team has been to go for a multilayer structure, laid down on the back of a sheet of glass. Their aim is to produce 15% efficient factory-produced solar cells at a cost of US$2 per peak watt within five years. But who knows, they may go even better: in 1995, the team showed what they were made of when a cell made by Dr. Aihua Wang and her husband, Dr. Jianhua Zhao, postdoctoral researchers working with the UNSW Centre for Photovoltaic Devices and Systems, turned in a 21.5% efficiency in independent tests at Sandia National Laboratories in New Mexico.
This performance eclipsed the previous best, also by Australian workers, of 17%. But while that was only a 4 cm\U2\u cell, in 1996, the team demonstrated another record-breaker, a 23.7% efficient large area cell (22 cm\U2\u). They went on to produce a large module which turned in a 22.7% conversion efficiency, proving that they can scale the success up effectively.
The roof of a house is a wasted space. Every dwelling has one, and few of them make any use of those spare acres and hectares of real estate. The roof keeps the rain out, but it does not actually produce anything. The UNSW team have their eye on all those roof spaces, working on tiles that collect light and deliver it to a smaller cell, mounted on the tile. Called the static concentrator tile, this will be a highly efficient contributor to future Australian power needs, since the typical Australian roof is sloped at the right direction to gain most from power of this sort.
This sort of power may be all very well in the home, but it won't do very much about running your toaster or TV. The power that comes out of these cells is direct current, the sort of stuff we get from car batteries, not the alternating current we get from the mains, and the voltage is all wrong as well. But that need not be a problem: all we need is an inverter, to convert the DC low voltage to AC mains voltage, to synchronise it with your mains supply, and trickle it into your system.
But if you have gone that far, why not go the whole hog? Why not pass the spare power on, so others can use it when you can't? That means "distributed utility connected photovoltaic systems", which use the grid as a storage device for your spare power. You make as much as you can, use what you need, and deliver the rest of the power to, or withdraw power from, the grid.
So while you are out at work, your roof at home can be merrily converting the sunlight on the roof into power needed to meet the peak demands of industry and commerce (including your work-place), all without any carbon cost, any contribution to the \Jgreenhouse effect\j, once the units are manufactured.
There are a few drawbacks, of course. The equipment is expensive, so users will either need to be subsidised in some way for adding the fittings, or paid a higher rate for the power they generate. One utility in \JGermany\j has offered just under $2 per \Jkilowatt\j-hour. This allows for these systems to have a reasonable financial pay back period. Net metering, where you pay (or are paid) for the balance of power used or delivered may be fairer, but they lead to prolonged payback periods.
There is also a risk for power workers: if the power is isolated in a section of line, but all the houses in the area are pumping electricity back into the lines, somebody could be hurt or killed. So there will need to be a fail-safe form of monitoring to ensure that all these miniature power stations are turned off when the grid goes down.
One thing is certain: around the world, the demand is there. In 1990, \JGermany\j started its "Thousand Rooftop Program" which saw between 1 and 4 kW of photovoltaic modules installed on more than two thousand residences by 1995, and other countries have also followed suit with residential rooftop systems.
\BOne for the road\b
One of the most promising prospects for the future is the solar car. When the Swiss \ISpirit of Biel II\i won the 1990 World Solar Challenge across \JAustralia\j, it was on Australian technology, using cells made by Telefunken under licence from the UNSW group, and nine of the first ten cars in the 1993 US Sunrayce used cells based on the same UNSW technology.
The large cells which were built in mid-1996 starred again when improved technology was used in producing large batches of cells used by the first and third-place getters in the 1996 World Solar Challenge. For the Sydney team and their licensees, this is now turning into a mature technology, rather than merely being an experimental science.
And just in time, too. Californian legislation required that 2% of all cars sold must, by 1998, have zero emission, up to 5% in 2001 and 10% by the year 2003. While the first two dates have now been dropped, the third remains in force, the effect of the legislation on electric car development has been huge. Other states are sure to follow, and general Motors new EV\D1\d has a regulated top speed of 130 km/h, can accelerate to 100 km in 9 seconds and has a range of over 100 km between recharges. That should do for a run to and from the workplace-especially if you have a few photovoltaic cells from the University of \JNew South Wales\j on your roof.
Just think of the social changes-undercover parking may even become a thing of the past!
#
"Car Navigation System Update",28,0,0,0
(Jan '97)
In the 1964 James Bond movie, "Goldfinger", we were introduced to the idea of a mapping system in a car. The fictional spy's device had a circular screen, with the user's position shown in the centre, superimposed on a map, while the evil-doer's car was represented by a "blip".
While we may not yet be able to track the Goldfingers of this world from Britain to \JSwitzerland\j, as James Bond did, a third of a century ago, we are getting closer to a worthwhile in-car navigational system which can tell us where we are, and where to go to reach a selected destination. The easy part, getting people from one town to another along the open road, has been in place for some time. The real problem, providing guidance to an exact destination in a large city, is still being worked on, but the answers are falling into place fast.
General Motors began to offer a route guidance system option called Guidestar in its Oldsmobile line of cars in 1994. At first the option was to be limited to cars sold in the \JSan Francisco\j Bay area, but within a few months, it spread to include Miami, Orlando, Washington and \JBoston\j. Guidestar, being an American system, offers scales from 220 yards across the screen to four miles - about 200 metres up to 6.5 km.
Soon after the GM announcement, the Avis Corporation said that it would be offering the GM Guidestar on some of the Oldsmobiles it rents. Hertz Corporation followed suit with an announcement that it would offer a route guidance system called Neverlost in selected cars and in selected geographic markets. The in-vehicle navigation system had been launched, in a manner of speaking.
Like every early technology, you get what you pay for, but sometimes you pay for more than you get. The American Automobile Association's automated version of its Triptik routing product, like the Royal Dutch Touring Association's Routewijzer, can be classified as place-to-place, or inter-town routing. They start at a well-known location in or around the city of origin, provide directions on the main roads to the destination city, and then leave the traveller at a landmark in the destination city. Before and after that, you are on your own.
Now the race is on to provide a system that will allow you to find your way to the first landmark, and then to navigate within the destination city. To do this, navigational systems will need to be able to sense and/or display all of these:
ò where the car is right now, and where it is pointing;
ò what traffic conditions lie ahead (one-way streets, turning restrictions etc);
ò what turn should be taken next, and what landmarks to look for;
ò what adjustments to make if the driver takes a different turning.
\BWhere the car is right now, and where it is pointing\b
Position can most easily be measured from the \Jsatellite\j-based Global Positioning System (GPS), a system which has long been available to the US military, \Jaircraft\j and \Jwater\j craft, but which is only just becoming available to the driver of an ordinary civilian motor vehicle. GPS relies on getting signals from several of the 24 satellites in the GPS chain, orbiting the \Jearth\j, by measuring how long it takes for signals at 1575 MHz from the satellites to reach the receiver.
In the past, GPS has been limited by the deliberate insertion of random figures known only to the US military, so that only the military had half-metre accuracy (from their own encrypted signal), while other users had to be satisfied with hundred-metre accuracy, which was good enough for most purposes, but not good enough for navigation in a city. In March 1996, all of that changed when Vice-President Al Gore and US Transportation Secretary Federico Pe±a ushered in "a new era of travel, time-saving and communication" when they signed a Presidential Decision Directive allowing the civilian and commercial use of GPS.
"Most people don't know what GPS is," Secretary Pe±a said in a press release. "Five years from now, Americans won't know how we ever lived without it. GPS will change the way we live in the way cellular phones, fax machines and the Internet have impacted daily life."
There are still limitations to the civilian use of GPS: in a city, the satellites needed for accurate navigation may not be in sight. That is why the car needs to sense where it is going, and how far it has gone since the last accurate "fix". There are also problems with interference, but plans are in place to add a second set of civilian signals, in early 1997, at either 1309 MHz or 1207 MHz, should increase the reliability of GPS.
The databases required for routing the right direction down a one-way street, and recommending legal or physically possible turns at intersections, are gradually spreading across the continent.
\BTraffic conditions ahead: the need for a database\b
The roads \Jdatabase\j is like virtual reality without the headsets. Every detail that a driver may need has to be stored in there. Intersections have to be distinguished from overpasses, traffic restrictions, turn restrictions, speed limits, direction of travel, all have to be there. If you may need it to plan the best route, the \Jdatabase\j needs to know it.
This means buying or obtaining maps, and laying down layer after layer of information, linking and cross-checking, to make sure that the user does not find himself looking at the mapper's nightmare: "the business end of a busy freeway off-ramp". But even there, the work has not finished: to be competitive, the \Jdatabase\j will need details on petrol stations, cash machines, hotels, tourist attractions, and more. In the future, the mapmakers may earn more from "Yellow Pages"-style listings than they do from selling the actual maps, with every business needing to be locatable by their customers as they drive by, guided by their all-knowing navigation systems.
Distribution will be a problem. A national \Jdatabase\j is not feasible because it is too large. It won't fit on a \JCD\j or any other media that are in the pipeline. In any case, the \Jdatabase\j is regional, and people will only want the areas they are planning to travel in, when they are going there, for the databases will have an accuracy shelf-life of only one or two years before they need updating. The car rental companies, Hertz and Avis, are using hard disks instead of removable media, but this is a special case.
Perhaps the answer will be to market regional CDs and something like to the strip maps put together by \Jautomobile\j associations for long-distance travel, covering a strip which is perhaps 100 km wide, running between two localities, perhaps specified by inputting a set of postcodes or zip codes to specify the strip. This will become easier to market as systems become more widely used and data formats become standardised and interchangeable.
\BDealing with variations\b
Any system mounted on a car, or any car system relying on a remote system, will need to use "dead reckoning", deductive reckoning of the position, based on the last accurate positional fix, plus movements since that time, assisted by any turns - if the system thinks it is five metres short of a left turn, but the driver has turned, it will need to accept that, in all probability, it is now entering the left turn in question.
Doing this requires, as well as a GPS system, a gyro compass, wheel sensors for map matching, an on-board computer powerful enough to perform complex route calculation and linking these components to a mass storage device and a display. The main problem is that cities tend to block access to satellites, hence the need to build on logically from the last accurate fix.
#
"Navigation Solutions for the Car",29,0,0,0
(Jan '97)
There is more than one way of skinning the navigational cat, and all of these solutions are being explored, or have been explored in the past:
\BDedicated Terminals\b
In the mid-80s, NavTech introduced a pay-per-use terminal called DriverGuide in the \JSan Francisco\j Bay area. Terminals were installed in a few hotels and made available free to hotel guests, as a sort of electronic concierge. The system was made up of a PC and printer built into a specially designed kiosk. Users could obtain address-to-address routes in the form of a narrative printout with turn-by-turn driving instructions.
The system was discontinued after a few hundred units had been installed. The systems, especially the printers, were difficult and costly to maintain and support, and the printed format required a passenger to read the instructions, or a risky drive. A later version, also from NavTech, had a touch screen, but this also failed to prove successful.
\BTravel Reservation Systems\b
Some airline booking systems will automatically generate printed information for travellers, outlining routes to be followed in getting to meeting places, but once again, this is usually in the form of narrative instructions, rather than as a map, so the same drawbacks are still apparent as with the dedicated terminals.
\BVoice Operators\b
This American scheme began as a way of promoting cellular phone services, and involves an operator using a computerised system to relay narrative advice on directions, or where convenient, faxing a hard copy to the caller. This has not been a raging success, by all accounts.
\BIn-vehicle Systems\b
These systems can be in the best James Bond tradition, with a map that moves, keeping the car's location in the centre of the screen, with either north being at the top of the screen, or the car's current direction being at the top of the screen. Other systems use voice instructions alone, or voice instructions plus a manoeuvre diagram for turns, entries, exits etc.
The digital map systems obviously require a large amount of storage for the maps, which means the system really needs to have a CDROM drive, and appropriate CD-ROMs for the area being travelled. The voice systems need a high level of accuracy, especially in inner city streets, where the "next left" may only be 15 or 20 metres from the previous left turn. That being said, the in-vehicle systems are the ones showing the greatest promise, and the greatest levels of development activity.
\BIn-hand Systems\b
These are dedicated computers, rather like a "Personal Digital Assistant", but with only a single function. These systems are restricted by the storage demands of maps. An area 10 kilometres wide and 6 kilometres long, a typical central slab of a moderately large modern city, will take 10 megabytes of storage, and the \Jdatabase\j of street names, numbers, directions for traffic and legal turns can easily take close to the same amount of storage. It might be a good idea to look very carefully before committing to an investment in this technology.
\BIn-vehicle systems with Pizazz\b
The industry is very much in the shake-out phase, and many of the fancy systems now being planned may find themselves overtaken by products such as GPSS, which is being widely distributed around the PC community. This is a Windows application intended for use within a sound-capable Notebook PC connected to a GPS \Jsatellite\j receiver carried within a car, or within a PC-compatible car computer system. Developed in Britain, it is now becoming available in other parts of the world.
It displays the car's position on a map while a voice speaks the position, saying something like: "We are 25 miles west of London and 1.5 miles south east of Ascot"; and gives guidance: "destination is 300 yards ahead at your 12 o'clock". The direction is given as if to an air pilot, so "6 o'clock" is directly behind the car.
GPSS can be used with mouse and keyboard, but can also work with voice recognition, letting the car driver keep watching the road. The system holds information about eating places, petrol stations and the like, so when the driver says: "Eating Place?", it should answer with, "OK, the nearest eating place is Little Chef, on the A329, 1 mile behind us, at your 7 o'clock". While there are still problems with voice recognition systems which translate an American saying "Recognise speech" as "Wreck a nice beach", the software is getting better all the time.
This is one area that may be worth watching and even investing in. It will certainly bear watching.
\BMessage systems\b
In a number of countries, low power transmitters can advise drivers of traffic conditions ahead, with enough time to allow drivers to plan and select an alternative route. Systems such as this may be extended, but they could also be extended with onboard or roadside equipment. Toyota is experimenting with CCD cameras to detect lanes on a road automatically.
\BMaking your own\b
Fugawi is a Japanese software system which allows users to scan in any map or add any bitmapped map, add a scale, and insert it into a GPS \Jdatabase\j by identifying three key points with a grid location based on any of a hundred standard systems. The systems corrects for skewing or stretching, and works with a variety of projections.
\BThe future\b
There is more to come: an experimental system is being tested in \JAustralia\j which will allow the navigation program to record times on alternative routes, and learn about the slow roads. While this might be catastrophic if all cars reacted in the same way, \Jday\j by \Jday\j, switching routes in unison, this is unlikely to happen in practice.
Closer to the present looks as though 1997 will be the year in which the promises of 1994 to 1996 start to bear fruit, as the databases are completed, and begin to interlock and overlap. With a gigabyte RAM chip on the drawing boards, with digital video disc (DVD) just around the corner, and with the software getting better all the time, self-contained navigation systems should really take off in 1998 - unless the new Nokia telephones with "built-in everything" show that they can access more brute processing force in a distant centre, and provide cheaper guidance from a distance.
As in every other new technology, you pay your money and take your chances. One thing is certain: paper maps will continue, if only because travellers can take them out of the car without losing any information: for now, the paperless car is about as likely as the paperless office.
NavTech did not have a \Jdatabase\j up and functional for \JAtlanta\j, but by the time of the Sydney Olympics in the year 2000, we can reasonably expect overseas visitors to arrive in \JAustralia\j, climb into their cars and navigate effortlessly around Sydney's maze of harbour crossings. And Paris, \JRome\j or London in the peak hour will be a breeze.
Sample map, taken from the GPSS advertising, showing their system in operation. This is one they give away free, and they say that while it may be a large-scale map, voice guidance has a resolution that will allow you to be guided to within 100 yards of your destination.
#
"Hubble Gets a Facelift",30,0,0,0
(Feb '97)
The second in a planned series of four servicing missions for the \JHubble Space Telescope\j took off on February 11. The main purpose was to install the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) and the Space Telescope Imaging Spectrograph (STIS), both of which were successfully placed.
The only real concern arose when one of the arrays of solar cells began to flap about, apparently as a result of air being vented from the air lock as shuttle crew moved out into space on one of their EVAs. In addition, one of the tape recorders was replaced with a state-of-the-art Solid State Recorder (SSR) and a gyro Rate Sensing Unit (RSU) was replaced with a Hemispherical Resonator Gyro (HRG) unit.
The Shuttle Discovery came in for a night landing at the Kennedy Space Centre in pre-dawn darkness on February 21, completing a 6.6 million \Jkilometre\j (4.1 million mile) mission of 150 orbits. It was the ninth night landing in Shuttle program's history. The crew of seven were able to celebrate a highly successful refurbishment of the \JHubble Space Telescope\j, which will be able to continue its fifteen-year mission. In five space walks, the crew replaced two scientific instruments, and also repaired the tattered thermal \Jinsulation\j of the observatory. As a parting gift, the shuttle boosted Hubble into a higher orbit.
This service flight was the second, following the service flight of December 1993, and further missions are planned in mid-1999 and 2002. These past and future servicing missions were always planned, and Hubble has grapple points, as well as 76 handholds to make servicing easier. The two instruments taken out, the Goddard High Resolution Spectrometer and the Faint Object Spectrograph, have been replaced by the Space \JTelescope\j Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS).
STIS is able to view two-dimensional images of spectra in the ultraviolet, visible, and near infrared wavelengths. It gathers 30 times more spectral data and 500 times more spatial data than existing spectrographs on Hubble, which only look at one place at a time.
Because it covers an area, rather than a point, STIS can supply information about the relative movements of stars in a galaxy, which will yield better information about supermassive black holes. NASA suffered a little from public misunderstanding, as the Goddard Spectrometer failed just a few days before the mission, and they have been at pains to point out that the replacement was just part of the standard schedule.
NICMOS is fitted with corrective \Joptics\j to compensate for the spherical aberration in the HST's primary mirror. NICMOS will give us a clear view of the universe at ear-infrared wavelengths between 0.8 and 2.5 micrometres, wavelengths beyond the power of our eyes to see. Because distant objects in the universe are red-shifted, we will be able to see further than we have been able to do with the other Hubble instruments, with sensitivity to light at optical and ultraviolet wavelengths.
#
"A New Radio Telescope in Space",31,0,0,0
(Feb '97)
This month saw the launch of a new Japanese \Jsatellite\j, a radio \Jtelescope\j created by the Institute of Space and Astronautical Science. The \Jsatellite\j is in an elliptical \Jorbit\j, varying between 1,000 and 20,000 kilometres (620 to 12,400 miles) from the \Jearth\j. This \Jorbit\j provides a range of distances between the \Jsatellite\j and ground-based telescopes, which is important for obtaining a high-quality image of the radio source being observed. It takes about six hours for the \Jsatellite\j to \Jorbit\j the \Jearth\j, and was successfully set into \Jorbit\j after its launch on February 12.
The \Jsatellite\j has unfolded into an 8-metre (26-foot) diameter orbiting radio \Jtelescope\j which will observe celestial radio sources together with a number of the world's ground-based radio telescopes. The \Jsatellite\j was launched from ISAS's Kagoshima Space Centre, the first launch with ISAS's new M-5 series rocket.
The principle is a simple one: readings taken at different points around the \Jorbit\j are added together, and the end result is the sort of image you would have if you had a dish the size of the \Jsatellite\j's \Jorbit\j, once the results are combined with the readings from other radio telescopes, all over the face of the globe. Observations will be able to be made at 1.6 GHz (18 cm), 5 GHz (6 cm) and 22 GHz (1.3 cm).
Following its successful launch, the \Jsatellite\j was renamed HALCA, an \Jacronym\j for 'Highly Advanced Laboratory for Communications and Astronomy'. The alternative \Jtransliteration\j from the Japanese is "Haruka", meaning far-away.
A Russian \Jtelescope\j will be added to the array as well: at last report, it was still scheduled for launch in 1998. The primary targets of the completed system are expected to be active galactic nuclei; \Jwater\j masers, OH masers, radio stars, and pulsars.
#
"Sheep Cloning a Success",32,0,0,0
(Feb '97)
February brought us news of the world's first cloned sheep. Workers at the Roslin Institute in Edinburgh have succeeded in a task which, up until now, has only worked with mice. The implication appears to be that what can be done with sheep can probably be done with humans, opening up a whole range of "Brave New World" scenarios, and jokes about Elvis have been resurrected as well-unlike Mr Presley, so far.
Credit is shared between the Roslin Institute, part of Britain's Biotechnology and Biological Sciences Research Council, and PPL Therapeutics, an Edinburgh biotechnology company, whose shares rose in value after the announcement.
Dr Ian Wilmut announced on February 22 that he had taken the DNA from a sheep's \Jovum\j, replaced it with the DNA from an adult sheep, and grew it into a living lamb. The DNA was taken from the udder of the "donor" sheep, but the major breakthrough was in getting the DNA to become inactive, or quiescent, to use the geneticists' term. He then took an \Jovum\j from another sheep, and removed all of the DNA from it.
The next step was to fuse the \Jovum\j with an adult udder cell, after which the udder cell DNA took over the \Jovum\j, and controlled its growth and division. Wilmut then implanted the embryo in yet a third sheep, who gave birth to a lamb which is genetically identical to the original DNA donor. Dolly was born in July last year, and during the last week of February, was responsible for more headlines bearing the phrases "Hello Dolly" and "Send in the Clones", than \JHollywood\j and Broadway ever inspired.
The next few months should see a flurry of bio-ethicists straining to make themselves heard about what the implications of this are, but the guidelines are already in place to deal with issues which surround human clones, so problems are unlikely, at least in the short term. In the longer term, the costs of breeding a master race are likely to be so large that no "secret program" will be possible, but a number of \Jtelevision\j script writers were probably reading the scientific press as February ended.
\BScientific background\b
No less than three sheep were produced by much the same \Jcloning\j method, but only Dolly was able to command serious scientific attention, as the other two sheep had been developed from cells taken respectively from a fetus and from an embryo. Given the existence of Dolly, the other sheep were of limited interest.
The genes in a cell become committed at an early stage of development, and while you can take a nucleus from one egg and put it in another egg, with some hope of achieving a result, the standard view has been that you could not take an adult cell and expect the genes to develop in any sort of normal way to grow an individual. When a cell has differentiated, specialised to form some kind of tissue, that should be enough to block it ever growing to a whole individual.
Against this, single plant cells can be taken and cultured to produce a whole plant, but somehow, plants all seemed to be a whole lot less complicated. Even when Wilmut's group succeeded in establishing clones from cell lines taken from early embryos (blastocysts), the standard barriers to successful \Jcloning\j seemed still to be in place. Mouse embryos could be cloned if you took nuclei from the eight-cell stage, but no later, because the genetic material had been switched to a pathway of development, and could not be switched back.
Another problem was getting the cell division cycles of the donor cell and the host cell lined up-remember that a key feature is putting the donor nucleus into a cell where the surroundings are egg-like-so that later cell divisions do not produce cells with non-standard numbers of chromosomes. Wilmut's team managed to hold the donor cells in an arrested division state called the diploid G0 phase of the cell cycle by serum starvation.
The effect of this was to get a better synchronisation between the host cell and the new nucleus, but Wilmut's group may also have been fortunate in another respect-the sheep embryo does not begin committing cells (called \Itranscription of the genome\i) until the 8-16 cell stage, against the 2 cell stage in mice, so there is more time for synchronisation to develop.
If this factor is important, then it casts doubt over whether or not other \Jmammal\j species can be cloned in the same way, as the start of transcription of the \Jgenome\j varies between species. In the first few days of March, a monkey \Jcloning\j breakthrough was reported which may or may not prove significant in the longer run.
The best analysis suggests that the \Jcloning\j of human beings by this method would be possible in somewhere from one to ten years from now. The first calls for banning actually went out before the story broke in \INature\i, with an email from an unnamed "Harvard academic" who urged that Nature not publish details of the procedures until more thought had been given to questions of bio-ethics. Soon after the publication, President Clinton urged a moratorium on all such experiments. In Washington, Jeremy Rifkin demanded that the attempt to clone humans be placed on a par with rape, child abuse and murder.
On the other hand, Axel Kahn, a French geneticist (also in the news this month over transgenic corn) has suggested that side-issue of the technique might help a woman who had a serious mitochondrial disease to have a healthy child by inserting a nucleus into a donor cell. While this is not \Jcloning\j, it may still be more acceptable than some of the other scenarios which are floating around.
#
"Lead Linked To Bad Teeth",33,0,0,0
(Feb '97)
Lead \Jpollution\j has long been linked to lower IQs in children. Now research by Francisco Gil and colleagues at the University of \JGranada\j in \JSpain\j suggests that lead \Jpollution\j is also linked to bad teeth. The study, based on the analysis of children's "milk teeth" shows that teeth with more lead have more cavities. Following on, they found that children with ten or more cavities and blood lead levels three times as high as children with no decay.
#
"Transgenic Corn in France",34,0,0,0
(Feb '97)
Axel Kahn, a leading French geneticist (see also the Dolly story above), has resigned as president of \JFrance\j's Biomolecular Engineering Commission, which regulates the way in which genetically altered organisms are used, in response to the government's decision to ban the growth of transgenic corn in \JFrance\j. This was an about-turn by the government, which had, just a week earlier, approved the transgenic corn for consumption by animals and humans, and just two months after the European Commission gave the approved the corn's sale in Europe, largely at the insistence of \JFrance\j.
A number of transgenic corns exist: the banned hybrid is resistant to the European corn borer, and was being marketed by Novartis. Another company, Mycogen, has an independent application in to sell their own transgenic borer-resistant corn, and both companies expect to sell increased quantities of their new hybrid corns in the US this year, with several other companies also introducing other corn borer-resistant varieties.
#
"Keeping the Worms Down",35,0,0,0
(Feb '97)
Nematodes can be major pests of plant crops, and researchers have had little success in breeding plants that are resistant. Now a gene for \Jnematode\j resistance has been found. Curiously, it bears some resemblance to previously discovered resistance genes for \Jbacteria\j and other pathogens. The next step: to see if the gene can be spliced into a variety of crop plants. The step after: to get the plants approved for sale to humans.
#
"Plants Can Shout For Help?",36,0,0,0
(Feb '97)
Plants in many groups are able to make oil of wintergreen-what the chemists call methyl salicylate. Evidence is mounting that this is released by diseased plants, and triggers other nearby plants to step up their defences. The latest evidence comes from studies on \Jtobacco\j plants which have been deliberately infected with \Jtobacco\j mosaic virus.
#
"Cancer Gene--How It Gets Nasty",37,0,0,0
(Feb '97)
A gene called src was the first such gene to be discovered. Normally, it lives harmlessly in normal cells, but it can suddenly become active if affected by a virus or by mutations. New evidence, reported this month, brings researchers close to identifying the "switch": that turns this gene into its undesirable form.
#
"Birds, Dinosaurs, and the Big Asteroid",38,0,0,0
(Feb '97)
Anybody who has seen \IJurassic Park\i will know that to some biologists, the dinosaurs are still with us, only now we call them birds. But if the birds are just fluffy dinosaurs, how did they get on when the Cretaceous turned into the Tertiary? Quite well, according to a study of the DNA in different bird groups, made public this month. It looks as though many bird lineages penguins, parrots, and chickens, arose before the \Jextinction\j events at the K-T boundary and flew, hopped and swam through it unscathed.
#
"Strong Spider Web",39,0,0,0
(Feb '97)
The black widow \Jspider\j of America (a close relative of the \JNew Zealand\j katipo and the Australian redback), \ILatrodectus mactans\i, produces the strongest silk of any \Jspider\j web yet tested. Anne Moore of Scripps College in Claremont \JCalifornia\j is the researcher.
#
"Spy Satellite Photos",40,0,0,0
(Feb '97)
Microsoft has arranged to publish very high resolution (to one metre) photos taken from Russian spy satellites during the 1990s. These are claimed to be the first Russian-satellite-origin pictures to appear on the \JInternet\j. The first ones up will show Los Angeles, Washington, D.C., \JSan Francisco\j, \JRome\j and London. They may be downloaded for a charge of $30 per square \Jkilometre\j, with the proceeds to be split between an American company which brokered the deal and the Russian space agency.
#
"Mobile Phones and Car Accidents",41,0,0,0
(Feb '97)
A recent University of Toronto research study shows that drivers who are distracted while talking on a cellular phone are four times more likely to be involved in a car accident. Insurance companies have no plans to raise insurance premiums, because overall accident rates have not increased. There was no real difference between the use of a receiver or hands-free model of phone, suggesting that the problem is one of mental, rather than physical preoccupation.
#
"Faster Modems on the Way",42,0,0,0
(Feb '97)
Originally planned for delivery in July 1997, then promised for the end of 1996, the new 56 kbps modems are coming Real Soon Now-or soon enough for the advertisers to be starting to promise them. Don't throw out that old modem: Hayes (http://www.hayes.com) are offering trade-in deals, US Robotics are offering a plug-in module to upgrade your modem, and several firms are now selling "upgradeable" 28.8 kbps modems. The new modems, by the way, are unlikely to deliver those speeds for a while yet, at least not in the US, where FCC rules will limit the power of transmissions, and so the speed. Since so many connections on the Web involve the US, this means almost everybody will be affected by a rule that dates from the past, when almost all \Jtelephone\j traffic was analogue.
Late update: US Robotics announced in late February that it had just shipped the first of its 56-kbps modems. Postponement before that resulted from the need to fix some bugs in the software. Motorola said they will introduce its equivalent products in a couple of months. The trap is that there will be no internationally agreed standard until 1998 for this speed of modem, so manufacturers are said to be trying to sell as many units as possible, in order to pre-empt the market, and establish a \Ide facto\i standard. Watch out for some very good offers. And some very cheap ones.
#
"Encryption",43,0,0,0
(Feb '97)
The number 56 was in the news in another way as well, when Digital Equipment Corporation, Cylink Corporation and Trusted Information Systems got the go ahead from the Commerce Department to export products using the 56-bit Data Encryption Standard \Jalgorithm\j. Before that, American companies were limited to exporting products with a key length of 40 bits or less, except for applications in the financial services sector. This is because the US government sees encryption software as munitions. But while the manufacturers are cheering, maybe somebody should tell them that researchers at the Weizmann Institute in Israel were able last November to crack this encryption easily, deciphering the secret key from a 56-bit Data Encryption Standard \Jalgorithm\j, using "differential fault analysis".
A web TV device, using the much more secure 128-bit encryption, planned by Phillips and Sony, looks as though it will not be able to be marketed for some time to come, again because it is regarded as a "munition".
#
"Morse Code Disappearing",44,0,0,0
(Feb '97)
During January, the French coast guard sent their last radio message in \JMorse code\j, while February saw several other nations, including Britain, announcing that they would be phasing out the use of Morse for long-distance signalling during 1997.
Royal Navy signallers will still learn Morse, so they can use Aldiss lamps to signal from ship to ship or ship to shore during times of radio silence, but the traditional "SOS" signal, three dots, three dashes, and three dots, is almost a thing of the past.
#
"Carbon on the Ocean Floor",45,0,0,0
(Feb '97)
Where would you expect to find most of the world's carbon reserves? As \Jcoal\j? No. As oil and gas? Again, no. The answer is that most of it lies on the sea floors of the world, in the form of a gas \Jhydrate\j, a solid made of \Jmethane\j and \Jwater\j which can only exist at high pressure and low \Jtemperature\j. Scientists looking at global warming effects will need to take this new discovery into account. The hydrates can be recognised by the way they reflect sound waves, and now samples have been retrieved in a pressurised vessel and analysed.
#
"Ancient Chewing Gum",46,0,0,0
(Feb '97)
Ancient chewing gum, some 6500 years old and found in Sweden has been analysed. It seems to have been made by heating birch bark inside a sealed container to make a chewy tar. Scientists speculate that children and teenagers may have been the main users, and that it was used for some medicinal purpose, perhaps to help get rid of milk teeth.
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"Black Hole Discovered in February",47,0,0,0
(Feb '97)
This time, at the centre of the galaxy M32. This galaxy has no quasars at its centre, which might indicate the presence of a black hole, but space-based spectral studies show stars travelling at speeds which indicate the presence of a large mass of around (3.4 ▒ 1.6) ╫ 10\U6\u solar masses, contained within a region only 0.3 parsec across. This is most likely to be a black hole, say scientists.
#
"A New Particle and a Fifth Force?",48,0,0,0
(Feb '97)
In late February, reports were circulating about the possible discovery of a new heavy particle, a "leptoquark", in \JHamburg\j. If it is confirmed, the particle's existence will imply the long-sought "fifth force", and may allow physicists to work towards a unified theory of the natural forces.
Two experiments, ZEUS and H1 have been running for some years, and it appears that the results have come from this work. (You can get beautifully illustrated information on H1 at http://dice2.desy.de:80/h1/www/general/public/detector.html in your choice of French, German or English, and on Zeus at http://www-zeus.desy.de/publications.html. The H1 site provides a wide range of information about the project, but at the end of February, still had no news about what, if anything, had been discovered.
#
"Obituaries for February",49,0,0,0
(Feb '97)
Melvin Calvin (1911-1997). Calvin was the chemist who elucidated the biochemistry of \Jphotosynthesis\j.
Paul Erd÷s (1913-1996). The \Jmathematics\j community paid tribute at a meeting in \JSan Diego\j, \JCalifornia\j in January to one of its legendary figures, who died last September. Erd÷s is considered the most prolific mathematician ever, yet he had no permanent home and no formal job after 1954-only a vast succession of collaborators and a gift for problems that opened productive new areas of research.
Erd÷s will probably be remembered mainly for the Erd÷s number, a whimsical number given to mathematicians. The Hungarian-born mathematician Paul Erd÷s is considered to hold the world record for the number of papers he has written in collaboration with other mathematicians. Erd÷s himself is accorded the Erd÷s number 0, while any person who has collaborated in the past with Erd÷s on a paper has an Erd÷s number of 1, while a mathematician who has collaborated with a collaborator is given an Erd÷s number of 2, and so on.
#
"Global Warming--Impact on Antarctica",50,0,0,0
(Mar '97)
Our major theme this month seems to be the \Jweather\j. Not the usual annual change in seasons, but something rather longer-term. In Mid-March, \ITime\i magazine ran a piece on the possible risk that the West Antarctic Ice Shelf might break up, causing sea levels across the world to rise. Puzzled as to how you would tell west \JAntarctica\j from east \JAntarctica\j, we began to investigate the science behind the story.
The difference between east and west \JAntarctica\j is most obvious when you stand on the meridian of Greenwich, somewhere in \JAntarctica\j. From where you are, west to the International date line, is the part known as lesser or western \JAntarctica\j, while east of you, all the way around on the other side, is greater or eastern \JAntarctica\j.
If you sit somewhere south of Tahiti on the globe, and look at \JAntarctica\j, you can see west \JAntarctica\j nearest you, with a tail running up towards \JSouth America\j, the Antarctic Peninsula, like a spinal cord leading out of the brain, an effect that is enhanced by the \Jcerebellum\j of east \JAntarctica\j, piled over the top. In our map (reference to the map on the CDROM), east \JAntarctica\j is on the right, and west \JAntarctica\j is on the left.
Now before we look at what is happening to the ice shelves and \Jsea ice\j of \JAntarctica\j, we need to look at what happens to glaciers when the \Jweather\j gets warmer, and that means we have to move a little north of \JAntarctica\j, to \JNew Zealand\j. Glaciers are very sensitive to slight shifts in the \Jtemperature\j, so what we see in \JNew Zealand\j will help us to understand what is happening further south.
When the \Jearth\j's average \Jtemperature\j rises, these global thermometers withdraw, pulling back into the mountains, and when it cools again, the glaciers descend into the valleys once more. The 127 glaciers of the Southern Alps of \JNew Zealand\j have been shrinking since the end of the Little \JIce Age\j, losing 25% of their area in the last century, and taking their fronts almost 100 metres back up the mountains, suggesting a warming of 0.6░C during that time.
This same warming has led to large pieces of the ice shelves around \JAntarctica\j breaking up. These ice shelves float on the sea, and surround the larger "grounded" masses of ice on and around the continent. In 1986, more than 11 000 square kilometres of the Larsen Ice Shelf and 11 500 square kilometres of the Filchner Ice Shelf broke off and floated out into the Weddell Sea, along with 1600 square kilometres of the Thwaites Iceberg Tongue.
This could be just a natural "calving", but the mass of ice released was equal to three or four years' accumulation of snow and ice across the whole of \JAntarctica\j. More than 1300 square kilometres of the Wordie Ice Shelf have broken away since 1966, and a 1993 Norwegian study revealed more icebergs than usual in southern waters. Then in February 1995, a 2600 square kilometre iceberg calved away from the Larsen Ice Shelf on the Antarctic Peninsula.
There has certainly been a warming in the area, and this would necessarily push the mean annual air \Jtemperature\j isotherms around \JAntarctica\j further south. As the ice shelves only seem to be stable past the -4░C mean annual isotherm, this could explain why the northern ice shelves are breaking up: they are certainly the most vulnerable. In the past fifty years, temperatures on the Peninsula have risen by some 2.5░C, but it is unclear whether this is a sign of global warming, or just a normal variation.
The famous greenhouse disaster scenario, of course, has all the polar caps melting, flooding the oceans and drowning the rich coastal fringes where most of the world's agriculture happens. Is this what we can see beginning? Not necessarily. The shelf ice that is breaking away was already floating on the sea, and even \JArchimedes\j could tell us that we don't have to worry about floating ice. It melts into the sea, and leaves no trace of a rise. We needn't worry about the ice shelves melting and drowning us in our sleep.
The other ice that is already in the sea, but sitting massively on the bottom of a deep marine basin is another matter. And so is the land ice tied up in ice sheets that are some 4.3 km (about two and a half miles) thick, but close to the sea. If those ice deposits get away, it will be like a very fat person climbing into the bath.
The problem is that there is a large weakness across and through the rock that lies beneath the West Antarctic Ice Sheet (WAIS). This is no mere gap, but a rift that could be as serious as the San Andreas Fault or the Rift Valley of eastern Africa. It is an area of regular volcanic activity and perhaps more. Some geologists suspect that there is a plate boundary there, and the recent discovery of a \Jvolcano\j beneath the ice makes them even more certain that their suspicions are correct.
The \Jvolcano\j is rather muffled by the layer of ice, but what would happen if there was a major eruption? Could enough steam and \Jwater\j be released to make the grounded ice unstable? The evidence that other scientists have been gathering from ice cores in \JGreenland\j and \JAntarctica\j are telling us that ice ages may begin and end very quickly. If the climate warms and ice sublimes or evaporates, the blocks will get lighter, they will begin to rise, and sea \Jwater\j can start to flood in beneath the ice, "greasing the skids" and speeding the flow of ice to the edge, increasing the instability. Is that what rings the changes, something as unpredictable as a volcanic eruption?
The east Antarctic ice sheets would produce a sea level rise of some sixty metres (200 feet) if they melted, but that seems a remote chance right now. The WAIS, on the other hand, would only produce a rise of six metres. But even six metres would be catastrophic for large parts of the world. Capital cities like London, protected from high tides only by tidal barrages in the Thames, much of the world's best agricultural land, river estuaries all over the world, and every \Jcoral\j \Jatoll\j, would all be threatened.
For now, the experts say that, while the WAIS is unstable, and probably contains 3.2 million cubic kilometres of ice, all resting in a deep marine basin, the ice is most likely to stay where it is, and the low-lying parts of the world remain safe.
So if the WAIS is not likely to be a problem, is the \Jsea ice\j shrinkage also something we can ignore? The qualified answer is yes, but only if we don't appreciate penguins. Some penguins need \Jsea ice\j so they can get access to the sea, both for the parents to feed, and for the young to launch themselves into the sea when they are ready to take on independence. As the \Jsea ice\j breaks up earlier in the southern summer, so the chances rise that the new juveniles will be trapped, with no easy jetty of ice to take them clear of the shallows and waves of the shore.
#
"Cloned Monkeys",51,0,0,0
(Mar '97)
Following on last month's sensation, the cloned sheep called Dolly, a cloned monkey in the first few days of March was almost an anticlimax. The technique used was similar, but instead of taking the donor DNA from a mature adult cell, it was taken from an early embryo.
Don Wolf of Portland's Oregon Health Sciences University, assisted by colleagues, used standard in vitro fertilisation procedures to produce the embryos, then removed the DNA from the recipient egg cells, and added DNA taken from embryos at the eight-cell stage. Three types of recipient cells were used: those which were newly fertilised, those which were past the best time for fertilisation, and cells which were "ripe" for fertilisation. Only the cells which were ripe for fertilisation were successful as recipient cells.
Cloning progress continues, with reports coming in during March of attempts to clone cows, in a process related to the method used at Roslin to clone Dolly, but with material taken from slaughtered cows. An Australian team has managed to produce 470 embryos from a single blastocyst, and hopes to end up with a method of \Jcattle\j production which is more efficient than the standard methods of artificial insemination.
Cloning regress also continues: the \Jcloning\j of Dolly seems to have provoked a different and rather curious form of \Jcloning\j around the world, as strange laws are thrust before the public. The Norwegian Parliament passed a law banning \Jcloning\j of humans and other "highly developed organisms." The law, would have blocked the \Jcloning\j of Dolly herself, and the race must now be on to see which band of enthusiasts can produce the most ridiculous legislation. The only Norwegian researcher who appears to be affected is Stig Omholt, who clones bee embryos!
In America, the enthusiastic bandwagon jumpers in Congress introduced bills to outlaw human \Jcloning\j, even as they were advised that the procedures for human \Jcloning\j were not going to happen overnight, and that the matter should be carefully considered first. Debate on the ethics and \Jbiology\j of \Jcloning\j has become a commonplace of the media during March, and is likely to continue during most of 1997. Information and rational discussion will hopefully follow, not too far behind.
\BAscent of the chimps?\b
Two Australian researchers offered a controversial suggestion in the \IJournal of Molecular Evolution\i, about the ancestors of chimpanzees and gorillas. Looking at a variety of genes in a number of primates, rats, mice and marsupials, they have recalibrated the "\Jfossil\j clock", and find that the ancestral chimpanzee and human stocks divided up less than 4 million years ago.
The problem is that this would mean that the chimps must have descended from \IAustralopithecus afarensis\i, who walked upright on the ground. Simon Easteal and Genevieve Herbert from the Australian National University have also suggested that \IAustralopithecus robustus\i (often called \IParanthropus robustus\i) is the ancestor of the modern gorillas, based on similar evidence. Neither suggestion has been received with joy by anthropologists, so we should not hold our breaths while waiting for universal agreement on this notion.
#
"Archaeological Findings in Germany",52,0,0,0
(Mar '97)
At the start of the month of March, news broke of an astonishing archaeological find in northern \JGermany\j, in a \Jcoal\j mine in Sch÷ningen, 100 kilometres east of Hannover. Wooden spears, bones and flint tools were uncovered from a \Jcoal\j mine. The spear shafts were spruce, about two metres long, no more than 5 cm in diameter, and with a balance similar to that of a modern javelin, showing that the spears were intended for throwing, and given the large number of horse bones, the nature of the targets seems to be fairly obvious.
The finds can be accurately dated to an interglacial period 400 000 years ago by correlating the surrounding sediments to well-known geological layers, in an area where the history is well-known and well-understood. The finds are exciting because it includes wood which normally does not last very long. The oldest previous wooden spear was just 125 000 years old, so this is a massive extension of the time in which clever humans were around in Europe.
In particular, the find casts doubt on the usual view of the early robust humans (these people were probably similar to the rugged human found at Boxgrove, since the spear throwers would have needed to be quite strong.
\BSiberia Findings\b
The following \Jday\j we learned that tools similar to those found in the Olduvai Gorge have been found in \JSiberia\j, and that thermoluminescence dating suggests a date of between 240 000 years and 366 000 years. Thermoluminescence dating is a sure way of exciting strong feelings among archaeologists, and so must be open to doubt, but it still seems that people have been sending themselves to \JSiberia\j for a long time.
#
"Seeing Yellow",53,0,0,0
(Mar '97)
Even at the end of the 20th century, we still do not have a clear understanding of how we really "see" colors. In particular, the way we see yellow seems to be important in determining whether yellow is perceived in the eyes, or in the brain, after separate signals from the eyes have been combined and processed in some way.
If you flash red on one eye and green on the other eye for a human, the subject "sees" yellow, suggesting that yellow is a brain perception, not an eye perception, because the nerve pathways from the eyes do not come together until the \Jcortex\j. Now it appears that the human visual system can also take a "yellow" stimulus and break it down into its red and green components.
If a flashed red line is superimposed on a moving green bar which is only visible for a short period of time, the flashed red line appears yellow. But if the flashed red line lasts for a longer period, it appears to follow after the moving green bar, but it appears red. The researcher responsible believes that this supports the idea that we "see" yellow in the visual \Jcortex\j, as proposed by Thomas Young, Hermann von Helmholtz, and James Clerk Maxwell. Only this model would explain why motion, which is perceived in the \Jcortex\j in primates, can interfere with the perception of yellow.
#
"Small Galaxy Disappears",54,0,0,0
(Mar '97)
A burst of intense gamma rays was detected by the Italian-Dutch \Jsatellite\j BeppoSAX, coming from the northwestern part of the \Jconstellation\j Orion. These mysterious events, known since the 1960s, have often been assumed to be caused by violent events on the surfaces of neutron stars, or by collisions between black holes and neutron stars, but this latest event was narrowed down to a section of the sky less than one arc minute across. (For comparison, the \Jsun\j and the moon each appear to stretch across 30 arc minutes, as seen from \Jearth\j.)
Careful observation of the area revealed that a small galaxy in the area had dimmed, and by March 8, the galaxy had disappeared altogether. This suggests that we may now be closer to knowing what causes the gamma ray bursts, but it will take more events, all carefully observed, before all of the wilder theories are laid to rest.
#
"GPS and the Himalayas",55,0,0,0
(Mar '97)
Global Positioning Systems (GPS) were the subject of a major article last month. This month, \INature\i has revealed a new use for GPS: calculating how fast the Indian sub-continent is pushing in under \JNepal\j. The best estimate, based on other measurements, is 20.5 ▒ 2 mm yr\U-1\u, while GPS delivers an overlapping estimate of 17.52 ▒ 2 mm yr\U-1\u. The researchers believe there may be enough strain already present in the rocks of western \JNepal\j to trigger another \Jearthquake\j like the Bihar/\JNepal\j quake of 1934, which had a \Jmagnitude\j of 8.1.
#
"Under Two Suns?",56,0,0,0
(Mar '97)
A dusty disc, possibly the precursor of a planetary system, has been identified around a young and massive binary pair of stars, BD+31░643, a thousand light years away, suggesting that planets may be able to experience sunrise and sunset at the same time, a notion which has long been popular with \Jscience fiction\j writers. The evidence comes in the form of a symmetrical band of light, around two stars which are about 1 million years old. Since 1984, only beta Pictoris, a main-sequence star, has been known to have such a dust disc, but if this suspicion is confirmed, then the search will be on for more "planetesimals".
#
"Earth Getting Hotter?",57,0,0,0
(Mar '97)
If you study surface air \Jtemperature\j records across the globe, 1995 was the hottest year on record, clear evidence, say some observers, for global warming. Over the period from 1979 to 1975, the trend has been for warming to occur at the rate of 0.13░C per decade.
Against that, \Jsatellite\j data on the lower \Jtroposphere\j imply a cooling trend of -0.05║C per decade, using data from the Microwave Sounder Unit (MSU). This, say the doubters, casts doubt on the validity of the doom-sayers' predictions. Now it appears that the cooling trend has been mostly generated by sudden drops which occurred on two occasions when there was a change in \Jsatellite\j. These drops, arising from a change in the measuring instrument, have probably produced a spurious cooling trend in the data. The real trend in MSU temperatures, say the latest studies, is likely to be positive, but fairly small.
#
"Ice Age An Earlier Phenomenon",58,0,0,0
(Mar '97)
We tend to think of ice ages as being a recent phenomenon, something which arose in the days of woolly mammoths and hairy humans, but now we have evidence of two much earlier glaciations, close to the then Equator. These two Precambrian glacial periods left deposits of glacial materials beneath accurately dated \Jlava\j beds, but the present picture is of a very long ice-free period, punctuated by two severe ice ages.
#
"Life on Martian Meteorite?",59,0,0,0
(Mar '97)
The famous Martian \Jmeteorite\j ALH84001 was, we were told quite recently, formed at temperatures far too hot to have allowed any life forms we were told, although as recently as August 1996, we were assured that it definitely bore traces of Martian organisms.
Now the \Jtemperature\j of formation may be cool enough for life again. The variation of isotopic ratios throughout the rock varies rapidly, and this is being interpreted as evidence that the \Jcarbonates\j in the rock must have formed at relatively low temperatures, perhaps less than 100 degrees \JCelsius\j. The reason for the claimed low temperature, say petrologists, is that these rocks, at high temperatures, would have been subject to more diffusion, more mixing-in of the various \Jisotopes\j.
Further evidence comes from the magnetic fields in fragments of crushed crystals. The directions of the field appear to reflect those in the original crystal, but if the rock had ever been heated above about 320 degrees \JCelsius\j, its magnetisation would have been wiped out, and the magnetism would then have been re-established in a new common direction.
The argument continues . . . just a few days later, the team making the original claim were back in the fray, claiming to have detected traces of "biofilms", carbon-based coatings more similar to dental plaque than anything else, which may have been left by \Jbacteria\j at some time in the past. As with all of the other claims, the voice of the sceptic is strong in the land.
#
"Thermoluminescence Dating Doubts",60,0,0,0
(Mar '97)
Thermoluminescence dating was among the methods which came in for some criticism at the Australian Archaeometry Conference on archaeometry which was held in Sydney during February, but several other methods were also questioned. Science is all about having healthy doubts, but some of those attending later reported that the sceptics had more fun than those being exposed to scepticism.
#
"Weird Flier Uncovered",61,0,0,0
(Mar '97)
Palaeontology is perhaps the last branch of science, in the era of Big Science, where amateurs also have a part to play. German amateur palaeontologists have collected some remarkable new specimens of the world's oldest known vertebrate flying animal. The 250-million-year-old \ICoelurosauravus jaekeli\i was originally known only from partial specimens, but new and more complete fossils have now been collected by dedicated fossil hunters who have willingly made their material available for expert study, allowing the discovery that the bones of the wings were quite different from the structures we now think of as standard.
Instead of extensions of the existing bones of the animal's body, bundles of bony rods formed in the wing's skin and opened like an old Japanese fan, radiating outward from the shoulder area. Just for once, \Jevolution\j seems to have made a breakthrough and solved a problem without adapting a pre-existing structure.
#
"Eye Evolution",62,0,0,0
(Mar '97)
Wings may have evolved more than once, but the evidence is getting better to say that the eye evolved just once in the history of life on \Jearth\j. Two years ago, it was shown that a mouse-eye gene, spliced into fruit flies, caused them to grow extra eyes in strange places, suggesting that the mouse and the fruit fly inherited their eye from some distant common ancestor.
Now the procedure has been repeated, with equal success, using a \Jsquid\j's eye gene. Two organisms with the same gene might just have been happenstance, but three organisms? The notion of a common ancestor seems rather more attractive.
#
"Hepatitis G--Not Guilty?",63,0,0,0
(Mar '97)
Researchers in America appear to have ruled out the mystery virus which is referred to as hepatitis G, as a genuine cause of hepatitis. The virus is found in about 1-2% of blood donors, and seemed to be associated with certain cases of hepatitis. But while the virus looks "clean", some researchers are remaining cautious, saying that it is harder to prove that something \Idoesn't\i cause disease than to prove that something \Idoes\i cause disease.
#
"Flu Virus of 1918 Identified",64,0,0,0
(Mar '97)
The flu virus which killed more people, soon after the First World War, than died in the whole of that war, has now been identified in lung tissue preserved from the corpse of a 21-year-old American private who died of the disease. The viral RNA extracted from the tissues has proven to be remarkably similar to flu viruses found in pigs. Previously, scientists assumed that human flu viruses came from bird populations: if the killer came from a pig, then health authorities will need to monitor pig populations more carefully.
On the other hand, it may soon be all up for the flu virus, as researchers begin to identify the genes that are needed for the flu virus particles to escape from one cell, and break into another. In another report, two such genes have now been identified, coding for the proteins, hemagglutinin and neuraminidase, both of which assist the viruses to break through the cell membrane. These two genes will be tempting targets for those looking to create a wonder drug which strikes at the foundations of the attack strategy of this virus.
#
"Obituary for March 97",65,0,0,0
No deaths of eminent scientists have been reported this month, but this month may, however, have seen the death of one of the world's deadliest killers, the \Jtobacco\j industry. Each year, an estimated three million people die of \Jtobacco\j-related causes, and by the time today's teen smokers are middle-aged, there will be ten million deaths a year from \Jtobacco\j. The cause of the possible death is the defection from the other manufacturers of a small American \Jcigarette\j manufacturer, the Liggett Group, which produces Chesterfields. Liggett has agreed to hand over certain documents, causing the other \Jcigarette\j company lawyers to start restraining actions. This is clear evidence, say observers, that the documents will prove to be most interesting reading.
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"Coming Events (Mar 97)",66,0,0,0
In the past, it has always been the creationists who have taken the evolutionists to court. While the evolutionists have always won the \Jday\j, the creationists have always bounced back again, in a slightly different guise.
Starting April 7, an Australian geologist, committed to the ideals of \Jevolution\j, will be pursuing one Australian creationist through the courts, using Australia's federal Trade Practices legislation, alleging that a group called Ark Search Incorporated and its head, Allen Roberts have engaged in "misleading and deceptive conduct".
As side dishes, an American former creationist has joined in the action, claiming that the Ark Search literature breaches his copyright, and Plimer, who holds a chair in \Jgeology\j at Melbourne University (where he is head of the School of Earth Sciences) will be questioning Roberts' claim to hold a legitimate Ph.D. from a \JFlorida\j (USA) university which has proved rather hard to locate in any physical way.
An ominous move, from Roberts' point of view, is that a number of leading Australian "creation scientists" are distancing themselves from him, at least in the run up to the case. At the same time, Plimer has been criticised by a number of Australian scientists who claim that, even with an apparently watertight case, Plimer may be defeated by legal manoeuvring, giving the creationist cause their first "win", which they would then interpret as court approval for their point of view. Plimer, on the other hand, says that only in a \Jcourt of law\j can he challenge Roberts without risking a long \Jdefamation\j suit in front of a possibly confused jury-this case will be before a judge alone.
It looks as though controversial trials in the future will not be complete without a Web site or two. The creationists' case will be found at http://www.christiananswers.net/aig/aighome.html, and the Australian Skeptics will present their views at http://www.skeptics.com.au
Given the strong feelings which are likely to emerge during the case, it will be interesting to see how long it takes for one or other of these sites to be the subject of separate court proceedings, although the creationists' site is already outside any Australian \Jjurisdiction\j, and the skeptics are sure to have friends in other countries who can offer them safe haven.
#
"One Hundred Years of Electrons?",67,0,0,0
(Apr '97)
So far as the history books are concerned, April 30 was the centenary of the \Jelectron\j, since it was on April 30, 1897, that Professor J. J. Thomson revealed to the Royal Institution in London his work on the mass/charge (m/e) ratio for the \Jelectron\j.
But the \Jelectron\j actually has a longer history than that. Around 1860, Julius Plucher in \JGermany\j found that he could deflect the rays in one of Johann Geissler's vacuum tubes with a magnet, which suggested that these "\Jcathode\j rays" were actually made up of a stream of particles. Unfortunately, Johann Hittorf, Plucher's student, was able to show that the rays made sharp shadows, which suggested to people that the "rays" were made of waves like light, and in the end, the German physicists went for the wave viewpoint.
In England, Sir William Crookes had a marvellous time playing with the same sorts of tubes, gaining results which strongly favoured the particle view of \Jcathode\j rays. In \JGermany\j, Heinrich Hertz and Philipp Lenard found that the \Jcathode\j rays from the \Jcathode\j ray tube could pass through a thin metal "window" in the end of the tube, clear evidence, they thought, that the rays really were rays. The English particle camp was divided: Arthur Schuster thought that the particles had to be the same sort of thing as the massive ions released in \Jelectrolysis\j-\Jhydrogen\j ions in our terms, while J. J. Thomson thought otherwise, but stayed fairly quiet.
In January 1897, Emil Wiechert argued that the electrons were particles much smaller than \Jhydrogen\j ions, and in April, Walter Kaufmann gained results which were similar to those Thomson was about to announce, but Kaufmann was worried about the tiny mass value that was implied, so he did not make his findings known, leaving the way clear for Thomson at the end of the month.
The most important points Thomson raised included that his observation that the value of m/e (or as we say today, e/m) remained the same, regardless of the gas which was left behind when you pumped out the vacuum tube. Getting a perfect vacuum on \Jearth\j is, of course, impossible, and it was accepted that the electrons came from the gas that was left behind when most of the gas was taken out. If the charged particle was one of the gas atoms, then you would expect to get variations in the e/m ratio as the mass varied.
But was April 30 the true centenary? The word "\Jelectron\j" has been around since 1891. The idea had been formally discussed by James Clerk Maxwell in 1873, and had been mooted by Michael \JFaraday\j even earlier than that.
More importantly, while the 1897 result told us that there was a constant ratio of mass to charge, there was still a problem: was the small value of m/e (in Thomson's terms) due to the small mass of the \Jelectron\j, or did it result from a large value for the charge on the \Jelectron\j? In 1899, Thomson would answer this in part when he published a paper with the title \I"On the Existence of Masses Smaller than the Atoms"\i, showing that the mass of the \Jelectron\j (by then the accepted term) was about 2000 times less than the mass of the lightest atom, \Jhydrogen\j.
Others might argue that the real birth of the \Jelectron\j only came later, when Robert Andrews Millikan did his famous oil-drop experiment, but we have now known for certain, for just over a hundred years, that the \Jelectron\j was a particle that we could work with.
When you look around the home, we haven't done too badly with that piece of knowledge during the past century. Quantum mechanics, nuclear physics and \Jelectronics\j have all stemmed from that one key measurement. Your computer, \Jtelevision\j, radio, \Jmicrowave oven\j and mobile phone all rely on discoveries which followed from Thomson's work.
#
"Europa's Ocean",68,0,0,0
(Apr '97)
It is almost twenty years since those first hazy \JVoyager project\j photos suggested to some scientists that there might be liquid \Jwater\j below the surface of Europa's icy surface. It was only on April 9 that we got our first clear evidence that there really is liquid \Jwater\j there, \Jwater\j which might support life. The pictures, released by NASA's Jet Propulsion Laboratory, were taken from 586 kilometres (363 miles) above Europa, and they cause immediate excitement.
Yet this is not surface \Jwater\j, crashing and pounding on the Europan shores, but \Jwater\j deep beneath the ice, where it is protected by a blanket of giant icebergs. So how can we be so sure that there is liquid \Jwater\j when we cannot see it? The pictures show us a terrain that scientists think could only have formed if the \Jwater\j had occasionally erupted through, melting part of the surface and churning up the icebergs as it went. The excitement of this discovery comes from the realisation that where there is \Jwater\j, there could be life, though it still remains an outside chance at best.
Europa is the smallest of the four "Galilean" moons of Jupiter, the moons which were seen by \JGalileo\j Galilei when he turned his primitive \Jtelescope\j to the night sky, and found, on January 7, 1610, what he called the "Medician stars", a bit of unsubtle flattery of the powerful Medici family.
Europa has a diameter of 3138 km, a bit smaller than our own moon, and it is the sixth largest moon in the \Jsolar system\j, and the smoothest object in the \Jsolar system\j, with no surface features more than 1 km high. With a visual \Jalbedo\j of 0.64, it is about five times as bright as our own moon, as you would expect from a large ice-coated object.
There are two main types of terrain on Europa. One is mottled brown or grey hills, the other is made up of broad plains, criss-crossed with cracks, some curved and others straight. This second type of surface looks remarkably like the surface of our \JArctic\j Ocean.
The jumbled terrain, say scientists, has ridges that have been squeezed up, rifts and cracks, crumpling and other features which are best explained by a thin layer of ice over a liquid ocean. The ice crust may be "no thicker than 150 km", say the scientists, though others favor a model with just a couple of kilometres of ice over a muddy ocean. There are also a few scientists who think the landforms have come from ice shifting around on ice.
The most important thing is the surface, which has very few craters, and very few large craters, supporting the idea that the surface is very young, that the shaping processes are still going on. But why should there be any liquid under the ice? The answer lies with tidal warming, the same effect which drives the volcanoes of Io. As Europa swings around the other satellites and Jupiter itself, tidal pulls release \Jenergy\j which warms or melts material at different places. While the outside ice is chilled by the cold of space, ice is also a good insulator, as every igloo-dweller knows, so there could easily be \Jwater\j down there somewhere.
Present theories assume that the core of Europa is probably mainly iron and sulphur, rather like Io. The density of Europa is 3.01 g/cm\U3\u, so the core is probably smaller than Io's core. There is also a very thin oxygen \Jatmosphere\j over the surface of Europa.
Galileo has been flying since October 1989, and reached Jupiter in December 1995, but there is more still to come: Europa gets another visit from Galileo in November this year, and the extended mission announced recently will involve Galileo in a further eight visits to Europa, as well as extra visits to Callisto and Io. During the later visits, scientists will be looking for the final proof of liquid \Jwater\j, a \Jgeyser\j of \Jwater\j and mud, bursting through to the surface.
That, they say, would be really something.
#
"Atomic Force Microscopes",69,0,0,0
(Apr '97)
"No one has ever seen, nor probably ever will see, an atom, but that does not deter the physicist from trying to draw a plan of it, with the aid of such clues to its structure as he has." That, at least, was the opinion of Maria Goeppert Mayer, later to share a Nobel Prize in physics for her detailed understanding of atoms, writing in 1953. No scientist of her day would have disagreed with that point of view, but now scientists can image single atoms, they can even move them around and organise them to spell out simple messages. The atomic force microscope is showing all sorts of new promise.
First described in 1986, this \Jmicroscope\j can resolve objects as small as a nanometre across. It does so by touch, feeling the surface it passes over, rather like an old-fashioned stylus on a vinyl record. Now, even DNA can be examined in this way, according to reports at the American Physical Society's annual meeting in March, too late for results to be included in our last update.
The big problem with dragging a probe over a surface is that you may snag or damage something, but you can get around that by vibrating the tip. Neil H. Thomson reported that this form of tip allowed him to get images of RNA polymerase working its way along a DNA molecule to make RNA that would be converted into a protein, just as it has always been drawn in the \Jgenetics\j textbooks. The difference? Instead of \Ideducing\i what must be going on, Thomson and his colleagues actually \Isaw\i what was going on.
Tip: watch out for more spectacular discoveries from the atomic force \Jmicroscope\j, or its cousin, the magnetic \Jresonance\j force \Jmicroscope\j, in the next year or two.
Japan has been working on better forms of \Jearthquake\j prediction since 1965, and currently spends around US$150 million each year on this research, but now the program appears to be in some doubt. The January 1995 Kobe \Jearthquake\j came in an area which had not been closely monitored, it cost many lives, and it was totally unexpected. So now Japanese officials are beginning to ask if there is any useful future in trying to predict earthquakes.
While the report has been partly leaked, it will not be officially released until the northern summer, so the next few months should see some interesting manoeuvring between those who want to stop the prediction studies, and those who wish to continue them.
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"Peer Pressure and Gene Pressure?",71,0,0,0
(Apr '97)
A recent study of twins in the USA suggests that there may be a genetic tendency to get a "high" from marijuana. Identical twins are much more similar in their responses than are fraternal (non-identical) twins.
So perhaps peer pressure gets people started, but then \Jgenetics\j takes over, encouraging some to stay with the drug, while others try once, and then decide it is not for them. Next step: identifying the drug, and working out how it operates.
Meanwhile, an Israeli study of 141 heroin addicts suggests that there may also be a gene for heroin addiction, a gene which produces a mutated form of a \Jdopamine\j receptor molecule known as D4. The gene was already known to be linked to \Jnicotine\j and alcohol abuse, so the finding is not particularly surprising.
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"A Gene for Alzheimer's?",72,0,0,0
(Apr '97)
The unravelling of Alzheimer's disease gets a step closer with the observation that most patients seem to have high levels of a mutant \Jenzyme\j, \Jcytochrome\j oxidase (CO), which is involved in providing \Jenergy\j to the cells. It has been known for some time that Alzheimer's patients have low levels of brain \Jenergy\j, and while the \Jenzyme\j is present in their brain cells, it does not work as it should, suggesting that it may be mutated in some subtle way.
CO is made up of thirteen proteins, and is found in the \Jmitochondrion\j, which has long been suspected as a key element in the transmission of Alzheimer's. The disease is more commonly found in the children of Alzheimer's women than in the children of Alzheimer's men, and mitochondria are only inherited from the mother-we get our mitochondria only from the \Jovum\j that we grow from, and never from the sperm that fertilises the \Jovum\j. Most importantly, mitochondria carry a small amount of independent DNA which they need to function properly.
When the mitochondria from Alzheimer's patients were cultured in cells lacking any mitochondrial DNA, the cells had lower \Jenergy\j production, and more oxygen free radicals, harmful molecules which are able to damage cells further. The CO mutations may not be the direct or indirect cause of Alzheimer's disease, but there are definite grounds for a strong suspicion.
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"Breast Cancer Genes",73,0,0,0
(Apr '97)
How do cancer genes work? How do they cause cancers in the human body? That is a major question right now, and this month saw some clues in two reports on the second human breast cancer gene to be discovered. BRCA2, as it is called, can be found in a mutant form in breast cancers. If we could only find out how the gene operates normally, we would have some clues as to how the mutant form causes cancer.
The reports seem to give different results: the normal BRCA2 gene is shown in one study to be involved in the control of cell proliferation, while a second study suggests that the gene interacts with a protein called Rad51, which is a DNA repair substance. This finding suggests that the normal gene assists to maintain the cell's DNA.
If the gene interferes with the cell's ability to repair damaged DNA, this would mean that the cancer cells would be more easily attacked by radiation.
The research involved breeding mice which lacked the gene. If mice lack both copies of the gene, they die in early development, suggesting that the gene's loss prevents cell growth somehow. The association with Rad51 led researchers to treat 3.5-\Jday\j embryos with radiation, a treatment which killed the embryos with no active BRCA2 gene, while those with one or two copies of the normal gene survived.
Currently, the most popular explanation is that the gene acts in a DNA repair role, and that when this repair role is not there, damage in the DNA accumulates and prevents further growth.
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"Cancer Gene Nabbed",74,0,0,0
(Apr '97)
A variety of human cancers, especially the aggressive brain tumors called gliomas, involve cells which lack part or all of \Jchromosome\j 10. This suggests that there may be a tumor suppressor on this \Jchromosome\j, and the hunt has been on to identify it.
New research has revealed a single genetic marker which was missing in two breast cancer samples, as well as from some prostate and brain tumor cell lines by one group of researchers, and in brain tumor cells by another group of researchers.
Dubbed PTEN (\Iphosphatase and tensin homolog deleted on \Jchromosome\j 10\i), or MMAC1 (\Imutated in multiple advanced cancers 1\i), this is by no means the first tumor suppressor gene to be discovered-there are about sixteen others already known-but early indications are that this marker is an important one. The two groups, one publishing in \INature Genetics\i, the other in \IScience\i, say that the gene appears to be associated with some major cancers of the human body.
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"Crash Victims, New Method To Identify",75,0,0,0
(Apr '97)
The same issue of \INature Genetics\i also reports on a genetic method of identifying human fragments found in air crashes. In August 1996, a jet carrying Russian and Ukrainian miners and their families to Spitsbergen Island crashed into a mountain, killing all 141 on board.
The body parts collected at the scene were shipped to Oslo, where it was realised that dental records and fingerprints would be of little help. So a different sort of fingerprinting, DNA fingerprinting, was brought into the investigation.
In just three weeks, they gathered 257 body parts, and sequenced eight stretches of "junk DNA" from each of the body parts, getting a total of 141 unique DNA types. This meant they could now link the separated parts to each other, but left the actual identification up in the air. By sequencing blood samples from the relatives of 139 victims, leaving just two to be identified in other ways
The team was lucky, in that the remains were preserved by the cold conditions at Spitsbergen, but their work shows what can be achieved under the right conditions.
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"Fish Antifreeze Gene",76,0,0,0
(Apr '97)
The gene for fish antifreeze seems to have evolved twice, independently. The fish of the Antarctic developed their version of the gene for an antifreeze protein around fourteen million years ago, just about the time when the Antarctic Ocean dropped below freezing. The gene in Antarctic notothenoid fish is derived from another gene in the same fish, a gene that produces a digestive \Jenzyme\j, but this new gene is taken from some of the junk DNA, useless bits of code which are found in most sequences of DNA.
In \JArctic\j cod, there is a very similar protein, but in that fish, the antifreeze gene cannot be linked to any known sequence in the cod, leading scientists to conclude that the gene must have evolved in a different way at a different time, a remarkable piece of convergent \Jevolution\j.
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"Life is Fractal",77,0,0,0
(Apr '97)
To many scientists, the meaning of life is more important than the physics of life. In physics, most measurements are compared by the way they differ in order of \Jmagnitude\j, of powers of ten. From a microbe to a whale, there is a difference of about 21 orders of \Jmagnitude\j-a whale is 10\U21\u times as large as a microbe.
The importance of this observation is that many measurable features of living things are related mathematically to the body mass of an adult. Metabolic rate varies as the 3/4 power of mass, so that larger creatures have slower metabolisms, life span varies as the 1/4 power of mass, age at sexual maturation varies as the 3/4 power of mass, and length of \Jpregnancy\j varies as the -1/4 power of mass.
Logically, if these things are reflecting the three dimensions, the relationship should be 1/3, implying a cubic or cube root relationship. Ecologists James Brown and Brian Enquist of the University of New Mexico, and physicist Geoffrey West of Los Alamos National Laboratory have been exploring this, and find that they can model animals as a fractal network of linear tubes and account for all of these oddities. Life, it seems is fractal.
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"Plants on the March?",78,0,0,0
(Apr '97)
Last month, we looked at the problems which came from changing from one \Jsatellite\j to another. The changes between infrared systems on three satellites led scientists to think there was no apparent change in \Jearth\j temperatures, when it now appears that the \Jearth\j was heating up after all. The differences, it seems were hidden in the changeovers between satellites.
This month, a report suggests that the \Jearth\j may be getting warmer, but this is based on the evidence of several sets of readings taken from different satellites which may or may not have been accurately calibrated. If the results are reliable, they show a huge increase in vegetation during the 1980s.
The National Oceanic and Atmospheric Administration (NOAA) launched a series of satellites, and data from three, NOAA-7, NOAA-9, and NOAA-11, indicate that plant life around the world has increased hugely during the decade. In some cases, the increase appears to be as great as 10% in the areas between 45░ and 70░ North, where snow has been disappearing earlier in spring.
Given the earlier example, a number of scientists are viewing the whole matter rather cautiously.
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"Clean Cars Get Further Away",79,0,0,0
(Apr '97)
Last month also saw a close look at the clean electric cars which we hope will be around in the future. In that article, we indicated that the targets for electric car developments in the USA would probably be delayed, and now the \JWhite House\j's Partnership for a New Generation of Vehicles (PNGV) is also beginning to have its wheels drop off.
Targeting more efficient use of conventional fuels, the PNGV plans set targets, but a new review suggests that these targets, relating to particles emitted and fuel use, are just not feasible. The quick version: don't hold your breath while you are waiting for clean air.
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"New Ancestral Apes?",80,0,0,0
(Apr '97)
April saw two claims for ancient ancestors of the \Jape\j line. \IKenyapithecus\i finds on an island in Lake Victoria, Kenya, point to this previously discovered \Jape\j being on the line leading to modern apes, but at 14 million years, that may not matter too much, because this month also saw a claim for another ape ancestor, reliably dated at 20.6 million years.
The new candidate, a large tree-dwelling \Jape\j called \IMorotopithecus\i was also already known from \Jfossil\j pieces found at Moroto in \JUganda\j, but new shoulder bones and leg bones have been taken to indicate that this also had the body form of an \Jape\j, and that it was in the habit of hanging from its arms like modern apes.
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"Adaptive Radiation",81,0,0,0
(Apr '97)
Adaptive radiation is an idea that Charles Darwin developed while he was looking at finches on the Galapagos Islands. The idea is that one species, having arrived on an unexploited island, divided up into several groups which specialised in feeding in different ways, and before you know where you are, new species have arisen.
Nobody has ever actually seen it happen, but we can see traces of it having happened in most island groups. Nobody ever expected to see it happen either, because people have always assumed that the time scale would be too long. All the same, those who considered the issue have generally had strong views on whether genetic drift or natural selection would play a larger part in selecting the new species.
Enter a group of scientists wanting to study \Jextinction\j on a small island. They took a small population of \IAnolis sagrei\i lizards from the \JBahamas\j, natives of Staniel Cay, and transferred some of them to other islands in the area. These lizards live on tree trunks, but their new islands were almost treeless, and this should have doomed them to \Jextinction\j, but this did not happen. So the researchers decided to study the populations, and see how they changed with time.
Anole lizards which live on bushes have shorter hind legs: they lose on speed, but they get greater agility, and the Staniel Cay lizards were all long-legged. Yet after just 10 to 14 years, the surviving lizards have not only survived, they now have shorter hind legs than their ancestors. This change is so rapid that some people have been drawn to suggest that the variation is environmental, rather than inherited-a bit like the muscles of a body-builder.
Most importantly, the lizards differed more on those islands where the vegetation was most different, making it more likely that the observed differences were due to inherited changes.
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"A Snake With Legs?",82,0,0,0
(Apr '97)
Everybody accepts that the snakes arose from lizard-like ancestors, but up until now, nobody had much idea what the ancestors of the snakes looked like. M W Caldwell and M S Y Lee reported to \INature\i this month about their findings on a Cretaceous \Jreptile\j, \IPachyrhachis problematicus\i, previously interpreted as a varanoid lizard like the Australian goannas and the Komodo dragon, is actually a primitive snake with a well developed pelvis and hind limbs.
The fossilised skulls show most of the derived features of modern snakes, and a body that is slender and elongated. But unlike other snakes, Pachyrhachis still had well developed hips and full hind legs.
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"Jurassic Park Ruled Out",83,0,0,0
(Apr '97)
The basis of the "Jurassic Park" movies is that DNA from mosquitoes trapped in amber can be used to "clone" dinosaurs. Given the recent news about Dolly the sheep (see last month), the chances looked even better. A detailed study, published in April and carried out at London's Natural History Museum, reveals that no credibly ancient DNA has been extracted from Dominican amber.
On the good news front, a US Patent was announced for a method of collecting ancient \Jbacteria\j and fungi, some of which may be able to provide new variations on the standard \Jantibiotics\j. The process involves cleaning the amber, cracking it under liquid \Jnitrogen\j, and extracting material from stingless bees' stomachs. The bees have been in the amber for 25 million years, so any \Jantibiotics\j would almost certainly be unknown to modern \Jbacteria\j.
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"Antibiotic-Resistant Bug Found",84,0,0,0
(Apr '97)
A report came in from \JJapan\j this month, indicating the isolation of a strain of \IStaphylococcus aureus\i which is resistant to all known \Jantibiotics\j, including the "last resort" antibiotic, vancomycin. While a similar report was received from \JCaracas\j three years ago, that incident was never confirmed, but there appears to be no doubt about it this time. The superbugs are now not just a bacteriologist's nightmare.
The implications are worrying: people can now, for the first time in half a century, get a "staph" infection which cannot be treated.
Parallelling this report, news was received this month of an industrial accident in which a worker in the poultry industry was wounded and infected with vancomycin-resistant \Jbacteria\j. It appears that the \Jbacteria\j may have encountered avoparcin, a similar antibiotic to vancomycin, which is routinely fed to chickens, and so become resistant to vancomycin as well.
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"Good Bugs in Our Computer Displays?",85,0,0,0
(Apr '97)
\IHalobacterium salinarium\i is a bacterium which grows in salt marshes. This organism produces an intensely purple protein pigment in its membrane called bacterial rhodopsin or bacteriorhodopsin. This protein is photosynthetic, and can be used by the bacterium to produce \Jenergy\j from sunlight.
It operates by "pumping" protons across a membrane barrier, and this has made the pigment a matter of intense interest for scientists in a number of fields. A thin film of the molecules produces an electrical field when light shines on it, allowing the pigment to be used in light detectors, for example.
In a similar way, an electric field acting on a film of bacteriorhodopsin causes the film to change colour, an effect called photochromism. While the usual change is a low-contrast shift from purple to blue, mutants of the bacterium are now known which produce a much greater contrast, going from pale blue to yellow.
The displays in laptop computers chew up most of their power lighting up the screen, so a screen made with material like this, and requiring no lighting, would be remarkably valuable. Already, people are beginning to talk about the mutant bacteriorhodopsin as "electronic ink", and wonder if this may not be the start of the electronic book.
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"Bacteria on a Blue Chip",86,0,0,0
(Apr '97)
Getting ahead of ourselves very slightly, as this issue went to publication in mid-May, news came through that genetically altered \Jbacteria\j are being added to chips as a way of detecting impurities. The current bugs glow blue light when they are in the presence of \Jnaphthalene\j: when they are placed in a porous matrix on a chip, their glow will cause the chip to trigger an alarm.
Perhaps not quite as attractive as the canaries that Welsh miners used to take down the mine with them, but far more specific, these chips could be used to detect a wide range of environmental pollutants.
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"Kasparov vs Deep Blue",87,0,0,0
(Apr '97)
Gary Kasparov has been playing chess against Deep Blue once again. At first, the two seemed fairly evenly matched, though there are claims that the machine should now have a rating of 3200, against Kasparov's 2800 rating.
We will bring you a full report of this contest next month, but on May 11, with three draws and a win each, Kasparov and Deep Blue faced up for a final game, in which Kasparov resigned after just nineteen moves. He later suggested that he would have beaten Deep Blue in a tournament play, but nonetheless, a computer has beaten the world's champion human chess player for the first time.
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"Cheetahs Slower",88,0,0,0
(Apr '97)
How fast is the fastest animal? According to most references, including the Webster's World Encyclopaedia, the cheetah can turn on an impressive 70 mph, or 110 kph, but recent studies have shown that this standard estimate is a mild exaggeration.
The cheetah remains the fastest animal on \Jearth\j, but the official record has now been corrected down to 65 mph (all of the measurements taken were in British units) which translates to about 103 kph-still a respectable clip to travel at.
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"Hubble Trouble?",89,0,0,0
(Apr '97)
Three of the four new instruments installed in the Hubble Space \Jtelescope\j are working fine after the recent upgrade, but NICMOS, the Near Infrared Camera and Multi-Object Spectrometer, has caused focus problems, leading to blurry pictures. If this cannot be fixed soon, it will begin to delay a number of studies, including work on young galaxies and on Pluto's moon Charon.
The problem may have been caused by a problem in the NICMOS cooling system-the camera is suppose to operate at -215░C, and will be sensitive to any slight failings in the cooling system. The result would be fuzzy pictures which will still be of some use, though not as much as scientists had hoped.
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"Volcano Erupts in Australia",90,0,0,0
(Apr '97)
Australia's second active \Jvolcano\j was discovered this month when a ship was sailing past McDonald Island, 4500 km southwest of Perth. The scientists aboard \IAurora Australis\i report seeing steam rising from the island, about 30 km from Australia's other \Jvolcano\j, on Heard Island.
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"Is the Universe Twisted?",91,0,0,0
(Apr '97)
One of the most basic rules of modern physics is Einstein's assertion that the laws of science apply in the same way everywhere. That being so, you would expect the radio waves reaching \Jearth\j from other galaxies to be randomly polarized-instead, the 160 known radio-emitters seem to have a bit of a twist to the way they are polarized. For the moment, the general opinion seems to be that this is interesting, but nobody seems to be rushing to bring out a revision of Einstein's work.
The study, reported in \IPhysical Review Letters\i, reports on the findings made by Borge Nodland and John Ralston, for those wishing to seek more information on the Web: key words to use in your search include Socorro and Sextans.
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"Controversy in Space",92,0,0,0
(May '97)
In 1981, a NASA rocket was launched, carrying two Dynamics Explorer satellites into elliptical orbits. One of these was in a polar orbit, swooping down to 550 kilometres, and climbing to 23500 kilometres, it carried an ultraviolet camera designed to gather information about auroral lights at the north and south \Jpoles\j.
Using false-color photography, the camera provided spectacular images of the \Jearth\j's "dayglow", an ultraviolet glow which results from interactions between the light of the \Jsun\j and atomic oxygen, high in the \Jearth\j's \Jatmosphere\j.
The pictures were superb, but marred by small black spots which appeared randomly across the pictures of our \Jplanet\j that were transmitted back to \Jearth\j. At first the speckles were assumed to be "noise", random interference in the camera system, possibly coming from a faulty component, but no cause could be found for them. Louis Frank and an undergraduate student, John Sigwarth, started to investigate more and more carefully.
They decided that the speckles had to be coming from a source on the ground, or a source on the \Jsatellite\j, or from radio interference. After eliminating all of the equipment on the ground, they ruled out radio interference because text information from the \Jsatellite\j came through cleanly. They began to suspect the on-board light counters which slowly built up each picture. There were two of these in the camera, and they transmitted alternate pixels, so maybe there was a fault in one of them that was creating the speckles.
It was a simple enough task to extract the two sets of pixels, and show that each picture showed exactly the same pixels. Next, they looked to see if the spots were constant between shots, and found indications that the spots were still there, but that they moved and changed between one picture and the next.
Sigwarth programmed the camera to concentrate on just small area, and showed that the spots did in fact remain, that they moved, and that they changed. There was no way that these spots could be set down as "noise" any more: they were real objects, and they needed to be explained. There was something moving between the \Jplanet\j and the \Jsatellite\j.
Now in a movie, this would be the point where a mysterious "expert" identifies the speckles as UFOs, and forbids any further investigation. In real life, scientists work like scientists, and deduce what the speckles must be, free from interference. The main point, Sigwarth and Frank realised, was that the speckles moved in the same direction across the face of the \Jearth\j. Whatever they were, they were moving objects which caused a disturbance that absorbed ultraviolet radiation, and the uniform motion suggested that these objects were small meteors of some sort.
Meteoric dust is generally travelling around the \Jsun\j faster than the \Jearth\j, so it catches up with the \Jearth\j from the "evening" side, showing what astronomers call prograde motion. That was what these things were doing, but what sort of \Jmeteor\j would cause large-scale absorption of ultraviolet?
In May 1983, Sigwarth presented a paper on their findings, just after graduating. The conservatively worded title was "Atmospheric Holes Possibly Associated with Meteors", drew a small audience, but over the next three years, they gave three more papers, with progressively greater interest.
As they continued trying to identify the cause, they eliminated dust effects, they decided that chemical reactions to remove the atomic oxygen that produces dayglow was too unlikely, so that meant some other absorber. It had to be a substance common in space, which made \Jwater\j look like a candidate, and they found that \Jwater\j vapor absorbed ultraviolet at just those wavelengths. Each, they estimated, would have to weigh about 100 tonnes, and there must be about ten million of them each year.
Now here they ran into a problem. A billion tonnes of \Jwater\j a year, raining down on \Jearth\j? No way, said the experts, it just doesn't happen. Of course, this is usually the way in science: somebody comes up with a new idea, the majority oppose it, and over time, either the evidence is gathered to prove the new idea has "legs", or more often, some crucial piece of evidence is produced to rule the new idea out, once and for all. But while the argument progresses, especially if the idea stands up to the first attacks, the exchanges can become more bitter and abrasive.
Louis Frank says that if he knew somebody else with a way-out theory like this, he would urge them to drop it, but being involved, he realised that if he let the idea go, and it turned out in the end to be true, many scientists would have wasted time. He could not simply walk away from the truth as he saw it.
You can point to different scientists and say "They laughed at X", but while we recall the occasional X who was right, we never hear about the five hundred scientists called A, B, C, and so on, who were laughed at, proved wrong, and never heard from again. And worse was to come, for Frank realised that these things they were calling meteors just had to be comets.
This was hot controversy, and the decision to publish the comets claim, and to explore the possibilities, was taken in spite of contrary recommendations from the referees of the journal in which the "story" broke, \IGeophysical Research Letters\i. One of the referees was anonymous (as is usually the case), but the other was known to Frank, and he urged him not to publish: apart from anything else, if the rain had been constant, it would have supplied enough \Jwater\j over the years to fill all of our oceans. And if that was the case, where were the oceans on the moon and the other planets?
The result was more than strong. " I was driving a bulldozer through dozens of the neatly planted fields of science and everyone was upset", said Frank afterwards. After that, the idea just sat there, not going away, but not wildly popular either.
In May 1997, Frank was able to display images which show there really are objects out there, but there is still considerable argument from the experts as to what the objects are. The new images are much finer resolution, and rather than showing single-pixel spots which might still have been noise, now we can see image that are ten to twenty pixels across, and shown in consecutive exposures.
If we have twenty comets a minute smashing into the \Jatmosphere\j, say the experts, they should light up the night sky, and they raise other problems as well. But in an interesting variation on the usual model for a paradigm shift in science, where one theory is overthrown by another, the word seems to have got out to the public.
This could be worth watching over the next two or three years, as the first paradigm shift, driven by public opinion, will be a paradigm shift in the way science works as well.
For those who wish to see more of Louis Frank's case, including a range of spectacular pictures, he has a Web site at http://smallcomets.physics.uiowa.edu
In the mean time, it is worth noting that the calculated level of \Jwater\j entry would raise the sea level by a \Jcentimetre\j every 4000 years or so. If that is the case, then maybe we are due for sea level rises, even if global warming is not happening!
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"Global Warming Theory in Doubt",93,0,0,0
(May '97)
The American Geophysical Union, where John Sigwarth presented the first paper on the mysterious comets, and the publisher of \IGeophysical Research Letters\i, met in Baltimore in May, where new measurements on global warming were presented, throwing some minor doubts on our present models for the nature of global warming.
Up until now, atmospheric temperatures have not risen as fast as predictions said they should. One speculation was that a haze of sulphates (produced during the burning \Jfossil\j fuels) was present in the upper \Jatmosphere\j was acting as a blocker, reflecting some of the \Jsun\j's light.
Atmospheric scientist Peter Hobbs of the University of Washington, Seattle, has been analysing the chemistry and reflective properties of the particles. He reports that he found more carbon particles than sulphate particles. As carbon absorbs more than it reflects, this should warm the \Jatmosphere\j, rather than cool it. A possible explanation may be that the carbon particles, although they are absorbers, may be acting as seeds for \Jcloud\j formation, and clouds most certainly \Ido\i act as reflectors of light.
#
"Ice Ages Theory Gains Ground",94,0,0,0
(May '97)
Sometimes the news for a theory is good, sometimes it is bad-in either case, it is just another example of the way science works. Scientists may argue passionately for their favorite theory, but in the end, it is facts which will decide the theory that will be accepted.
Once, people accepted quite happily that the main cause of Ice Ages was small variations in the Earth's \Jorbit\j. Then, over about the last decade, this theory has been in doubt, until some good news came through for the \Jorbit\j fluctuations, based on more careful checking of the dates of ancient corals.
The problem came from carbonate deposits brought up from Devil's Hole in Nevada in the USA, deposits which seemed to record warming at the wrong times, given what astronomers know of the patterns of the \Jearth\j's \Jorbit\j. Now Lawrence Edwards of the University of \JMinnesota\j and his colleagues have used a new clock, based on the decay of uranium 235 to protactinium 231, counting the individual atoms by mass spectrometry, and they have also dated \Jcoral\j records of se-level change from \JBarbados\j. Sea levels fall in an \Jice age\j, as more and more of the \Jearth\j's \Jwater\j is tied up as glaciers over the land.
The good news is that the \JBarbados\j corals show ice ages at the right place, with the last interglacial at around 129 000 to 120 000 years before the present. The bad news: the Devil's Hole data stand up as well, suggesting that these must have recorded a more local warming, but nobody is sure why this is so.
#
"Shoemaker-Levy--An Ominous Sign?",95,0,0,0
(May '97)
So we are being pelted with tiny comets, the \Jweather\j has gone feral on us, so what hope is there for us? Comet Shoemaker-Levy, which ploughed so spectacularly into Jupiter in 1994 is estimated to have been some millions of time larger than the small \Jwater\j comets that Louis Frank contemplates, so we should be comparatively safe, unless another Cretaceous-Tertiary boulder hits us, right?
Wrong. There are plenty of other large craters on \Jearth\j, and the estimated 10 km diameter boulder that probably wiped out the dinosaurs is not alone. And now some cheerful workers have simulated the results of such a hit, using a new supercomputer which is under development at the Sandia National Laboratory to simulate the formation of the suspected K-T crater, Chicxulub, in the Yucatßn peninsula in Mexico.
Rather than using a Hale-Bopp sized object (weighing in at some ten trillion tonnes), they used a conservative 1 billion tonne rock, the sort that hits the \Jearth\j about once every 300 000 years. After 48 hours processing, they came up with two animated movies showing the \Jcomet\j sliding in at an angle of 45░ and hitting the ocean. This hits with a power of some 300 gigatonnes of TNT-about ten times more than all of the nuclear weapons in the world at the height of the \JCold War\j.
The "splash" involves the vaporisation of between 300 and 500 cubic kilometres of ocean, some of it blasting into space. But if you think that sounds like bad news, there is worse. The same computer code was used two years ago to predict what would happen when Shoemaker-Levy hit Jupiter, and produced a good model of what happened when the \Jcomet\j eventually hit the giant \Jplanet\j. So the simulation is not only spectacular, it is almost certainly highly accurate. Catch the movie if you can: it should be better than the real thing.
#
"Hans Bethe Speaks Against Hydrogen Bomb",96,0,0,0
(May '97)
Hans Bethe, one of the original builders of the atomic bomb, is now 90. It is now almost sixty years since he worked out how nuclear fusion powers the \Jsun\j, and he is still worrying about the same issue.
The winner of the Nobel Prize for Physics in 1967 says that it is time to stop work on any further nuclear weapons. In a letter sent to President Clinton in April, released to the public in May, Bethe called for the end of all physical nuclear tests, no matter how small, and an end to "computational experiments or even creative thought designed to produce new categories of weapons".
Bethe's letter was released this month by the Federation of American Scientists as the US Senate was getting ready to debate the ratification of the Comprehensive Test Ban Treaty. They believe that the Treaty, even if ratified could leave the way open for the military to develop "pure" fusion weapons which do not use a fission device as their trigger.
It is well-known that the standard fusion device uses a fission explosion to get it started. It is less well-known (in fact, many people believe it is still a secret) that the fission explosion produces an intense burst of X-rays, and that these are then focused (in a method which thankfully does remain rather more secret) onto the fusion fuel, which is usually \Jlithium\j deuteride, starting the fusion process which we call a "\Jhydrogen\j bomb". (Deuterium is an isotope of \Jhydrogen\j with twice the usual mass.)
One of the drawbacks of this form of explosion is that it produces \Jradioactive fallout\j from the fission trigger, while a "pure fusion" bomb would presumably be a great deal "cleaner". Bethe believes that such a development is unlikely, but he is concerned that if people even contemplate such a study, then nuclear disarmament plans could be placed at risk, right across the world.
Court action was also started against the National Ignition Facility, the clean trigger for fusion which is planned to be built at the Lawrence Livermore National Laboratory, and against other nuclear weapons programs under the control of the US Department of Energy. The action was launched by the Natural Resources Defense Council and 38 other environmental and activist groups, in the US District Court.
Bethe's argument against the National Ignition Facility has also been supported by Herbert York, formerly the director of the Livermore Laboratory. "You can't stop people from thinking," he said, "but you can tell them you're not going to pay them for it."
#
"AIDS Updates",97,0,0,0
(May '97)
\BTriple whammy\b
A potent combination of three drugs, used together, seems likely to be effective in reducing the levels of \JHIV\j virus in the \Jlymph\j nodes, a major reservoir for the virus. The aim is to attack two enzymes that the virus requires. One of these, \Ireverse transcriptase\i, (RT) is used to convert the viral "\Jchromosome\j" RNA to a DNA form, which allows the virus to lie concealed as DNA. (The "normal" transcription is from DNA to RNA, hence the name given to this enzyme.)
The second \Jenzyme\j is \Iprotease\i, an \Jenzyme\j which breaks down proteins. In the treatment, \JHIV\j patients (that is, people who were \JHIV\j-1 seropositive) were given two RT inhibitors, AZT and 3TC, along with a protease inhibitor called ritonavir. In the study, the three-drug mix lowered the viral concentrations by 99% in the \Jtonsils\j, a type of \Jlymph\j node. There are reasonable grounds to think that the same results might be achieved in the major \Jlymph\j nodes, which up until now have been out of reach for treatments.
But while there is hope, nobody has yet been cured, and the lowered levels will probably rely on continuing the treatment. And more importantly, there seems to be no ready way of dealing with the cells which contain \JHIV\j DNA, which can break out at any time, producing more virus particles to reinfect the body.
\BAIDS vaccine plan from Clinton\b
President Clinton, echoing President Kennedy's target for a moon landing, has called for a ten-year timetable to create an AIDS vaccine. Some researchers feel that the timetable is folly, that the vaccine will come when certain unknown discoveries are made at an unknown time, while the moon landing program was a straightforward exercise in \Jengineering\j. Others feel that the timetable adds a sense of urgency to the issue of finding a vaccine.
\BBaltimore challenges the standard view\b
Nobel laureate David Baltimore suggested during May that \JHIV\j may actually disarm the cytotoxic T-lymphocytes (CTLs), white blood cells which are commonly thought to seek out and destroy \JHIV\j-infected cells, all on their own. If Baltimore is right, this could explain why some experimental vaccines work in monkeys.
The immune system can only make CTLs to attack a specific pathogen if bits of that pathogen are held on the surface of the infected cell, acting as a flag to indicate that the cell has been taken over. According to research that Baltimore described, an \JHIV\j protein called nef seems to block the cells from sending this signal.
If monkeys and humans are infected with \JHIV\j strains that lack the nef gene, they do not seem to be affected in the usual way, presumably because the immune system is able to stimulate the production of CTLs which will then seek out and destroy any infected cells.
David Baltimore has announced that he will be moving to the \JCalifornia\j Institute of Technology as its new president. He will, however, remain as the head of the AIDS vaccine advisory committee at the National Institutes of Health, a post which he only recently took up.
#
"Genetics News",98,0,0,0
(May '97)
\BWatson and Hitler\b
Another Nobel laureate in the news addressed a molecular medicine conference in \JGermany\j, and raised howls of annoyance over his comments. James D. Watson was the co-discoverer of the structure of DNA, and the founder of the Human Genome project, so when he urged \JGermany\j to be less hostile to \Jgenetics\j research and to focus on the great benefits that applying \Jgenome\j research can offer humankind, it might have been better if he had not added that it is time to " . . . put Hitler behind us."
The Nazi regime of Adolf Hitler hijacked the name "\Jeugenics\j", and used it to justify all sorts of atrocities, including the infamous concentration camps, and the German reaction to anything involving \Jgenetics\j has been colored by this ever since. After making even more contentious remarks about the Nazi era, and the fate of those who served the regime, Watson turned to what the Germans are doing about the human \Jgenome\j project. German funding for the project, he suggested, was too low. "Your budget is still totally inadequate for \JGermany\j to have a real impact" he said. "You are putting money in to use the \Jgenome\j, not to get it."
#
"Gene Patents",99,0,0,0
(May '97)
European patent law states that an inventor cannot take out a patent on any discovery that has already been made known to the public. One result of this is that DNA data, once published are no longer patentable under European law. In the United States, discoverers are allowed a one-year "period of grace" in which to prepare and lodge a patent application, after the results in question have been reported in the scientific literature.
The members of the international Human Genome Organisation (\JHUGO\j) have called for a similar provision to be offered to European scientists, so they can report their results just as fast as they get them. Failure to allow this could undermine the whole standard of scientific cooperation that scientists accept as normal.
At the same time, the \JHUGO\j's 10-member intellectual-property committee who made the plea also criticised the American Patent and Trademark Office, whose director has suggested that patents should be granted on short stretches of genes known as "expressed sequence tags." This, they say, could mean that somebody who merely describes a sequence, without identifying its function, would be able to lay claim to it.
#
"A Complete Genome",100,0,0,0
(May '97)
As an example of the sort of cooperation which scientists regard as normal, May 29 saw the first publication of a complete \Jgenome\j or a eucaryotic organism: in this case, the yeast, \ISaccharomyces cerevisiae\i, which was published as a separate supplement to the week's issue of \INature\i.
\BGenomics\b
But once we have the information, how do we use it? During May, a consortium of companies stitched up a 5-year $US40 million deal to develop what they call "functional genomics" at the \JMassachusetts\j Institute of Technology (MIT).
There are probably 60 000 to 100 000 genes in the human \Jgenome\j, and the Human Genome Project has brought us to the stage where we have a rough map of the 3 billion nucleotides in human DNA. These maps are studded with thousands of the landmarks called "sequence tagged sites" that the director of the US Patents and Trade Marks Office thinks ought to be patentable.
Now it is time to put that information to work in biomedicine, and to speed up the identification of sequences. The companies in the consortium will get access to the new technologies that will develop during the program. This area of science may well soon be part of industry and business, rather than a part of science.
#
"DNA--Double Double Helix",101,0,0,0
(May '97)
Just when we think we know what it is all about, as we sequence genes, clone sheep, insert genes into other animals and more, up comes a surprise nobody ever expected. The name "double helix" is synonymous with DNA for all scientists, and even for those lay people with some general interest in science, but now DNA has been spotted which does not fit this label. Instead, it is a quadruple helix.
This is not entirely a new phenomenon, because some types of synthetic DNA have been known to form quadruple strands, but these were unusual forms of DNA, and some researchers thought the quadruple strand could have been formed during the preparation of the samples. Now a report from Stephen Salisbury and his colleagues at the Cambridge Crystallographic Data Centre describes a quadruple \Jlinkage\j in natural DNA.
In normal DNA, the two strands are linked when a \Jthymine\j and an \Jadenine\j form an AT \Jlinkage\j, or when a \Jcytosine\j and a \Jguanine\j form a CG \Jlinkage\j. In the quadruple strand, two AT pairs in one double helix have managed to link to two TA pairs in the other double helix. A positive sodium ion "glues" the arrangement by exerting a pull on four negatively charged oxygen atoms on the four \Jthymine\j molecules.
The conditions in which the quadruple strand formed are fairly normal, leading Salisbury to speculate that such arrangements might play a part in real life, perhaps in the process of "crossing over" which occurs as gametes are formed, when \Jchromosome\j pairs swap material with each other. These exchanges of material need to happen at exactly the right place, or faulty chromosomes will be formed. That means that the chromosomes need to be lined up perfectly, so maybe the quadruple strand is something that happens in all sorts of cells, all the time, ensuring the formation of perfect genetic sets of sperm cells and ova.
#
"A Gene for ADHD?",102,0,0,0
(May '97)
Cynical teachers have remarked for years that attention-deficit \Jhyperactivity\j disorder (ADHD) is caused by a failure of parents to pay due attention to their offspring, that the problem is hypoactive parents, rather than hyperactive children. This attitude is due in large part to the enthusiasm with which some parents seek to have their children diagnosed as "ADD", but behind that, there is a genuine condition which affects around 4% to 6% of school-age children. These children fidget, fiddle, call out impulsively in class, and have a short attention span.
Previous research has indicated that there could be multiple genes involved, with chromosomes 5, 6 and 11 all being identified as sites for such genes. That research, however, did not indicate whether the condition was an "all or nothing" problem, or whether ADHD came in a variety of levels, possibly requiring different responses or levels of response.
In the June issue of the \IJournal of the American Academy of Child & Adolescent Psychiatry\i, an Australian researcher, Florence Levy of the Prince of Wales and Sydney Children's Hospital, reports on a survey of almost 2000 families with children aged between 4 and 12. In the survey, Levy and her team asked parents to rate their children on fourteen ADHD symptoms identified by the American Psychiatric Association.
By looking at siblings, non-identical and identical twins, the team were able to analyse the data. They conclude that genetic factors account for 75% of the variability, much higher than the levels seen with other behavioral problems that are inherited, like \Jschizophrenia\j or \Jalcoholism\j.
More interestingly, those groups with more of the fourteen symptoms did not seem to show increased levels of heritability, suggesting that ADHD is not a case of an "all or nothing" condition. (If it were an "all or nothing" situation, the probability of inheriting should be increased when those involved carried a high genetic load.)
#
"DNA of Worms",103,0,0,0
(May '97)
DNA sequencing has become a powerful tool for taxonomists, the scientists who classify plants and animals. A recent study suggests that the moulting invertebrates have some family resemblances, and that the ability to moult arose once only in the history of life, descending into the different phyla as \Jevolution\j progressed.
On this basis, researchers argued this month for a grouping called the Ecdysozoa, the moulting animals, made up of arthropods, tardigrades, onychophorans, nematodes, nematomorphs, kinorhynchs and priapulids. Interestingly, \Jgenome\j research on the invertebrates has concentrated on the nematode \ICaenorhabditis elegans\i and the fruit fly \IDrosophila melanogaster\i (an arthropod), which are generally thought to be very distant relations, but which both fit into the proposed new group.
\BDo worms get cancer, too?\b
More than a third of the human genes which have been linked to different diseases are echoed in the genomes of our most distant relatives. Even worms, yeast and \Jbacteria\j show similarities to ourselves. Scientists are now wondering if this means that they will be able to carry out research and tests on simpler animals to deal with these problem genes, or at least to unravel the biochemistry involved.
The researchers identified a number of genes linked to conditions like bowel cancer and \Jobesity\j, and then scanned for related sequences in databases of gene sequences for the yeast \ISaccharomyces cerevisiae\i, the \IEscherichia coli\i \Jbacteria\j, and the \ICaenorhabditis elegans\i \Jnematode\j worm. While they got hits in the 10-20% range for \Jbacteria\j and yeasts, the worm database produced a matching rate of 36%.
#
"Entire Human Chromosome in a Mouse",104,0,0,0
(May '97)
A Japanese team announced that they had succeeded in transferring a whole human \Jchromosome\j, regulatory sequences and all, to a mouse. This is about fifty times more DNA than has ever been transferred to a mouse before-the usual has been just a few isolated genes, which often do not operate fully when they are inserted in isolation. The work was reported at the end of the month in the June issue of \INature Genetics\i.
#
"MS Cure in Mice",105,0,0,0
(May '97)
Researchers at Stanford University reported in the \IJournal of Experimental Medicine\i on a form of gene therapy which worked in treating mice with a condition which mimics multiple sclerosis (MS). While this is only a small step, it must offer some hope that there is a future for gene therapy for those with the human MS condition.
\BA model for Alzheimer's in mice\b
The last issue of \INature\i for the month revealed that scientists have developed a strain of mice who appear to model the early stages of Alzheimer's disease. The mice show neuron and memory loss without plaques, which means that they may be suitable test animals for drugs intended to slow the onset of the condition.
#
"Alzheimer Remembered",106,0,0,0
(May '97)
Recent studies of 90-year-old \Jmicroscope\j slides have revealed the patient whose case probably got the name of German physician Alois Alzheimer into the medical textbooks. The original case, as described by Alzheimer, did not suffer from Alzheimer's disease, as we now understand it, as Auguste D (as the case is identified) had hardening of her arteries.
The second case, Johann F, is still with us in the form of ninety-year-old slides of brain tissue, and these reveal the tell-tale plaques of the disease. The slides and other records have been found in the basements of the University of Munich, where they have been "lost" for decades.
Even so, Johann F was not a typical case, since he lacked a gene, the Alzheimer's susceptibility \Jallele\j apo-epsilon-4, which is carried by two in every three Alzheimer's sufferers. The name of the disease-"Alzheimer'sche Krankheit" in German, was published in 1910, just before Johann F died, and Alzheimer wrote the name of the disease in the autopsy book. The full report appeared in \INeurogenetics\i this month.
#
"Breast Implants Dangerous?",107,0,0,0
(May '97)
One of the problems with the "scare campaigns" that start up from time to time is that some of them are just that-scare campaigns. And one of the problems with refutations of the scare campaigns is that they can sometimes be wrong.
For some time now, it has been a "well-known fact" that breast implants cause all sorts of problems, and statistics have been produced to demonstrate this, comparing the implantees with other women, and showing that they have a greater incidence of certain problems. Careful analysis has even shown that you could expect problems to arise.
But what if the women who elect to have implants are not typical of women as a whole? Would it be reasonable to compare them with other women? During May, the \IJournal of the American Medical Association (JAMA)\i reported that the women who have implants for cosmetic purposes are very different from their unimplanted sisters.
A sample of 3570 women were sampled in the study, including 80 women who had augmented their breasts for cosmetic reasons. The group of 80 were three times more likely to have seven or more alcoholic drinks in a week, nine times more likely to have had 14 or more sexual partners, and more than twice as likely to have used the \Jbirth control\j "Pill", or to have had an \Jabortion\j.
They were less likely to be overweight, and used hair dyes more, and these factors could all have a "confounding effect", which is scientist-speak for "could cause some or all of the observed differences".
Against that, a 1995 comparison of women who had reconstructive implants and women who had cosmetic implants showed very similar symptoms, suggesting that "life style" causes could be ruled out. As is so often the case in science, the jury is still out on this one.
#
"Prions--How They Work",108,0,0,0
(May '97)
Cells are undoubtedly alive, since they reproduce on their own. Some people argue that viruses are alive, because they can reproduce, even if they only do it in cells, and they have nucleic acid to store a sort of "\Jchromosome\j". What are we to make of prions, the proteins which are believed to cause BSE (mad cow disease), scrapie, and Creutzfeld-Jakob disease (CJD)? These proteins have no nucleic acids, and we have little idea of how they carry out their role-not until now, anyhow.
At the end of May, \ICell\i reported on work by a group led by yeast cell biologist Susan Lindquist of the University of \JChicago\j, who have been exploring the way in which prions operate. They found that there was a characteristic in yeast which could be passed to new generations of yeast, but which involved no changes in the yeast's DNA, a characteristic which causes the yeast cells to clump together.
The cause seems to be a protein, identified as Sup35. When this protein is kept in the test tube, it polymerises into long fibres like those seen in the prion diseases. If a small amount of the polymerised protein is added to a fresh sample of Sup35, the whole solution polymerises more quickly. This matches what has previously been suggested for the operation of prions, and so makes researchers more confident that they know what the mechanism is. The next step: to try the same experiment with the prion proteins.
#
"Cockroaches Linked To Asthma?",109,0,0,0
(May '97)
A report in \IThe New England Journal of Medicine\i during May suggests that cockroaches may be a significant cause of \Jasthma\j in disadvantaged households in the US. The study looked at the effects of three common allergens associated with \Jasthma\j, the faeces of dust mites, the faeces of cockroaches, and feline skin flakes, the equivalent of cat \Jdandruff\j.
The research revealed that children who were allergic to cockroaches, and who also had high levels of cockroach allergen in their bedrooms, were more than three times as likely to be admitted to \Jhospital\j for \Jasthma\j attacks than other children. Even after other factors were taken into account, the effect remained significant, but the researchers say that they have not been able to rule out the possibility that fungi, or rat or mouse droppings may also be involved. In the mean time, it looks as though there is a good market out there for environmentally friendly roach baits.
#
"Chernobyl Still A Risk",110,0,0,0
(May '97)
It is now more than eleven years since the disastrous explosion at \JChernobyl\j, but the risk is not over yet. An international program costed at $US780 million will be set in operation over the next few months, aimed at reducing the risks of a second explosion.
After the first explosion, a plume of radioactive \Jisotopes\j poured out, and the fuel of the reactor melted and flowed into the rooms below the reactor chamber, and then cooled and solidified. A concrete shell, referred to as a sarcophagus has been built over the chamber, but gaps have allowed \Jwater\j to leak in-as much as 3000 tonnes of it. This could act as a moderator, slowing neutrons and triggering a faster reaction, or even a full explosion, as a \Jchain reaction\j takes off.
In a normal reactor, controls are in place to stop any \Jchain reaction\j running wild, but the uncontained fuel is not in a position to be controlled. The risk of the mass of fuel "going critical" is thought to be low, but without the \Jwater\j, there will be no risk at all. There have been at least three occasions since 1990 when the neutron flux increased inside the sarcophagus, reminding us that the present low risk is not enough.
The rescue program involves fitting new neutron detectors, draining the radioactive \Jwater\j, building a new sarcophagus, and creating robots that can move into the "hottest" parts of the sarcophagus, where humans cannot venture. These robots would be able to take fuel samples and measurements, allowing better planning to be carried out.
#
"Dinosaurs Ancestors of Birds?",111,0,0,0
(May '97)
Most palaeontologists say that the dinosaurs were the ancestors of the birds, and a few of them will even go so far as to claim that the dinosaurs are still alive today, only we call them birds. (This point of view is represented in the original "Jurassic Park" movie in the scene where the small dinosaurs are observed to be "flocking this way".)
The problem is that there are a few gaps in the record from "\Jdinosaur\j" to "bird", but an Patagonian \Jfossil\j, revealed during May, may help to close the largest of the gaps. A team from the Argentinean Museum of Natural Sciences, led by Fernando Novas, found a \Jfossil\j \Jdinosaur\j, about 1.5 metres tall, with a pelvis which was intermediate between the pelvis of \IDeinonychus\i (picture the \IVelociraptor\i of Jurassic Park) and that of Archaeopteryx, which had feathers 150 million years ago, and is usually recognised as the "first bird".
The \Jfossil\j theropod, named \IUnenlagia comahuensis\i, is only about 90 million years old, so it is ruled out as a bird ancestor, but the \Jscapula\j (shoulder blade) of the beast suggests that it ran with a flapping motion, exactly the sort of motion you would expect to see if flight is evolving. The assumption is that some of \IUnenlagia\i's ancestors carried their flapping into the air, while others just continued to use it on the ground.
#
"Largest Dinosaur Unearthed!",112,0,0,0
(May '97)
Also revealed in May was the skull of the biggest meat-eating \Jdinosaur\j seen on \Jearth\j, dwarfing even \ITyrannosaurus rex\i, but with many of the same unfriendly features (if you are a smaller piece of meat, that is). Along with \IT. rex\i and \ICarcharodontosaurus\i, a giant meat-eater found by Paul Sereno in Morocco, the 100 million year-old \IGiganotosaurus carolinii\i of Rodolfo Coria is in good company, but it retains top position, with a skull 180 cm long.
Palaeontologists are now beginning to consider that there may be more riches to be uncovered in the sediments of \JSouth America\j: after that, it will be time to explore the other parts of \JGondwanaland\j, \JAntarctica\j and \JAustralia\j, to see what secrets they are harbouring.
\BChina in the wings\b
Then the hunt will need to move on to China, where a massive new deposit has been found in the Yixian formation of the Liaoning province of north-east China. Hundreds of early birds and dinosaurs are to be found there, and already a female dinosaur called \ISinosauropteryx\i has been excavated which has a fossilised \Jmammal\j carcass in its gut and an egg in its oviduct. The site is on the edge of the Jurassic-Cretaceous boundary, and promises to reveal a great deal more over the next few years.
#
"Humans Once Giants?",113,0,0,0
(May '97)
As an example of the sort of problem which can only be solved by studying whole populations of fossils, a letter to \INature\i (May 8) estimates that the body mass of humans has dropped 13% over the past two million years, having climbed to a peak about 1.4 million years ago, and only dropping to modern levels about 100 000 years ago. The authors, C B Ruff, Erik Trinkaus and T W Holliday, have developed a new method of estimating body mass, and applied it to a sample of 163 Pleistocene \IHomo\i specimens.
#
"Brain Surgery in Stone Age",114,0,0,0
(May '97)
A skull, more than seven thousand years old, has been excavated from a Stone Age burial site in \JAlsace\j. Trepanning, or removing sections of the skull bone is a common African treatment for a variety of conditions ranging from headache to \Jepilepsy\j, but this skull suggests to us that the practice of trepanation was known and used in Stone Age Europe. There are two holes in the skull, the larger one being 9 cm in diameter.
#
"Modern Humans in Europe, 800 000 y.a.",115,0,0,0
(May '97)
New human remains, believed to be 800 000 years old, have been found at Atapuerca in \JSpain\j. They appear to have had a face rather like that of modern humans, and are being treated by some as the ancestors of both the Neandertal people and \IHomo sapiens\i. But this claim, and the claim for a separate species, \IHomo antecessor\i, are both being questioned by many palaeontologists.
This is hardly surprising given that the palaeontologists are largely divided into "splitters" and "lumpers", those who hail new species at every opportunity, and those who would squeeze everything into a small box with just a single label.
The discoverers, palaeoanthropologists JosΘ Berm·dez de Castro and Antonio Rosas of the National Museum of Natural Sciences in Madrid and their colleagues, have uncovered 80 fossils from a boy and five other early humans. They clearly identify themselves as splitters, since they refer in their report to \IHomo heidelbergensis\i, but the claim, based as it is on the facial features of the boy, intermediate between modern humans and the Neandertal people, is going to need a lot of support before it finds general favor.
#
"Mapping Fossil Hot Spots",116,0,0,0
(May '97)
Across the Pacific ocean, chains of volcanic islands show us where the plates of the crust have dragged across stationary hot spots. As the crust passes over the "hot spot", where a plume of hot rock is pushing up from deep inside the \Jearth\j, the hot rock occasionally bursts through, forming a marker for a former position of the hot spot which remains as the crustal plate trundles on.
Many of the volcanoes only exist as seamounts, volcanic mountains eroded down until they sink beneath the sea, mountains which then remain as comparative shallows, completely hidden under the sea. The recent release of declassified \Jsatellite\j data gave Paul Wessel and Loren Kroenke of the University of Hawaii just what they needed: information on 8800 Pacific seamounts.
Three accepted hot spots are near Hawaii, Rarotonga, and \JLouisville\j, but the aim of the study was to find more of these, including the hot spots which have since "burned out". Using simple \Jgeometry\j, the researchers were able to back-track the three established hot spots, but none of the other dozen or so expected hot spots stood out. This failure has led some researchers to question the plume theory, but it may also stem from something as simple as shallow hot spots which drift over time.
Most interestingly, the \JLouisville\j hot spot is now likely to lie on the Hollister Ridge, south of the Eltanin fracture zone.
#
"Corn Plant's Defence",117,0,0,0
(May '97)
The \Jmetaphor\j of warfare is a popular one to describe \Jevolution\j, but corn plants seem to have elected to take the \Jmetaphor\j seriously. Beet armyworm caterpillars chewing on corn leaves dribble as they go, and the dribble contains a chemical which stimulates the leaf to release chemical vapors. Unfortunately for the caterpillar, the chemical vapor acts as a dinner call for parasitic wasps which fly in, laying eggs in the caterpillar, so the grub eventually dies.
Researchers have shown that mechanical chewing has no effect on the leaves. Without caterpillar spit, there is no reaction at all. But given the spit, which contains a chemical that researchers have dubbed "volicitin", the corn pumps out a mix of terpenoids and indole which calls in an air strike of wasps every time.
Now come the problems: working out why \Jevolution\j has left the caterpillars producing this chemical, which must be important to them, and how this can be used to help control crop pests. There is no future in spraying volicitin on crops, as this would simply confuse the wasps, and prevent them finding places to lay eggs, but somewhere in there, scientists think there are some useful tricks, just waiting to be found.
#
"Nereus, A Close Look",118,0,0,0
(May '97)
Japanese plans to explore an asteroid looked firmer this month, after NASA indicated that they will supply a robotic rover and ground support to the mission, due for launch in January 2002 on a 20-month mission to \JNereus\j.
In theory, the \Jasteroids\j are original rocks, unchanged since the start of the \Jsolar system\j, the sort of stuff that we see when meteorites fall to \Jearth\j. In this case, however, the samples will be free of any heating effects from friction, so the samples will reveal just how close these meteorite samples are to the rocks of space.
MUSES-C, the US$104 million \Jspacecraft\j, will drift alongside the asteroid for two months, landing three times to collect samples. The main problem will be collecting rock samples on conditions that are close to zero-gravity. The plan is to fire a metal projectile at the asteroid, knocking off fragments of rock, some of which will be caught in a funnel and carried into the \Jspacecraft\j.
Japan's Institute of Space and Astronautical Science (ISAS) will be working on some exciting new technologies, especially an ion-thruster propulsion system which should reduce the weight of the fuel that rockets must carry by a significant amount.
#
"Hubble Looks At M84",119,0,0,0
(May '97)
There was slightly bad news and very good news from Hubble this month. As we indicated in the April update (\IHubble trouble\i?), the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is causing some worries. Two of the cameras are doing very well indeed, but the continuing loss of coolant means that the camera is likely to have only half its expected life, so schedules have been rejigged to give NICMOS up to 50% of the Hubble's time over the next 18 months. Still, not everything was gloomy.
"You can have any color you like," Henry Ford is supposed to have said of his Model T, "so long as it's black." Logically, a black hole emits no light, and can have no spectrum, but the gas which whirls around, close to, but beyond the black hole's horizon, does indeed have a spectrum. The Hubble Space Telescope's Space Telescope Imaging Spectrograph (STIS) has taken a close look at the centre of M84, a galaxy 50 million light-years away, where there is a black hole at the galaxy's centre. They have come up with a spectrum for the light coming from the gas and dust which orbits the black hole at 400 kilometres/second, 1.5 million kilometres or 900 thousand miles an hour.
Why does this matter? Well, given that speed, you can work out the mass of the black hole, which apparently weighs as much as 300 million copies of our \Jsun\j. As we explained in the February update(\IHubble gets a facelift\i), the STIS is able to sample multiple points simultaneously, so it can survey an entire black hole in just twenty minutes, and researchers expect to survey hundreds of black holes over the next few years. With a population of black holes to work on, physicists hope to have a better understanding of the way the universe works over the next few years.
#
"Dark Matter Mystery Gets Worse",120,0,0,0
(May '97)
There are certain basic assumptions that physicists and astronomers take for granted. One of these is that orbiting bodies which travel incredibly fast can only do so if they are travelling around a very massive object. The mass of the orbiting body itself does not matter-it can be very light, very heavy, or anywhere between, and it will still move in exactly the same orbit. A heavier orbiting body feels a greater pull from gravity, but also needs more force to keep pulling it into its orbit.
Still, if you have very fast orbiting bodies, you can at least tell that there has to be a lot of mass at the centre. This rule applies also to a galaxy where the stars are travelling swiftly around the orbital centre. But what lies at the centre? Some kind of "\Jdark matter\j" is the best answer we can give right now, making the identification of the "\Jdark matter\j" very interesting to astrophysicists.
Infrared observations of NGC5907, a spiral galaxy similar to our own, reported in \INature\i at the start of the month, indicate that the centre of that galaxy contains a large number of very small stars which are rich in heavy elements. The only snag is that our galaxy seems to have no such stars, and theory tells us that these stars, deep in the galactic halo, should be poor in heavy elements. Instead of helping, these observations seem only to have made matters worse. It's enough to make a physicist sick.
The penguins must certainly be feeling sick. A resistant avian virus, infectious bursal disease, appears to have been spread to emperor penguins in the Antarctic. The disease, which is common in domestic chickens, causes haemorrhaging and breathing difficulties, and often kills its victims.
The cause of the spread of the disease is unknown, but it has likely to have been introduced after the careless disposal of the remains of chicken products. In tests, up to 65% of the penguin chicks tested around the Australian Antarctic base at Mawson showed \Jantibodies\j to the disease.
This month, Mark Sobsey told an American Society of Microbiology meeting that sewage pumped from tanks on airliners routinely contained infectious viruses which had survived the disinfectants used in the tanks. Should we be suspicious about airliners flying tourist trips to \JAntarctica\j, and discharging their tanks, or worse, their kitchen refuse? Not so, according to our spy in the airline industry, who says that all wastes are carried back to the airport where the plane lands.
#
"Mitochondria, The Evolution",122,0,0,0
(May '97)
How did the mitochondria, the power houses of the cells, evolve? The most popular answer today is that they arose by \Iendosymbiosis\i. Rather than creating such things by themselves, large cells engulfed smaller cells with useful powers, and rather than digesting the smaller cells, they adopted them, setting up a mutually satisfactory arrangement, where the small cells had a safe home, but made their own special contribution to the operation of that home.
One piece of evidence supporting this theory is that the mitochondria have their own DNA, or at least their own scraps of DNA, but up until now, nobody has been sure what the original mitochondria were like, though the rickettsial group of alpha-proteobacteria fills the role of "usual suspect".
A freshwater protozoan \IReclinomonas americana\i has a huge helping of mitochondrial DNA, with 69 034 base pairs making up 97 genes, the largest collection of genes so far identified in any mtDNA that has been studied. There are even four genes specifying a multi-subunit, eubacterial-type of RNA polymerase. Together, these discoveries (reported in \INature\i this month) suggest that this \Jmitochondrion\j is closer to the original form of free-living \Jmitochondrion\j than any other studied so far.
#
"Red Algae Rewrite Family Tree",123,0,0,0
(May '97)
And in a related story which broke at the very end of April, the red \Jalgae\j were promoted into a new branch of life, at least by some researchers who reported in the \IProceedings of the National Academy of Sciences\i about the family tree of the red \Jalgae\j.
John Stiller and Benjamin Hall of the University of Washington, Seattle have been studying the gene for RNA polymerase in chloroplasts. Like the mitochondria, the chloroplasts probably had an independent origin, and were taken up by other cells in endosymbiosis. The usual assumption is that this invasion, occupation or whatever happened once and once only, and that all chloroplast-bearing cells are descended from that event.
Looking at the gene for RNA polymerase, the researchers find evidence that the simple common-ancestor model has problems. It looks as though one of three scenarios was played out, although it is hard to say which one, since all offer some attractive explanations of other observations:
ò an ancestor of the green \Jalgae\j engulfed a \Jchloroplast\j, and so did an ancestor of the red \Jalgae\j, or
ò all organisms once had chloroplasts, and many of them lost them, or
ò the ancestor of the green plants engulfed a red algal cell to gain the \Jchloroplast\j through \Isecondary endosymbiosis\i.
Changes to family trees, base on the analysis of single genes, tend to be changed back when a few more genes are examined, but in the mean time, quite a few people are looking at the read \Jalgae\j in a different light.
#
"Jupiter Update (May 97)",124,0,0,0
We already knew that Ganymede has a magnetosphere and a magnetic field, and this raised hopes that Callisto might also have an internally generated magnetic field. New reports in from the analysis of \JGalileo\j space-craft results tell us that this is not the case. The \Jelectron\j density around Callisto indicates that the moon is a generator of plasma, perhaps from a thin Callistan \Jatmosphere\j, rather like the wispy \Jhydrogen\j \Jatmosphere\j of Ganymede. \JGalileo\j flew just 1100 km from the surface of Callisto.
If (as seems likely, given the magnetometer results so far) Io also has a magnetic field, then it will have a large metallic core, while scientists are now fairly confident that Ganymede is made up of a metallic core, a silicate mantle, and a deep outer layer of ice, while they assume that Callisto is most likely to be a homogeneous object consisting of a mixture of 40% compressed ice and 60% rock, iron and iron sulphide. They speculate that perhaps Ganymede was melted in a period of resonant tidal heating by Jupiter, allowing the different parts to mix together.
#
"New Radio Telescope",125,0,0,0
(May '97)
The world's biggest radio interferometer is the New Mexico Very Large Array (VLA), but astronomers are never satisfied with what they have. Astronomers in \JAustralia\j, Canada, China, India, the Netherlands and the United States are planning the Square Kilometre Array Interferometer (SKAI). With 75 times the area of the VLA, this will cost an estimated $US150 million, and involve 34 elements.
Each element will have an area the size of a 200 metre dish, and the elements will be in a circle with a radius of 150 kilometres (100 miles). The resolution will be even better than that obtained by the Hubble Space \Jtelescope\j. While it is in the early planning stages, and a site has yet to be chosen, the planners hope to begin construction on SKAI by the year 2005.
#
"Deep Blue Beats Kasparov",126,0,0,0
(May '97)
As the shock news broke, that Deep Blue had beaten Gary Kasparov, the stories ranged from references to a "Grandmaster machine" through to dismissive headlines along the lines of "giant calculating machine beats Kasparov".
Overall, the consensus was that the machine, while effective in producing winning moves in a chess game, was by no means a thinking machine, and did not play chess in any real sense. Kasparov won the first game, Deep Blue won the second, and the next three games in the six-match series were draws, making the final game into a "sudden death" playoff, where the winner would take all.
As it turned out, Kasparov lost the game, rather than Deep Blue winning, when he made a blunder on his eighth move. It is a well-documented error, and one that a player of Kasparov's standing would be expected to know. The most charitable interpretation is that he showed his humanity, something that even the strongest supporters of Deep Blue would not claim for the machine.
On the other hand, Deep Blue's play in the other games showed what experts called errors, and yet the machine was able to hang on to an ultimate draw. In part, this may have been a result of Kasparov changing his game in an attempt to exploit what he thought were the machine's weaknesses-it is this which lay behind Kasparov's comment that if he had been playing a human of the same strength, he would have won. In chess at high levels, \Jpsychology\j is all-important, but it looks as though, in this case, Kasparov was largely responsible for his being "psyched out".
#
"ALH84001 Less Likely To Contain Signs of Life",127,0,0,0
(May '97)
A report in \INature\i this month indicates that the "Martian life \Jmeteorite\j", ALH84001, contains \Jcarbonates\j which formed at high temperatures. The original argument was that the \Jmeteorite\j, which is undoubtedly of "shocked" origin (that is, it was struck a very hard blow at some point, and it is very probably of Martian origin. What was less certain is whether or not the \Jcarbonates\j in the rock are associated with globules formed by living things. If the \Jcarbonates\j formed at low temperatures, they may well have formed around life forms of some sort.
New petrological studies show that the \Jcarbonates\j, plagioclase and \Jsilica\j were all melted and partly redistributed in the same shock event that crushed the pyroxene in the \Jmeteorite\j. It now looks as though the \Jcarbonates\j crystallised from shock-melted material, in which case, there is little chance that the globules in the rock are anything more than artifacts. It looks as though we will have to look again, before we find Martian fossils.
#
"51 Peg's Planet in Doubt Again",128,0,0,0
(May '97)
The \Jplanet\j of Pegasus 51 (alias 51 Pegasi to the astronomers) was reported in December 1996, and reported to be under attack in February 1997, when the \Jplanet\j signs were dismissed as no more than a sloshing on the star's surface. Now astronomers at the \JCalifornia\j Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory suggest that the "\Jplanet\j" may in fact be another star, that 51 Peg is a binary star, in fact.
#
"Leptoquarks Less Likely",129,0,0,0
(May '97)
Although the discovery of the leptoquark was reported in late February (see February update: \IA new particle and a fifth force?\i), searches since then have found no confirmation for the claim. While this does not rule out the existence of the leptoquarks, it makes them less likely-at least in the simple form described in the claims that were coming out of \JHamburg\j.
#
"Breast Cancer",130,0,0,0
0
(May '97)
Two reports published in the \INew England Journal of Medicine\i during May suggest that the so-called breast cancer genes, BRCA1 and BRCA2, may not be such sure signs of a cancer risk as most people think.(See Breast Cancer Genes, April update)
The BRCA mutations are rare, and sampling for the genes has concentrated on families with severe rates of breast and other cancers which break out in young members of the families. In cautious language, the researchers reported that this may well have biased the sample, and any radical action taken with women who carry the gene may be unwise.
More importantly, only 16% of women with a family history of breast cancer proved to have a BRCA1 \Jmutation\j, much lower than the 45% found in previous studies. There is a real risk, say researchers, that if general screening is carried out, women may assume that the absence of the gene means they are not at risk, when a significant risk still remains.
#
"Fermat's Last Case?",131,0,0,0
(Jun '97)
Pierre de Fermat died 332 years ago, leaving behind him what we now call Fermat's last \Jtheorem\j. When he died, it was just one of the many theorems he left behind, but the others were fairly easy to prove, and it soon became the "last". Andrew Wiles was thought to have managed to prove the last theorem in 1993, but there were minor flaws in his proof which were not solved until 1995. Because so many other "proofs" have come up over the years, the committee waited two years before awarding the prize to Andrew Wiles. So it was not until late in June that Professor Wiles finally received the cash prize of a little under $US 100 000, a prize which at one stage was worth almost fifteen times as much.
#
"Blue Planet Prize",132,0,0,0
(Jun '97)
British scientist James Lovelock of Coombe Mill, for many years an independent researcher, and best known as the inventor of the Gaia hypothesis, won this year's $430 000 Blue \JPlanet\j Prize, which is awarded by the Asahi Glass Foundation of \JTokyo\j to people who have helped resolve global environmental problems.
In 1957, Lovelock invented the highly sensitive \Jelectron\j capture detector, which made possible the measurement of ozone-destroying \Jchlorofluorocarbons\j in the \Jatmosphere\j and pesticides in foods, but the award to Lovelock, who is now 77, is rather more for his offbeat Gaia hypothesis. This suggests that the Earth controls its climate and chemistry for the benefit of life, acting as some sort of super-organism. While most scientists find the Gaia theory hard to swallow, it has helped foster their recognition of the role of living systems in influencing climate, and stimulated a great deal of research.
#
"Crafoord Prize",133,0,0,0
(Jun '97)
Another independently-minded Englishman, Sir Fred Hoyle, has just shared this year's Crafoord Prize with Edwin Salpeter of Cornell University, for work the two have done in the area of \Jcosmology\j. This prize is controlled by the Royal Swedish Academy of Sciences, and it is used to cover areas missed by the \JNobel Prizes\j. Each will receive $US 250 000.
In the 1950s, the two astronomers independently predicted the \Jenergy\j level that must exist in the nucleus of carbon atoms if carbon was to be synthesised in stars. This was one of the first examples of the use of an astrophysical argument to predict a fundamental property of matter. Hoyle will always be remembered as the man who coined the phrase "\Jbig bang\j", although, as a follower of the competing "steady state" model of the universe, he intended it to be a disparagement of his opponents' ideas. Hoyle has also written \Jscience fiction\j in the past.
#
"Mir's Problems",134,0,0,0
(Jun '97)
The former \JSoviet Union\j's 11-year-old spaceship "Mir" got into serious trouble in late June. A "Progress" cargo carrier, remotely guided by a Mir \Jcosmonaut\j, ran into the Spektr science module of Mir, opening a hole which was estimated from air loss rates to be about the size of a postage stamp. The main problem was that the hole could not be seen, and may be either a puncture or a gash. In either case, the hole needs to be found and patched, if it can be.
So far, nobody has been hurt, but the U. S. \Jastronaut\j, Mike Foale, had a narrow escaped from the Spektr module as its air escaped into space after the collision. Early July will see two astronauts, Vasili Tsibliev and Aleksandr Lazutkin, going outside the station in pressure suits to try to fix the \Jsolar power\j supply which normally provides 55% of the station's power, as one of the four solar panels was damaged in the collision. They may have difficulty getting through the 80 cm hatch on the Spektr module in their space suits, which were designed for a 100 cm opening.
This is not the first glitch Mir has encountered this year. A faulty oxygen generator, a major fire and \Jtemperature\j control problems have all plagued the craft, along with a near miss from another supply craft last March, and now the whole future of Mir is now up for grabs. The problem is that any decision to shut down Mir will probably lead to delays in the whole Russian space program, including the International Space Station-the first module of which is due for launch in just a year from now, all going well-if it can.
#
"Red Centaur Asteroids Spark Interest",135,0,0,0
(Jun '97)
A group of Centaur \Jasteroids\j can be found in the outer \Jsolar system\j, well beyond the \Jorbit\j of Jupiter. Two of these were described at the American Astronomical Society conference during June, because they are of particular interest. The Centaurs in question, 5145 Pholus and 1995 GO, are redder than any other \Jasteroids\j in the entire \Jsolar system\j.
According to David Weintraub, who led the study of these \Jasteroids\j, this red color is likely to be due to a covering of raw organic matter and minerals, similar to the stuff that life in the \Jsolar system\j (wherever it may be found) was assembled from. Most \Jasteroids\j have a bluish color, but it is possible that the orbiting bodies in the Kuiper Belt, out beyond Pluto, are likely to still carry the original material because there are fewer collisions, and there is less heating to abrade or remove these materials.
Weintraub believes that some of the Centaurs have strayed in towards the orbits of Neptune, Uranus and Saturn, and that the occasional Centaur can then be slung out into interstellar space, or in towards the centre of the \Jsolar system\j. The red color, he suggests, comes from compounds rich in carbon and \Jnitrogen\j, pointing to the need for more study.
#
"Asteroid in Earth's Lagrangian Points",136,0,0,0
(Jun '97)
A new companion of the \Jearth\j has just been unmasked. Asteroid 3753 (1986 TO), discovered in 1986, seems to be trapped in a complex \Jorbit\j that involves the \Jearth\j. The \Jorbit\j swings out towards Mars, and in towards Mercury, but the centre of the \Jorbit\j traces out a horseshoe pattern around the \Jearth\j, with a full orbital cycle of 385 years.
There are many near-\Jearth\j \Jasteroids\j, ranging in size from a few metres to more than 30 km across, many of them on orbits crossing that of the Earth, but none has previously been identified as having an orbit associated with our own. 3753 is just 5 km across, and it moves in a "horseshoe orbit, a familiar feature of the gravitational three-body problem, but only known otherwise from two satellites of Saturn, Janus and Epimetheus, both of which have orbits less intricate than that of 3753. The asteroid's orbit is an "overlapping horseshoe", dynamically locked to the Earth.
Apart from the Moon, 3753 is the only known natural companion of the Earth. While theorists had long recognised the possibility that our \Jplanet\j might have a small partner conducting a complex orbital dance like this, it remained hidden until three astronomers, Paul Wiegert and Kimmo Innanen of York University in \JOntario\j and Seppo Mikkola at the University of Turku in \JFinland\j analysed the path of a small asteroid.
As far back as 1772, Joseph Louis Lagrange demonstrated the existence of what we now call lagrangian points, positions in space where a third object, like an asteroid, can sit comfortably in a stable \Jorbit\j. While astronomers have found swarms of \Jasteroids\j in Jupiter's lagrangian points, \Jasteroids\j known as the Trojans, no such companions for \Jearth\j had been found. 3753 follows a circuit which takes it around both lagrangian points, travelling first around one Lagrangian point, then going the long way around the Earth's \Jorbit\j to the other lagrangian point, circling it, and going back again, to complete the cycle in 385 years.
But that is only the asteroid's average path, and it swoops off to cross the path of Venus at times, before swinging back across our path from time to time. But there is no need to worry: we are unlikely to collide soon, even on the next occasion that the orbits are predicted to intersect, in 2750 years.
#
"Lost Friendly Planet?",137,0,0,0
(Jun '97)
Nobody has ever really been able to explain how Bode's Law, more correctly called the Titius-Bode Law, works. It successfully predicted the location of Uranus, but has nothing to say about the locations of Neptune and Pluto, besides predicting a \Jplanet\j more or less where the asteroid belt is today. In fact, the asteroid belt was once thought to be made of Bode's missing \Jplanet\j, reduced to a rockpile by some nasty catastrophe.
Working from a different direction, says Dimitris Christodoulou, also addressing the American Astronomical Society, he has come up with a similar answer to Bode. Christodoulou was modelling the way in which gas and dust would settle out around the young \Jsun\j, using a Bessel function, a complex equation. Because he did not know where the peaks of the function would arise, he made the reasonable assumption that the third \Jplanet\j lies at the third peak, and looked to see what else would happen.
Mercury, Venus and Earth neatly fill the first three slots, with the fourth peak empty, Mars close to the fifth, the Hungaria \Jasteroids\j at the sixth, the main asteroid belt across the seventh to tenth peaks, while the outer planets fit neatly into slots, although leaving some free. But what about that empty fourth slot, asks Christodoulou? Does it indicate the \JPlanet\j that Never Was, or does it indicate a planet that formed and went away again? Other astronomers are sceptical for the moment, pointing to the other empty peaks among the outer planets, so for the moment, the Christodoulou model remains in the realm of curious but interesting.
#
"Hubble Sees Double Vision",138,0,0,0
(Jun '97)
At the same meeting of the AAS, researchers announced what they think is the aftermath of a collision between two supernovas. It began with astronomers looking at a bright object 17 million light-years away in the \Jconstellation\j \JCepheus\j, which turned out to be a very bright object, too bright to be a young supernova, as astronomers had first suspected. More importantly, a dust \Jcloud\j rushing away from the object implied an age of several thousand years. The Hubble space \Jtelescope\j has now been used to resolve the issue, and it has found not one, but two objects, about 40 light years apart. The shock waves of expanding gas from each star had collided, compressing the shells and providing a stellar light show second to none.
#
"Boomerang Nebula--Coldest Spot?",139,0,0,0
(Jun '97)
Space is cold at the best of times, but some bits are colder than others. Now astronomers think they have found the universe's coldest spot in the Boomerang Nebula, a \Jcloud\j of gas and dust that is being ejected by an old star before its core collapses into a white dwarf. By studying the signature of carbon monoxide in the gas \Jcloud\j, they find that the expanding and cooling \Jcloud\j is absorbing heat from the background radiation, making it cooler than 3 K. The discovery brings a problem with it: if very old stars are very cold, this may mean that they will be very much harder to detect.
#
"Robots on Mars",140,0,0,0
(Jun '97)
With the landing on Mars the main news as this report is assembled (more on that next month), plans are already under way for bigger and better expeditions. At the high end, NASA is dreaming about people on Mars by 2010, while at the low end, a new robot was let loose on the high Chilean \JAndes\j during June, controlled from a mere 8000 kilometres away, rather easier than the 20-minute delay with a Mars robot.
Scientists at Carnegie Mellon University were behind the project, working from the Carnegie Science Center in \JPittsburgh\j as they ran Nomad. Its predecessors include Dante II, which explored a \Jvolcano\j in \JAlaska\j 2 years ago, after a disastrous earlier attempt in \JAntarctica\j. Nomad is expected to cover 5 kilometres of the Atacama desert a \Jday\j, and to simulate several sorts of search, as well as providing 360░ images, stereo color photographs and information from assorted sensors and metal detectors.
#
"Cyberlaw Code of Conduct",141,0,0,0
(Jun '97)
So far as the USA is concerned, if you want to use secure encryption systems and you are a foreigner, forget it. If you are an American citizen, you may not transmit software which carries out encryption, and even the algorithms for encryption are prohibited exports, being classed as munitions. Why? Well, if Uncle Sam gets into a war with you, Uncle Sam wants to know what you are thinking and saying. And Uncle Sam has decided against "giving guns to the Indians", a lesson they learned in the Wild West, and now apply to the world. So even the most unlikely future enemies are denied access to really secure encryption tools, no matter what their need.
Aside from military considerations, the US government is also determined to stop drug dealers and other criminals getting access to encryption tools, so only encryption systems using a 40-bit key could previously be exported, although this has recently been raised to allow 56-bit key systems. A 40-bit system means that anybody wanting to crack a coded message had to be able to find a number which lies somewhere between 0 and 2\U40\u, or about 1.1 trillion. In a 56-bit system, the number can now be as large as two raised to the 56th power, or about 72 quadrillion, which is 72 followed by fifteen zeroes.
Unfortunately, one of these 56-bit systems has already been cracked, so now the US government has offered to allow longer keys, but only under conditions which critics say could leave the whole system open to abuse, since your message must contain its own key, encrypted according to a US government standard that they can read. This "key recovery" system would make a single point of failure which hackers would fall upon with glee.
The comparatively weak 56-bit Data Encryption Standard (DES) was trumpeted in January this year, when the secure software maker, RSA Data Security set up a $10 000 challenge, with a message posted on the \JInternet\j in encrypted form. Decoded, it reads "Strong encryption makes the world a safer place". They were less than embarrassed when the challenge, expected to last for years, was met within four months. RSA president Jim Bidzos, who had offered a $10,000 bounty to the successful code-cracker, said "We've been saying for a long time that DES is no longer secure and here is the proof."
The code was broken by Rocke Verser who recruited up to 14 thousand \JInternet\j users to crunch through up to 7 billion keys a second, using their spare computing time to crank through the possible keys. In the end, Verser was lucky, finding the key after just 17 quadrillion keys had been tried. Slowly, ever so slowly, the barriers are coming down: during June, Pretty Good Privacy Inc. obtained U. S. government approval to export 128-bit encryption technology to foreign subsidiaries and branches of large US companies. This encryption software is free of key recovery features, but it is still being kept away from any "Indians".
\BCDA struck down\b
The ill-fated attempt by the US Congress to control what they do not own, died quietly during June. The Communications Decency Act was ruled invalid in an unsurprising decision by the US Supreme Court, which found that the law was unconstitutional because it impinged on freedom of speech.
The Congressional supporters of the original bill threaten to come back with a second attempt. According to civil liberties lawyers, the first bill was flawed by the proponents' total misunderstanding of what the \JInternet\j was and is, but they are quietly confident that no bill can be put up which remains constitutional while muzzling the \JInternet\j. At present, the CDA supporters' ploys seem to involve a narrower definition of decency and a mandatory rating system for all Net materials, conveniently forgetting that US Congress has no power beyond the shores of the United States.
The court's ruling was summed up by Justice John Paul Stevens: "It is true that we have repeatedly recognised the governmental interest in protecting children from harmful materials. But that interest does not justify an unnecessarily broad suppression of speech addressed to adults. The government may not reduce the adult population ... to ... only what is fit for children.''
Ahead of the CDA ruling, the \JWhite House\j positioned itself in readiness for a defeat, basically taking the position that regulation of the Net should be left to industry. Commented David Sobel of the Electronic Privacy Information Center: "To come in right after the Supreme Court decides the issue and say we didn't really mean what we said up to now-I can't imagine anything that would be seen as more of a waffle than that. It raises waffling to an art form."
European sources greeted the ruling with relief, suggesting that it would now be possible to get some cooperation under way to regulate \JInternet\j content effectively, and that the Supreme Court's ruling may spur other nations to begin developing their own laws, rather than rely on the CDA to do it all for them.
At almost the same time, state laws in New York and Georgia which put limits on free speech over the \JInternet\j were overturned. The New York legislation was struck out because it sought to regulate transactions outside the state's borders, thus violating the Constitution's interstate commerce clause. In the Georgia case, an injunction was granted against a law which made it illegal to use a name that "falsely identifies" the sender of an electronic message, such as a pseudonym or an anonymous e-mail address.
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"French Laws and the Internet",142,0,0,0
(Jun '97)
In \JFrance\j, opinion polls must be kept secret for a week before a parliamentary vote, but before the June elections, poll data were posted anonymously on a number of Web sites, where all French Web users could access them. As \ILe Monde\i (a slightly left-of-centre newspaper) commented: "From here on, it is the globalisation of communications that renders the law obsolete."
The French legal system also lost out against Georgia Institute of Technology, an American University accused of breaking \JFrance\j's law which forbids the sales of goods and services in a single language unless that language is French. The university has an English-only Web site about its operations at a \Jsatellite\j centre in the town of Metz, which will be allowed to continue. The decision, however, was on narrow legal grounds, and does not really settle whether French law can control the \JInternet\j. Two French language groups which started the case are looking at appealing the decision.
In better news for Francophones, a Quebec computer store, Micro-Bytes Logiciels, has taken most of its English-language site from the Web after receiving notice from the \IOffice de la Langue Franτaise\i that the company is in violation of the French Language Charter, which says that all catalogues, brochures, leaflets, commercial directories and other similar publications must be in French. The following week, Quebec's Culture and Communications Minister, Louise Beaudoin said that if left up to the federal Heritage Minister, there would be no French-language content on the \JInternet\j.
We use Edupage as a source of cyberlaw news. To subscribe to Edupage, send mail to listproc@educom.unc.edu with the message: subscribe edupage Louise Beaudoin (if your name is Louise Beaudoin, otherwise, substitute your own name).
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"Cybernews Bits",143,0,0,0
(Jun '97)
\BSpam free?\b
FTC commissioner Christine Varney says the Federal Trade Commission will increase its efforts under existing \Jfraud\j laws to punish e-mail spammers, saying that much of the spam mail is of a fraudulent nature. One available source reports that unsolicited \JInternet\j messages account for 5 to 30% of the 15 million messages received by America Online subscribers every \Jday\j.
\BCheaper chips\b
Intel has found a way to shrink its Pentium and Pentium MMX chips by about 10%, which means Intel can fit more chips on a single silicon wafer, cutting manufacturing costs. In July, the price of a 200 MHz Pentium MMX processor should drop from $US492 to about $US240.
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"Urine Test of Benefit",144,0,0,0
(Jun '97)
Most people who are required to undergo a urine test do so unwillingly, but a new test offers the chance to do patients some good, as it will identify damage caused by free radicals after bypass surgery or heart attack therapy. The test shows promise as a way of developing better antioxidant vitamin therapies against free radicals as well, pointing to the best dosage of \Jantioxidants\j that could prevent free-radical damage in cardiac patients.
After bypass surgery and other cardiac therapies, the improved blood flow to the heart carries in extra oxygen and causes the \Joxidation\j of, and damage to, heart tissue. This leaves higher blood levels of oxidised compounds, but the very act of drawing blood samples can oxidise chemicals, leading to false results. The new urine test identifies the presence and levels of a chemical formed after free radicals such as \Jperoxide\j and superoxide attack the common lipid arachidonic acid in the blood.
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"Growing Blind",145,0,0,0
(Jun '97)
Premature babies and people with diabetes often suffer from a form of \Jblindness\j which is caused by the abnormal growth of new blood vessels in the \Jretina\j of the eye. This seems to be triggered by oxygen deprivation. The most common treatment is \Jlaser\j surgery, but prevention would obviously be better, and it now seems that growth hormone (GH) is part of the problem, as is \Jinsulin\j-like growth factor-1 (IGF-I).
In the past, removal of the pituitary \Jgland\j was used to restore vision in some blind diabetics, but this rather drastic removal of a major source of chemicals needed for \Jmetabolism\j, including growth hormone only as one of many products-makes people tired, intolerant of stress, and susceptible to infections. On the other hand, \Jlaser\j surgery can damage or destroy the \Jretina\j, as well as reducing peripheral vision.
A team led by Lois Smith, a paediatric ophthalmologist, starved mice of oxygen, inducing blood vessel growth near their retinas. Using normal mice and mice genetically engineered to inhibit the effects of growth hormone, the transgenic mice showed 34% less growth of the new blood vessels which lead to \Jblindness\j. Normal mice treated with MK678, a growth-hormone-suppression drug, showed a drop of up to 44% in blood vessel growth. Treating the mice with IGF-I wiped out the protection afforded by the drug, pointing squarely at this hormone. So in the future, rather than ripping out the whole hormone factory, doctors may be able to suppress a handful of \Jhormones\j, and achieve the same cures.
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"Marijuana--Just as Bad",146,0,0,0
(Jun '97)
Sensationalists tell us that all drugs are bad, while people on the fringes of the drug scene tend to distinguish between "hard drugs" and the supposedly less harmful "soft drugs" like marijuana. New evidence this month suggests that the sensationalists may have been right all along about the dangers of marijuana. Two separate reports published in \IScience\i this month show disturbing similarities between marijuana's effects on the brain and those produced by highly addictive drugs such as \Jcocaine\j and heroin. Marijuana withdrawal turns on the same stress system in the brain triggered by withdrawal of opiates and alcohol, and a second study points to marijuana activating the same reward pathway as heroin.
The cannabinoid THC (tetrahydrocannabinol) was injected to rats over a two-week period, once a \Jday\j, to mimic heavy marijuana use. At the end of that time, the researchers injected the rats with a drug which counteracts THC, producing classic withdrawal symptoms. The rats were found to have two to three times as much of a substance called corticotropin-releasing factor (CRF), which is related to the anxiety and stress felt by people withdrawing from alcohol, \Jcocaine\j, and opiates.
Meanwhile, rats in \JItaly\j were being treated with THC, and checked for increases in \Jdopamine\j levels in a brain region called the nucleus accumbens. Surges in \Jdopamine\j level are found in heroin users, and this brain reaction is usually regarded as the system which reinforces, or encourages, continued brain use.
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"Neutrinos--Do They Have a Mass?",147,0,0,0
(Jun '97)
At a specialist neutrino conference in the Italian resort of Capri, three groups of physicists reported evidence that neutrinos can "swap their identities". This phenomenon would require that the neutrinos have mass, while physicists' current picture of particles and forces assumes that neutrinos are massless. So if the reports stand up, the reports could revolutionise the way we see the universe.
Massive neutrinos would be prime candidates for a role as the universe's missing \Jdark matter\j, the mass that astronomers believe must be out there but have not been able to pin down, and which is needed to explain simple things like the speed at which our galaxy rotates without flying apart.
If massive neutrinos can "swap", this could explain why the number of neutrinos coming from our \Jsun\j, the solar neutrinos, appears smaller than we should expect from the \Jsun\j's nuclear reactions as we understand them. If they are changing between the three types or "flavors"-\Jelectron\j, tau, and muon neutrinos-some of the solar neutrinos might have eluded detectors in the past.
The evidence comes firstly from neutrinos created by cosmic rays colliding with the \Jatmosphere\j. \JJapan\j's underground Super-Kamiokande detector can detect both atmospheric neutrinos and solar neutrinos, and this detector is seeing fewer muon neutrinos relative to \Jelectron\j neutrinos than expected from the cosmic ray collisions, possibly because muon neutrinos are transforming into another "flavor".
At the Soudan2 experiment, in the Soudan iron mine in Northern \JMinnesota\j, researchers have noted a similar apparent skewing of atmospheric neutrinos, as has the Liquid Scintillator Neutrino Detector at Los Alamos in New Mexico, which detects neutrinos from reactors. It is early days yet, but there is a tantalising pattern here, and if the researchers are correct, they have fingered a point where either there are vital data missing, or there is a serious misunderstanding. In either case, the way forward is clear.
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"New Genomic Data",148,0,0,0
(Jun '97)
The partners in a major genomics combination have gone their separate ways, say William Haseltine and J. Craig Venter, hailed as the "Gene Kings" in 1995. Haseltine's medical product development firm, Human Genome Sciences Inc. (HGS) in Rockville, Maryland, and Venter's non-profit The Institute for Genomic Research (TIGR), also in Rockville, ended business relations on 20 June. TIGR will give up more than $US38 million which it was due to receive from HGS over the next 5 years, and HGS will release TIGR from patent requirements and publishing delays on future research, but HGS retains rights to TIGR's earlier work.
The main result has been a flood of data. TIGR released 40 million base pairs of DNA sequence data from 11 organisms, including portions of the genomes of the microbes responsible for tuberculosis, \Jcholera\j, and \Jsyphilis\j, and \Jchromosome\j 2 of the \Jmalaria\j parasite, within a few days of the break-up.
The problem seems to be that Venter was more interested in sequencing organisms of little medical importance, and in human \Jgenome\j sequencing, also of limited value for a company like HGS which is interested in genes as drug targets, while TIGR found itself unable to release data until all commercial possibilities had been explored. Tensions like this are probably always going to plague every situation where the scientific culture says "publish" and the commercial culture says "patent" or "hide".
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"HUGO News",149,0,0,0
(Jun '97)
In May, gene mappers at their annual meeting at Cold Spring Harbor Laboratory in New York reported that they are now at the stage of sequencing pieces of the human \Jgenome\j, rather than just mapping the genes. Taken together, work now totals some 52.4 million bases of the 3 billion-base \Jgenome\j. The researchers predict that by May 1998, they will have hit around the 200 million mark, which will see them 7% of the way to their scheduled completion date of the Human Genome Project in 2005.
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"Gene and Parkinson's Disease Link",150,0,0,0
(Jun '97)
Scientists have pinpointed the gene which, when defective, causes a hereditary form of Parkinson's disease. A team led by Mihael Polymeropoulos of the National Human Genome Research Institute in Bethesda, Maryland, say the disease affects an Italian family. It develops at an early age, and shows a strong genetic \Jlinkage\j to a region on \Jchromosome\j 4. They identified other chromosomal markers which seemed to be inherited with the disease, and pinned the gene down to a section of the \Jchromosome\j 6 million base pairs long. Within this region, the alpha-synuclein gene stood out as a suspect.
When they sequenced this gene in the Italian family, they found the affected members had a \Jmutation\j not present in unaffected members, and they also found the same gene in three of five affected Greek families., but not in any of 300 controls drawn from \JFrance\j and \JItaly\j, or in 52 Italian patients with sporadic Parkinson's disease. It probably only accounts for a few percent of all the cases of the disease, but unravelling the way in which the mutated protein causes its damage, they will have a hint as to what kills off crucial neurons in the much larger number of patients with non-hereditary Parkinson's disease.
Early in June, \INature Medicine\i reported on a study which suggested that electrical stimulation of the brain can reduce the symptoms of Parkinsonism. Electrodes were inserted in the portion of the brain, the globus pallidus, which usually acts to slow down the rest of the brain in affected patients. Sending rapidly oscillating electrical pulses to the globus pallidus triggered increased blood flow to the premotor cortical areas, brain regions that are responsible for planning and initiating movement, and at the same time, the patients' movements became faster and less jerky. But while the effect is established, nobody yet knows what causes it.
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"Down's Syndrome and Trisomy",151,0,0,0
(Jun '97)
The condition once known as "mongolism", and more commonly called Down's syndrome (or Down syndrome in some parts of the world) arises from a trisomy, the presence of a third copy of a \Jchromosome\j. In Down's syndrome, this is always \Jchromosome\j 21, but nobody knows why the condition is caused by the trisomy.
Many cases of trisomy lead to early and spontaneous \Jabortion\j, but this trisomy is able to affect some normal functions while leaving others intact, and allowing the person to survive to adulthood. It now appears that a section of the \Jchromosome\j, a 20-million-base-pair stretch on the long arm of \Jchromosome\j 21 called 21q11-21, has a low percentage of cytidine and guanosine nucleotides. This suggests low gene content, in a sea of "junk DNA", which makes the area interesting.
Where only five genes had been found in the area before, Fa-Ten Kao, Jinjwei Yu, and their colleagues at the Eleanor Roosevelt Institute for Cancer Research in \JDenver\j have managed to locate 18 potential genes, at least nine of which had been "switched on".
One of the basic principles of development is that genes are normally switched off, and only switched on when they need to act in some way. Under normal circumstances, some 90% of the DNA in this odd region is methylated, a \Jchemical reaction\j in which DNA is tagged and deactivated with methyl groups. It now looks as though the extra \Jchromosome\j somehow interferes with the methylation process, leading to the conditions which define the syndrome. Once the human \Jgenome\j sequence for the whole \Jchromosome\j is available in a few years, this will probably prove to be a key discovery.
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"Plants and Chromosomes",152,0,0,0
(Jun '97)
Plants, as opposed to humans, have no equivalent to Down's syndrome, and no real problem with extra chromosomes, and commonly use tetraploidy, a doubling of the number of chromosomes, as new species develop, so that taking a karyotype, a chromosome count, is often a good hint to the species relationships in some plant genera.
With the release of the entire \Jgenome\j of \ISaccharomyces cerevisiae\i, it is now possible to look for evidence of this yeast duplicating its entire \Jgenome\j. Why would it bother? Well, when you have a spare set of genes to monkey around with, you can do so, as long as one of each pair of genes can still carry out its old task.
A study reported in June in \INature\i indicates that there must have been a whole doubling of the \Jgenome\j in \ISaccharomyces\i, just after it diverged from \IKluyveromyces\i, and that many of the genes were later deleted, but still leaving a significant number of duplicates to be seen today.
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"Origins of New Species",153,0,0,0
(Jun '97)
Where do new species arise? For some time, theorists have said that the new species would not arise in the heartlands, in habitats where everything is just right for the individuals which ere there. Rather, the new species would arise in the \Jbadlands\j, where excess individuals had been pushed to live or die as best they could. The edges, the "ecotones", they said, were probably still too close to the original mass of genes, and any new developments would be swamped by newly ejected members of the original species.
Now it appears that ecotones may be the places where new \Jrainforest\j species emerge. Thomas Smith of \JSan Francisco\j State University and his colleagues studied the \JCameroon\j's little greenbul, \IAndropadus virens\i, a small green bird which lives in both the tropical \Jrainforest\j and the ecotone. As a general rule, the ecotone-dwelling little greenbuls are heavier and have deeper bills and longer wings and legs than their \Jrainforest\j cousins. Genetic analysis, however, reveals many similarities between the populations, suggesting a considerable gene flow, equivalent to about one to 10 migrants per generation joining each population of birds from the other "camp".
In other words, the selection pressures in the two zones can overcome any "swamping effect". So if gene flow isn't a barrier to the formation of new species , then perhaps the ecotone may be more important than theorists have thought.
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"Dogs Evolved Earlier Than Thought",154,0,0,0
(Jun '97)
How long have dogs been teamed up with humans, and how important are they to human \Jevolution\j? The quick answer, say some theorists, may be "very" to both questions. Archaeologists, on the other hand, can only trace domesticated dogs back to about 14 000 years ago.
A study in \IScience\i this month suggested that the wolf may have become a dog as much as 100 000 years ago, or even more. At the same time, the study shows that the dog has only one wild ancestor: the wolf, and revealed that there is no such thing as a "pure breed".
A team led by Robert Wayne, an evolutionary biologist at the University of \JCalifornia\j, Los Angeles, studied samples from 162 wolves from around the world, and 140 dogs from 67 breeds, and five mixed breeds. They extracted a haplotype from the DNA in the mitochondria, which was similar in all dogs or wolves, but different from the same regions of jackals and coyotes. The dog haplotypes did not sort by breed, so individuals of the same breed might carry different haplotypes, indicating a mix of ancient doggy ancestors, even in the "purest" of dog breeds.
Using a "genetic clock" method, Wayne suggests that the dog and the wolf diverged 135 000 years ago, although others are doubtful about this dating, which may have been flawed by selection effects at certain points. But if dogs and humans have been together for that long, this will probably end up having strong implications for the history of human \Jevolution\j-a human's linguistic and toolmaking skills, coupled with the dog's senses of smell, vision and hearing, would make a formidable hunting and fighting team.
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"Fossils in the News",155,0,0,0
(Jun '97)
\BGetting blood out of a stone\b
It turns out to be possible after all, provided the stone is a \Jfossil\j that was once a bone. And maybe it's not quite blood, but haemoglobin, the oxygen-carrying protein in blood, has been found, say researchers from Montana State University, \JIndiana\j University, and the University of Wyoming report that they have found haemoglobin in a 65- to 67-million-year-old \ITyrannosaurus rex\i bone. The team, led by Montana's Mary Schweitzer, extracted material from the \Jfossil\j and tested it with a whole range of techniques, including ultraviolet, visible, and Raman \Jspectroscopy\j, nuclear magnetic \Jresonance\j, and \Jelectron\j spin \Jresonance\j, all of which seem to indicate that they have the core of haemoglobin.
To test the matter further, the team injected some of the material into rats and showed that it caused the formation of \Jantibodies\j. Better still, the haemoglobin resembles bird haemoglobin, exactly what we would expect if today's canary was once yesterday's \Jdinosaur\j.
This could, of course, be the start of something big, not in the \IJurassic Park\i sense, but in the sense of unravelling relationships, using haemoglobin variations to draw up reliable family trees. Others are less hopeful, pointing out that 50 000 year old haemoglobin is unusual.
\BOldest young dinosaur\b
Portuguese scientists report finding a \Jdinosaur\j embryo which is 140 million years old at Lourinha, a small seaside town 60 kilometres north of \JLisbon\j, and known for decades for its wealth of Jurassic fossils.
The egg cache which contained the embryo was found by two local amateur \Jfossil\j-hounds, Oratio and Isabel Mateus, who have a small \Jdinosaur\j museum in Lourinha. One of the crushed eggs, about 18 cm long, was found to contain bones, possibly of a theropod, a three-toed, meat-eating dinosaurs (including \IT. rex\i), since theropod remains have been found in the area before. Virtually all previous finds have been of Cretaceous dinosaur embryos, making this an exciting find. Aside from anything else, it would allow palaeontologists to start linking isolated eggs to particular species.
\BChitin in ancient fossils\b
Chitin is a common biological molecule which is found in many organisms, notably arthropods such as crabs, \Jcrayfish\j and insects. Chitin has always been thought to degrade rapidly when it is buried in sediments and so unlikely to be preserved in the \Jfossil\j record beyond a few hundred thousand years. A June report records the finding of \Jchitin\j in \Jfossil\j insects preserved in shales nearly 25 million years old. So whatever determines \Jchitin\j preservation and degradation, it is not time alone.
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"Nuclear News",156,0,0,0
(Jun '97)
\BRussian nuclear incident\b
Chernobyl couldn't happen again, could it? Perhaps. Better safety procedures are in place throughout the Russian nuclear industry, aren't they? Not quite, though we don't hear much to the contrary.
At the Federal Nuclear Centre in the town of Sarov, one of \JRussia\j's restricted research cities, some 350 kilometres east of Moscow, a physicist called Alexandr Zakharov was injured by a burst of radiation from a research reactor in June. Researchers are supposed to work in pairs, but Zakharov was working alone when he mistakenly added too much of a radioactive substance, exceeding the \Jcritical mass\j, and was hit with a 1000-rem dose of neutrons, more than twice the maximum safe dose.
Apparently Zakharov, as a well-qualified senior researcher, was allowed to work on his own. Some days later, the only available report indicated that the laboratory was still being hit with a neutron flux too high to allow anybody to enter and take control of the reactor, and plans were in place to send in a robot under remote control to turn off the reactor.
\BSuperphenix sinks back into the ashes?\b
The new French government claimed its first victim in June, when the new French prime minister Lionel Jospin said that the troubled French Superphenix nuclear reactor was to be abandoned. His socialist-led government is a coalition which includes the greens, one of whom, now the environment minister, Dominique Voynet, called the $10.5 billion reactor in Creys-Malville a "stupid financial waste" and promised to close it down during the election campaign.
The 1200 megawatt Superphenix was planned 20 years ago as the world's largest fast breeder reactor, but it has produced power only now and then. In 1994 the former government agreed to downgrade it to use as a research reactor for disposing of \Jplutonium\j waste from other reactors, and the conversion began six months ago. The closure could have implications for the whole nuclear power industry in \JFrance\j, especially regarding the disposal of long-lived \Jactinides\j, by-products of nuclear power generation which would have been no problem with Superphenix. As \JFrance\j draws more than half of its power from nuclear sources, this could end up producing major changes in French society. While the first protests about job loss have already taken place, the reactor is widely regarded as a commercial disaster, so its closure will also leave a number of people, some of them in the pro-nuclear camp, feeling more relieved.
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"El Nino Rides Again!",157,0,0,0
(Jun '97)
Fasten your seat belts, we're in for a stormy season or two-El Ni±o is back, bigger and tougher than before. The warming of the tropical \JPacific Ocean\j has been building during the past several months, and it will soon trigger a sequence of drastic shifts in \Jweather\j patterns all the way from India to \JCalifornia\j, say the experts.
After the more chaotic El Ni±o events of the early 1990s, this one looks like a classical pattern, leading forecasters to suggest that it will be like the El Ni±o of 1972, so this summer in the Northern Hemisphere should see the Indian monsoon weaken and the Caribbean region dry out. Next southern summer, at the end of this year, \Jdrought\j should strike \JAustralia\j, South Africa, and north-east \JBrazil\j. At the same time, storms will bring extra \Jwater\j to \JCalifornia\j and the Southeast, or even much of the southern half of the United States.
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"Gaia Hypothesis Update",158,0,0,0
(Jun '97)
The Gaia hypothesis of James Lovelock had led supporters of the idea to suggest that tiny \Jalgae\j, the ocean \Jphytoplankton\j, are in some way involved in acting as a thermostat to regulate the \Jearth\j's \Jtemperature\j. Now it appears, in a report by oceanographers Timothy Bates and Patricia Quinn of the US National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory in Seattle, that the thermostat may not exist. Writing in Geophysical Research Letters in April, they question the idea that ocean \Jphytoplankton\j produces dimethyl sulphide (DMS), which enters the \Jatmosphere\j and forms tiny particles which accumulate \Jwater\j vapor to form \Jcloud\j particles, reflecting the \Jsun\j and cooling the \Jearth\j.
Their study of a fifteen-year record of DMS in tropical Pacific waters shows little variation across that time, in spite of wide El Ni±o-induced swings in \Jtemperature\j and \Jcloud\j cover during that period. So if Gaia is interacting with El Ni±o in some way, it either isn't happening there, or it is happening in some other way.
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"World Population Growing More Slowly",159,0,0,0
(Jun '97)
In much of the world, \Jbirth control\j and other family planning measures have reduced fertility rates during the 1990s; but the United Nations still predicts that the world's population of almost 6 billion people, will peak at about 11 billion by 2100. Now there is good news: the human breeding rate is falling away. That seems to be the point of an unusual forecast made in \INature\i this month, where rather than giving the usual "low", "middle" and "high" estimates for future population, the researchers have suggested probabilities for different population sizes in 13 regions of the world up to 2100, and they find that there is a probability of two-thirds that the world's population will not double in the twenty-first century.
On the other hand, the proportion of elderly people will rise, and some of the poorest parts of the world, like the \JMiddle East\j and sub-Saharan Africa could still see their populations triple over the next 50 years, as India has done since independence in 1947, while eastern Europe is actually expected to have a drop in population, but the increase in the number of aged people is said to be "almost certain".
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"Russians Dwindling Faster",160,0,0,0
(Jun '97)
The rise of the grey folk may not be seen in \JRussia\j, it seems. Hard-drinking Russian men continue to die young these days, but Russia's recent downward spiral in life expectancy hides the fact that life expectancy in the former \JSoviet Union\j (FSU) levelled off more than 30 years ago before falling during the last decade, according to a report released by the U. S. National Research Council (NRC).
The latest figures collected by the U. S. Census Bureau reveal that the average life expectancy for men in \JRussia\j, for example, fell from about 65 years in the mid-1980s to 57 years in 1994. Life expectancy numbers began levelling off in the \JSoviet Union\j as early as the 1960s, shot up in the late 1980s, after Gorbachev's short-lived vodka prohibition, but soon plunged again.
So it may be the vodka that is causing it, or then again, it may not. A Russian study of European noble families suggests that daughters of older fathers may have shorter life-spans. They suggest that the finding reflects the accrual of gene mutations as fathers age-specifically, damage to "housekeeping" genes on the paternally transmitted X \Jchromosome\j.
Leonid Gavrilov and his wife, Natalia Gavrilova, studied data from 700 families, including 2159 daughters and 4942 sons born in the 1800s, tallying only children who survived past 30, to minimise the effect on mortality of infectious diseases. Daughters born to fathers in their thirties lived, on average, to an age of 74.5, but if the fathers were in their fifties, daughters' life-spans were about 2 years shorter-72.4. When the data are controlled for maternal age, parental longevity, and other variables, the difference is closer to 3 years.
The logic is that ova are manufactured early on, and stored by the mother until they are released in \Jovulation\j, safe from \Jmutation\j. Sperm cells are manufactured throughout adulthood, and so are vulnerable to mutations that accumulate over time. Boys, getting a Y \Jchromosome\j with very little information on it, seem not to be affected, while girls, getting an information-rich X \Jchromosome\j, may be affected by the mutations it carries. The only problem is that other chromosomes, common to both males and females, should also have an effect as the father ages, but this seems not to be there.
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"United States 1997 Census",161,0,0,0
(Jun '97)
The USA is gearing up for its biggest ever \Jcensus\j, and as happened in 1890, they are running into problems. Consider the \JConstitution of the United States\j of America, especially Article One, Section Two of that document. Politicians are a particularly suspicious breed, and the American colonial ones who created the US Constitution were no different. To prevent any single state from dominating Congress, they provided that the membership of the Congress should be in proportion to the \Jcensus\j which was to be taken at ten-year intervals.
This scheme was fine for the first hundred years or so, when there was only a small population, but the United States was opening up fast, and the swarms of immigrants were pouring in from Europe. By 1886, there was trouble: the results of the 1880 \Jcensus\j would not be available by the time the 1890 \Jcensus\j came due. In 1880, there were slightly more than fifty million Americans to be counted, by 1890, there were over sixty three million, and it seemed certain the provisions laid down by the Constitution were about to be defied. Something \Ihad\i to be done!
(In \JAustralia\j, the local politicians were framing the Australian constitution at about the same time, and they were cunning enough to commit themselves only to using the "latest statistics of the Commonwealth", and giving the Commonwealth the power to make laws about censuses and statistics.)
The solution then was the invention of the Hollerith card. Many of the questions on the \Jcensus\j form called for yes/no answers, and these could be represented by holes on a card, just as they were in a Jacquard loom. The more complex questions, such as age, could be coded with a group of holes. Once the cards were punched, they could be read by gently lowering pins onto the surface of the card.
Where there was a hole, the pin made an electrical connection with a pool of mercury below. Where there was no hole, there was no connection. The 1890 \Jcensus\j was completed in a little over two years, and Hollerith had founded one of the companies which was later to become \JIBM\j. Now there are more than 250 million Americans, and the bulk of data is no problem, but the bulk of missing data is a serious concern. According to the National Research Council (NRC), the U. S. Census Bureau should use sampling techniques to estimate the number of people not tallied by traditional surveys.
Last year, the Bureau proposed that door-to-door surveys be carried out for 1% of all U. S. households as part of the 2000 \Jcensus\j. The survey results would be used to confirm the accuracy of the standard mail-in questionnaires and also to estimate data for the uncounted population. The bureau believes that such techniques would save about $700 million. Many Republican members of Congress have objected to such sampling, however, in part because they claim it might boost counts for urban areas, resulting in some congressional districts being redrawn in favor of Democrats.
Now the plan has been given the nod of approval, with a few suggested improvements, by the NRC, who say that sampling would yield a much more accurate national head count at a more reasonable cost. It was the dark suspicions of politicians in the late 18th century that gave us the punched card in the late 19th century, and the computer age of the late 20th century. Who can say where the dark suspicions of today's politicians may lead in 200 years time? Your reporter thinks it may have something to do with better sampling methods.
#
"Scrapie, An End To It?",162,0,0,0
(Jun '97)
The British government has announced a boost to spending aimed at wiping out scrapie, the mysterious prion disease, linked to mad cow disease (bovine spongiform encephalopathy or BSE), which in turn has been linked to a variation of human Creutzfeldt-Jakob disease. The disease has been present in British sheep flocks for over 200 years. This is part of a larger plan to wipe out BSE.
Oddly, scrapie is found in Europe and America but not in \JAustralia\j or \JNew Zealand\j, despite the fact that many of the animals in those countries originally came from U. K. flocks that may have been infected by the disease, raising the question of how environment (or perhaps a long sea voyage?) influences the way a disease is transmitted and maintained in a population.
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"Bill To Outlaw Cloning",163,0,0,0
(Jun '97)
Reacting to the news of Dolly the sheep, President Clinton commissioned a report on \Jcloning\j from the National Bioethics Advisory Commission (NBAC), and now indicates that he will be sending a bill to Congress that would outlaw the \Jcloning\j of humans.
President Clinton had already ordered a moratorium on human \Jcloning\j with federal funds, and asked the NBAC to report in ninety days. The report has avoided ethical questions for the moment, looking instead at the safety issues. It took 227 attempts to get a single healthy lamb, and so the NBAC concludes that there would be too many risks, not only for the "child", but also there would be a risk of psychological harm to infertile couples who might be tempted to pursue the method.
While noting that such methods could, in the future, offer ways of saving lives, the President agreed that the time was not right. This may be seen later as a dangerous precedent, since it makes certain types of research a criminal activity, but at least it is not a blanket ban of the sort urged by some of the more uninformed critics of \Jcloning\j.
#
"Men Are Inferior After All?",164,0,0,0
(Jun '97)
In humans, gender is determined by the chromosomes. Every \Jovum\j contains an X chromosome, sperm cells contain either a Y chromosome or an X chromosome. The Y chromosome, apparently almost free of genes or information, is found in males (identified as XY), while women have two X chromosomes (XX).
A few women have what is known as Turner's syndrome, and are found to have just a single X \Jchromosome\j (X0). Their intelligence is usually normal but they often have social adjustment problems. Turner's syndrome is a condition that affects about one in 2500 females who have short stature and often demonstrate social problems at school and throughout their \Jadolescence\j.
A study from a team led by David Skuse of London's Institute of Child Health, and reported in \INature\i during June compared Turner's women for whom the X \Jchromosome\j came from the mother (45,Xm), and where it was paternal (45,Xp). Members of the 45,Xp group were found to be significantly better adjusted, having superior verbal and higher-order executive function skills, all of which mediate social interactions.
Using genetic markers, the team identified 55 subjects who had received the \Jchromosome\j from their mother and 25 who had it from their father. Using information from school counsellors about any social difficulties experienced by the girls, Skuse's group found that 40% with the maternal X \Jchromosome\j were likely to have problems at school, against only 16% of girls with the paternal X. In other words, there was a clear effect, but it is by no means a perfect pattern.
It appears from this that there is a genetic locus for social cognition, which is imprinted and is not switched on from the maternally derived X \Jchromosome\j. Now males, who are known to have a wider range of developmental disorders of language and social functioning, such as autism, than are 46,XX females, but males only have an X \Jchromosome\j from their mothers, suggesting a possible explanation of this established fact.
In the past, the differences have mostly been blamed on social conditioning or hormonal effects: now it looks as though the causes of these conditions lie far deeper. But why is it only \Isome\i males?
#
"Arecibo Awakes",165,0,0,0
(Jun '97)
Good news for astronomers: the Arecibo crater is awake and active once more. Arecibo, a mountain sinkhole, is the world's largest radio \Jtelescope\j, with the crater being turned into a dish 305 metres (1000 feet) across. While this dish cannot be directly steered, operators can move the collecting equipment over the dish surface, effectively pointing it at different parts of the sky. This month, after a $27 million revamp, taking five years, the \Jtelescope\j is working once more.
#
"Wasps Help Date Rock Painting",166,0,0,0
(Jun '97)
How do you date a rock painting on a cave wall or a rock overhang? Carbon dating is often useless, and other dating methods are all open to criticism by those who disagree with you. Perhaps wasps can help, according to a paper in \INature\i this month, co-authored by eleven of \JAustralia\j's top names in the dating field.
Mud-nesting wasps build nests that become petrified after they are abandoned. In northern \JAustralia\j, the nests may lie over paintings, or be covered by them, and these nests contain \Jpollen\j, spores and phytoliths which can yield information about local plants from the time when the nest was made.
The authors used a mix of optically stimulated \Jluminescence\j (OSL), and accelerator mass spectrometry (AMS) 14C dating of \Jpollen\j to determine the ages of mud- wasp nests associated with rock paintings in the Kimberley region of Western \JAustralia\j. They dated individual sand grains in the mud, and showed that some paintings showing human figures are older than 17 000 years.
While this is less exciting than the claim of up to 176 000 years made last December, it offers us a technique which is applicable all over the world where the mud wasps are found, and it offers us a confirmed date which can now be extended.
#
"Solid Lubricants",167,0,0,0
(Jun '97)
When the going gets tough, machines need lubrication. When the going gets even tougher, in heat or in cold, or in the vacuum of space, working parts still need lubricants, but the traditional liquids are no use any more. And so we enter the world of the solid lubricant, such as \Jgraphite\j.
Now there is a new kid on the solid \Jlubricant\j block, a hollow tube, rather like the tubular fullerenes, made of \Jtungsten\j disulphide. Instead of slipping between weakly bonded crystal planes, these nanoparticles may lubricate by rolling. The tubes are chemically inert, and they seem to be able to roll because of their peculiar cage-like structure.
Metal dichalcogenides with the formula MX\D2\d (where M is, for instance, molybdenum or \Jtungsten\j and X is sulphur or \Jselenium\j) are widely used as solid lubricants, but the hollow nanoparticles (often referred to as HNs) are a new development.
#
"DNA Fingerprints From Fingerprints",168,0,0,0
(Jun '97)
A new method has now been found which will allow crime scene examiners to extract DNA from the fingerprints left behind at a crime scene. Swabs taken from objects such as \Jtelephone\j receivers and knife handles yielded enough DNA to produce a genetic profile, sometimes several profiles of several individuals who had been in contact with the object. Now police will need to be even more careful to avoid "contamination" of the crime scene.
#
"Equatorial Ice Cores",169,0,0,0
(Jun '97)
Ice cores from equatorial glaciers are just as useful as those from high latitudes in providing evidence of ancient climates. The ice core record from the Guliya ice cap (Qinghai-Tibetan Plateau) extends in detail back past 100 000 years ago and may even contain ice deposited 500 000 or more years ago, and this is the subject of serious research at the moment.
Tibet, however, stays cold long enough to allow serious study. The mountains of \JBolivia\j are not such a good place to examine ice, and to extract the air bubbles trapped in the ice. The answer is to take the ice cores down the mountain, but that means going down into tropical heat which melts the ice and destroys the record. The creative solution: hot air balloons, which can be launched from the \Jglacier\j, drift clear of the mountain, and then drop quickly to deliver the ice cores to the freezers, waiting below!
#
"Ark Debate, Plimer vs Roberts",170,0,0,0
(Jun '97)
Professor Ian Plimer had what could only be described as a minimal victory in his case against creationist Allen Roberts in Sydney, \JAustralia\j. While it was described by some as "a rerun of the Scopes trial", the case was launched against Roberts in the Federal Court on the ground that he had breached the Australian Trade Practices Act, in that he had distributed "misleading and deceptive" materials.
Plimer's case, which ran for seven expensive days in April, was that Roberts was selling tapes and publications which made claims about a supposed site for Noah's Ark in Turkey, and that this meant Roberts was engaged in trade or commerce. Roberts' organisation, operating as ArkSearch, had an income in excess of $50 000, but according to the judgement, it "lacked the necessary degree of system and continuity" to be considered a business.
While Justice Ronald Sackville found in his June 2 verdict that some of Roberts' claims were false, he thus ruled that they did not constitute trade or commerce, meaning that the matter could not be a matter for his court. "The courts should not attempt to provide a remedy for every false or misleading statement made in the course of public debate on matters of general interest," said Sackville, whose ruling may be found at http://www.austlii.edu.au/au/other/fca
A joint case by a marine salvage expert against Roberts, for breach of copyright, gave the claimant a verdict of $2500 for damages, some small consolation to Plimer, but he was able to use the court as a forum to place in the public domain a great deal of information which is damaging to the continuation of any claims that Noah's ark is waiting for true believers, high in the mountains of eastern Turkey.
The way is open for Plimer to appeal the Sackville ruling that Roberts' actions did not constitute trade or commerce, and on June 20, he went ahead, lodging an appeal that will be heard by three Federal Court judges.
#
"No Ice On The Moon After All",171,0,0,0
(Jun '97)
Last December, we reported a hopeful account of ice on the moon, which reported that a radar signal from Clementine bounced very strongly off an area inside a large crater, the South Pole-Aitken. This signal was much more than could be expected from silicate rocks, and this suggested frozen volatiles of some sort. Because the crater was in permanent shadow, ice seemed like a possibility.
Now similar strong reflections have been found in other craters, ones which are not in permanent shadow, making it likely that something else is responsible, possibly surface roughness. Or could it be some of the small comets, proposed by Louis Frank and John Sigwarth? Who knows, maybe they \Iare\i splatting into the moon after all, freezing until they sublime back into space.
#
"Deep Blue Goes Data Mining",172,0,0,0
(Jun '97)
Fresh from its chess win against Gary Kasparov (see May), \JIBM\j's computer has demonstrated the difference between human intelligence and machine power by switching programs and turning to data mining, researching new drugs and maximising stock market returns. This sort of machine is best suited to searching large databases to find new answers.
We have to hope that Deep Blue's owners will keep in mind the old message GIGO, or Garbage In, Garbage Out. An infinite number of monkeys, given sufficient time, will produce anything, even the complete works of Shakespeare, and given enough data mining, you can find any pattern in any data set. A report in Business Week during June revealed that the single best predictor from a United nations \JCD\j-ROM of data for the variations in the Standard & Poor 500-stock index was butter production in \JBangladesh\j.
#
"Obituary for June 97",173,0,0,0
(Jun '97)
\BJacques Cousteau (1910-1997)\b
Jacques Cousteau was co-inventor of the aqualung, and the person who, more than anybody else, made two generations aware of the watery world around them. Ocean explorer, \Jtelevision\j host and confirmed conservationist, his passing will be regretted by many.
He perfected the Aqua-Lung during World War II, while he was a member of the French Resistance, a breathing device which led to the SCUBA diving system, together with engineer Emile Gagnan. He also made some of the first underwater films with the help of a waterproof camera case he designed. It was the underwater films that he and his team later made which made his name a household word.
#
"Pathfinder Touches Down!",174,0,0,0
(Jul '97)
Mars is the \Jplanet\j that features most in \Jscience fiction\j as a place where life might be or might have been. The world's most expensive beachball landed on Mars, on time on July 4, the first successful mission to Mars since the two Viking probes landed there in 1976, and deployed almost exactly as planned, at the end of a journey which began last December.
Slowed by a parachute and then by retrorockets, the airbag-surrounded craft dropped the last few metres to the ground, bounced, and then settled to the ground in a giant outflow channel called \JAres\j Vallis. Just after reaching the surface, the \Jspacecraft\j began sending its first images of Mars, which were immediately taken up by Web mirror sites all around the world.
On July 5, a six-wheeled "micro-rover," called Sojourner had rolled out onto the Martian surface. The size of an ordinary \Jmicrowave oven\j, Sojourner is fitted with a wide range of scientific equipment, and it is designed to pilot itself between the rocks, study the composition of the soil and rocks and send the data back to the Earth.
While Sojourner has been described as an expensive remote-controlled car, this is not really the case. It takes eleven minutes to get a radio signal to the "car", and during that time, even at a rate of 0.4 metre a minute, the "car" has travelled quite a long way. And even worse, Sojourner only takes still pictures, and they take eleven minutes to arrive back on \Jearth\j.
So Sojourner has an on-board computer, camera and \Jlaser\j scanner to help it select the safest way to its destination, once the \Jearth\j controllers have indicated where they want it to go. The rover is programmed to detour around any unforeseen obstacles, and because it only has enough power to either move or navigate, it progresses slowly, moving half a wheel-turn forward, then stopping to scan and analyse before moving cautiously forward again.
The pictures from the \JAres\j Vallis look broadly like those from the Viking landing site, some 850 kilometres away, two red deserts strewn with assorted rocks, but they are actually quite different. The Viking site was an old \Jlava\j flow, but Sojourner appears to be wandering among rocks that have been carried there from great distances, presumably by the action of past floods. Nearby hills show bands which may be sedimentary layers or benches cut into the valley by rushing \Jwater\j.
Most scientists are hoping for sedimentary layers, where fossils might be found, but this must remain as an open question until the next century, as Sojourner is unable to carry out such a search. Early next century, NASA hopes to return Mars rock samples to the \Jearth\j for detailed analysis.
Sojourner transmits its data to Pathfinder, which relays it to the \Jearth\j, as well sending back meteorological data on the thin Martian \Jatmosphere\j from its built-in \Jweather\j station.
Perhaps the most surprising finding has been that Mars is more like \Jearth\j than anybody expected. A rock, nicknamed "Barnacle Bill" was given a chemical analysis by the rover's alpha proton X-ray spectrometer. The result: "Barnacle Bill" is richer in silicon than any meteorites of known Martian origin, about 10% richer, making it similar to the common \Jearth\j rock, \Jandesite\j.
The standard theory about the \Jearth\j's \Jandesite\j is that the \Jquartz\j (\Jsilica\j) and silicon levels are raised by the action of \Jplate tectonics\j. High-\Jsilica\j rocks on Earth generally come from volcanic eruptions fuelled by the sinking of plates of surface rock into the \Jplanet\j's interior, a process thought to be uniquely terrestrial. Now scientists will have to decide whether the theory is right, or whether Mars has aspects that nobody expected, like \Jplate tectonics\j, or liquid \Jwater\j, which can also be involved in the \Jsilica\j-enrichment process!
There is certainly evidence of liquid \Jwater\j there, and large amounts of it at that. The landforms around the site show evidence of what appears to be flood damage, including 4-metre-high ripples nearby, spaced 20 metres apart, exactly the sort of ripples left by the late stages of a catastrophic flood. The flow direction suggested by the ripples matches the orientation of a stack of boulders piled up against each other, as if by a flood, and the flow direction also matches the direction that orbiter images suggest the flood took.
Sojourner has been studying rocks at close range, and matching the \Jreflectance\j at different wavelengths with their chemical properties. Later, the \JHubble Space Telescope\j will be able to examine Mars at long range, identifying areas on the surface with similar reflecting properties, so one result of the mission should be a detailed geochemical map of the red \Jplanet\j.
Pathfinder is one of NASA's new Discovery program, which aims to conduct important space science experiments for less than $150 million. According to NASA, the budget for Pathfinder was less than one fifteenth of the Viking program, after adjusting for \Jinflation\j over the past twenty years. Another program in the same series is the NEAR probe, which sent back high-resolution images of the asteroid Mathilde in July, described next.
Pathfinder is the first round of NASA's Mars Surveyor Program, a series of missions to be launched every 26 months over the next decade, so whatever is left unanswered by this mission should be here soon, without any more twenty-year gaps.
Next time, the robots will have some serious clout. The newest version, "Rocky 7" has been going through its paces in the Mojave Desert. Rocky or its successor, will fly to Mars in 2001 - 2002. The existing Rocky has already travelled more than a \Jkilometre\j, placing scientific instruments and taking 500 photographs, manoeuvring with the help of stereo cameras mounted on its front.
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"Mathilde--Not Your Average Asteroid?",175,0,0,0
(Jul '97)
During July, the Discovery program's Near Earth Asteroid Rendezvous \Jspacecraft\j (NEAR) passed close to the deeply cratered asteroid Mathilde, and gathered data showing that the asteroid is surprisingly light. Now scientists are beginning to wonder if the \Jasteroids\j are just loose collections of flying rubble. The flyby happened in late June, but the details were only available in the first few days of July, when they were largely submerged in Sojourner fever.
Asteroids are important to us, here on \Jearth\j, with one blamed for the wiping out of the dinosaurs and another now being linked to the late Eocene \Jextinction\j event. Another suspected asteroid impact destroyed thousands of square kilometres of forest near Tunguska, \JSiberia\j, in 1908. More importantly, the \Jsolar system\j's \Jasteroids\j, comets, and meteorites, the so-called primitive bodies, are where we can expect to find clues to the processes that controlled the formation of the early \Jsolar system\j, clues that will long since have been destroyed on larger bodies.
The NEAR mission has been the first close approach to a serious asteroid (Mathilde was estimated before the fly-by to be about 60 km across, larger than Gaspra and Ida, both visited by \JGalileo\j, several years ago), but there will be an even better approach to an asteroid when NEAR approaches 433 Eros in early 1999. Mathilde is presently near its perihelion point, q=1.94 AU, providing this flyby opportunity to the NEAR \Jspacecraft\j. Until then, Mathilde is our best "shot".
Mathilde (253 Mathilde to the precise) is a main-belt asteroid. Discovered in 1885, it is believed to be named after the wife of the then vice-director of the Paris Observatory, Moritz Loewy. Unlike Gaspra and Ida, both S-type (stony) \Jasteroids\j like Eros, Mathilde is a carbonaceous, or C-type, asteroid. The carbonaceous \Jasteroids\j are mainly found in the outer regions of the asteroid belt and they make up more than 75% of the known \Jasteroids\j. Chemically, they are rather like what the \Jsun\j would be if you boiled off the \Jhydrogen\j, \Jhelium\j, and other volatiles, or easily vaporised elements.
We now know that Mathilde is very lightweight, with a very dark surface, and it is covered with enormous craters, begging the question: how has it survived the huge impacts that must have made those craters? And how or why does it rotate so slowly (just once in every 17.4 days), when those cratering impacts should have left it spinning rapidly?
The observed craters range from over 30 km (18 miles) across to less than 0.5 km (0.3 miles) in diameter. There are more than five craters larger than 20 km in diameter on the 60 percent of Mathilde's surface that NEAR was able to photograph as it raced past at 36 000 km/hr, far beyond Mars' \Jorbit\j, and just 1210 km (750 miles) from the surface of the asteroid. In just 25 minutes, NEAR collected 534 images of Mathilde. The 30 km crater is 6 km deep.
NEAR's observations tell us that Mathilde is slightly smaller than astronomers thought: only 53 kilometres (32 miles) in diameter, and surprisingly low in density, "weighing in" at around 1.3 grams per cubic \Jcentimetre\j, hardly more than \Jwater\j. An ordinary adult on the surface of this asteroid would weigh about a pound (500 gram), due to the low gravity.
Mathilde remains one of the darkest objects known, reflecting only 4 percent of the incoming light, and the material making it up is surprisingly uniform-even the bottoms of the craters seem to be the same pale grey. When NEAR swung away from Mathilde it took a series of images that astronomers intend to scour for signs of a tiny moon, but so far, no reports have been heard on this search.
Eros was first observed in August 1898, and it is about 14 x 14 x 40 km, with a rotation period of 5.27 hr. It is thought to be a silicate rock, and it has an \Jorbit\j inclined at 10.8 degrees, an aphelion (distant point from the \Jsun\j) of 1.78 AU, and a perihelion (close point to the \Jsun\j) of 1.13 AU. It appears to be about 35 km across at its widest point, and it is the largest of the "near-\Jearth\j \Jasteroids\j," objects whose orbits take them menacingly close to our \Jplanet\j.
The NEAR craft is fitted with a multispectral imager system, an X-ray/gamma-ray spectrometer, a near-IR spectrograph, a magnetometer and a \Jlaser\j rangefinder. It will study the size, shape, volume, mass, gravity field, and spin state of Eros, and send back data on surface properties such as the elemental and mineral composition, \Jgeology\j, morphology, and texture, while measuring internal details such as the mass distribution and magnetic field.
Unlike the earliest missions which used tape recorders, NEAR is well-equipped with data storage, having 1.7 gigabytes of solid-state storage. It will need this memory, because it will \Jorbit\j Eros for a year, studying its surface from altitudes as low as 24 kilometres (15 miles). The probe will end its mission on February 6, 2000, with a controlled landing onto Eros' surface.
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"Big Holes in Vesta",176,0,0,0
(Jul '97)
The asteroid Vesta, which is only 525 km in diameter, has a 450 km impact crater on it. Peter Thomas of Cornell University and his colleagues reported at the annual meeting of the Division for Planetary Sciences in July that repeated imaging of Vesta using the \JHubble Space Telescope\j had revealed a large jagged bite taken out of the asteroid's southern hemisphere.
By recording the silhouette of Vesta, they mapped a classic impact crater 450 km across and 8 km deep with a 13-km-tall peak in the centre. The so-called basaltic achondrite meteorites are now likely to be bits of Vesta, thrown off in that impact. These meteorites look very much like small, 5-km \Jasteroids\j near the zone in the asteroid belt where Jupiter can fling rocks gravitationally towards the Earth.
In the past, the puzzle has been to explain the force that tore these pieces away, but an impact capable of making a crater that size would certainly be able to hurl lumps of rock, several km across, out into space, setting them on an eventual collision course with the \Jearth\j.
The final answer will probably depend on sending a probe to Vesta.
#
"Death By Asteroid",177,0,0,0
(Jul '97)
"The asteroid that wiped out the dinosaurs" is now widely accepted by scientists, but how many other extinction events were caused in similar ways? Siberia, home of the Tunguska event, is also the home of the Popigai impact structure on the Anabar shield. Popigai is a remnant of a huge crater, 100 km across. The crater was formed some time between 5 and 65 million years ago, although it was probably older than 29 million years. Nobody could be more precise than that, until age determinations were carried out using argon isotope ratios.
Now the impact is dated at about 35.7 ▒ 0.2 million years ago, almost the same time as the Chesapeake Bay crater off the coast of \JNorth America\j, and raising the interesting question that the two impacts may have been two parts of the same object, and suggesting that the impacts may have caused the mass \Jextinction\j of the late Eocene.
We now know that northern \JItaly\j has an iridium anomaly and shocked \Jquartz\j in Late Eocene deposits, and the dating for these finds is consistent with the Popigai dates. This age is also similar to that of the North American tektites, which have been associated with the Chesapeake Bay impact structure in the eastern United States, making it even more likely that the events were close together, and part of something big.
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"Japan's New Telescope in Space",178,0,0,0
(Jul '97)
July saw the release of the first images from a new orbiting radio \Jtelescope\j, called HALCA, whose data were combined with signals from ground-based telescopes to simulate an enormous collecting dish. The images show a powerful jet of subatomic particles spewing from a \Jquasar\j, and demonstrate the power of a system with a hundred times the resolving power of the \JHubble Space Telescope\j.
HALCA is the first space-based radio antenna designed for interferometry, using a technique that combines data from far-flung telescopes and create the equivalent of an enormous collecting dish. In effect, HALCA, once it is linked with other dishes on \Jearth\j, simulates a dish with a diameter greater than 30 000 km.
HALCA was built by scientists at the Japanese Institute for Space and Astronautical Science. Launched in February, it should allow astronomers to see further than ever before and make precise observations of objects that emit radio waves, such as quasars and black holes. The particle jet in the first images comes from a quasar which may contain a black hole within it, though this remains uncertain.
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"Sulfur and Earth's Outer Core",179,0,0,0
(Jul '97)
Sulfur hit the news in July, when a group of scientists led by Philippe Nasch offered a new view on an old problem. The outer core of Earth is mainly molten iron, but there must be some lighter alloying elements in the outer core as well, because the compressional sound waves which travel through the outer core do not match up with the expected measurements, based on experimental determinations and extrapolations of the properties of molten iron.
There are several possibilities, including sulfur, nickel, oxygen, and \Jhydrogen\j, but it can now be shown that sound velocity seen in ultrasonic interferometry in an Fe-Ni-S liquid increases with increasing \Jtemperature\j. This is unexpected, and the researchers suggest that the anomalous behavior is due to the presence of sulfur and believe that this behavior could be used to distinguish sulfur from other candidate core components.
While not being a discovery as such, the finding reflects the way in which science progresses, with a small observation opening the door for further developments.
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"Sulfur in a Solar Nebula",180,0,0,0
(Jul '97)
Chondrites are meteorites which contain "chondrules" that are assumed to represent condensates from the earliest formed components of the solar nebula. They also contain a set of sulfide minerals which seem likely to have been formed by an interaction of iron-nickel alloys with \Jhydrogen\j sulfide gas, according to work led by Dante S. Lauretta, a young research scientist who appears to have a bright future in front of him, no word-play being intended.
According to Lauretta and his colleagues in \IScience\i, the chondritic sulphides may be condensates from the solar nebula and so be available to be used as tracers of the \Jtemperature\j in the nebula when these phases formed. The work stems from placing a solar composition Fe-Ni alloy in a \Jhydrogen\j sulfide-rich gas.
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"Europa Has An Atmosphere",181,0,0,0
(Jul '97)
Remember \JGalileo\j, our emissary to Jupiter? While \JGalileo\j has been touring the Jovian system, it has been taking the odd glance at Europa, studying occultations, when Europa has been located between \JGalileo\j and a star.
The purpose of the sneaky looks: to identify any signs of an \Jatmosphere\j around the \Jsatellite\j. It now appears that there may be a thin \Jionosphere\j, produced by particles impacting on the \Jwater\j ice that covers the \Jsatellite\j. If the \Jatmosphere\j is rich in oxygen or \Jwater\j, as appears to be the case, the \Jtemperature\j of the tenuous gas could be as high as 340 kelvin, about 65 degrees \JCelsius\j or 150 degrees Fahrenheit, because the moon lies inside Jupiter's magnetic field, its magnetosphere, as do Ganymede and Callisto. Because of this unusual position, Europa's \Jionosphere\j will be heated by the action of the \Jplanet\j's magnetic field.
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"Rhea and Dione Can Have Ozone Holes",182,0,0,0
(Jul '97)
Similarly, Saturn has two satellites, Rhea and Dione, which \Jorbit\j inside that \Jplanet\j's magnetosphere. This means that they are subjected to continual particle radiation from trapped ions, much as happens on the three Jovian satellites mentioned above.
All five satellites have \Jwater\j-rich surfaces, and the presence of \Jwater\j-oxygen atmospheres was predicted by laboratory studies before the recent discoveries of atmospheres on Ganymede and Europa. Now it appears that there is a measurable build-up of ozone on Dione and Rhea, detectable from a distance by spectrometer, matching the earlier discovery of ozone on Ganymede.
#
"Dating the Old World Monkeys",183,0,0,0
(Jul '97)
Among the monkeys, those of Africa and Asia are known as the Old World monkeys, while the South American monkeys are the New World monkeys. Until now, we have only been able to hazard a guess that the monkeys split off from the stock which became us, somewhere between the late Oligocene and early Miocene, 28-22 million years ago.
Now the discovery of the oldest known \JOld World monkey\j skull, which is some 15 million years old, provides further fuel for debate about the division, which eventually resulted in the \Jevolution\j of Old World monkeys on the one hand, and the great and lesser apes, and humans, on the other.
Skull structures are commonly used to draw conclusions about the various members of the different \Jape\j genera. Unfortunately, good \Jfossil\j skulls, unbroken and uncrushed by the weight of sediments, are uncommon, and this makes it hard to work out which characteristics are primitive, there from the start, and which are recently derived. Obviously any characteristic which has evolved separately in two groups is not good evidence for any sort of relationship.
The discovery of a complete and undistorted skull of \IVictoriapithecus\i in middle Miocene deposits from Maboko Island, \JKenya\j, provides evidence that some of the characteristics which have been ignored in the past are primitive, allowing the experts to delve a great deal further into the relationships between different groups.
\IVictoriapithecus\i represents a branch of \JOld World monkey\j that appears to be intermediate between today's cercopithecids (Colobinae and Cercopithecinae) and the common ancestor they shared with apes (Hominoidea). This \Jfossil\j possesses a number of key skull features, and if these features were present in the ancestral form, they were probably not derived separately by \Jfossil\j forms such as \ISivapithecus\i and \IDryopithecus\i from Eurasia and the living orang hutan (or \Jorang-utan\j) (\IPongo\i) from \JBorneo\j and \JSumatra\j. You can expect to hear more arguments based on \IVictoriapithecus\i over the next few years.
#
"Chimp Retirement Plan",184,0,0,0
(Jul '97)
Large populations of chimpanzees have been bred in the USA for AIDS research and then not used, once people realised that the animals proved to be a bad model for the disease. An expert panel has now proposed that the National Institutes of Health acquire the approximately 1000 chimps the government already supports and shelter them for the rest of their lives. Or will the economic rationalists have them sent to a new theme park?
#
"Neandertal Man Partly Cloned",185,0,0,0
(Jul '97)
The individuals most of us learned to call \JNeanderthal Man\j, although the modern spelling of "Neandertal" is now more common, have been partly cloned.
That is to say, the mitochondrial DNA of one Neandertal has been extracted and analysed, but the results will be less than pleasing to the "lumpers" who see the Neandertals as humans like us, but of a slightly different form, but pleasing to "splitters" like Chris Stringer of London's Natural History Museum, who has long held that the Neandertals were a different species. On the evidence, the Neandertals were not our ancestors, but an evolutionary dead end.
More importantly, the results have been replicated in an independent laboratory, so there now appears to be no doubt that the individual sequenced was well separated from our own line of development. The evidence comes from a small amount of independent DNA, found not in the nucleus, but in small bodies in our cells, the mitochondria, and it says that there is a gap of 500 000 years of independent \Jevolution\j between the Neandertal studied, and modern humans, half a million years of travelling down different evolutionary branches.
We only inherit our mitochondria from our mothers, so while we have no way of knowing much about our fathers or our male ancestors on either side of the family tree, we can trace an individual's female ancestry back to the year Dot through a single unbroken female to female line. Every person alive today has inherited mtDNA through a line of female ancestors that disappears into past ages.
As time goes by, mutations slowly creep in at unimportant points in the DNA, and from this, we can estimate how far back two different lines diverged. The mitochondrial DNA does nothing but sit there like a luggage label, so there is no evolutionary selection operating on it, so far as we know. So when you sequence the mtDNA of two individuals, you can tell, from the differences, how long it is since they had a common female ancestor on that key female to female line.
In \IHomo sapiens\i, the mtDNA is simply a marker which seems to say that, without a doubt, we all had a common ancestor 200 000 years ago, or maybe a bit more, as the "clock" is open to some question. That at least is what the "mitochondrial Eve" supporters say. Based on clear and incontrovertible evidence from mitochondrial DNA, there existed a female in Africa, some 200 000 years ago, who was the ancestor of us all. Not surprisingly, the lady has been dubbed mitochondrial Eve.
The opposing theory says humans evolved in Africa two million years ago, radiated out as \IHomo erectus\i, and then evolved into \IHomo sapiens\i in their new homes. A variety of racial groups arose, but they were all part of the human story, and all contributed to the modern pool of genes that is humanity. When we look at the \Jfossil\j skulls, and there are several hundred of them available, the evidence seems to point quite strongly to a much longer and more continuous relationship. We came out of Africa, say the fossils, and Peking Man became the modern Chinese, \JJava Man\j became the people of the Pacific and \JAustralia\j, and so on.
That argument is still a matter for some dispute, with "Eve" supporters wanting to exclude the Neandertals from our line of development, and the "Eve" opponents wanting to include all of the humans into our general family tree. They point to a typically Neandertal skull characteristic, still found in 4% of modern Europeans, and argue for a Neandertal input into our make-up.
A report in the journal \ICell\i this month would appear, on the surface, to push the Neandertals out of our tree. Scientists in \JGermany\j and the United States worked on a sample from the upper arm bone of the prototype Neandertal skeleton, discovered in \JGermany\j in 1856. Working with extreme care to avoid contamination, Matthias Krings and Svante PΣΣbo of the University of Munich and Anne Stone and Mark Stoneking of \JPennsylvania\j State University all took part. Krings used the polymerase \Jchain reaction\j to amplify part of a particular sequence called the control region in the DNA of mitochondria.
The team found variations in stretches of the DNA which never vary in modern human samples, showing the DNA is ancient and uncontaminated. When they compared the Neandertal sequence with 986 distinct sequences from living humans, they found that the ancient DNA was three times more different than any two modern human sequences, putting it outside the statistical range of modern human variation.
The "splitters", of course, are delighted, but there is still room for the lumpers to retain some hope. The mtDNA only tells us about the female to female line of inheritance, and Neandertal genes could have come down to us from a line of descent that passed through a male at some stage. To the splitters, the finding implies that the Neandertal and "sapiens" lineages diverged before the first known Neandertal at about 300 000 years ago, and long before the first modern humans at less than 200 000 years ago.
As with so many other issues in science, there is evidence for each interpretation. Scientists tend to believe based on a selective view of the data, shaped by their friendships and associations, and shaping those associations in accordance with their views. Each side tries to fault the methodology of the other side, but it is all done in a carefully scientific manner.
But will we see Neandertal Park? It is unlikely in the near future. To have even got this much material was something extraordinary, since DNA degrades over time, and is so easily contaminated. As one palaeoanthropologist commented: "The fact that they managed to find DNA from a region of prime importance is proof that there is a God who likes palaeoanthropology."
#
"AIDS Transmission By Kissing",186,0,0,0
(Jul '97)
A case was reported in July of the \JHIV\j virus being passed on in kissing. A man who was \JHIV\j-positive has passed the virus to his partner, apparently after kissing her, just after brushing his teeth and flossing, which caused his gums to bleed. While the virus does not normally survive long in \Jsaliva\j, it apparently lasted long enough to make the transfer. Doctors have ruled out any alternative avenue of infection.
#
"Language Acquisition",187,0,0,0
(Jul '97)
Humans have had a speech area in their brains for maybe 1.9 million years-a \IHomo habilis\i skull of that date has the imprint of a frontal-lobe language-sensitive region known generally as "Broca's area", according to Phillip Tobias, one of the world's experts in the arcane art of reading the inner side of skulls to get clues about the brains they once contained. We all use Broca's area to speak our native language, where "grammar knowledge" is stored, but where are other languages' grammar knowledge stored?
It seems that it depends when you learn the next language. Children who grow up bilingual process the two languages differently from those who learn a second tongue later in life. The bilingual children store both languages in Broca's area.
In a report in \INature\i during July, Joy Hirsch and her colleagues at the Memorial Sloan-Kettering Cancer Center in New York City described their studies on two groups, "early bilinguals", and "late bilinguals" who learned their second language as adults. The subjects were asked to \Ithink\i of a story in each language while the researchers used functional magnetic \Jresonance\j imaging (fMRI) to monitor brain activity. They had to only "think" the story, as any body movement, even the movements of speech, can distort an fMRI image.
In this "thought tale" in the native tongue, several areas of the brain "lit up" including Broca's area, and in early bilinguals, the same part of Broca's area lit up, while in late bilinguals, the activity centred on a region 9 mm away. In both late and early bilingual subjects, another part of the brain, the temporal-lobe language-sensitive regions (Wernicke's area) showed little or no separation of activity based on the age of language acquisition.
Based on this, it seems possible that adults learn new languages in a different way from the way they learned as young children. Or is the native language region "closed off" to a second tongue after a certain age?
#
"Baby Talk",188,0,0,0
(Jul '97)
Maybe the difference has something to do with the way that a language is passed to the learner-how many adults acquire a second language through baby talk? Patricia Kuhl of the University of Washington in Seattle has been looking at the effects of baby talk, and she believes that baby talk may help infants to learn the key features of vowel sounds.
Kuhl has been looking at "parentese" in three different languages-English, Swedish, and Russian-and with her colleagues, she has found that in all three languages, mothers produced exaggerated versions of vowels when talking to their babies , emphasising the features that distinguish the vowels from each other. Adult speech varies, and children must learn how to identify the differences which are important, and the differences which are unimportant, so any tendency to emphasise the important differences will obviously be useful.
While this observation does not prove that children need this sort of speech to learn language, it does suggest some very interesting lines for future enquiry, such as identifying cultures using different amounts or types of parentese, and the ways children lean in those cultures.
Gram-positive \Jbacteria\j are those which are stained by Gram's stain. They all have cell walls made mainly of peptidoglycan, and they lack the outer membrane of lipopolysaccharide, lipoprotein and other large molecules, found in the Gram-negative \Jbacteria\j. \IBacillus subtilis\i is a Gram-positive soil bacterium which grows on simple media. Other Gram-positive \Jbacteria\j include \IStaphylococcus aureus\i, and the \Jbacteria\j causing \Janthrax\j and tetanus.
\IB. subtilis\i is a common laboratory species, and it is often used for studies on protein secretion, and for growing enzymes for industry. It is now the first of its group to have its \Jgenome\j completely sequenced.
After 5 years of work, leaders of a team of 37 laboratories announced the complete sequence of the 4.2-million-base \Jgenome\j in July. EU scientists completed 60% of the sequence, with Japanese researchers doing 30%. The remaining work was done by laboratories in the United States, Korea, and other countries. If you go to http://www.pasteur.fr/Bio/SubtiList.html, you will find 63% of the information stored there in an accessible \Jdatabase\j. More is expected to be online soon.
In mid-July, President Clinton urged Congress urged Congress to pass a new federal law forbidding discrimination based on a person's genes, in an effort to prevent the misuse of human genetic data. Once this law is in place, it will remove a potential roadblock from some types of genetic research, so the proposed law is only partly about safeguarding the individual.
Mr Clinton said he wanted to make it illegal for any health insurance company to deny coverage to a healthy person on the ground that medical data indicate that the person is at risk for an inherited disease. The proposed law will also rule out insurance companies raising premiums on the basis of genetic data. A background statement added that the law would also protect privacy by stopping health plans from releasing or demanding access to genetic information without a subject's consent. At the same time, the law will make provision for responsible use of genetic information for biomedical research.
Broad support appears to be available in Washington, but it remains to be seen how far this can be undermined by lobbying from the insurance companies, or whether other nations will follow suit.
#
"Genetically Engineered Viruses",191,0,0,0
(Jul '97)
Maybe genetically engineered viruses are not so bad after all. Researchers at the Johns Hopkins Oncology Center in Baltimore, working with a Californian company called Calydon, have produced a mutant strain of the common cold virus which will target and attack the cells of the prostate \Jgland\j. As prostate cancer is the second biggest cancer killer of men in the western world (after lung cancer), this is good news indeed.
The virus can enter any cell, but only becomes active when it finds PSA (prostate specific \Jantigen\j) in the cell. PSA is a protein involved in the formation of semen, and only rarely found in other cells, so its presence is a very effective identifier of prostate cells.
The problem was to make the virus recognise that it is in a prostate cell. This was achieved by finding the human gene that produces PSA, and then identifying the regulator gene which only switches on in prostate cells. Then they added this to a gene in the viral \Jgenome\j which is needed for replication, so the switch now triggers viral replication, but only in cells of the prostate.
A report in this month's Cancer Research (57:2559) shows tumors have been reduced to about a sixth of their former size in mice, and human trials are due to start soon. Like other cancers, prostate cancer sloughs off cells that move to other parts of the body in a process called metastasis, and the researchers hope in the future to use intravenous injections to send patrolling viruses around the body, seeking and destroying rogue prostate cells.
There is some evidence of the virus replicating in non-prostate cells, but it is unlikely that these will present problems, say the researchers, pointing out that the virus itself is one that we all have and manage to deal with, except that it can only grow in a limited range of human cells, rather than in most of them.
#
"Monkeypox Makes A Comeback",192,0,0,0
(Jul '97)
In the Democratic Republic of \JCongo\j, monkeypox virus appears to be transferring between people more easily than in the past. Smallpox vaccinations used to give resistance to this disease as well, but these were so successful that the smallpox vaccinations were stopped some two decades ago, leaving a large pool of people who are unprotected against the related monkeypox.
This raises the question of whether or not the world's remaining stocks of smallpox should be killed off or not. It may be that future researchers will need the smallpox virus as they try to defeat something like the monkeypox outbreak, which causes almost identical symptoms in its victims.
Between February 1996 and February 1997 at least 92 cases of the disease and 3 deaths were reported in a remote region of what was then Zaire. This compares with just 37 recorded cases from 1981 to 1986. Of the 89 survivors, 73% seem to have been infected by other people, while the 1981-1986 studies reported no more than a 30% "secondary contact" rate, according to the Czechoslovakian epidemiologist and monkeypox expert, Zdenek Jezek, who carried out the study.
Immunity problems may stem only from the lack of smallpox \Jvaccination\j, but it is further compromised because the Democratic Republic of \JCongo\j has high rates of infection with \JHIV\j, which cripples immune systems. The \Jcivil war\j may have contributed another factor as villagers, faced with the risk of starvation may have increased their hunting of animals that carry monkeypox, which include monkeys, squirrels, and rats. The unrest has also made it risky for scientists from the U.S. Centers for Disease Control and Prevention (CDC) to work in the area. Until the area settles down, the way in which the disease is transmitted must remain a mystery, and a slightly worrying mystery at that.
#
"Sarawak's New Killer Disease Strikes Children",193,0,0,0
(Jul '97)
A mystery disease killed 31 children in \JSarawak\j, from its first appearance in April, up to the start of July. The children, twenty boys and eleven girls, were aged from 5 months to six years, and their symptoms appeared similar to the "hand foot and mouth disease", caused by the Coxsackie A16 virus and other enteroviruses, which has been raging on the Malaysian mainland, affecting more than 2000 children. The mystery disease causes the same rashes on the hands, feet and mouth region.
There is one big difference: the HFM disease does not normally kill its victims. This disease triggers heart failure in its victims, while none of the mainland patients has died so far. A team of the recognised centre of expertise, the U.S. Centers for Disease Control and Prevention (CDC), is now in \JMalaysia\j trying to help the government identify the cause.
Malaysian health officials think that Coxsackie B virus, which is linked to myocarditis, could be a possible cause of the heart failure disease. Yet another possibility is enterovirus 71, which is known to cause heart failure and which has been isolated from several of the dead children. So far, researchers have managed to eliminate a number of viruses with serological studies, so they know that they are not looking at Japanese \Jencephalitis\j, \Jdengue\j, yellow fever or a Rickettsial infection, but that still leaves a very wide range of possibilities.
The latest details are to be found by accessing this URL, although it should be noted that some of the press releases are in Malay: http://ftp.\Jsarawak\j.com.my/org/jkns/outbreak/virus1.htm.
#
"Yeast Prion Model",194,0,0,0
(Jul '97)
Diseases like Creutzfeldt-Jakob disease (CJD) in humans and scrapie in sheep, and "mad cow disease" (bovine spongiform encephalopathy or BSE), are all fatal neurological diseases, all marked by the accumulation of protein deposits in the brain. While all of these have been blamed on prions or "infectious proteins", evidence has been lacking up until now, and arguments for the theory have appealed rather more to logic than to fact.
During July, a report in \IScience\i described a yeast protein which behaves in the test tube exactly like the hypothesised prions. The idea has been that prion proteins convert from normal helixes into durable sheets, and then act as a template, converting other proteins to the same sheet form. The technical details are too complex to describe fully here, but the results seem to support the prion hypothesis.
#
"New Zealand Rabbits Escape Calicivirus",195,0,0,0
(Jul '97)
The \Jrabbit\j calicivirus disease (RCD), also known as \Jrabbit\j haemorrhagic disease, has spread from Asia into Europe over a number of years, and been deliberately introduced into \JAustralia\j in recent times. Trials in \JAustralia\j involved its use at an experimental station on Wardang Island, off South \JAustralia\j, but it escaped (or was deliberately or accidentally carried) to the mainland in 1995. After that, it was artificially carried across the country, both officially, and also unofficially by enthusiastic farmers.
In many areas, the disease has served to reduce drastically the number of rabbits in farming areas. The rabbit is a widely recognised pest, introduced by English colonists in the 19th century, and found across most of \JAustralia\j. Many areas of infestation remain, but the virus has reduced rabbit numbers in other areas, and accompanied by baiting, ripping and fumigation, has given many Australian farmers their best season for a decade or more. The only Australian complaints have come from rabbit trappers who trap rabbits either for food or for their skins, used to make the traditional Australian felt hat of "the bush".
New Zealand, however, has decided to wait and see what happens in \JAustralia\j before trying to unleash the virus on their own introduced rabbits. They say they are still uncertain about how effective the virus would be in New Zealand, which lacks some insects probably responsible for spreading the disease in \JAustralia\j. New Zealand may also be too damp for the virus to spread effectively, say scientists.
Rabbits cause severe damage to about 9% of \JNew Zealand\j land, mainly in the South Island, and farmers in the South Island are less than impressed at the decision, while in \JAustralia\j, a large legal firm which specialises in litigation is planning to file a negligence suit against the CSIRO, the Australian government research body which was running the trials on Wardang Island.
#
"Genes May Be Patented",196,0,0,0
(Jul '97)
During July, members of the European Parliament approved an outline of legislation to determine what biotechnology inventions can be patented in the European Union. Genes and genetically modified animals may be patented under specific conditions, but plant and animal varieties and techniques directly related to human germ line manipulation or human \Jcloning\j are on the no-go list.
#
"Quantum Physics Update",197,0,0,0
(Jul '97)
Quantum physics has some most unpleasant and brain-hurting aspects, not only to ordinary mortals, but to people like Albert Einstein as well. He was fond of generating challenges that seemed to "prove" that quantum theory had flaws in it. Now one of Einstein's "impossibilities" appears to be possible.
The problem runs like this: when a particle such as an \Jelectron\j breaks down and generates two photons, these are in an indeterminate state. If they separate by several light years, and you then measure one of them, this act of measurement shifts both the measured photon and the other photon as well, at the same instant, into a determinate state. This means there has been an action at a distance, an action which has travelled far faster than the speed of light. Not possible, said Einstein.
Bad news, Albert. Researchers using the fibre-optic lines of the \Jtelephone\j system in \JSwitzerland\j have shown that the links persist up to 10 kilometres. One cynic has told your reporter that this will lead to a situation where \Jtelephone\j companies will be able to bill you for calls before you make them.
#
"Cambrian Explosion",198,0,0,0
(Jul '97)
Something happened, around 540 million years ago, something that triggered an explosion in animal life forms, often referred to as the Cambrian explosion. That something may have been the \Jevolution\j of vision, the \Jevolution\j of hard parts to protect growing bodies, or maybe they were just signs of something else. The latest theory is high-speed tectonic plates.
That is, high speed in geological terms, though slow in ours. Fossil magnetism from several continents suggests for example that \JAustralia\j rotated 90 degrees in just 30 million years, and this sort of shift would have produced rapid variation in habitats, enough to trigger rather rapid evolutionary events. All of the major continental plates rotated and moved rapidly during the Early and Middle Cambrian, to some extent, say the researchers.
#
"Magnetic Fields and Cancer",199,0,0,0
(Jul '97)
A major study was reported in the \INew England Journal of Medicine\i, ending the claims that have been made since 1979 that exposure to electromagnetic fields (EMFs) from home wiring causes cancer. A major epidemiological study on 638 children with acute lymphoblastic leukemia, and a set of 620 matched controls in nine midwestern and mid-Atlantic states of the USA has investigated field strengths in each child's bedroom over a period of 24 hours. They also made spot measurements in the kitchen, the family room, and the room where the mother had slept during her \Jpregnancy\j.
The survey found no link between EMFs of 0.2 microtesla, the level previously alleged to be enough to trigger cancer. There was a "hint" of an association in homes with field strengths of 0.4 to 0.499 microtesla, but there were only 14 cases and 5 controls in this group, not enough to establish a case, and the "hint" was absent in homes with fields greater than 0.5 microtesla.
The NEJM editorial suggests that it is time to stop wasting research resources on this question.
#
"Paradoxical Ice Shelves",200,0,0,0
(Jul '97)
Spectacular pictures of ice crashing off towering glaciers on the Antarctic Peninsula have been used to illustrate the threat of global warming. Yet according to a report in \INature\i this month, global warming may actually cause the massive ice shelves of \JAntarctica\j to thicken.
The Antarctic glaciers have flowed out beyond the shore, where they float on the sea as attached ice shelves. In winter, when \Jsea ice\j forms further out in the oceans, the \Jsea ice\j is pure ice with no salt, because the salt is forced out of the ice crystals as they form. So the remaining unfrozen sea \Jwater\j is now more salty and so more dense than before. This brine is also at the surface freezing \Jtemperature\j of ice, and as the denser salt \Jwater\j sinks, it holds this \Jtemperature\j.
Flowing below the ice shelves, 1500 metres below the sea, the \Jwater\j is still at the same \Jtemperature\j, because there has been no heat flow in or out. But the brine is now a degree warmer than the freezing/melting point of the deep ice, because the melting point is lower 1500 metres down, due to the increased pressure. So now the "warm" \Jwater\j can carve away ice from below. The flow of this "warm" \Jwater\j is greatest in winter, according to a team from the British Antarctic Survey, led by Keith Nicholls, who have been drilling through the Ronne Ice Shelf and studying the \Jwater\j below.
Global warming, with milder winters, says Nicholls, is likely to produce less \Jsea ice\j in winter, and that means less brine, and so less melting out of the underside of the ice shelves. But snow is still falling on the upper side, adding to the amount of ice on the ice shelf, and so the ice shelves will get thicker. So it may be that the ice shelves have less to fear from climate warming than we first thought.
#
"Penguins and Voluntary Hypothermia",201,0,0,0
(Jul '97)
Penguins can stay under \Jwater\j for a remarkably long time, even allowing for their blood being more oxygen-rich than ours. Now it looks as though the birds that fly under \Jwater\j have mastered the art of cutting off circulation to unimportant parts and going into voluntary hypothermia.
Trained human divers can stay down for up to four minutes, and reach depths of 100 metres, but given their body size and oxygen consumption, a penguin should only be good for about two minutes. A king penguin weighing 12 kg can stay down for more than 7 minutes, and reach a depth of 300 metres, while 30 kg emperor penguins get to 534 metres in dives lasting almost 16 minutes. This is well beyond what the penguins should be able to do, given the oxygen they are carrying with them when they dive.
A report in \INature\i this month explains how the mystery was cracked, by implanting \Jtemperature\j sensors in penguins' stomachs and monitoring their feeding habits. They found that the penguins' stomach temperatures dropped from a normal homoiothermic 38░C to as low as 19░C. This was unsurprising, since the temperature of the fish the birds consume is only about 4░C. What was surprising was that the temperature of the rest of the \Jabdomen\j dropped to just 11░C, much cooler than could be explained by the penguin's chilly diet.
It seems that the penguins are restricting the oxygen supply to some of their tissues, and this means using less \Jenergy\j and less oxygen, and producing less heat. The effect is not new in one sense: whales cut down on blood flow to their outer layers, but the difference is that the penguins are reducing their core \Jtemperature\j.
#
"White House Looks At Greenhouse",202,0,0,0
(Jul '97)
Ask most concerned climatologists, and they will tell you despairingly that politicians simply do not care about greenhouse effects, carbon emissions, or any decisions that might inconvenience the electors, however mildly. July may have seen one small twinkle of hope to counteract that pessimism.
President Bill Clinton and Vice President Al Gore called in a group of seven scientists to address them on the topic, but the duo seemed to have a political agenda as well, to educate the American public in preparation for a major international meeting on climate change in December in \JKyoto\j, \JJapan\j.
"We see the train coming, but most ordinary Americans in their day-to-day lives can't hear the whistle blowing," said the President. It was a message echoed by one of the speakers, John Holdren, a professor of environmental science and public policy at Harvard University, who commented on the many linkages between the developed world and the developing world in a time of climate change: "you can't sink just one end of a boat".
Commentators say the meeting indicates that Clinton has been convinced by Gore and other environmentalists in his administration to try to build public support for action on climate change, as the environmentalists have been seeking. Unfortunately, the US Senate remains unmoved, unanimously backing a resolution calling on the administration not to agree on anything in \JKyoto\j that would damage the US economy or set emission limits for developed countries while leaving developing countries without restrictions. As the senate will have to ratify any convention, it appears that maybe the President needs to educate his senators first and foremost-unless he is counting on the public to do it for him.
The same selfish "not-me-first" line has been adopted by a number of countries, especially \JAustralia\j, one of the worst per capita carbon dioxide emitters in the world, due to that nation's reliance on \Jcoal\j-fired power stations.
#
"What Drives the Ice Ages?",203,0,0,0
(Jul '97)
The standard model for some decades has had ice ages triggered by cyclical changes in the elliptical shape of Earth's \Jorbit\j about every 100 000 years. Not so, according to a paper in Science this month. Muller and MacDonald have been looking at several types of oceanic climate records, and they have questioned this assumption. Instead, they suggest, changes in the inclination of Earth's \Jorbit\j relative to the plane of the \Jsolar system\j have taken our \Jplanet\j into a climate-altering \Jcloud\j of cosmic dust.
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"New Athletic Training Method?",204,0,0,0
(Jul '97)
How do you get ready for the big race? Do you head for the high country, and stimulate your body to generate additional red blood cells, and run the risk that altitude will cause \Jinsomnia\j or loss of appetite, or because there simply isn't enough oxygen in the air, run the risk that you will not use your muscles fully?
Races are won by very small percentages, and a great deal of research effort goes into finding ways of shading the odds to favor an athlete. Now it appears that runners can shave crucial seconds off their time if they live at high altitudes but train closer to sea level.
Benjamin Levine and James Stray-Gundersen, from the University of \JTexas\j Southwestern Medical Center in \JDallas\j, gathered 39 amateur competitive runners and timed them in a 5-\Jkilometre\j race at sea level before assigning them randomly to one of three groups.
The first group lived and worked out at sea level, a second lived and trained at 2500 metres, and the third group lived at 2500 metres but trained at 1200 metres. After four weeks, the runners were brought together again, and timed once more.
Neither the high-high nor the low-low group showed any real advance, but the high-low group gained about 13 seconds on average, equal to about 100 metres over the 5 km race. How long will it be before athletes start sleeping in sealed low-pressure vessels?
#
"Chemistry Update",205,0,0,0
(Jul '97)
"How many atoms does it take to do an analysis?" may sound a bit like a lightbulb joke, but when it comes to the transuranic elements, where half-lives are fractions of a minute, this is an important question. More importantly, the heaviest atoms are also the ones in which relativistic effects can make the elements behave in unexpected ways.
The transactinide elements, beginning at element 104, have now been identified with a high level of certainty, up to element 112. The first two of this series, elements 104 and 105 show variations from the chemical behavior that would be expected from a simple glance at the \Jperiodic table\j and its trends.
From \INature\i this month, we now have some knowledge of element 106, often called Seaborgium. Using just seven atoms, each lasting just a few seconds, scientists have shown that element 106 is clearly in Group 6 of the \Jperiodic table\j, beneath \Jtungsten\j and molybdenum, rather than continuing the trend of wayward behavior established by elements 104 and 105. But does this make the chemists happy, to see an element performing as it should? No chance: they now want to know why it behaves in such a coventional manner.
#
"Extinction on High Seas?",206,0,0,0
(Jul '97)
Some biologists are now suggesting that the oceans are not as resilient as we once thought, and that we may be on the edge of a massive marine \Jextinction\j event. At the same time, while only 275 000 marine species have ever been described, new estimates suggest that \Jcoral\j reefs by themselves support around a million species, and that the deep sea floor, once dismissed as a barren desert, may support another ten million species. For the moment . . .
But are corals as fragile as people think? They seem vulnerable in the short term to all sorts of changes, yet they have persisted over hundreds of millions of years. A new study in \INature\i in July shows that corals enter into symbiotic associations with many different types of \Jalgae\j, and that the \Jalgae\j involved at any one time can vary considerably as corals adjust to changing conditions.
On this basis, the phenomenon of "\Jcoral\j bleaching" may not be the problem it was once considered to be. Coral bleaching has been known now since it was observed on the \JGreat Barrier Reef\j of \JAustralia\j in the 1920s, but studies in the Caribbean have typified the bleaching as a changeover, rather than a death event.
The ecologically dominant Caribbean corals, \IMontastraea annularis\i and \IM. faveolata\i provide a home to a variety of dinoflagellates (\ISymbiodinium\i spp.), and compositions vary with light levels. The dinoflagellates are generally classed as \Jalgae\j, and they are able to carry out \Jphotosynthesis\j, allowing them to "pay" for their accommodation in the coral. The analysis described by Rowan, Knowlton, Baker and Jara showed that the bleaching process they observed involved the elimination of a dinoflagellate which was less able to stand up to high light levels.
And even though reefs in Southeast Asia and the Caribbean are crumbling, most reefs in the Pacific and Indian Ocean appear to be in good health, says a report this month.
#
"Ecosystem Inter-Reliance",207,0,0,0
(Jul '97)
It is a polite fiction that ecosystems are isolated from each other. In fact, most ecosystems leak significant amounts of \Jnutrients\j and \Jenergy\j into other ecosystems, and receive much the same amount of leakage in return. Because the two effects largely balance out, the interchanges can generally be ignored, but what happens if a stream is unable to gather leaf litter from the ground around it?
During July, a group of scientists reported on a three-year study of the effects of keeping leaf litter out of a stream. When the stream bottom was composed of cobble, pebble, and gravel substrate, the effects were dramatic. All invertebrates, from detritus eaters to predators dropped away, but in areas with moss-covered bedrock, the removal of fallen leaves had no effect, suggesting that different food webs were involved.
The implications for stream restoration efforts are fairly clear: no leaf litter means no \Jinvertebrate\j diversity.
#
"Cloned Transgenic Lamb",208,0,0,0
(Jul '97)
From the same lab that gave us Dolly the sheep: in July, the first cloned transgenic lamb, a lamb containing foreign genes. This has been hailed as the first step to developing domestic animals which could make, for example, human proteins for therapeutic use.
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"Mir--A Suitable Case For Treatment?",209,0,0,0
(Jul '97)
There is little to report on the Mir situation. No action was undertaken during July, but a new crew joined the space station in August, and were preparing to make repairs later in the month.
Many of the current experiments on board were halted immediately, as power was lost, and some experiments were irretrievably damaged. Some members of the U.S. Congress are openly questioning whether NASA should continue to participate in experiments aboard Mir, and questions about the future of any international space station were asked. As the crews changed over in mid-August, a new deadline was set, with Mir's \Jwater\j recycling system failing. A new supply of \Jwater\j will need to be taken to Mir by the next shuttle flight, and if this is delayed for any reason, the cosmonauts could be in very serious trouble.
In the event of a disaster, will Mir mean the end of space stations and space flight? If it does, it will only be because people have not properly considered the risks. Space station supporters were busy in July, pointing out that there has been about one death for every 10 000 hours of space flight time, while civil \Javiation\j has one death for every 37 000 flying hours. And if you take it on kilometres flown, they say, space flight is the safest form of transportation around.
#
"No Watery Comets After All?",210,0,0,0
(Jul '97)
Louis Frank's minicomets (May, "Controversy in Space"), may not be the source of our oceans after all. Measurements of the ratio of ordinary \Jwater\j molecules to molecules containing \Jdeuterium\j in the comets Hale-Bopp and Hyakutake were reported at recent meeting to show a marked departure from the ratio found in seawater.
Tobias Owen and Roland Meier of the University of Hawaii's Institute for Astronomy and their colleagues used the James Clerk Maxwell \JTelescope\j on Mauna Kea to pick up radio emissions from the \Jdeuterium\j-containing molecules in the \Jcomet\j, Hale-Bopp, and found three atoms of \Jdeuterium\j (\Jhydrogen\j with a neutron in the nucleus) for every ten thousand ordinary atoms, around twice the ratio found in ordinary sea \Jwater\j. This determination agrees with measurements of last year's \Jcomet\j Hyakutake last year, and also released recently.
Opponents of Frank say that his theory is in trouble, that we could not accept the idea of making the bulk of Earth's oceans with \Jwater\j from these sorts of comets, but Frank is unconvinced. Frank says that the large comets like Hale-Bopp have nothing to do with the \Jwater\j in our oceans. His comets, he points out, are "small and fluffy", with a different make-up, and quite possibly in their \Jdeuterium\j to \Jhydrogen\j ratios. So until somebody manages to capture a minicomet and measure the comet's composition, the question will have to remain open.
#
"Resistant Antibiotics",211,0,0,0
(Jul '97)
The antibiotic-resistant \Jbacteria\j (see April) continue to be a problem around the world, and medical researchers have launched a new program, called Sentry. This links up 72 hospitals and clinics worldwide to keep tabs on these threats to human health and well-being. Funded by the drug manufacturer, \JBristol\j-Myers Squibb, Sentry will cost several million dollars over the next three to five years, in return for which, the manufacturer will get access to the bacterial samples involved.
In one aspect of a pilot trial, swabs of South American patients revealed that the \Jbacteria\j that commonly cause urinary tract infections were resistant in about 30% of cases to common cephalosporin \Jantibiotics\j.
#
"Antibiotics Useful For Cardiac Conditions",212,0,0,0
(Jul '97)
A bacterium called \IChlamydia pneumoniae\i has been found in the arterial blockages of 75% of patients with \Jatherosclerosis\j, or partially clogged arteries. A report in the journal \ICirculation\i this month suggests that \Jantibiotics\j may be useful in treating some types of \Jheart disease\j.
In a trial, 80 of 213 male patients who had previously suffered a heart attack had high antibody levels to the bacterium, suggesting a \Jchlamydia\j infection. Researchers treated half these patients for 3 days with azithromycin, an antibiotic that wipes out \Jchlamydia\j infection, and found that, 18 months later, only 8% of the treated men had suffered another heart attack or other serious cardiac event or died, while 28% of those who were untreated or who were given placebos suffered such a fate.
This could be important in developing countries like India, where \Jheart disease\j rates are rising, but where facilities and costs largely rule out usual western procedures such as bypass surgery and \Jballoon\j angioplasty.
#
"Obituary For July 97",213,0,0,0
Eugene Shoemaker, co-discoverer of the \Jcomet\j Shoemaker-Levy which crashed into Jupiter, died in a traffic accident in northern \JAustralia\j in mid-July, where he was on an annual visit to look for impact craters. His wife, also part of the \Jcomet\j discovery team, was injured but survived the accident.
Shoemaker was 69. His wife and longtime scientific collaborator, Carolyn, suffered broken bones, and is in stable condition. Shoemaker was a front runner among planetary scientists in arguing that the \Jearth\j has long been bombarded by meteors and comets, and identified the Barringer Meteor Crater, near Winslow, \JArizona\j as the result of a strike by a meteor which exploded upon impact.
The Shoemakers discovered more than 800 \Jasteroids\j, but they have left a lasting mark with their share in the discovery of the \Jcomet\j Shoemaker-Levy which plunged into Jupiter as scientists watched.
#
"Robots For the 21st Century",214,0,0,0
(Aug '97)
Quite apart from reports during the month of "robot sheepdogs" practising on ducks ("which behave like sheep, but more slowly"), Sojourner has continued to look around the Martian landscape, while Nomad has been having an extended desert vacation in \JChile\j.
Nomad? The next generation of Martian exploring machines will look much like Nomad, which travelled 215 kilometres in six weeks, found some meteorites which had been planted in the desert for it to find, and even found a type of rock not previously seen in \JChile\j.
A Carnegie Mellon University project, Nomad was controlled from 8000 km away, providing \Jfeedback\j from a camera that could image the 250 kg robot's full horizon. Next year, it will have an Antarctic break, when it is sent to look for meteorites on the ice. Regrettably, Nomad's strange rock, which fitted a profile for sedimentary rocks that might contain fossils, did not produce any traces of life, although the rock was indeed sedimentary. It was, however, a major victory just to have Nomad find the rock and identify it as different.
Robots have an active social life: the month also saw RoboCup '97 in \JNagoya\j, running from August 23 to August 29. RoboCup involves teams of six robots playing a form of \Jsoccer\j against each other. According to the organisers, in order for a robot team to actually perform in their modified \Jsoccer\j game, "various technologies must be incorporated including: design principles of autonomous agents, multi-agent collaboration, strategy acquisition, real-time reasoning, robotics, and sensor-fusion".
The RoboCup site provides a great deal of background information on the competition, and gives links to other pages as well. The organisers have listed a number of expected changes for the future: the walls which surround the playing field are to go soon, the current system allows a global vision system from above the field, but this is to be banned, and they are planning to introduce an offside rule, placing more demands on computational power.
No doubt the 21st century will see \Jsoccer\j matches between autonomous teams of robots, playing on the level playing fields of Mars.
#
"Genome News",215,0,0,0
(Aug '97)
Late July saw a report about the complete mapping of human \Jchromosome\j 7, with 170 million genes, some 5% of the entire human \Jgenome\j. The X \Jchromosome\j, of course, is already complete, leaving just 21 chromosomes and the y chromosome to go.
Mapping is not the same as sequencing the \Jchromosome\j, which identifies every single base pair on the \Jchromosome\j, but it provides a set of landmarks, mapping a sequence tag site that could be detected by a PCR assay every 100 000 base pairs, right across the human \Jgenome\j.
#
"Completed Bacterial Genome",216,0,0,0
(Aug '97)
The complete 1 667 867 base-pair sequence of \IHelicobacter pylori\i was published in early August, involving 1603 (or 1590, depending on how you look at it) genes altogether. The new work reveals many features, among them the machinery that the \Jbacteria\j use to exist in the acid environment of the \Jstomach\j. It is estimated that the bacterium infests the intestines of half the world's population.
This is the sixth bacterium to have had every last \Jnucleotide\j base-pair of its DNA recorded and published, so the excitement is now a little muted, but \IH. pylori\i is an important bacterium. Until recently, gastric ulcers were blamed on diet and a stressful life-style: now we know that ulcers are cause by infections of this bacterium.
The sequences in the circular \Jchromosome\j were calculated by fragmenting the bacterial DNA, sequencing the bits, and then using a very powerful computer to link the sequences back together again, based on duplications and overlaps.
#
"Worms in the News",217,0,0,0
(Aug '97)
Meanwhile, one of the larger animals under genomic study (the entire \Jgenome\j of the \Jnematode\j \ICaenorhabditis elegans\i is due to be completed soon), can store up fat and enter a state of suspended animation (the "dauer phase") for 2 months or longer. They do this when they detect a shortage of food by slowing their \Jmetabolism\j, and now researchers have cloned and sequenced daf-2, the gene which controls this.
Curiously, the protein that the gene encodes appears to be the worm equivalent of the human \Jinsulin\j receptor. This molecule "listens" for the hormone \Jinsulin\j, which is secreted in response to a rise in blood sugar, and passes its \Jmetabolism\j-enhancing signal to our cells' interiors. This raises the question: are changes in \Jglucose\j \Jmetabolism\j the key to slowing the ageing process in higher organisms, including humans? Nobody knows where these studies will lead, but it could even bring us to a better way of treating diabetes.
\BAnd yeasts\b
If the worms don't have the answer, maybe the yeasts will. A rare genetic form of accelerated ageing in humans, Werner's syndrome, has just been reproduced in yeast. The work is likely to help researchers trace out the molecular changes that underlie aging in humans as well as in yeast.
It may seem improbable, but yeast cells age. After dividing about 25 times, the normal yeast cell stops dividing and dies. About halfway through that range, the cells normally cease sexual reproduction, but the new mutant form reaches this point after just five normal divisions.
A team led by Leonard Guarente at the \JMassachusetts\j Institute of Technology studied brewer's yeast, \ISaccharomyces cerevisiae\i, in order to shed light on the function of the Werner's syndrome gene. It looks as though the protein encoded by the normal form of the Werner's gene prevents premature ageing, and that it does this in the nucleolus of the cell, a part of the nucleus where the protein-synthesising ribosomes are assembled. This confirms earlier evidence which linked the nucleolus with the prevention of ageing.
#
"Birds Indicate Warmer Climate",218,0,0,0
(Aug '97)
Welsh \Jcoal\j miners used to take canaries into the mines to warn of gas build-ups, because the birds were more susceptible to gas concentrations. Now wild British birds seem to be sounding a similar note of warning for the whole world, by nesting and laying eggs eight days earlier than they did 25 years ago, just as the growing season for British plants is now eight days earlier, and at a time when British amphibians have been seen to breed earlier.
Britain's compulsive bird watchers have been collecting nesting records, more than a million of them, since 1939, covering 225 species of bird. While some of this information is less available for statistical analysis, some 75 000 records covering 65 species have been extracted by Dr Humphrey Crick and his colleagues from the British Trust for Ornithology in Thetford, Norfolk. In all but one of the species, there is a trend to laying eggs earlier, and in twenty of the species, the difference was enough to pass statistical tests of significance.
The one species which did not fit the trend is the stock dove (\IColumba oenas\i), which nests throughout the year, not just in spring, so that it could hardly have been expected to match the pattern followed by the spring breeders.
Whales may also have good reason to worry about the \Jweather\j-or at least about our concern with it. Gerald Eddlemon is an ecologist at the Oak Ridge National Laboratory in \JTennessee\j who has been looking at \Jweather\j balloons in the Antarctic. About 10 000 of these are launched each year, falling eventually into the sea, where there appears to be about a 7% chance that a random whale will encounter a balloon each year while feeding.
The \Jpolythene\j used to make most balloons would last for years in cold Antarctic waters, says Eddlemon, who suggests that it is possible the balloons are having an undesirable effect on some \Jendangered species\j of whale, especially the filter feeders which "sweep" large volumes of ocean each year.
On the other hand, marine mammals would probably be more worried by the news this month that DNA testing has shown that most of the whale meat sold in \JJapan\j seems to be of species other than those allegedly targeted in \JJapan\j's "scientific whaling". There have been dark allegations from conservationist groups about organised crime syndicates cashing in on the lucrative trade in whale meat. Whether criminals are involved or not, we know the names of the innocent parties: several dolphin species, as well as blue, humpback, fin, Bryde's and Baird's beaked whales were found in the samples of meat alleged to be from minke whales.
Perhaps the whales can find comfort in a report this month, showing that the cetaceans (that is, the whales, dolphins and porpoises) form a clade with the artiodactyls (animals such as pigs, hippos, camels and ruminants), which is science-speak for these groups sharing a common ancestor which was not related to any of the other mammals. Perhaps the answer is to modify \Jcattle\j so they can produce something indistinguishable from whale meat?
#
"Global Warming--Too Early To Judge",219,0,0,0
(Aug '97)
Back to the \Jweather\j, Europe relies heavily on the North Atlantic Current for warmth, a system which is driven by convective overturning at the northern end of the Atlantic. This consists of a mix of cool and warm currents, but the pattern could easily be about to change in response to just a small change in \Jtemperature\j and rainfall patterns. So the common political stance that we have seen no problems so far may be, as some scientists are now suggesting with increasing stridency, a bit like the person who jumps from the twentieth storey of a building, and reports no problems after completing 95% of the fall.
What they mean by this analogy is that the problem may have more to do with rates of change than degrees of change, that we are venturing into the unknown, and nobody knows what to do to switch the North Atlantic Current back if it \Idoes\i fail. What we do know already is that sea surface \Jtemperature\j oscillations have been observed in the Atlantic which persist for several years, and coupled with surface pressure variations, probably form a whole-ocean oscillation which may cycle over years or decades.
One of the more useful indicators, a \Jsatellite\j view of the changing color of Earth's oceans, can reveal the growth and death cycles of microscopic ocean plants across the globe and help establish their role in climate change. With the launch this month of SeaWiFS, the Sea-viewing Wide Field-of-view Sensor, the necessary data will be more freely available.
SeaWiFS will send down a complete color picture of Earth's surface every two days, giving us a broader and more frequent coverage than any earlier oceanographic \Jsatellite\j. From accurate information on the cycles of plankton growth, scientists should learn how much carbon dioxide the plankton absorb from the \Jatmosphere\j and then be able to refine their models of global warming.
SeaWiFS will also tell us more about how the El Ni±o current which is now warming the eastern Pacific affects \Jphytoplankton\j growth. As the El Ni±o hot spot develops, it blocks the upwellings of cold \Jwater\j, packed with the minerals that \Jphytoplankton\j require. This blockage decreases the plankton levels enormously, and without the \Jphytoplankton\j at the base of the food pyramid, everything else declines as well.
\BMonsoons as well\b
When you look at climatic interactions between the ocean and \Jatmosphere\j, the two most important are the Asian monsoon in the Indian Ocean and the El Ni±o-Southern Oscillation (ENSO) in the \JPacific Ocean\j, so it seems only logical to look for links between those two systems. Evidence reported this month, based on the oxygen isotopic compositions in banded corals from the western Indian Ocean says there is such a link. The oxygen isotope ratios reflect the sea surface \Jtemperature\j, and the pattern reflects the ENSO pattern. The data, which extend back to 150 years, suggest that the \Jlinkage\j has held up even though the ENSO pattern is quite variable.
#
"New Discoveries on the Sun",220,0,0,0
(Aug '97)
The news stories treated it as "\Jweather\j on the \Jsun\j", but the true story was even more exciting. Data from the Solar and Heliospheric Observatory (SOHO) \Jspacecraft\j tell us there are doughnut-shaped zones of relatively rapid flow, rivers of solar material, near the solar north and south \Jpoles\j of the \Jsun\j.
The flows would never have been seen from \Jearth\j-based observations, but SOHO's Michelson Doppler Imager (MDI), one of 12 instruments on board the European Space Agency craft, watches the \Jsun\j continuously from a point 1.5 million kilometres closer to the \Jsun\j, and makes sensitive measurements of the undulations and wiggles on the \Jsun\j's surface at about three quarters of a million points at once. The wiggles show where sound (acoustic) waves are emerging on the \Jsun\j's surface, and they carry with them tell-tale traces of the conditions in the regions they have passed through.
The "rivers" which have been revealed are about 30 000 km across and 40 000 km below the surface. The flows are hard to explain, but may be similar to the jet streams that operate in the upper reaches of the \Jearth\j's \Jatmosphere\j.
#
"Supernova, Quest To Understand",221,0,0,0
(Aug '97)
Where would you look for signs of an exploding star? An international team of physicists plans to go underground, almost a \Jkilometre\j down into deep salt deposits, where they will set up a pair of subterranean observatories to capture thousands of the elusive particles called neutrinos, which should come from the core of a \Jsupernova\j.
The project proposal carries the name Observatory for Multiflavour Neutrinos from Supernovae, or OMNIS, and it is to be a set of low-maintenance detectors which could easily wait years to uncover a brief burst of neutrinos that would announce the occurrence of a type II \Jsupernova\j in our galaxy.
A type II \Jsupernova\j happens when a star runs low on fusion fuel. As the star cools, the internal pressures which maintain the star against the pull of gravity get less, and the star collapses inwards before exploding and firing a shock wave from the core, out through the upper layers.
As the shock wave slows, a blast of neutrinos boils up out of the core, blowing the star apart, and driving the outer layers off into space. A \Jsupernova\j is a random event, and for now at least, entirely unpredictable, so it will be necessary to set the system up and wait for the inevitable \Jday\j when the neutrinos pass by.
As the neutrinos race past , a few will crash into nuclei in the salt walls of the chamber, or into nuclei in metal slabs near the detectors. As they do so, neutrons will be thrown off, ready to be detected by plastic or liquid scintillation detectors, where they would produce countable flashes of light. Only a few of the neutrinos will do this, producing about 2000 events in a period of ten seconds, but this sequence and pattern will allow physicists to decide whether or not they understand what happens inside a \Jsupernova\j.
OMNIS would have one major advantage over existing neutrino detectors, since it would be able to detect all three "flavors" of neutrinos. Information gained from this might help to shed light on the question of whether or not the neutrinos have mass (see Neutrinos--Do They Have a Mass?).
The location, deep underground in a salt mine, means that only neutrinos are likely to reach the sensitive detectors.
#
"Ex-sun 1987A Still Going Strong",222,0,0,0
(Aug '97)
There's no \Jsupernova\j like a new \Jsupernova\j-unless it's an old \Jsupernova\j, still going strong. Around 167 thousand years ago, the \Jsupernova\j we now call 1987A blew itself apart. Spheres of gas have formed up, about half a light year from the centre of the star, and these are moving slowly outwards. Now new material appears to be running into these slow ripples in space, and an exciting light show, across the visible and x-ray spectrum, is expected.
The light from the original \Jsupernova\j ("as bright as 100 million suns") told us a great deal about how stars die, but it also left a great deal unsaid. Seven years after the \Jsupernova\j first came to our attention, the \JHubble Space Telescope\j revealed a puzzling trio of rings around the exploded star, probably formed by the star some tens of thousands of years before the final explosion. While the gas surrounds the \Jsupernova\j as a set of spheres, \Jearth\j-bound observations see them as a set of rings.
Now the material that was thrown out by the final explosion is close to the gas rings, and the coming collisions should light up the debris, revealing the elements in the debris, their speeds and their directions. To be precise, something which is travelling fast is close to the gas rings-the debris was not expected to catch the rings for about another ten years, but the theory around supernovae is far from perfect. That, after all, is why scientists study them.
#
"New Planet?",223,0,0,0
(Aug '97)
A network of telescopes in South Africa, \JAustralia\j and \JSouth America\j has detected tell-tale flickers from a star in the centre of the \JMilky Way\j. The PLANET network has been looking for stars becoming apparently brighter, perhaps because a dimmer star, complete with planets, has drifted across the line of sight, bending the more distant star's light with their gravitational fields.
The flickers which have been detected match the signature of a Jupiter-sized \Jplanet\j orbiting a \Jsun\j-sized star, but further analysis will be required to pin down the exact planetary pattern shown by the flickers. One thing is certain: the flickering is confirmed, having been detected by another international group known as GMAN.
It began as a sharp spike around June 19, followed by a slow increase in the brightness, and perhaps a strange double hump around 24 July, before it dimmed away again. The pattern is assumed to have risen when a dim star moved across our line of sight to a brighter, more distant star, rather like a magnifying glass passing between us and the star. If there are planets present, their presence acts like specks of \Jwater\j on the \Jlens\j, adding small extra-bright spots to the overall picture.
The pattern will show planets as large as Jupiter, but \Jearth\j-sized planets do not have enough gravitation to show up on this sort of scale. So it will be some time before if we know whether the star in question is home to clever vegetables, humanoids, or scaly things with spines, a bad attitude and serious teeth.
#
"Hidden Fluoride Found",224,0,0,0
(Aug '97)
One thing now appears certain: if there are creatures living at the centre of the \JMilky Way\j, they may well have good sets of teeth. A report which is to appear in the October issue of \IAstrophysical Journal Letters\i suggests that the \Jfluorine\j found on \Jearth\j today is matched by \Jfluorine\j that can be found in the clouds of interstellar dust.
The evidence of absorption spectra, the patterns created when light passes through assorted chemicals, has identified more than a hundred different molecules in space, but \Jfluorine\j compounds have always been hard to detect. This is because each molecule absorbs light radiation at characteristic wavelengths, and our \Jatmosphere\j blocks the frequencies which would come from \Jhydrogen\j \Jfluoride\j, likely to be the most common \Jfluorine\j compound in space. In effect, the air we breathe casts a shadow that hides the signs of \Jfluorine\j compounds. In space, the air is no longer a problem.
David Neufeld and colleagues at Johns Hopkins University used the Infrared Space Observatory, a European Space Agency \Jsatellite\j, to see further and more clearly. A \Jsatellite\j-based instrument called the Long Wavelength Spectrometer on the ISO was pointed at the \JSagittarius\j B2 \Jcloud\j, around 20 000 light-years from Earth.
The amount of infrared radiation passing through the \Jcloud\j dipped at the wavelength absorbed by \Jhydrogen\j \Jfluoride\j, indicating a \Jfluoride\j concentration at 0.3 parts per billion, just one tenth of the concentration of \Jfluorine\j in our \Jsolar system\j. Neufeld has suggested that there may be more, but that it is hidden, existing as tiny clumps of frozen \Jfluorine\j, which would not be detected by infrared methods.
Because the \Jfluorine\j has been found in deep space, astronomers now consider it likely that the \Jfluorine\j there, like the \Jfluorine\j in our non-stick fry-pans and toothpaste, has all come from sources like this.
#
"Xenon Still Missing",225,0,0,0
(Aug '97)
The \Jsun\j and meteorites have more \Jxenon\j than the \Jearth\j's \Jatmosphere\j, and one explanation in the past has been that the \Jearth\j's \Jxenon\j was stored in the \Jearth\j's core, alloyed somehow with iron. But is the inert gas able to form alloys with iron? Until recently, nobody knew, but a study reported in Science this month reports on attempts to combine \Jlaser\j-heated diamond anvil cell experiments with extrapolated, thermodynamic calculations. The conclusion of this study is that \Jxenon\j is unlikely to alloy with iron even at pressures of at least 100 to 150 gigapascals.
#
"Missing Dark Matter Present As Hydrogen?",226,0,0,0
(Aug '97)
Some astronomers have proposed that some of the missing \Jdark matter\j of the universe may be present as neutral \Jhydrogen\j, lurking in dim, hard-to-spot galaxies, or in the clouds that lie between the galaxies. Unfortunately for that idea, a radio survey of the nearer parts of the universe has failed to turn up any sign of the \Jhydrogen\j.
It is unlikely that the \Jhydrogen\j is hidden in metallic form. Given sufficiently high pressures, molecular \Jhydrogen\j should become a solid metal, but no matter what experimenters have tried, this metallic form of \Jhydrogen\j has never been observed. Now it looks as though maybe this type of \Jhydrogen\j cannot exist, not if a newly predicted spontaneous asymmetry of the \Jhydrogen\j molecule occurs as theorists think it may. We will keep you posted.
#
"Arctic Sea Floor Uncovered",227,0,0,0
(Aug '97)
Back on our own \Jplanet\j, in the \JCold War\j, the coldest part of the war must have been played out by the nuclear submarines that prowled beneath the \JArctic\j ice cap. Unlike the South Pole, which sits on the continent of \JAntarctica\j, the \JNorth Pole\j is a sheet of ice sitting over liquid sea \Jwater\j. Between 1957 and 1982, US Navy submarines travelled 220 thousand kilometres under the ice, and now the records of those journeys are to be released for scientific use. The depth charts that the submarines used will now be available to help scientists understand \JArctic\j \Jgeology\j and the transport of contaminants by \JArctic\j currents.
For the first time in many years, scientists will know more about the surface of the \Jearth\j under the north polar ice than they do about the surface of the \Jplanet\j Venus. According to a report in August, the data will be converted from rolls of chart recorder paper into digital form, to be posted on the \JInternet\j, where the information will join other data already supplied by the US Navy, such as \Jtemperature\j and \Jsalinity\j data.
#
"Vaccinating the Sheep",228,0,0,0
(Aug '97)
Fly strike is a serious problem for sheep farmers, especially in \JAustralia\j, where a fly called \ILucilia cuprina\i is a serious pest of sheep. The larvae of this fly invade the sheep, feeding on sheep tissues. Now Australian scientists have hit upon a solution which may help farmers to keep down the levels of pesticides in livestock, making the meat from the animals safer to eat.
The larvae have a lining to their gut, the peritrophic membrane (or PM), which serves to keep out parasites and microorganisms, as well as aiding in digestion. The PM also keeps out host \Jantibodies\j, so if sheep blood is full of \Jantibodies\j to the PM, which will cling to it, it seemed that the \Jantibodies\j might then clog the larval peritrophic membrane, stopping the larvae from absorbing food.
Ross Tellam and his colleagues at the Australian government's Commonwealth Scientifice and Industrial Research Organisation vaccinated sheep with a PM protein. They then took some of the blood of the sheep, separated the serum from the blood, and cultured fly larvae in the serum. They found that the PM \Jantibodies\j in the serum significantly slowed the larval growth, in a dose-dependent way, according to a report published in the \IProceedings of the National Academy of Sciences\i.
This is only a start: future trials will need to involve \Jantibodies\j to several different proteins, as Tellam estimates that the growth rate of the larvae will need to be reduced by at least 80% to kill a significant number of larvae. But with customers around the world more and more aware of the insecticides and other chemicals in their meat, solutions like this are desperately needed.
#
"Weevil News",229,0,0,0
(Aug '97)
Weevils and other beetles have been in the news this month, some of them getting a good press, some of them not being held in very high regard at all.
A Eurasian weevil taken into the US and Canada to deal with invasive introduced thistles has turned out to be a cure worse than the condition it was brought in to deal with. The weevil, \IRhinocyllus conicus\i, was released widely in \JNorth America\j after 1968 to control several species of introduced thistles. Now it turns out that the weevil enjoys the flower heads of five native thistles which are a natural part of ecosystems in that part of the world.
The long-term effect of the weevil may be to prevent the thistles from setting seed: in the 1996 flowering season, up to 70% of all flower heads in the native thistles were infested with weevils, and seed production had dropped in study areas in \JColorado\j and South Dakota.
#
"Pest Weevils",230,0,0,0
(Aug '97)
On the other hand, some weevils can be simple pests with no redeeming qualities, such as the weevils which attack commercially important plants. British researchers, working on the vine weevil which destroys strawberry, raspberry and other soft fruit crops, have turned to monoclonal \Jantibodies\j as they seek to identify the most helpful carnivorous beetles to assist their fight.
Sifting through the intestines of various caribid and staphylinid beetles, the scientists used monoclonal \Jantibodies\j to find whether different beetles have been eating weevil eggs, weevil grubs, or adult weevils. While this provides useful information about the species most likely to eat weevil eggs and prevent any damage to crops, the promise is limited-until somebody finds a way to rear carnivorous beetles cheaply but in isolation, so they cannot eat each other! For the moment, the researchers are looking at ways of improving the conditions which favor the predators, such as leaving leaf litter on the ground to provide shelter for the hunters, which feed mostly at night.
#
"Beetles Help Fight Loosestrife",231,0,0,0
(Aug '97)
Other beetles are playing an important control role in the wetlands of north America, where \ILythrum salicaria\i, otherwise purple loosestrife, is now under attack from beetles imported from its original home in Europe. The American version of the plant seems to have evolved to lose some of its natural defences, transferring its biochemical efforts more to reproduction, rather than to creating defences against a non-existent enemy. Now the enemy has returned, and the loosestrife is vulnerable. Given a choice, the introduced beetles actually prefer the American variants over the original European forms that the American plants sprang from.
Loosestrife has been a problem mainly because it has forced out bulrushes, sedges, and other edge plants which are required shelter plants for vertebrates such as tortoises, amphibians and waterbirds. Now, with some infestations reduced to just 5% of their former size, and new beetle species still to be set loose, the prospect for restoring north American waterways to their original condition looks good. And in this case, there appear to be no untoward side effects.
#
"Bacteria in the Wheat Blight Fight",232,0,0,0
(Aug '97)
The \Jfungus\j \IFusarium graminearum\i can wipe out a wheat crop, both killing the plants themselves and contaminating the survivors with a toxin, vomitoxin or deoxynivalenol, which sickens humans and animals. In the past, the best solution has been to change wheat varieties often, and vary the time of planting, so as to reduce the very real risks. Now a bacterium has been brought into the fray.
Typical "winter wheat" spends more than 8 months of its life putting down roots and growing leaves as it gets ready for a six-week burst of activity to make grain. If there are just a few days of rain when the wheat is flowering, the \Jfungus\j, also known as wheat scab, can take hold, reducing yields by as much as a third, and devaluing the rest of the crop as a result of the presence of the toxin.
Researchers at the Brazilian Wheat Research Center in Passo Fundo, Brazil have found three useful \Jbacteria\j in a screening study of thousands of different microbes, and seem to have struck it lucky. Plants which had their heads sprayed with the bacterium \IPaenibacillus macerans\i not only yielded 15% more grain than their untreated counterparts, they also had dramatically lower levels of vomitoxin, less than one-tenth the levels seen in control plants. The next step will be developing effective methods of delivering the \Jbacteria\j to the plants under field conditions.
#
"Colorful Fossils",233,0,0,0
(Aug '97)
Andrew Parker, a biophysicist at the Australian Museum, one of the world's great natural history museums, may be about to find out what color fossils should be.
The standard view of fossils is that they are made up of pieces of mineral that have replaced the material that was once a living thing. The old \Jcartoon\j joke of a dog stealing fossil bones has no relevance, according to the standard view of fossils, because the fossils are rocks in the shape of bones, not actual bones.
Andrew Parker was looking at ostracods, marine crustaceans, when he realised that the cell structures that give them a sheen today were also present in \Jfossil\j ostracods. Ostracods have hardly changed on their structures over the last 350 million years, but what of their colors? On the evidence of the \Jdiffraction\j gratings found in the fossils and also in modern ostracods, they must have looked pretty much the same.
This finding led Parker to investigate a range of other well-preserved fossils, and he found remnants of the cells which control color in many animal skins, cells called chromatophores. More importantly, he found traces of the \Jpigments\j from the chromatophores, providing a strong suggestion about the colors of some early animals. In one placoderm, an armored fish, Parker found traces of red pigment above, and silvery \Jdiffraction\j gratings below.
Exploring other animal fossils, Andrew Parker and his colleagues found it easy enough to reconstruct the colors of other animals as well.
#
"Argon Dating",234,0,0,0
(Aug '97)
When Mount Vesuvius erupted in 79 AD, there may have been no media coverage in our modern sense, but it was widely studied and reported, and we even know that the Roman writer on scientific matters, Pliny the Elder, died when he got too close to the \Jvolcano\j, which also destroyed \JPompeii\j. So if we know the date so accurately, why would anybody bother to try to determine the age of the volcanic debris that flowed forth in that eruption?
The answer is found in a single word: \Jcalibration\j. Accurate \Jradiometric dating\j of young rocks is essential for scientists in many fields and where samples from the Holocene, the last ten thousand years are involved, the primary method has been \Jradiocarbon dating\j. The problem with relying on just one method is that it may be open to some kind of systematic error, such as the slow seepage of newer carbon into old deposits, topping up the carbon-14 levels and giving us spuriously young ages for material which is more than 40 000 years old. Nobody can say for sure if this is a problem or not, at least until an independent way of assessing ages can be used alongside the carbon method.
So if we can use the \Jargon\j-40/\Jargon\j-39 method to date material in the historical period, this will give us a second version of the dates we have established. Paul Renne, a geochronologist at the University of \JCalifornia\j, Berkeley, and his colleagues have reported to Science that this is exactly what they can do.
Argon dating tells us how long it is since an eruption, when \Jlava\j solidified and trapped radioactive elements in its crystal lattice, setting the radio clock to zero. All you have to do is measure the ratio of \Jpotassium\j-40, a radioactive isotope with a half-life of 1.25 billion years, compared with the concentration of its daughter product, \Jargon\j-40.
The method has been around for many years, but recent major refinements have made it possible to detect tiny amounts of \Jargon\j, making it possible to calculate the age of younger rocks. Because the \Jdecay rate\j is so slow, quite a few years have to pass before the \Jargon\j levels are high enough to allow accurate measurement, so that until now, the youngest rocks dated this way were more than 5000 years old, and the accuracy was no better than 10%.
By heating samples of volcanic ash with a very precisely controlled \Jlaser\j in careful steps, Renne and his team were able to date the 1918-year-old rock to 1925 years, plus or minus 94 years, a remarkably accurate result. (Note that dates like this always come with a confidence level: there is only a 5% chance that the rock is outside the range 1831 years to 2019 years.)
This may open the way to even more exciting possibilities, such as dating strata a long way from volcanoes by dating volcanic ash that blows into a deposit. More importantly, the occasional fall of volcanic ash onto an ice core may serve to place a set of time stamps on levels in the core where the ash has fallen.
New volcanoes were also in the news this month. The record for hottest volcano and hottest \Jmagma\j looks to belong to Io, one of Jupiter's satellites. At the start of the month, Alfred McEwan told the American Astronomical Society's Division of Planetary Sciences about the most recent \JGalileo\j results. It seems that the volcanoes on Io have a \Jtemperature\j of around 1800 K, some 200 degrees hotter than on \Jearth\j, and this translates to a \Jmagma\j \Jtemperature\j of about 2000 K, suggesting that the \Jmagma\j is a molten silicate rock which is rich in \Jmagnesium\j.
#
"mc2=e",235,0,0,0
(Aug '97)
People who know nothing else about Einstein are able to parrot "e = mc\U2\u", and many can even explain that mass can be converted into \Jenergy\j, a fact which they invariably relate to "atomic bombs". At the end of August, we learned of a report from physicists at the Stanford Linear Accelerator Center (SLAC) to appear in the 1 September \IPhysical Review Letters\i, describing the inverse process, turning light into matter.
The team collided large numbers of photons together so violently that the interactions spawned particles of matter and antimatter, electrons and positrons (which are anti-electrons). Physicists have long known that this kind of conversion is possible, but they have never observed it directly. The trick was to focus an extremely intense \Jlaser\j beam at a beam of high-\Jenergy\j electrons. When the \Jlaser\j photons collided head-on with the electron beam, they got a huge \Jenergy\j boost, changing them from visible light to very high-\Jenergy\j gamma rays.
These high-\Jenergy\j gamma ray photons then rebounded into the path of incoming \Jlaser\j photons, interacting with them to produce \Jpositron\j-\Jelectron\j pairs. Unlike similar effects seen in the past in \Jparticle accelerators\j, where at least one of the photons involved is "virtual", the photons here have an independent existence, so this is the first time matter has been created entirely from ordinary photons. The future for this sort of work will lie in using powerful lasers to look at the interactions of photons and electrons as described in the theory known as quantum \Jelectrodynamics\j (QED).
#
"Sojourner Completes 30-day Mission",236,0,0,0
(Aug '97)
The robot Sojourner completed its 30-\Jday\j mission on August 3. By then, it had captured far more data on the \Jatmosphere\j, \Jweather\j and \Jgeology\j of Mars than scientists had ever expected. In all, Pathfinder returned 1.2 gigabits (1.2 billion bits) of data and nearly ten thousand pictures of the Martian landscape. Since that time, it has continued to explore an ancient outflow channel in Mars' northern hemisphere, but the information flow on Sojourner quietened as NASA scientists went into analysis mode, and got ready for the arrival of Global Surveyor in September.
The mission of Sojourner was followed with great interest via the World Wide Web. Twenty different Pathfinder mirror sites between them recorded 565 902 373 hits world-wide during the period from July 1 to August 4. The highest volume of hits in one \Jday\j occurred on July 8, when a record 47 million hits were logged, which is more than twice the volume of hits received on any one \Jday\j during the 1996 \JOlympic Games\j in \JAtlanta\j.
#
"Distant Close-Up on Mars",237,0,0,0
(Aug '97)
Meanwhile, a careful analysis of Martian meteorites (that is, meteorites which are believed to have been blasted out of Mars by major impacts) has just appeared in \INature\i, suggesting that Mars is a peaceful \Jplanet\j, with limited plate motion, no giant impacts, and no large-scale mixing for 4.53 billion years.
The study is based on an analysis of \Jtungsten\j \Jisotopes\j, and the conclusion is that the large-scale convection patterns, which drive plate tectonic motion and mix the Earth's mantle, appear to have been unimportant during most of the history of Mars. Instead, it looks as though Mars formed fast and differentiated early in the \Jsolar system\j's history, about 20 to 40 million years faster than the time taken for the \Jearth\j to separate out into core, mantle and crust.
The current best estimate for the time of \Jplanet\j formation is about 4.57 billion years ago, when the planets started to clump together from a huge \Jcloud\j of interstellar gas, dust and debris left over from the formation of the \Jsun\j. As the materials gathered, molten metal would drift to the centre, while silicates stayed on the outside. Since the time when Mars' core formed, some 4.53 billion years ago, the planet seems to have been remarkably stable and free of geological upheaval. Such inferences, drawn from an \Jearth\j-bound observation, will be able to be assessed much more closely when Global Surveyor settles into a circular \Jorbit\j, and can begin resolving structures as fine as 1.5 metres across.
The researchers, Alexander N. Halliday and Der-Chuen Lee, based their study on the assumption that any pre-existing \Jtungsten\j would have been enriched by the formation of further \Jtungsten\j-182 as hafnium-182 decayed to that isotope. The hafnium, they say, tends to end up among the silicate rocks, while \Jtungsten\j "sticks" to iron, and so is dragged down into the core. This means that the mantle is rich in hafnium, but deficient in \Jtungsten\j, at least until the hafnium decays, and that is all they needed to set up their "clock".
#
"Venus Still Active?",238,0,0,0
(Aug '97)
Two researchers, Smrekar and Stofan, have presented a model in \IScience\i in which some Venusian features are formed by upwelling associated with plumes. They suggest that some of the plumes may still be active. The features they point to include circular collections of faults and ridges that range up to 2600 kilometres across, known as coronae.
#
"Extra Plates on Earth",239,0,0,0
(Aug '97)
Magnetic sea floor anomalies and seismic data indicate that the Indo-Australian plate is not one plate, but three plates with diffuse boundaries. This knowledge will make it easier to understand the deformational history of this region, including the collision of India with Eurasia to produce the \JHimalayas\j.
#
"New Zealand Rabbits Get Calicivirus After All",240,0,0,0
(Aug '97)
New Zealand's decision not to release calicivirus (see New Zealand Rabbits Escape Calicivirus, July) has been overtaken by the actions of New Zealand farmers, apparently several months ago, in importing and distributing infected tissues in New Zealand.
An outbreak of \Jrabbit\j calicivirus disease (RCD) in \JNew Zealand\j was confirmed by the \JNew Zealand\j Ministry of Agriculture (MAF). This report was followed up with threats of prosecution, road-blocks and no-fly zones in the region around Cromwell in the South Island, but to no avail. Plans to shoot and poison the infected rabbits were dropped as gleeful farmers welcomed the news of outbreaks well beyond the five properties initially identified as having RCD.
The MAF already had RCD vaccine ready to be administered to pet rabbits, and could not really have been surprised by the event, which they say is no accident. The outbreak has happened at the wrong time of the year for an insect vector to be involved, and rabbits were infected across a wide area at the same time.
The virus was probably obtained from farmers in \JAustralia\j, and probably carried across the \JTasman Sea\j, some three hours by plane, as infected tissue in a sealed container. Customs and quarantine barriers between \JAustralia\j and \JNew Zealand\j exist, but are not particularly strongly enforced. There are fairly severe penalties for deliberately importing such a species as the RCD virus, but angry farmers, suffering from the effects of serious \Jrabbit\j infestation, were obviously willing to take that risk.
#
"Bacterial Resistance",241,0,0,0
(Aug '97)
The past few years have seen an upsurge in bacterial resistance to \Jantibiotics\j, with infections such as tuberculosis, \Jpneumonia\j and meningitis all on the rise, and even serious killers like bubonic plague showing dangerous trends. Now it looks as though there may be some hope for a "fix".
The answer, described by Nobel laureate Professor Sidney Altman and his colleagues Dr Cecilia Guerreir-Takada and Dr Reza Salavati in the \IProceedings of the National Academy of Sciences\i, involves a way of disabling the genes that the disease \Jbacteria\j use to block \Jantibiotics\j like chloramphenicol or ampicillin. Innovir Laboratories already has a licence from Yale University to develop this technology, and they say that the results are promising.
While there may be other \Jantibiotics\j out in the field, just waiting to be discovered, this is unlikely, and it will most certainly be hugely expensive. If today's front-line \Jantibiotics\j can be used once more, this will bypass that huge expense, undoing the damage wrought by decades of indiscriminate use of \Jantibiotics\j in many parts of the world.
In simple technical terms, the researchers have produced a marker which can be passed between \Jbacteria\j as a plasmid. This marker attaches itself to a specific part of the bacterial mRNA and then calls in an \Jenzyme\j which is found naturally in all bacteria, an \Jenzyme\j which splits the specified gene into two useless pieces. If the marker is targeted on a resistance gene, the resistance gene is destroyed, leaving the bacterium vulnerable to \Jantibiotics\j once again.
The first step in the development involved introducing synthetic genes into a standard \Jgenetics\j workhorse, the common intestinal bacterium \IEscherichia coli\i (usually referred to by its shorthand name of \IE. coli\i). In this case, the strain used is one that is resistant to both ampicillin and chloramphenicol. The synthetic genes code for "external guide sequences", the markers which do the actual damage.
Other groups have tried to make genetic sequences which bind to the gene which gives the \Jbacteria\j resistance, but this approach has had only limited success. Altman's group have used a more cunning approach, fooling the bacterium's own \Jenzyme\j into attacking the resistance genes by fixing a message which says "come and get me!" to the gene, or at least to the copy of it which is used in managing protection.
Next, these new genes were fused into loops of DNA, known to geneticists as plasmids, which have an independent existence inside the \Jbacteria\j. Plasmids are mostly used by \Jbacteria\j to spread and share new genetic material, and are the method used to transfer resistance genes from one cell to another, so the researchers were essentially beating the \Jbacteria\j at their own game: if the \Jbacteria\j destroy this mechanism, they also destroy their ability to pass on resistance.
Once they enter a new bacterial cell, the plasmids use the host's replication machinery to make more plasmids, and so on. And more importantly, the host begins to synthesise the external guide sequence, or EGS, which calls in the \Jenzyme\j RNase P, which then does the real damage.
Putting it in more technical terms, the EGS binds to messenger RNA (mRNA) at a point specified by the sequence on the artificial gene, which is an "antisense" version of the mRNA for a particular gene. RNase P usually works by snipping RNA at a point opposite the genetic sequence ACCA. Altman's strands of antisense RNA bind to the sections of mRNA which represent the resistance gene, while leaving the signal sequence (ACCA) dangling free at one end. The resistance gene would normally code for an \Jenzyme\j which confers resistance to the \Jantibiotics\j chloramphenicol or ampicillin. If the gene is cut in two, it cannot code for that \Jenzyme\j.
The effect of the marker is rather like that of infantry calling in artillery or an air strike: the RNase P destroys the offending mRNA by cutting it in half, leaving the \Jbacteria\j open to \Jantibiotics\j once more. Better, the EGS emerges unscathed, ready to tag another mRNA molecule, and best of all, it does all this while using the enemy's weapons.
While this method has worked in culture, it still remains to be seen if the defence will work when applied in a sick patient, riddled with rapidly multiplying \Jbacteria\j, where even a few surviving \Jbacteria\j may be able to stage a recovery, but it looks as though the method will work well in cases where infections are found on the lung, in the intestines, or on the skin, three of the situations where some of the toughest of the resistant \Jbacteria\j are usually found.
A spokesman for Innovir says that researchers there have already had some success at EGS treatments of mice infected with a drug-resistant hepatitis virus, so the end of this particular story is by no means in sight at the moment.
The process may also have other uses: knocking out the mRNA responsible for producing the toxins of \Jdiphtheria\j and food-poisoning \Jbacteria\j. All that is needed is a knowledge of a part of one of the sequences in the target mRNA, and the rest is as easy as ABC-or as easy as ACCA. Until, of course, the \Jbacteria\j find a way of evolving around this problem as well . . .
#
"Vancomycin Unravelled",242,0,0,0
(Aug '97)
A new software package, called SnB, has allowed scientists to unravel the structure of Vancomycin, providing information needed to synthesise new forms of the drug which should be able to wipe out those \Jbacteria\j which have started to win the battle against this, the last resort antibiotic.
Vancomycin is called this because it is the only antibiotic effective against certain life-threatening infections that resist all other known \Jantibiotics\j, but even it is now losing its effect against some diseases, like the often-fatal \Jstaphylococcus\j infection. Now SnB has allowed scientists to determine the structure of Vancomycin.
The antibiotic, which has a number of nasty side-effects, has an extremely complex structure, so that it has always been "brewed" from soil microorganisms, cultured in huge vats. Now the structure is known, it may be possible to synthesise it directly, but more importantly, it will be possible to "ring the changes", varying the structure in small ways which will defeat the existing resistance mechanisms, while still killing \Jbacteria\j. With luck, the new structures may even prove to be missing the side-effects.
SnB, which has solved other complex structures in as little as hours or days, took about a month to yield the correct result, but this was nothing compared with the eight months or so of processing time that the team spent trying other methods, all of which failed.
#
"Watery Comets After All?",243,0,0,0
(Aug '97)
The watery comets of Louis Frank ("Controversy in Space", May) are still in the public eye, with new evidence arising this month. The \Jmesosphere\j, the atmospheric region lying between 50 and 90 kilometres, is supposed to be almost bone dry, but \Jsatellite\j measurements suggest that the water vapor levels in the \Jmesosphere\j may be as much as 50% greater than predicted.
The results have come from an instrument deployed from the \Jspace shuttle\j. The Middle Atmosphere High Resolution Spectrograph Investigation, has found an abundance of hydroxyl radicals, a breakdown product of \Jwater\j, at this altitude.
This, say the watery comets "camp", is clear evidence that the outer reaches of the \Jatmosphere\j are being hit by fluffy, house-size comets 20 times a minute, releasing water that damps down the \Jmesosphere\j as it descends to the ground below. Opponents say that the levels detected are still only a quarter of what would be found if Frank's interpretation is correct. Louis Frank's view is that just finding excess water at those levels is a big step.
#
"Blindness Cured By E-Mail",244,0,0,0
(Aug '97)
It may sound almost like a faith-healer's trick, but Johns Hopkins researchers are serious about using an automated camera and e-mail to identify diabetics who have a potentially blinding eye disease well before it leads to actual \Jblindness\j.
The camera, called a DigiScope, is similar to devices used now by ophthalmologists to photograph retinas, but it can be operated by unskilled staff in a GP's surgery. This means that diabetics are able to have a check done close to their homes, with the images being transferred digitally to a specialist for accurate diagnosis. Doubtful cases may then be referred to an ophthalmologist for further checking.
Diabetic retinopathy is the most frequent cause in the USA of new cases of \Jblindness\j in adults. The screening program will be expanded in the future to include \Jglaucoma\j and age-related macular degeneration, which are also major causes of \Jblindness\j.
#
"Malaria Still Under Attack",245,0,0,0
(Aug '97)
Yet another war has been declared on \Jmalaria\j, just a hundred years after the discovery by Sir Ronald Ross that mosquitoes transmit the disease. In 1887, Charles Laveran had shown that patients with \Jmalaria\j carried a protozoan parasite in their blood, and doctors began speculating that mosquitoes spread the parasite, but it was only in August 1897, when Ross dissected the guts of an \IAnopheles\i mosquito that had just fed on a \Jmalaria\j patient, that the link was confirmed.
The mosquito-\Jmalaria\j connection pointed to an obvious answer to \Jmalaria\j transmission: kill mosquitoes, and prevent them from biting or breeding. When mosquito control measures have been diligently followed, they have succeeded in limiting the disease, but the mosquitoes and the \Jmalaria\j parasites have been fighting back ever since.
To workers in the field, each "war" on \Jmalaria\j just brings a slightly more tired smile to their faces, and each loudly-hailed plan to conquer \Jmalaria\j produces a little more tightening of the jaw muscles, because \Jmalaria\j is more widespread now than it was a hundred years ago. Several million dollars have been set aside for the latest "war", so that \Jmalaria\j, causing 2.5% of the world's illness, is being attacked with 0.05% of all research funds. Malaria researchers are said to be underwhelmed.
#
"New Worms",246,0,0,0
(Aug '97)
New species can turn up in the oddest of places. During July, some polychaete worms of a new species were found in the Gulf of Mexico. Most unusually, they were living on \Jmethane\j ice, and they were at a depth of 700 metres, some 250 km south of \JNew Orleans\j.
Methane ice is a solid crystal formed by \Jwater\j, \Jmethane\j, and other \Jhydrocarbons\j, which forms under conditions of low \Jtemperature\j and high pressure. Deep-sea biologist Charles Fisher from \JPennsylvania\j State University reported the find during August, saying that the worms appeared to be drawing \Jenergy\j from the \Jmethane\j, though whether they do so directly, or by feeding on \Jbacteria\j which harness the \Jmethane\j, nobody knows. The odds, however, are on \Jbacteria\j playing a role, which means there is probably at least one new species of bacterium still to be discovered.
Sections of the \Jmethane\j ice have been brought to the surface, where scientists have discovered that the worms have burrowed right through the ice.
#
"New Subnuclear Particle?",247,0,0,0
(Aug '97)
Once upon a time, a single physicist's name would attach to a new particle. Evidence is to be published on September 1 in \IPhysical Review Letters\i of a new sub-nuclear particle, one of the theorised "exotic mesons", and aside from professors Cason, William Shephard, John LoSecco and James Bishop, 47 other investigators are involved in this discovery.
The breakthrough experiment, called E852 and conducted at Brookhaven National Laboratory on Long Island, is reported in the dissertation of Notre Dame doctoral student David Thompson. Mesons are very unstable, medium-mass elementary particles with short life spans. They are similar to, but smaller than, a proton or neutron. All three particle types are made up of the most basic elementary particle, the quark. Protons and neutrons are made up of three quarks, while ordinary mesons are composed of one quark and one antiquark.
One of the exotic mesons, on the other hand, is made up of a quark, an antiquark and a \Jgluon\j, another elementary particle that "glues" together the quark and antiquark. The meson that has been identified is definitely not made up of a quark and antiquark, which means it must be an exotic meson. The particle cannot be used to make up any larger form of matter, because they are so unstable, but the discovery is exciting, since it will help physicists to learn more about the fundamentals of natural forces.
#
"Cannibals Back In Vogue",248,0,0,0
(Aug '97)
For many years, it has been the height of political incorrectness to suggest that any culture engaged in cannibalism. Any report of cannibalism, no matter how carefully documented, was to be disregarded as travellers' tales at best, and racist propaganda at worst.
Now it seems that the scepticism of the 1970s through to the 1990s is about to be rolled back again. Archaeologists now have a rigorous new set of criteria for identifying its marks on human fossils, and the dead bones are telling their tales. There appears to be a strong case for accepting that there was cannibalism in our family tree as long as 800 000 years ago, our Neandertal cousins were given to the practice, and so were the Anasazi, the Aztec of Mexico, and the people of \JFiji\j.
But the cannibals were not around in \JIce Age\j Europe, not unless they hunted their human prey with nets. Where we have a picture of those people as big game hunters, new finds in the Czech Republic suggest that the \JGravettian\j people, who lived between \JSpain\j and southern \JRussia\j some 29 000 to 22 000 years ago, used nets rather than speed and might to capture hares, foxes, and other mammals. That would make them the earliest known net hunters, and it may help explain the larger, more settled populations that seem to mark \JGravettian\j settlements.
#
"Dams Cause Environmental Damage",249,0,0,0
(Aug '97)
For many years, hydroelectricity has been seen as the "clean alternative", offering power which is free of the carbon costs associated with burning \Jfossil\j fuels. In reality, these dams need to run for about 300 years to recoup the carbon costs associated with building them, making and hauling the concrete, the \Jphotosynthesis\j from ground cover that is lost, and the \Jmethane\j production that takes place, deep within the dams, as vegetation rots.
During all of that time, the dam acts as a source of environmental damage, and this has now been recognised for the first time. The US Federal Energy Regulatory Commission licenses most of the power-producing dams in the United States: now it has recommended removing a dam on Maine's Kennebec River. The Commission says the removal would be the best and cheapest way to help the Kennebec's struggling migratory fish populations, which have been blocked by the dam from reaching their spawning grounds upriver. Now environmentalists will be seeking to make this a precedent for taking down other dams, right across the United States.
#
"Safer Superconductors",250,0,0,0
(Aug '97)
Many of the best superconductors, those with a transition \Jtemperature\j above 120 kelvin rely on unpleasant elements like thallium and mercury. A new variety has just been discovered, a new family of \Jbarium\j \Jcalcium\j copper \Joxides\j with transition temperatures up to 126 kelvin.
#
"Armadillos Are Unique",251,0,0,0
(Aug '97)
Elephants' trunks, like human tongues, hold their shape because they are hydrostats. The pressure of the fluid inside the organ is balanced against the tension of fibres in a surrounding sheath, and manipulating these fibres allows the organ o move around. The sheath of fibre has to be strong, and in the past, has always consisted of helically would fibres which run in a helix, diagonally around the organ.
Now the pattern has been broken: a new study reveals that the penis of the nine-banded \Jarmadillo\j is reinforced by longitudinal and circumferential fibres, along and around the organ, a pattern that has never been seen before.
#
"Predicting Heart Attacks",252,0,0,0
(Sep '97)
Would you trust a computer to watch over your heart's health? In an issue of the American Heart Association journal \ICirculation\i this month, researchers report on some early successes in using artificial neural networks to diagnose heart attacks. The computer-based method was more accurate than the cardiologist in reading the electrocardiogram (ECG), a test often used to predict or detect heart problems in patients seen for chest pain in \Jhospital\j emergency departments.
Lars Edenbrandt, M.D., Ph.D., and co-author Bo Heden, M.D., Ph.D., of the University Hospital, Lund, Sweden, say the neural networks performed better than an experienced cardiologist, indicating that they may be useful as decision support.
Neural networks are designed to "think" like humans. They do this by drawing on records of knowledge and decision-making, analysing the experience of large numbers of actual human decisions. To teach a neural network how to recognise hand-writing for example, you might give it ten thousand samples to work from, and to teach a system to recognise the signs of heart attacks, researchers followed the same method. They exposed the computer to thousands of electrocardiogram readings, more than any cardiologist could possibly read in a lifetime.
In all, the computer "studied" 1120 ECG records of people with heart attacks and 10 452 ECGs records that were normal. The neural networks were 10% better at identifying abnormal ECGs than the most experienced cardiologists on staff, say the researchers. As many as 25 percent of ECG readings are "misjudged or overlooked" by the physician, and a person in need of help may be sent home from the \Jhospital\j without a correct diagnosis: any improvement on this average is obviously a benefit.
So far, the machines have one drawback: doctors will still need to talk to patients about their symptoms and medical history, and draw conclusions from that. But it may not be long before even that is solved.
#
"Computer Diagnosis?",253,0,0,0
(Sep '97)
One common piece of \JInternet\j "humour" concerns the psychological help line, where a recorded voice tells obsessive compulsives to press 1 repeatedly, dependent personalities are asked to get somebody to press 2 for them, multiple personalities are advised to press 3, 4, 5 and 6, schizophrenics are instructed to listen for the small voice which will tell them what to press, while paranoids are told they need press no button "since we know who you are and what you want", and depressives are not to bother since the service will take no notice anyhow.
The factual problem with this joke is that diagnosis is required first, but now even that may be possible, not only from a computer, but from a computer contacted by \Jtelephone\j. In mid-September, JAMA, the \IJournal of the American Medical Association\i, reported on how a computer which can diagnose common psychiatric disorders could become a helpful aid to busy physicians. Once again, the computer might not be perfect for the task, but it would make screening for \Jmental disorders\j much more common.
Curiously, with some disorders, patients seem more willing to confide in the \Jtelephone\j-based system which is described, than in their personal physicians. Kenneth Kobak, a \JWisconsin\j psychologist who headed the study, set up a computer to ask questions based on a common questionnaire, called the Primary Care Evaluation of Mental Disorders, which is used to diagnose alcohol abuse, major depression, bulimia, and other disorders. They set up an interactive voice response system, similar to that used by many companies for customer assistance, where the computer asks a question, and the listener responds.
So maybe all the heart people need is a suitable screening test, covering such matters as life-style, family history and diet.
#
"Gene Therapy Gets Smarter",254,0,0,0
(Sep '97)
At least one of the problems of gene therapy now seems to be fairly well under control. Most forms of gene therapy rely on viruses to carry desirable genes into cells. But because a virus usually infects all types of tissues indiscriminately, the gene often appears in cells where it is not wanted. While viruses which only attack certain tissues might be a solution, a better approach is now available to the old blunderbuss method.
According to a report in the 1 September issue of the \IJournal of Clinical Investigation\i, a group of researchers at the University of \JChicago\j fitted a gene with a "genetic switch" that was able to turn the gene on only in smooth muscle cells in experimental animals.
Cardiologist Michael Parmacek and his colleagues at the University of \JChicago\j deleted two genes from the common cold virus. Without these genes, the virus is unable to cause any sniffling or fever, but they then replaced the deleted genes with a marker gene that turns out an easily detected protein and with the gene for the SM22 promoter, which "switches on" genes in smooth muscle cells that surround arteries. Injecting this virus into rats, they showed that the smooth muscle cells, and only those cells, had the marker gene active.
A gene which stops cell proliferation could be useful in many treatments, but what happens if a blunderbuss virus carries that gene into your liver or your lungs? If the new gene is tied in with the SM22 promoter, then the gene will only be switched on when the virus gets into smooth muscle cells, the tissue that sometimes blocks arteries in heart patients. So even if the gene got into your liver and lungs, the SM22 promoter would not be switched on in those cells, and so the cell proliferation control gene would not operate either.
The test on rats shows that any useful gene, once it is identified, can now be fitted into a virus, and sent in to do battle against smooth muscle cells. While this is only one of hundreds of tissue types in the human body, this single example would help the twenty people in ten thousand who have angioplasties each year, six of whom will need a second procedure after proliferating smooth muscle cells reblock the arteries. Gene therapy has not lived up to many of its promises so far, but an article in \INature\i during the month argued that the main problem has been in designing efficient delivery systems. Nonetheless, say the authors, the prospects are good that by the year 2010, gene therapy may be as routine a practice as heart transplants are today.
#
"Concern Over Gene-Therapy Experiment",255,0,0,0
(Sep '97)
There may be stormy days ahead as we move towards the year 2010. A September meeting sponsored by the Recombinant DNA Advisory Committee (RAC) of the (US) National Institutes of Health was warned that within 2 years, a researcher somewhere will propose a gene-therapy experiment that, although it starts out as a cure for disease, could eventually be used to enhance a trait in healthy people, as most discoveries seem eventually to spill out beyond the problem they were first supposed to solve.
The consensus was that decision makers should treat all such proposals with caution until ethical concerns such as fair distribution and the potential for \Jeugenics\j can be addressed. The nature of scientific discovery being what it is, even that sort of caution is unlikely to "keep the lid on" the problem much beyond the year 2000, as even approved experiment will have unforeseen spill-over effects. This is built into the very nature of science. If the results of experiments were predictable, there would be no point in doing them.
#
"British Columbia Travelling North",256,0,0,0
(Sep '97)
In a textbook example of the way science develops, we now have a new model for the west coast of \JNorth America\j. Vancouver Island was once at the latitude of Baja \JCalifornia\j, several thousand kilometres to the south, according to a team of geologists and geophysicists in a September issue of the major weekly journal, \IScience\i. A few beautifully preserved fossils have validated traces of ancient magnetism that suggest this piece of crust has trekked north over long distances in the past 70 million years.
The idea is not new, having been around for about twenty years, based on the magnetic fields preserved in rocks. The Earth's magnetic field is horizontal at the equator but vertical at the \Jpoles\j, so the inclination of a rock's magnetism shows how far north it was when it formed. This value, called the palaeomagnetic inclination, shows lower values along the west coast of \JNorth America\j than should be found, if the rocks were formed at the latitudes where they are now found.
From this, many researchers assumed that these tracts of rock, or terranes, had slid up the coast from far to the south, much as \JCalifornia\j west of the San Andreas fault is sliding now, but others had their doubts about this. The shallow angle of the magnetic inclinations could have been misleading, because most of these measurements came from great masses of frozen \Jmagma\j, which could easily have been tilted from their original orientations.
Sedimentary rock would solve that problem because it is laid down in recognisable horizontal layers. But sedimentary rocks from the largest terrane, the Insular superterrane, which makes up much of the coastal crust from northern Washington state into \JAlaska\j, seemed to have been heated long after they formed, wiping them clean of their original magnetic signature.
So how do you find the rocks that have not been heated, that still retain their original palaeomagnetic inclinations? Joseph Kirschvink of the \JCalifornia\j Institute of Technology realised that \Jtemperature\j-sensitive fossils could identify rock that hadn't been heated and magnetically altered. Palaeontologist Peter Ward of the University of Washington, in turn, knew of fossils from islands off the east coast of Vancouver that could fit the bill.
Fossil ammonites and inoceramids in 131 rock samples from the two islands, Hornby and Texada, off Vancouver Island, retain the pearly lustre of living animals. And the palaeomagnetic inclinations in the surrounding rock, about 25░ shallower than expected at Vancouver Island's current latitude, are thus trustworthy.
The pearly lustre of the fossils, indicates the presence of the original \Jaragonite\j, or mother of pearl. If the surrounding rocks had been subjected to heating, the \Jcalcium\j carbonate in the shells would have turned to black calcite. Ward reports that all of the ammonites discovered so far on neighbouring Vancouver Island are black.
Ward's calculation of the speed of the northward drift of the rocks is too fast for some. He suggests that the rocks began migrating from Baja \JCalifornia\j perhaps 75 million years ago, arriving at their present position about 60 million years ago. That rate of movement, about 3000 km (2000 miles) in 15 million years, indicates a slippage of about 21 centimetres (about 8 inches) a year, compared with the San Andreas fault's current movement of 4 centimetres a year. "That is fast, but not science- fiction fast," says Ward, who points out that crustal movements around \JIndonesia\j are just as rapid.
The huge landmass, he says, must have slipped its way north along a giant crustal fault stretching from \JCalifornia\j to British Columbia. But, say his critics, there is no evidence of such a fault. Ward believes the fault is certainly extinct, and because it is buried deep in the Earth's crust, it may never be detected. He also dismisses comments that fossils in the British Columbia rocks show no evidence of tropical marine life, typical of today's Baja \JCalifornia\j. He points out that the rocks were formed in the Cretaceous era when the Earth was uniformly warm, with very little latitudinal differences in animal and plant life.
Ward also rejects suggestions that the sedimentary beds may have been compacted and flattened, causing the crystal angle (and hence the magnetic inclination angle) to change, saying that if this had happened, the ammonites would also be flat and deformed. "An ammonite is very squishable," he says. "If you had compaction the \Jfossil\j would not be as pristine as our samples."
As with any other scientific discovery, people will continue to probe at it, looking for evidence that Ward's assumptions are wrong. This may seem mean-spirited, but it is the way that science advances. To this outside observer, Ward seems to have made a very strong case.
#
"Lead Linked To Dental Decay",257,0,0,0
(Sep '97)
In February, we reported on an apparent link between lead levels and cavities in teeth (Lead linked to bad teeth, February). Now the same work has been replicated in rats, leading to a report in the September issue of Nature Medicine, suggesting that exposure to high amounts of lead is likely one cause of the high rates of tooth decay found among certain groups, such as children raised in the inner city.
It seems that lead makes the rats more susceptible to cavities in some way. William Bowen who carried out the work is a Rochester professor of Dental Research, and he says that lead, while it has been removed from most petrol (\Jgasoline\j), it is still present in old paint and commonly in soil or dust around contaminated buildings in those areas with the highest levels of dental \Jcaries\j.
The researchers found that the pups of lead-exposed rats produced 30 percent less \Jsaliva\j, which protects teeth against cavities by neutralising acids. Saliva also provides minerals, and helps protect the teeth in other ways. More importantly, they detected levels of lead in the mothers' milk which were 10 times higher than the lead levels in their blood.
In this study, the rats were drinking \Jwater\j that contained a relatively high 34 parts per million (ppm) of lead, giving the mother rats blood lead concentrations quoted as "40 micrograms/deciliter" (4 ppm), at the high end of human blood concentrations, but not extremely high in terms of what you could expect to find in humans.
In another article, dentists Martin Curzon and Jack Toumba of the Leeds Dental School in Britain point to breast milk as a likely route of lead transfer from mother to offspring. Their logic is that lead and \Jcalcium\j have similar chemistry, so lead is stored in bones. During \Jpregnancy\j and \Jlactation\j, when the mother breaks down bone to gain extra \Jcalcium\j, the lead is released as well. (People often fail to realise that bone is living tissue, and that bone is continually being broken down and reformed.)
#
"Building Better Bones",258,0,0,0
(Sep '97)
A study reported in early September indicates that supplements of \Jcalcium\j and vitamin D can significantly reduce bone loss and the risk of fractures in older people. The report, in the \INew England Journal of Medicine\i of September 4, authored by Bess Dawson-Hughes and colleagues at Tufts University, indicates that the treatment is cheap, easy and safe.
The finding applies to both men and women, and with older people living longer than ever, increasing the intake of \Jcalcium\j and vitamin D can be an important lifelong strategy for both sexes. It seems that as people get older, they reduce their ability to absorb \Jcalcium\j and vitamin D, just as production of vitamin D by the skin drops. This drop in vitamin D production and absorption reduces their ability to take up dietary \Jcalcium\j and contributes to bone loss as people age. This is a problem when low bone density is an underlying cause of increased hip fracture among the elderly.
Dawson-Hughes studied 389 men and women aged 65 and older for 3 years. The participants kept to their usual diets, in which they were generally getting the old recommended dietary allowances of \Jcalcium\j and vitamin D. At bedtime, about half of the study participants took \Jplacebo\j pills of no nutritional value. The other half took two separate pills, one containing 500 milligrams of \Jcalcium\j in the form of \Jcalcium\j citrate malate and the other pill containing 700 International Units of vitamin D. All participants visited Tufts every 6 months for measurements of bone mineral density and other tests.
Over the 3 years, the \Jcalcium\j/vitamin D group lost significantly less total body bone, and, in some areas, actually gained bone mineral density. In men, where the findings were more clear-cut, those taking placebos lost about one percent of their bone density at the hip over 3 years. Men taking the \Jcalcium\j/vitamin D combination increased their bone density by about 1 percent. The benefit at the hip for men added up to a 2 percent improvement in bone density for the supplemented group. For women, the positive effects were most notable in the total body bone density, with lesser effects at the hip and spine.
The group taking supplements did considerably better in avoiding fractures. Some 5.9 percent of the participants taking the \Jcalcium\j and vitamin D suffered fractures, compared with 12.9 percent of those who did not take the supplements. Most of the fractures occurred in women.
#
"Broccoli and Cancer Prevention",259,0,0,0
(Sep '97)
President George Bush won popularity with many in the population when he said he did not like broccoli, but his supporters in that matter may be wise to think again, given the plant's abililty to help protect us against cancer. Broccoli is good for you in any form, but now it seems that 3-\Jday\j-old sprouted broccoli seeds may be even better at protecting against cancer than the adult plants, according a paper published in mid-September in the \IProceedings of the National Academy of Sciences\i.
Epidemiologists have known that broccoli and other vegetables could prevent cancer for more than 20 years, and for the past five years, Johns Hopkins pharmacologists have had a possible biochemical explanation. Broccoli, \Jcauliflower\j, and related cruciferous vegetables contain a chemical called sulforaphane that stimulates a cell's natural anti-cancer machinery. This helps to switch on the so-called Phase 2 enzymes. These in turn attack cancer-causing chemicals such as free radicals and prevent them from damaging DNA, which can lead to cancer.
The problem is that the amount of sulforaphane in broccoli varies widely between strains of the plant. While they were trying to maximise the sulforaphane levels in laboratory broccoli, workers at Johns Hopkins University made a surprising discovery: that the seeds were exceedingly rich in these compounds, and that young sprouts contained between 20 and 50 times higher levels than mature plants.
Tests on rats show that the extracts from sprouts make significant cuts in cancer levels, cutting cancer rates by a half. Perhaps more importantly, Paul Talalay, the main researcher, reports that the sprouts have a 20 times lower concentration of related chemicals, called indole glucosinolates. These chemicals can work against sulforaphane and promote the growth of some tumours in laboratory animals, so once again, the sprouts appear to be better for you than the adult plants.
Clinical studies are currently under way to see if eating a few tablespoons of the sprouts daily can supply the same degree of chemoprotection as one to two pounds of broccoli eaten weekly. The sprouts look and taste something like \Jalfalfa\j sprouts, according to Talalay. But while \Jepidemiology\j studies clearly show the benefits eating mature broccoli, further study will be needed to make sure there are no other hidden effects in the consumption of the broccoli shoots.
But here's the bad news: the broccoli plant \Jgenus\j \IBrassica\i also takes in Brussels sprouts, cabbage, \Jkale\j, \Jcauliflower\j and turnips. What else is going to turn out to be good for us?
#
"Weeds and Depression",260,0,0,0
(Sep '97)
To Australian farmers, St John's Wort, \IHypericum perforatum\i, is just a weed, and weeds are things that cause farmers to feel depressed. Now it looks as though they might be able to do something about the depression by eating the weeds.
Well, not really, but the plant is now being looked at as the source of a cure for this problem condition. A three-year study is planned, involving, among other things, 336 patients with major depression who will be randomly assigned to one of three treatment groups for an eight-week trial, with one third of the patients receiving a uniform dose of St. John's wort, another third getting a \Jplacebo\j, and the final third taking a selective \Jserotonin\j reuptake inhibitor (SSRI), a type of antidepressant commonly prescribed for depression.
St John's Wort is commonly used as a herbal remedy in \JGermany\j, but there have been no long-term and systematic studies of the herb's effectiveness.
#
"Search For Safer Cancer Drugs",261,0,0,0
(Sep '97)
A study at The Rockefeller University in New York City is about to begin on a number of plant compounds which have the potential to be safer than cancer-thwarting nonsteroidal antiinflammatory drugs (NSAIDs), widely used aspirin-like drugs known to prevent colorectal cancer as well as reduce related deaths by a half. The NSAIDS have bad side effects such as irritating the \Jstomach\j lining or damaging the liver or \Jkidneys\j, but the three plant-derived compounds, curcumin, rutin and quercetin, may lack these side effects.
In the study, these substances will be compared with the NSAID sulindac. All three are potent \Jantioxidants\j and antiinflammatories, but it remains to be seen if they can act like sulindac in prompting cells to "turn on" a program of regulated cell death called apoptosis.
Curcumin has long been used as an antiinflammatory agent. It is the pigment that gives the yellow colour to the seasoning curry, mustard and turmeric, and it is the powdered form of the root of \ICurcuma longa\i, a member of the ginger family. Quercetin can be naturally found in most fruits and vegetables, such as cranberries and onions, as well as in tea. Quercetin, when digested in the colon, breaks down into rutin.
Many colorectal cancers begin as noncancerous growths, called polyps, in the mucosal lining of the colon and \Jrectum\j, the last part of the digestive tract. An inherited defective gene can cause some forms of the disease, but not all. The polyps develop because the normal routine of cell division and apoptosis (controlled death, directed by the p53 protein) goes awry. When apoptosis is disabled, tissues that rely on it no longer have a way to regulate their cell populations and cancer may follow, so the study will be looking for effects of these compounds on polyp development in people with a history of polyp formation.
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"Green Tea of Benefit",262,0,0,0
(Sep '97)
"Take a little wine for thy stomach's sake", we read in the Bible. Wine drinkers who once had to rely on this admonition have recently had a better case, sipping their red wine for its beneficial antioxidants. Now they may wish to switch their beverage of choice to a nice hot cup of green tea.
A report to the American Chemical Society this month showed that an antioxidant found in green tea is 3.5 times as effective as the antioxidant in red wine, and more than 100 times as effective as vitamin C at protecting cells and DNA from damage believed to be linked to cancer. Antioxidants are generally believed to mop up highly reactive compounds called free radicals before they have a chance to react and tear apart DNA or other cellular components.
These chemicals are common in fruits, vegetables, red wine and even tea leaves are known to have a similar effect. Lester Mitscher and his colleagues at the University of Kansas have now undertaken a detailed study of the comparative effects of the \Jantioxidants\j in tea and other foods.
They looked at the effects of a number of possible antioxidant compounds in green tea, red wine, and vitamins C and E for their ability to prevent bacterial cells from mutating. This is a standard method of assessing possible anti-cancer chemicals.
They incubated some of their bacterial cultures with \Jhydrogen\j \Jperoxide\j, a powerful free radical producer, along with varying concentrations of one of several \Jantioxidants\j. The most effective of the \Jantioxidants\j turned out to be epigallocatechin gallate (EGCG). EGCG protected about 68% of the cells from oxidative damage, resveratrol, the antioxidant in red wine, protected only 20%, while vitamin E protected 1.5% and vitamin C protected only 0.6%.
Interestingly, a number of cancers have a much lower incidence in \JJapan\j: this research could help to explain some of these effects, as green tea is commonly used in \JJapan\j.
#
"Kombucha Tea Cause of Illness",263,0,0,0
(Sep '97)
Early October brought some not-so-good news about tea. Kombucha tea is a popular "cure-all" made by steeping Kombucha "mushrooms" (actually an aggregate of yeast and \Jbacteria\j covered by a permeable membrane, available in health food stores) in tea and sugar to create a tonic. It is claimed to be a cure for everything from wrinkles to cancer, as well as lowering blood pressure, increasing vitality, increasing T-cell counts, relieving \Jarthritis\j pain, cleansing the gall bladder, alleviating \Jconstipation\j, fighting acne, and restoring grey hair to its original colour.
The beverage (also known as Manchurian or Kargasok tea), has now been identified as the cause of a number of illnesses in the United States, reported in the \IJournal of General Internal Medicine\i in early October. The symptoms seem to be mainly in the form of allergic reactions, but the report's principal author, Radhika Srinivasan, suggests that there may be some form of toxicity in Kombucha tea. There are, unfortunately, only four cases of problems with the tea known so far, and there would be some ethical problems in testing the tea for toxic side-effects in humans, so they can do little more than sound a note of warning.
#
"Male Fireflies Eaten For Repellent",264,0,0,0
(Sep '97)
More than 30 years ago, researchers discovered that females of the \Jfirefly\j \Jgenus\j \IPhoturis\i could lure males of another \Jgenus\j, \IPhotinus\i, by faking \IPhoturis\i females' blinking patterns. Both types of fireflies contain chemicals that protect them from predators, but the predatory \IPhoturis\i fireflies have only about one-third as much of the repellent compounds, called lucibufagens, as \IPhotinus\i.
It occurred to Thomas Eisner at Cornell University that perhaps \IPhoturis\i was stealing its protection from the gullible \IPhotinus\i males. The courtship ritual involves a male flashing its "fire", then the female responds with a pattern which identifies her species, and then the male approaches to mate. But when the \IPhotinus\i males approach a \IPhoturis\i female, they end up as dinner.
Eisner reared some larval \IPhoturis\i in Petri dishes. With no other fireflies to eat, the females grew into lucibufagen-free adults, which hungry jumping spiders were quite willing to eat. But after they had eaten some \IPhotinus\i males, other captive \IPhoturis\i females had high levels of lucibufagens and were rejected by jumping spiders. The spiders also avoided \IPhoturis\i females who were fed a solution containing lucibufagens.
That is the neat part: the messy part is that nobody knows where \IPhotinus\i gets the lucibufagens, but they certainly can't manufacture them. A number of predatory species of \IPhoturis\i live across the United States and \JSouth America\j, and all the females respond to the mating flashes of several other species, at least for meals, so now the scientists working on this group will need to re-examine their work and their conclusions.
#
"Sound Robot Design",265,0,0,0
(Sep '97)
Last August saw a report in the \IJournal of the Acoustical Society of America\i, its cover article, in fact, on Yale University electrical \Jengineering\j professor Roman Kuc's new \Jsonar\j robot. Inspired by the methods used by bats and dolphins to locate prey, the robot uses ultrasonic sound to locate objects and navigate. It is so sensitive that it can tell whether a tossed coin has come up heads or tails.
Getting a camera powerful enough to duplicate human vision is proving difficult, but Rodolph (short for robotic dolphin), Yale's new robot, is equipped with three \JPolaroid\j electrostatic transducers that can act either as transmitters or receivers to serve as the robot's "mouth" and "ears." This \Jsonar\j detection system, says Kuc, could prove easier and less costly than camera vision for identifying an authorised customer at an automated teller machine, detecting production flaws on an assembly line, or helping someone who is paralysed interact with a computer.
The transducers are similar to those used in \JPolaroid\j autofocus cameras to gauge an object's range, and in acoustic digital tape measures that use echoes to measure distances. The centre transducer emits a 60 kHz signal, as often as ten times a second, while the outer transducers, controlled by a Pentium 120 processor in a PC form rotating "ears" that help pinpoint and amplify the sound of the returning echoes. The system has a claimed accuracy of 0.1 mm, good enough for most purposes, says Kuc.
So far, only the sensing arms have been built. The next stage will be to mount the detector system on a mobile base, so that it can move around, exploring its environment.
#
"Fish and Ultrasonic Sound",266,0,0,0
(Sep '97)
It is unlikely that Rodolph will ever go to sea to hunt down a fish meal for us. Many fish will avoid dolphins when they can see them, but a report in \INature\i this month tells us that at least one dolphin-avoiding fish, the shad, can detect ultrasonic tones in the frequency range that dolphin use for \Jecholocation\j.
In the past, fish seemed only to hear low-frequency sounds, basically below 3000 Hz, but \Jherring\j will swim away when fishing boats switch on their echo sounders to locate schools of fish, and sardines and shad can be scared off by bursts of ultrasonic sound.
To find out what sounds the fish were actually hearing, University of Maryland neurobiologist, Arthur Popper, together with Zhongmin Lu and David Mann conditioned five fish, American shad, to associate a low-frequency sound-that the researchers knew the fish could detect-with an electric shock, which lowered the fish's heart rate.
Under normal circumstances, a conditioned fish will lower its hear rate when it hears the sound, in anticipation of the expected shock. While the fish did best at 200 to 800 Hz, the fish also responded to ultrasound between 25 000 Hz and 130 000 Hz. The shad responded to simulated dolphin \Jecholocation\j pings of 80 000 Hz.
The study may help acoustic engineers design better underwater sound systems to deter these fish from entering the water-intake pipes of power plants. "Pingers" have been used before to scare away fish, but without any real knowledge of what the fish can actually hear. Now, for the first time, we have some precise knowledge, and more importantly, a proven method for more investigations.
#
"Ciclid Fish in Danger of Extinction",267,0,0,0
(Sep '97)
Pity the poor cichlid, though, who seems not to be all that hot in the hearing game, and now is having trouble seeing. The colourful cichlid fish, which live in Africa's Lake Victoria, lying between \JKenya\j, \JUganda\j and \JTanzania\j, are notable for their rapid \Jevolution\j. Now they are also notable for their rapid decline.
Eutrophication of the lake, an increase in nutrient levels has caused lake turbidity (opaqueness) to increase. This is a problem for fish which maintain their differences by colour-associative mating, which is correlated with light conditions. The cichlid species will normally mate only with their own kind, but under low light conditions, they are unable to make the necessary visual distinctions, and many closely related species may end up interbreeding themselves out of existence.
The lake was once home to at least 500 species of small fish called haplochromine cichlids. Over the last 70 years, some hundreds of these species have become extinct. Originally, this \Jextinction\j was blamed on the predatory power of Nile perch, introduced into the lake in the 1950s, but it has recently become obvious that even species which the perch did not eat were disappearing.
Researchers then found that there were just five distinct cichlid species in murky \Jwater\j that allowed the transmission of a 100 nanometre segment of the light spectrum, but that there were about 20 species in clearer \Jwater\j that allowed the transmission of a full 500 nanometre segment. The researchers believe the murky \Jwater\j "turns the lights off," making even the most brightly colored males appear drab and indistinct to females, leading to breeding mistakes, the loss of distinct species, and an increase in hybrids.
So rather than classical \Jextinction\j, a slight change in the ecological balance is capable of "blinding" the fish to differences which would prevent them mating in clear \Jwater\j, wiping out species after species. In reality, these species were only species-in-waiting, populations which had been separated out into different breeding groups, and which, as separate genetic pools, were ready to embark on an evolutionary voyage which would have seen genetic barriers raised over time. Now, thanks to the turbid waters of the lake, that will never happen.
Eutrophication arises when logging and farming allow greater surface run-off, carrying mineral \Jnutrients\j such as nitrates and \Jphosphates\j into the lake. These \Jnutrients\j support larger concentrations of \Jalgae\j, and so of the plankton that live on the \Jalgae\j. You can see the same "clouding" effect by taking three jars of well-mixed pond \Jwater\j, giving one a small amount of "complete fertiliser", and second one a large amount of the same fertiliser, while the third remains untouched. Leave these on a sunny window-sill for a week or so, and watch to see how the \Jwater\j goes cloudy over a week or two.
#
"First World AIDS, Third World No Aid?",268,0,0,0
(Sep '97)
How do you feel about providing expensive AIDS treatment to \JHIV\j sufferers in the Third World? One reaction is to say that AZT cannot be afforded in the Third world, so we should seek more affordable measures. Yet AZT is regarded as the standard in the developed world, and intensive treatment of pregnant \JHIV\j-positive women with AZT can reduce transmission of \JHIV\j from mother to child by nearly 70%. So how can you justify doing anything less in those countries in Asia and Africa where \JHIV\j is running wild?
A closed meeting of the United Nations' AIDS program, UNAIDS discussed this issue and others during September, but no results had been released at the time of writing this report. Pressure groups and the \INew England Journal of Medicine\i argued during the month that any such trials would be unethical, and another problem is looming now, as hopes of an effective vaccine begin to surface.
How do you test an AIDS vaccine if everybody in the trial is also getting powerful anti-AIDS drugs? This was one of the considerations behind a number of American doctors indicating during September that they were prepared to trial AIDS vaccines on themselves.
One thing is certain: \JHIV\j/AIDS will have a huge financial cost on the world, so even if the economists can show that each life saved is only worth a few dollars in economic activity, the cost of leaving that case actively spreading the disease will spiral to a huge amount in a very small time: the world cannot afford not to do what it must to wipe out this disease, even if the victims are too poor to be able to pay for their treatment.
#
"Modified Virus To Fight AIDS?",269,0,0,0
(Sep '97)
In other \JHIV\j/AIDS news in September, researchers have engineered a vesicular stomatitis virus (VSV), which normally infects \Jcattle\j, to attack the AIDS virus in humans. In \Jcattle\j, the virus causes a mouth infection that stops the \Jcattle\j eating, but in the laboratory, the modified version has been shown to selectively target and destroys \JHIV\j-infected human cells, with no other effects.
After \JHIV\j binds to the \JCD\j4 receptor on a white blood cell, it also must link to another molecule found on the cell's surface, a chemokine receptor, and after this, the \JHIV\j can gain entry to the cell. Pieces of the virus then appear on the cell's surface, flagging the cell as one that has been attacked.
The modified VSV carries genes which code for \JCD\j4 and one of the \JHIV\j's chemokine \Jreceptors\j, CXCR4. This makes the VSV home in on the AIDS-infected cells, which it quickly kills, but the modified VSV lacks the surface protein it would need to attack normal cells, and so it leaves them alone.
This is a novel approach, but only time will tell us whether it is a practical approach: some workers in the area feel that the HSV levels needed may be too high to ever knock out all of the cells infected with \JHIV\j. Perhaps this treatment would be useful with the three patients described in the next story.
#
"Drug Solution To AIDS?",270,0,0,0
(Sep '97)
A conference in Baltimore was told in mid-September about an \JHIV\j-infected German man who has "undetectable" levels of the virus in his blood 9 months after he stopped taking a powerful combination of drugs to tackle the infection. Usually, viral levels rebound when patients stop taking anti-\JHIV\j drugs, but in this case, this seems not to happen.
The patient sought treatment soon after being infected, and was given indinavir, ddI, and hydroxyurea, drugs that have different mechanisms of action, which reduced his \JHIV\j levels to the point that the most sensitive polymerase \Jchain reaction\j assays could not detect any virus, a fairly common occurrence with the drugs now available.
Five months after the start of treatment, the man developed hepatitis A, which should have driven up \JHIV\j levels by itself, but this did not happen, and nine months later, the virus still remains undetectable in his blood. All that remains is what is described as a faint signal in his \Jlymph\j node where the bulk of \JHIV\j is usually to be found.
The report is the second anecdotal account of long-term viral suppression in the past few weeks. A paper published in the 30 August \ILancet\i describes two other patients who also have not seen their \JHIV\j levels rebound after being off drugs for 1 year, but some researchers question whether these individuals really were infected, saying that the patients in question had extremely low \JHIV\j levels to begin with.
These patients were, however, also being treated with hydroxyurea, which is not an approved AIDS drug in the United States. It certainly points to a useful direction for further exploration.
#
"CPR Debate",271,0,0,0
(Sep '97)
An American expert panel has questioned the usefulness of "mouth to mouth" in cardio-pulmonary resuscitation (CPR). They suggest that in many cases of adult cardiac arrest, mouth-to-mouth ventilation as a part of CPR rarely helps, and may even harm the patient.
Basically, they believe that mouth-to-mouth ventilation can interfere with the rescuer's efforts to perform chest compressions and cause significant adverse effects. It also makes CPR harder to teach, and apparently puts people off getting involved, especially when the patient is a bit "unhygienic", compared with the training dummies or manikins that they learned on.
Exhaled air contains 17% oxygen, less than the 21% of fresh air, and 4% carbon dioxide which can inhibit cardiac contraction. Studies have found that from 10 to 35 percent of patients who receive CPR inhale into their lungs \Jstomach\j contents, emitted after air is blown into the \Jstomach\j rather than to the lungs.
They say that the key factor in survival is the time from the cardiac arrest until defibrillation, when the heart is shocked back into a normal rhythm, but they also say that it is probably too early to do away with mouth-to-mouth ventilation just yet, and that it is still essential in cases of drowning. By the year 2000, they expect to have made a definitive statement on the matter.
#
"SHEBA's Winter",272,0,0,0
(Sep '97)
Two Canadian Coast Guard ice-breakers left Tuktoyaktuk, Canada in the middle of the month to establish Ice Station SHEBA in the \JArctic\j Ocean. Getting its name from the Surface Heat Budget of the \JArctic\j Ocean project, SHEBA will see the one of the ships frozen into the ice and left as a floating science platform for 13 months.
They will arrive at their station, approximately 75 degrees north and 143 degrees west, around October 1. One, \IDes Groseilliers\i, will remain in place until next year, while the other ship, \ILouis S. St. Laurent\i, will leave the area around October 15. The purpose of the freeze-in is to gather data on \Jweather\j and climate in the \JArctic\j so that forecasts of global climate change can be improved. You can follow SHEBA's progress at http://sheba.apl.washington.edu/default.html, with links taking you to regular reports on the status of the ships, and photographs showing the ice (and stopping the presses for a moment, even a \Jpolar bear\j sighted from \IDes Groseilliers\i.
#
"Crystal Star?",273,0,0,0
(Sep '97)
Astronomers pre-announced an October article in September, reporting on an interesting star. In theory, white dwarf stars may have a crystallised core. Most dwarf stars are thought to be too hot to crystallise, but now a team has identified a possible exception, a pulsating white dwarf star, called BPM 37093, tens of light-years away in the southern \Jconstellation\j \JCentaurus\j.
A two-week study, using the Whole Earth \JTelescope\j, has been scheduled for next March, which should provide enough data to determine the answer one way or another.
#
"Quark Star?",274,0,0,0
(Sep '97)
An even more exciting story broke this month, in the 1 September issue of \IPhysical Review Letters\i, where astronomers argue that the radio pulses from spinning neutron stars may reveal signs of the stars turning into "quark stars", where the core turns into a soup of free quarks.
The effect would show up as changes in density. As the pulsar slows down, the "centrifugal force" gets less, and the star becomes denser. As it crosses a critical density threshold, the neutrons should break down into quarks, which are more compressible, so the star will move inwards. This has the same effect as a skater pulling her arms inwards, so the star will then spin faster, producing a characteristic radio signal.
#
"Evolution Fraud Rediscovered",275,0,0,0
(Sep '97)
Once upon a time, one of the cornerstones of \Jevolution\j could be found in a catchphrase to the effect that "ontogeny recapitulates phylogeny". In plain English, the development of "higher" animals was supposed to show the embryo going through all of the stages that it had passed through on its evolutionary path.
While it has long since been rejected as a key element, it is still often trotted out in \Jbiology\j textbooks, usually with Ernst Haeckel's drawings, now well and truly free of copyright, to show the effects. Now a British researcher has photographed the standard embryos drawn by Haeckel, and reminds us of something which Haeckel apparently admitted at the time: Haeckel had "fudged" the drawings somewhat, as he drew them from memory in such a way as to emphasise the alleged recapitulation.
#
"Lungfish Our Nearest Relative?",276,0,0,0
(Sep '97)
"Old Four Legs", the coelacanth, has long been regarded as the closest of our gilled relatives, the species closest to the first fish to take a step out of the water onto the land. Now it seems that those scientists who thought the lungfish was our nearest relative were right all along. A new DNA analysis sees the lungfish promoted to number one spot in the land vertebrate tree. Of course, we need to avoid Haeckel's error, and remember that the lungfish has been evolving as well, but if you want an idea of what our ancestors may have looked like as they came ashore, that is where you need to go.
#
"Birds Get Older",277,0,0,0
(Sep '97)
Most of the many North American bird species were thought to have originated at the time of the \Jglaciation\j of the Late Pleistocene, during the Ice Ages around 100 000 and 250 000 years ago. Logically, that was the time when individual populations of a species were isolated by barriers of inhospitable territory, either ice or \Jtundra\j, and would be driven to follow their own genetic paths and diverge into separate species.
Logical perhaps, but not factual, not if you take account of the mitochondrial DNA analysis of 35 pairs of \Jsongbird\j species reported in September in \IScience\i. The birds were selected because they were closely related, and so presumably only evolved recently. In theory, birds which diverged in the more recent \JIce Age\j should differ by about 0.2%, while those which diverged at the earlier \JIce Age\j should show a difference of about 0.5%. These differences are simple random fluctuations in unimportant DNA, and so can usually be relied on as an evolutionary clock.
Instead, many of the bird pairs showed differences suggesting that their last common ancestor was much older, around 2.5 million years old, in fact! The next step in a study of this sort will be for the doubters to question the validity of the "biological clock".
#
"Fallacies About Evolution",278,0,0,0
(Sep '97)
There are two standard fallacies about \Jevolution\j: the first is that small is always replaced by large as \Jevolution\j proceeds, and the second is that every step in \Jevolution\j goes forward.
The second fallacy is easier to deal with, since if life forms always improved, they would never go extinct. The first fallacy was given to us by a 19th century American \Jfossil\j-hunter, Edward Drinker Cope in a proposition eponymously known as Cope's Rule: over time, the average body size within a \Jgenus\j of animals will tend to enlarge. Now we have evidence that Cope's rule has been flouted by a lowly \Jmollusc\j. In a paper in \INature\i this month, David Jablonski reports that molluscs have shrunk in size through the aeons.
Jablonski studied almost 1100 species of clams, oysters, and snails from the Gulf and Atlantic Coastal Plain of \JNorth America\j that evolved within 191 genera over 16 million years. One-third of the genera did indeed get bigger; but one-third got smaller. Smaller is better, it seems, when it is advantageous to reproduce early and often.
#
"Microprocessor Size Limit",279,0,0,0
(Sep '97)
According to Moore's Law, chips are getting smaller and more powerful all the time. (To be precise, Moore's Law states that the logic density of silicon integrated circuits has closely followed the curve d = 2^(t - 1962), where d is the density in bits per square inch and t is the year.)
But this era of growth may be coming to an end. The microscopic silicon chips of today are getting so small that eventually they will contain too few atoms to work, say observers.
"The 'road map' says that in about the year 2010 the limit will be reached. Microprocessors will be as small and as fast as they can get. This unhappy news will have an enormous impact on the national economy," said Kevin Jones, professor of materials science and engineering and co-director of the University of Florida's SoftWare and Analysis of Advanced Material Processing, the SWAMP Center.
If you think you have heard all that before, so has his fellow co-director, Mark Law. "For 30 years, people in the computer industry have predicted the 'just-a-decade-away' demise of the continually shrinking, ever-faster but still inexpensive computer chip," said Law. "But clever people have been able to push that 10-year window ever farther out." The point, say both men, is that the window cannot be pushed out forever.
The heart of the Pentium processor transistor, a layer that once was thousands of atoms thick, is getting so small that it soon will be only 50 atoms thick, and the Pentium processor's descendants may eventually shrink themselves out of function when the transistor inside the chips gets to be fewer than 10 atoms thick, in just over a decade. Unless there is a revolutionary change in computer technology, the trend toward smaller, faster computers will have reached its limit.
#
"Fossil Contention",280,0,0,0
(Sep '97)
The press in September were rightly excited over a 65-million-year-old \ITyrannosaurus rex\i named Sue (after the discoverer's girl-friend), said to be the largest and most complete theropod ever found. Due to be auctioned on October 4, people wondered where the bones would end up, and whether they would still be accessible to science.
Sue was seized by the US government in 1992 precisely to ensure that the skeleton would be accessible to science. The bones were discovered on a South Dakota Indian reservation by commercial \Jfossil\j hunters. Although they paid the landowner, Maurice Williams, a Cheyenne River Sioux, $5000 to excavate the \Jfossil\j, federal officials seized the bones, claiming that it hadn't been determined that they were rightfully taken. Williams holds his land in a tax-free trust arrangement with the federal government, which meant government permission is required to sell it or what's under it. After confiscating Sue, the government charged the discoverer, Peter Larson, with numerous felonies related to trafficking in illegally excavated fossils, and he was convicted for not reporting international financial transactions, for which he received a 2-year sentence, last year. Meanwhile, the courts finally decided that Williams was the rightful owner of Sue.
To deflect criticism from scientists, Sotheby's offered museums three interest-free years to pay what was expected to be a very high price, since a less complete skeleton is currently on offer for US$12 million. In the end though, the price in early October, including the auctioneer's 10% commission, to be paid by the purchaser, \JChicago\j's Field Museum, was just on US$8.4 million.
#
"Largest Specimen of Tyrannosaur Unearthed",281,0,0,0
(Sep '97)
A fossilised skeleton believed to be the largest specimen of a tyrannosaur ever unearthed was found this summer in Montana by a field crew headed by J. Keith Rigby, a University of Notre Dame palaeontologist. It may be either a \ITyrannosaurus rex\i or something very much like it. It differs from other specimens of \IT. Rex\i, of which there are now about fifteen, and the pubis, one of three main bones in the pelvis, measures at least 52 inches, compared to 48 inches in the largest known \IT. rex\i. The femurs or thigh bones, which palaeontologists normally use to estimate the size of dinosaurs, await excavation at the site, or so said a press release in early September.
Unfortunately, the site near the Fort Peck reservoir was on a \Jcattle\j ranch, and the former owners, who had been forced off the land because of debts, decided to excavate the \Jfossil\j themselves, in order to sell it and pay off the debt which had forced them off the ranch in the first place. Rigby had employed two of the family to cook for them as work proceeded, so they were well aware of the location, which Rigby had left to return to teaching at Notre Dame, planning to finish the dig next year.
Judging from the position of the surface bones and the other bones so far unearthed, Rigby believes the whole bone bed may cover 6 hectares (15 acres), making it one of the largest \Jdinosaur\j graveyards of the Late Cretaceous ever found. The material on the site was due to be placed in a museum planned to open in the area in 2005.
When Rigby returned late in September, he found two-thirds of the left side of the skull had gone, along with both lower jaws, although the jaws have since been recovered.
#
"Better Superconductors",282,0,0,0
(Sep '97)
Modern high-\Jtemperature\j copper oxide superconductors have a problem: as currents pass through them, magnetic vortices, eddies of magnetic force, are generated within the material. This results in finite electrical resistance and prevents the desired loss-free \Jconduction\j of current through the material. If mercury is introduced into the material, and then it is bombarded with high \Jenergy\j protons, this creates defects in the structure which inhibit the vortices, allowing it to act as a superconductor at temperatures above 130K.
#
"Cleaner Water, Better Medicines",283,0,0,0
(Sep '97)
Getting chemical products or pollutants from \Jwater\j is not an easy task, and often involves the use of toxic organochlorine solvents. Liquid carbon dioxide would be an ideal solvent for the task as it is cheap and non-polluting, but until now, its use has not been practical. Joe DeSimone and his colleagues at the University of \JNorth Carolina\j, Chapel Hill, have used dendrimers, molecules which branch repeatedly from a central point, to do the cleaning job for them. The dendrimers are soap-like in their action, clinging to the carbon dioxide on one side, and to the target molecule on the other.
Working under high pressure, a layer of \Jwater\j and methyl orange was covered with a layer of liquid carbon dioxide containing dendrimers. The process took about three hours, but seemed to remove every trace of the dye from the \Jwater\j. Carbon dioxide is cheap and easy to obtain: this sort of process, or a similar one using another carbon dioxide solvent helper called the reverse micelle, could be used to extract heavy metals from \Jwater\j, or pharmaceuticals from a culture broth, once suitably "targeted" endings have been created for the dendrimers.
#
"Mounds as Old as the Pyramids?",284,0,0,0
(Sep '97)
Long before Europeans arrived in the Americas, the Native Americans dotted the eastern side of the continent with thousands of huge \Jearth\j mounds. Previously dated to the period from 3700 to 2700 years, a new dating sets them back to about 5300 to 5400 years, based on radiocarbon dates, putting them in the same age range as the oldest pyramids, at a time when archaeologists believed the agriculture and trade networks necessary to build such structures had not been established in \JNorth America\j.
The dating question arose because the Watson Brake mounds lacked any of the artefacts that were expected, items made by a group called the Poverty Point people. Auger cores revealed ancient soil horizons, suggesting great age, and radiocarbon did the rest.
#
"New Tumour Suppressor Gene?",285,0,0,0
(Sep '97)
The p53 protein is found to be mutated in more than 50% of human cancers, earning it the name of "guardian of the \Jgenome\j". It appears that so long as p53 is active, cancers are held at bay, but when it breaks down, the cancers have an open go, because p53 is no longer able to control cell growth and death in a process called apoptosis. A previously unknown protein, called p73 has now been discovered and characterised, and it seems to share structural and functional similarity with p53. More tests need to be done before p73 can be confirmed as a \Jtumour\j suppressor, according to a report in \INature\i this month. Significantly, the gene for p73 lies on \Jchromosome\j 1, already believed to be "home" to one or more \Jtumour\j suppressors. The gene maps to the short arm of the \Jchromosome\j, in a region which is frequently deleted in neuroblastomas.
#
"DNA All Wrapped Up",286,0,0,0
(Sep '97)
Popular accounts of the \Jchromosome\j usually present it as some sort of long thread, tucked into the nucleus like a ball of string. The problem is that the typical cell has about two metres of DNA in it, and that much string, even in a large pocket, tends to get tangled: how much worse would it be with the super-fine thread that is DNA?
The picture is wrong. The simple DNA double helix is coiled into a super-helix (rather as the twisted wires in a keyboard cable are coiled into a helix, then that is coiled into a super-super-helix, and the whole thing is bound together with proteins called histones. Imagine wrapping a keyboard cable around your arm a few times, slipping your arm out and taping the coils together, and you will have the general idea.
Now, researchers have determined the x-ray crystallographic structure of the molecular machinery responsible for this feat, a fundamental DNA packaging unit called the nucleosome core particle. The structure's resolution-2.8 angstroms-is good enough to distinguish about 80% of the atoms in the protein component of the particle and all of those in the DNA.
#
"Left-Handers Rule in Space",287,0,0,0
(Sep '97)
Proteins are made of amino acids which can occur in two mirror-image forms, just like our hands, DNA, and even computer keyboard cables. On \Jearth\j, nearly all life-based amino acids occur as the left-handed form, as L-enantiomers, rather than right-handed D-enantiomers. When an excess of L-amino acids was discovered on the Murchison \Jmeteorite\j, it seemed that our chemical bias might have had an extraterrestrial origin; but then questions were raised about contamination of the samples.
The bad news for right-handers is that the extraterrestrial nature of this excess has now been confirmed in a \INature\i report this month. The origins are confirmed by a careful study of the amount of \Jnitrogen\j-15 in the amino acids, which was different from that found in terrestrial material.
In a test tube, equal amounts of the two forms of an amino acid will form, but living things only react with the L-enantiomers. This finding makes it just a little more likely that life originated with the insertion of large amounts of left-handed material into the \Jearth\j's \Jatmosphere\j and waters. That still leaves open the question: what caused the imbalance in space?
#
"E. coli Sequenced",288,0,0,0
(Sep '97)
\IEscherichia coli\i was first isolated in 1922, and it has been a standard workhorse for laboratory \Jgenetics\j for more than three decades. This month, researchers reported the complete sequence of all 4.6 megabase (4.6 million base pairs) \Jgenome\j of the bacterium. Because it has been so intensively studied for so long, researchers will now be able to go back over old work, tying it in to the new information, which includes a fold-out showing the arrangement of putative and known genes, operons, promoters, and protein binding sites.
#
"Cassini Trials",289,0,0,0
(Sep '97)
The $3.3 billion Cassini space mission to Saturn was still due to take off on October 15, but amid a rising clamour of protest over Cassini's load of \Jplutonium\j in a reactor designed to power the mission into the next millennium. Cassini will have overcome \Jinsulation\j and cooling problems, discovered in early September, which caused a postponement of the launch from October 6, first to October 13 and than to October 15.
The problem was with the European Huygens probe, which is attached to the Cassini orbiter, but the whole \Jspacecraft\j had to go back to the Kennedy Space Center for checking, with only a narrow launch window that closes out on 4 November. Any launch after that date would use much more fuel, limiting what the \Jspacecraft\j could do when it got there.
The \Jplutonium\j at the centre of the fuss is contained within several layers of \Jinsulation\j which has been tested and re-tested using explosives. In no test case has the \Jplutonium\j been exposed to the \Jatmosphere\j. Also it is designed to break into chunks, rather than dissolve into dust, so it cannot be inhaled or carried on the wind, while the protests are based on a worst-case scenario, where all of the \Jplutonium\j is pulverised and then breathed by humans.3
Upon its arrival at Saturn in 2004, the \Jspacecraft\j will spend four years orbiting Saturn and many of its 18 known moons, providing a flood of new data on what many view as a miniature \Jsolar system\j. Professor Larry Esposito, chief scientist on the Ultraviolet Imaging Spectrograph, or UVIS, said it will be used to study the \Jatmosphere\j of Saturn, the surfaces and atmospheres of its moons and the structure and dynamics of the fabulous ring system.
#
"Science Prize News",290,0,0,0
(Sep '97)
The 1997 Nobel Prize for Physiology or Medicine has gone to Stanley Prusiner for his work on prions.
In other prize news, this year's Albert Lasker medical research awards, each worth $25 000, have been awarded to two scientists who have done pioneering work in \Jgenetics\j and to a physician who brought vitamin A therapy to children throughout Africa and Asia.
The Basic Research Award went to Mark Ptashne, of the Memorial Sloan-Kettering Cancer Research Center in New York City, for his work on the molecular basis of gene regulation, the process that turns genes on and off. Thirty years ago Ptashne isolated the lambda repressor, a protein that binds to a specific DNA location and turns off expression of certain genes of a virus that grows inside \Jbacteria\j. The lambda repressor and its associated proteins became one of the best understood systems of gene regulation and helped Ptashne and other researchers understand the process in many higher organisms.
Victor McKusick, of Johns Hopkins University received a Special Achievement Award for advancing the study of the genetic basis of disease, work that lead to the Human Genome Project, while the Clinical Medical Research Award went to Alfred Sommer, also of Johns Hopkins, for his work on vitamin A therapy for children in the developing world. Although vitamin A deficiency was already known to cause \Jblindness\j in many developing countries, Sommer showed in 1983 that it also dramatically increased child mortality from other, more serious diseases. This finding was applied to aid programs sponsored by the World Bank, which believes that vitamin A supplements for children constitute one of the most cost-effective treatments in medicine.
#
"Nobel Prize in Physiology or Medicine (1997)",291,0,0,0
The Nobel Assembly at the Karolinska Institute has awarded this prize for 1997 to Stanley B. Prusiner for his discovery of prions, a new biological principle of infection, believed to cause transmissible spongiform encephalopathies (TSEs). These are diseases like scrapie in sheep, "mad cow disease" (BSE or bovine spongiform encephalopathy) and Creutzfeldt-Jacob disease (CJD) in humans. The award represents the first time since 1987 that this prize has been given entirely to a single person. All the other recent prizes have been shared by two or three researchers.
Most infectious diseases are caused by organisms which contain nucleic acids. Even viral diseases (where we can split hairs about whether or not viruses are really organisms or not) involve viral RNA. Prion disease is different: it appears to be caused by pieces of protein which "flop" into a different shape, and somehow act as a template, causing more of the protein to fall into the different shape.
This is important, because the chemical properties of any molecule will depend on, among other things, the shape of the molecule, and the way charge is distributed across it. When the protein "flops", it has a new shape, and the charge distances are different. According to Prusiner, this is how these diseases are able to be transmitted.
Prusiner himself created the name "prion", an \Jacronym\j derived from "proteinaceous infectious particle", in 1982. But while there is now widespread support for the prion theory, and many scientists are delighted for Prusiner, others say the award may be a bit hasty, that prions as the cause of disease remain theory not fact. Although normal prion protein molecules can be distorted into the disease shape in a test tube, simply by adding distorted protein from the brains of people who died of TSEs, this converted protein is not itself infectious.
For a century, disease causes have been identified in accordance with Koch's postulates, a set of rules assembled by Robert Koch. These state that:
1. The "causing" organism must always be found in diseased animals, but never in healthy animals;
2. The organism must be cultured in a pure culture away from the animal body;
3. When this culture is inoculated unto a susceptible host, the characteristic symptoms of the disease should appear; and
4. The organisms isolated and recultured from the experimental animals should be the same organism as those originally cultured.
Obviously Koch's postulates were written to fit the standard "germ cause of disease" paradigm or model of the late 19th century, but they can be applied fairly well to the prion hypothesis with just a few changes. The sticking point is postulate 4, where the final protein, if it is really the same, should still be able to cause the disease. It can't, so for the moment, there is something missing, and no one knows what the missing factor is. The \Icomplete\i cause of TSEs has not yet been identified, and this is the justification for the critics to say that Prusiner should not get the award just yet.
Other scientists argue that if you wait for something like this to be finally sorted out, it may never be the subject of a Nobel prize, as these awards are never made posthumously. The missing link, suggests Prusiner, may be a second protein which "chaperones" the conversion of prion molecules from the healthy state to the diseased state. Others want to assume that the "chaperone" is a virus or other traditional disease-causing particle.
The problem began with the mystery of scrapie, a disease in sheep, first known from \JIceland\j in the 18th century, and transferred to Scotland in the 1940s. As early as 1967, Tikvah Alper, an English researcher, performed experiments in which she showed that there seemed to be no genetic material involved in disease transmission. In 1968, John Griffith suggested that TSEs could, in theory, be caused by a single protein, but the idea more or less died at that point. Alper was a radiation biologist and Griffith was a physicist, and their evidence came from the fact that brain tissue remained infectious even after Alper had subjected it to radiation that would destroy any DNA or RNA.
In hindsight, Griffith's insight was a brilliant one: he suggested that perhaps a protein, which would usually prefer one folding pattern, could somehow misfold and then catalyse other proteins to do likewise, but as a physicist, attacking the whole basis of molecular \Jbiology\j, he had little chance of being taken seriously, so scrapie became an interesting minor footnote in \Jbiology\j books.
As the 1970s progressed, Prusiner became interested in the problem when one of his patients died of CJD. As often happens when there is a new idea, the opposition was strong, if only because Prusiner's ideas went against the prevailing paradigm. The accepted model was based on the central dogma of molecular biologists that all self-replicating life-forms had to contain DNA (or at least RNA) in order to reproduce.
Like any perceived "maverick" in science, Prusiner had to argue long and hard, and was often accused of dogmatism himself, so it is little wonder that he commented after the announcement of the prize that he felt vindicated. The critics, though, are still there, and they still argue that vindication is not proof.
Let us review the evidence for Prusnier's ideas. We know the prion protein gene is found in all mammals, and that the "scrapie" form of the protein is more stable than the normal form, remaining stable even when attacked by chemicals or subjected to high temperatures. This suggests that the dangerous form slowly accumulates until damage begins to happen.
This long incubation period makes it hard to collect pure samples of the prion protein, as it took mice some 200 days to develop useful quantities of the protein, a figure that was cut when it was shown that scrapie prion can be grown much faster in hamsters.
We know the normal prion protein is an ordinary component of white blood cells (lymphocytes) and that it is found in many other tissues as well. Prusiner has even shown that the hereditary forms of prion diseases like CJD are caused by mutations in the prion gene. Transgenic mice carrying the mutated form of the gene were shown to develop a scrapie-like disease. More importantly, mice which lack the prion gene altogether (and which thus lack the protein) are immune to the scrapie-like disease, even when they are treated with disease-causing prion protein. Curiously, the mice lacking the prion gene are apparently healthy, suggesting that the normal prion molecule is not an essential protein in mice, making its normal biological role something of a mystery.
Mink, cats, deer and moose are all affected by similar diseases, the "mad cow disease" is now probably the most widely known prion disease, but the kuru, or "laughing sickness of the Fore (pronounced "4ray") people of New Guinea was also caused by a prion, though at the time when Carleton Gajdusek received the 1976 Nobel Prize in Physiology or Medicine, it was thought to be a "slow virus".
Another prion-like disease is Gertsmann-StrΣussler-Scheinker (GSS) disease, a hereditary \Jdementia\j resulting from a \Jmutation\j in the gene encoding the human prion protein. Approximately fifty families with GSS mutations have been identified. The illness takes from two to six years to kill its victims after evidence of first symptoms. Fatal Familial Insomnia (FFI) is due to another mutation in the gene encoding the human prion protein. Nine families have been found that carry the FFI mutation. FFI takes about one year from first symptoms to death, as does CJD.
Creutzfeldt-Jacob Disease affects about one person in a million. In between 85% and 90% of cases, CJD occurs spontaneously. The remainder are mainly caused by mutations in the prion protein gene, with a few rare cases caused by infection, like the infections transmitted through growth hormone preparations prepared from the pituitary \Jgland\j of infected individuals, or brain membrane transplants. About 100 families are known carriers of CJD mutations.
Recently, a new form of CJD has arisen. Here, the likely cause is thought to be related to the transfer of the BSE prions to humans. Since 1995 about twenty British patients have been identified who exhibit CJD-like symptoms, attributed to "vCJD" (variant CJD).
Within days of the Nobel committee's announcement, a report appeared in \IScience\i, indicating that vCJD and BSE in mice appear to be one and the same, and distinguishable from normal forms of CJD. This appears to confirm that the vCJD cases were caused by eating infected beef. While vCJD has similar symptoms to classic CJD, vCJD tends to strike younger people, and it develops much more quickly than the classic form.
Moira Bruce of the Institute of Animal Health in Edinburgh, Scotland, and her colleagues, injected mice with infectious brain samples from cows with BSE, from patients who died of vCJD, and with equally infectious samples from classic CJD patients. A paper in \INature\i at almost the same time came from a different direction, showing that BSE prions can turn normal human prions infectious in mice.
All in all, it does not seem fair to claim the Prusiner's prize was too early. But if it \Iwas\i too early, it was only be a matter of days. And Ralf Pettersson, deputy chair of the Nobel Committee at the Karolinska Institute, says the panel was not bothered by the unanswered questions. He says the prize was awarded for the discovery of the prion and its role in the disease process. "The committee is well aware of where the field stands," said Pettersson. "The details have to be solved in the future.
#
"Nobel Prize in Chemistry (1997)",292,0,0,0
The Royal Swedish Academy of Sciences has decided to award the 1997 Nobel Prize in Chemistry with one half to Professor Paul D. Boyer, University of \JCalifornia\j, Los Angeles, USA, and Dr. John E. Walker, Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom for working out the enzymatic mechanism underlying the synthesis of \Jadenosine triphosphate (ATP)\j in the cell, the other half going to Professor Jens C. Skou, Aarhus University, Denmark for the first discovery of an ion-transporting \Jenzyme\j, Na+, K+-ATPase.
ATP functions as a carrier of \Jenergy\j in all living organisms from \Jbacteria\j and fungi to plants and animals including humans. ATP is produced mainly by the Krebs cycle, which makes the synthesis of the molecule from adenosine diphosphate (ADP) and inorganic phosphate an important study. Skou's discovery of another \Jenzyme\j, sodium, \Jpotassium\j-ATPase, gives us vital information about how an organism maintains the balance of sodium and \Jpotassium\j ions in the living cell.
ATP captures the chemical \Jenergy\j released by the \Jrespiration\j ("controlled combustion") of \Jnutrients\j and transfers the \Jenergy\j to the reactions that require \Jenergy\j. This involves it in processes as different as the building up of cell components, muscle contraction, transmission of nerve messages, to name just a few.
Considerable quantities of ATP are formed and consumed in an organism. At rest, an adult human converts a quantity of ATP corresponding to about one half of his or her body-weight every \Jday\j, and during hard work the quantity can rise to almost a tonne per \Jday\j. This is possible because the products of ATP use, adenosine diphosphate (ADP) and inorganic phosphate, are the raw materials of ATP synthesis. Most of the ATP synthesis is carried out by the \Jenzyme\j ATP synthase, while at rest, Na+, K+-ATPase uses up a third of all ATP formed, making it the body's biggest ATP user.
ATP was discovered by the German chemist Karl Lohmann in 1929. Around 1939-41, Fritz Lipmann (Nobel laureate 1953) showed that ATP is the universal carrier of chemical \Jenergy\j in the cell and coined the expression "\Jenergy\j-rich phosphate bonds". In 1948, Alexander Todd (Nobel laureate, 1957) chemically synthesised ATP.
By the 1970s, researchers had discovered that ATP synthase is made up of three connected sets of protein assemblies: a wheel-like structure inside an internal mitochondrial membrane, a rod with one end fixed to the wheel's hub, and a large cylinder that wraps around the other end of the rod. They already knew that ATP is created at a trio of sites on the cylinder, and that the rod played a key role in turning on the catalytic activity at these sites. But again, the exact mechanism was unclear.
Boyer theorised that the whole system might spin as protons pass through the mitochondrial membrane. This rotation slightly alters the structure of three active sites within the \Jenzyme\j, causing each in turn to catalyse the binding together of building blocks that make up ATP, synthesise a molecule of ATP, and release it. In 1994, Walker and his colleagues at the Medical Research Council Laboratory of Molecular Biology in Cambridge, United Kingdom, verified Boyer's theory by using x-rays to create an atomic-scale map of the catalytic portion of the \Jenzyme\j.
Skou approached the fuel cycle from the other end. In 1957, he discovered the first \Jenzyme\j that burns up ATP to transport ions across cell membranes. Skou's \Jenzyme\j, known as sodium, \Jpotassium\j-ATPase, uses ATP to \Jpump\j sodium and \Jpotassium\j ions across cell membranes, an activity essential for nerve signal firing as well as a host of other cell functions. Hundreds of related enzymes have since been discovered which have similar functions.
As far back as the 1920s, the ion composition within living cells was known to be different from that in the surroundings. Inside the cells the sodium concentration is lower and the \Jpotassium\j concentration higher than in the liquid outside, so there had to be some sort of one-way \Jpump\j moving the ions. Englishmen Richard Keynes and Alan Hodgkins (Nobel laureate 1963) established at the start of the 1950s that when a nerve is stimulated sodium ions pour into the nerve cell.
The difference in concentration is restored by sodium being transported out once more. It seemed likely that this transport required ATP, since the transport could be inhibited in living cells by inhibiting the formation of ATP. Starting from this point, Jens Skou searched for an ATP-degrading \Jenzyme\j in the nerve membrane that could be associated with ion transport. In 1957 he published the first article on an ATPase, which was activated by sodium and \Jpotassium\j ions (Na+, K+-ATPase).
(In standard biochemist-speak, the -ase ending added onto a chemical name means an \Jenzyme\j which breaks down that chemical, so RNase breaks down RNA, while a protease is an \Jenzyme\j that breaks down protein.)
Jens Skou worked mainly with finely ground crab nerve membranes. The ATP-degrading \Jenzyme\j found in the preparation required the presence of \Jmagnesium\j ions and was stimulated with increasing quantities of sodium ions up to a certain limit. Above this Skou was able to obtain further stimulation if he added small quantities of \Jpotassium\j ions.
Significantly, he observed the largest stimulation at the concentrations of sodium and \Jpotassium\j that normally occur in the nerve, suggesting that the \Jenzyme\j was coupled to the ion \Jpump\j in some way. In his further studies of the \Jenzyme\j mechanism, Skou showed that sodium ions and \Jpotassium\j ions bind with high affinity to different places in the \Jenzyme\j. He also showed that the phosphate group separated from ATP also binds to ATPase.
This is described as a phosphorylation of the \Jenzyme\j, and we now know that the \Jenzyme\j is dependent on sodium ions when it is phosphorylated and on \Jpotassium\j ions when it is dephosphorylated. Substances known to inhibit sodium/\Jpotassium\j transport are certain \Jdigitalis\j \Jalkaloids\j such as oubain, and Skou showed that oubain interferes in the \Jenzyme\j's activation by sodium.
Skou was thus the first to describe an \Jenzyme\j that can promote directed (vectored) transport of substances through a cell membrane, a fundamental property of all living cells. Many other enzymes have since been demonstrated to have essentially similar functions, but Skou was the first, and so well deserving of his share in the prize.
#
"Nobel Prize in Physics (1997)",293,0,0,0
The Royal Swedish Academy of Sciences has decided to award the 1997 Nobel Prize in Physics jointly to Professor Steven Chu, from the USA, Professor Claude Cohen-Tannoudji, from \JFrance\j, and Dr. William D. Phillips, also from the USA, for developing methods used to cool and trap atoms with \Jlaser\j light.
Chu was born 1948 in St. Louis, Missouri, USA., and has been the Theodore and Frances Geballe Professor of Humanities and Sciences at Stanford University since 1990. He was awarded the 1993 King Faisal International Prize for Science (Physics) for development of the technique of \Jlaser\j-cooling and trapping atoms.
Cohen-Tannoudji was born 1933 in Constantine, \JAlgeria\j, and is now a French citizen, and has been a Professor at the CollΦge de \JFrance\j since 1973. Cohen-Tannoudji was awarded the 1996 Quantum Electronics Prize (European Physical Society) for, among other things, his pioneering experiments on \Jlaser\j cooling and the trapping of atoms.
Phillips was born 1948 in Wilkes-Barre, \JPennsylvania\j, USA. He was awarded the 1996 Albert A. Michelson Medal (Franklin Institute) for his experimental demonstrations of \Jlaser\j cooling and atom trapping. He works at the National Institute of Standards and Technology, Gaithersburg, Maryland, USA.
Hailed as master jugglers and as "masters of manipulating atoms with light", able to "make atoms float in optical molasses", their achievement has been to use \Jlaser\j beams to slow atoms down by bombarding them with \Jlaser\j light, until their \Jtemperature\j is just millionths of a degree above \Jabsolute zero\j. At the temperatures we live at, gas atoms and molecules rush around in different directions at a speed of about 4000 km/hr. While it may be considered unsporting to shoot a sitting bird, physicists find it far easier to study a sitting atom. The problem was: how do we absorb all that extra \Jenergy\j, and slow the atoms down?
In a real sense, \Jtemperature\j is a measure of speed, so a cooled atom moves more slowly, but even temperatures as low as -270░C involve speeds of about 400 km/hr. Only as the temperature approaches \Jabsolute zero\j (-273░C) does the speed fall greatly. When the temperature is one-millionth of a degree from this point (1 ╡K, or 1 microkelvin), free \Jhydrogen\j atoms move at speeds of less than 1 km/hr (= 25 cm/s).
The other problem is that gases turn into liquids and solids at very low temperatures, making it harder to pick out individual atoms. The \Jhydrogen\j atoms in normal gas samples, are no longer free, so the problem becomes one of cooling very thin gas in a high vacuum to a very low temperature. In a high vacuum, condensation and freezing effects can be minimised, and we have a mass of slowly-moving gaseous atoms.
Chu, Cohen-Tannoudji, and Phillips developed methods of using \Jlaser\j light to cool gases to the ╡K \Jtemperature\j range and found ways of keeping the chilled atoms floating or captured in different kinds of "atom traps". The \Jlaser\j light functions as a thick liquid ("optical molasses"), in which the atoms are slowed down. Individual atoms can be studied there with very great accuracy and their inner structure can be determined. As more and more atoms are captured in the same volume, a thin gas forms, and its properties can be studied in detail.
As a result of their work, we now know a great deal more about the interactions between radiation and matter. In particular, their work has opened the way to a deeper understanding of the quantum-physical behaviour of gases at low temperatures, where most of our intuitive ideas about the "real world" break down.
In our everyday world, the one that our intuition understands, light is light and matter is matter. Yet inside the world of quantum physics, light may be described as a stream of particles that we give the name \Jphoton\j. These photons have no mass in the normal sense but, just like a rolling billiard ball, they have a certain momentum. A flying stone that collides with an identical rock can transfer all its momentum (mass times velocity) to that second rock, and itself become stationary. In the same way, a photon that collides with an atom can transfer all its momentum to that atom.
This will only happen if the \Jphoton\j has the right \Jenergy\j level, which is the same as saying the light must have the right frequency, or colour. This is because the \Jenergy\j of the \Jphoton\j is proportional to the frequency of the light, which in turn determines the \Jphoton\j's colour, a matter that was first worked out by Max Planck.
Because of this relationship, red light is made up of photons with lower \Jenergy\j than those of blue light. To move beyond this point, though, we need to consider the Doppler effect.
Aside from giving a train whistle a higher pitch when the train is approaching than when it is standing still, the Doppler effect also changes the frequency of light shining on an atom, depending on the way the atom is moving. If the atom is moving towards the light, the light must have a lower frequency than that required for a \Jphoton\j approaching a stationary atom, if it is to affect that atom.
Imagine a moving atom, moving fairly fast, and coming into collision with a collection of photons. If the photons have the right \Jenergy\j the atom will be able to absorb one of them and take over its \Jenergy\j and its momentum. The atom will then be slowed down somewhat, but within a short period of time, around a hundred-millionth of a second, the slowed-down atom emits a photon, at a random direction, giving the atom a certain small recoil velocity.
Because the directions of \Jphoton\j emission are random, while the absorption is all from one direction, the overall effect is to slow the atom down. With just the right arrangement of the \Jlaser\j beam, the slowing effect is comparable to the effect of the gravity of a \Jplanet\j the mass of a hundred thousand \Jplanet\j Earths. This will only happen if the \Jlaser\j frequency is matched to the atoms it is blasting.
Around 1985, Chu and his colleagues set up three opposing \Jlaser\j beam pairs at right angles to each other at the Bell Laboratories in Holmdel, \JNew Jersey\j. Sodium atoms from a beam in vacuum were first stopped by an opposed \Jlaser\j beam and then conducted to the intersection of the six cooling \Jlaser\j beams.
The light in all six of the \Jlaser\j beams was slightly red-shifted compared with the characteristic colour absorbed by a stationary sodium atom, meaning that the photons would interact with atoms coming towards them, but "ignore" atoms going away from them. So whichever direction the sodium atoms tried to move, they were met by photons of just the right \Jenergy\j and pushed back into the area where the six \Jlaser\j beams intersected.
This leads to something that observers said looked like a glowing \Jcloud\j the size of a pea, consisting of about a million chilled atoms. This is called Doppler cooling, and the sodium atoms were found to have speeds of about 240 ╡K. This is equivalent to a sodium atom speed of about 30 cm/s, and agreed very well with a theoretically calculated \Jtemperature\j-the Doppler limit-then considered the lowest \Jtemperature\j that could be reached with Doppler cooling.
At this point, the atoms are cooled but not captured: they still fall under the influence of gravity. Here we need to turn to the work carried out by Phillips and his colleagues. By the beginning of the 1980s by William D. Phillips and his co-workers were using magnetic traps to slow down and completely stop atoms in slow atomic beams.
They used a "Zeeman slower", a coil with a varying magnetic field that affects the atoms' characteristic \Jenergy\j levels by the Zeeman effect, so that they can be slowed even more as they are slowed by a \Jlaser\j beam. This sort of trap is relatively weak, and though Phillips had "stopped" sodium atoms by 1985, the atoms were hard to retain. Once Chu managed to cool atoms in optical molasses, Phillips designed a similar experiment and started a systematic study of the \Jtemperature\j of the atoms in the molasses. He developed several new methods of measuring the \Jtemperature\j, including one in which the atoms are allowed to fall under the influence of gravity, the curve of their fall being determined with the help of a measuring \Jlaser\j.
By 1987, the researchers had constructed a magneto-optical trap (MOT). This uses six \Jlaser\j beams in the same sort of array as in the first experiment, but it also has two magnetic coils that give a slightly varying magnetic field with a minimum in the area where the beams intersect. A Zeeman force develops which is greater than gravity and which therefore draws the atoms in to the middle of the trap. The atoms are now really caught, and can be studied or used for experiments.
In 1988, Phillips found that a \Jtemperature\j as low as 40╡K could be attained, six times lower than the theoretically calculated Doppler limit. This would later be explained by the recognition that the Doppler limit calculations were based on an unrealistically simple model of the atom.
Meanwhile, Claude Cohen-Tannoudji and his co-workers at the ╔cole Normale SupΘrieure in Paris had already studied more complicated cooling schemes in theory. The recoil velocity an atom gains when it emits a single \Jphoton\j corresponds to a \Jtemperature\j termed the recoil limit, which depends on the atom's mass. For sodium atoms the recoil limit is 2.4 ╡K and for heavier caesium atoms, about 0.2 ╡K. Working with Cohen-Tannoudji and his colleagues, Phillips showed that caesium atoms could be cooled in optical molasses to about ten times the recoil limit, i. e. to about 2 ╡K. Later, they found that under the right conditions, atoms can be cooled to a \Jtemperature\j about five times higher than the recoil limit.
The next step was to make stationary atoms go into a "dark" state, where they are unaffected by photons. Cohen-Tannoudji and his group developed a method based on the Doppler effect which converts the slowest atoms to a dark state between 1988 and 1995, at least with \Jhelium\j atoms, able to get as low as 0.25 ╡K with two opposed \Jlaser\j beams, sixteen times lower than the recoil limit. Then with six \Jlaser\j beams, they reached a state in which the whole velocity distribution corresponded to a \Jtemperature\j of 0.18 ╡K. Now the \Jhelium\j atoms were crawling along at a speed of only about 2 cm/s.
Since then, Chu has built an atomic fountain, in which \Jlaser\j-cooled atoms are sprayed up from a trap like jets of \Jwater\j, until the pull of gravity slows them. By illuminating the atoms at the top of their climb with \Jmicrowaves\j, it is possible to sense the atoms' inner structures, hopefully leading to atomic clocks with a hundredfold greater precision than at present. Other applications may include lasers made of coherent "waves" of atoms, and other uses have been identified in areas as far apart as \Jbiology\j, physics, and even sensing gravitational anomalies that can reveal underground oil fields.
In 1995, other researchers used the same methods to create a "Bose-Einstein condensate," in which the cold atoms' quantum-mechanical waves all overlapped to create a new state of matter.
#
"Economics Nobel Prize (1997)",294,0,0,0
Even the "dismal science" has its equivalent of a Nobel Prize these days. The Royal Swedish Academy of Sciences has decided to award the Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, 1997, to Professor Robert C. Merton, \JHarvard University\j, Cambridge, USA and Professor Myron S. Scholes, Stanford University, Stanford, USA for a new method to determine the value of derivatives. Merton was born in 1944, Scholes was born in 1941. Together with the late Fischer Black, they developed a pioneering formula for the valuation of stock options. Their method has paved the way for economic valuations in many areas and facilitated more efficient risk management in society.
While many see the futures markets as new places and ways for gamblers to lose money, these markets were created to assist producers and manufacturers to manage the risk of huge price shifts up or down. The derivative is a reflection of the market's judgement on future trends, and necessarily rises or falls faster than the commodity price from which it is derived. This is why it was possible for bad bets on derivatives to bring down Barings, Britain's oldest bank, and for equally bad bets to drive Orange County, \JCalifornia\j, into \Jbankruptcy\j.
Markets for options and other so-called derivatives have a legitimate use in daily business. They are important in the sense that agents who anticipate future revenues or payments can ensure a profit above a certain level or insure themselves against a loss above a certain level. (Futures carry an obligation to trade at a nominated price and are two-sided, but options allow for \Jhedging\j against one-sided risk-options give the right, but not the obligation, to buy or sell a certain security in the future at a prespecified price.)
Before you can efficiently manage risk, you need to be sure that such instruments are correctly valued, or priced. A new method to determine the value of derivatives is thus one of the most important contributions to economic sciences over the last 25 years. And that is where Merton, Scholes and Black come in, although Black is unable to share in the prize, as he died in mid-1995. In 1973, Black and Scholes published what we call the Black-Scholes formula (which, as Black made clear some years ago, had an input also from Merton). Robert Merton also devised another method to derive the formula that turned out to have very wide applicability; he also generalised the formula in many directions.
The \JChicago\j Board Options Exchange introduced trade in options in April 1973, one month before publication of the original Black-Scholes option-pricing formula. By 1975, traders on the options exchange had begun to apply the formula, using especially programmed calculators, to price and protect their option positions. Nowadays, thousands of traders and investors use the formula every day to value stock options in markets throughout the world, in a global trade that is believed to be worth some $70 trillion each year.
#
"Nobel Prize for Literature (1997)",295,0,0,0
This has been awarded to Dario Fo "who emulates the jesters of the \JMiddle Ages\j in scourging authority and upholding the dignity of the downtrodden". Fo, a dramatist and actor, was born at Lago Maggiore, and is 71. His education included studies at the Academy of Arts in Milan. He is married to the actress and writer Franca Rame.
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"Nobel Peace Prize (1997)",296,0,0,0
The Norwegian Nobel Committee has decided to award the Nobel Peace Prize for 1997, in two equal parts, to the International Campaign to Ban Landmines (ICBL) and to the campaign's coordinator Jody Williams for their work for the banning and clearing of anti-personnel mines.
There are at present probably over one hundred million anti-personnel mines scattered over large areas on several continents. Such mines maim and kill indiscriminately and are a major threat to the civilian populations and to the social and economic development of the many countries affected.
#
"Gairdner Awards for 1997",297,0,0,0
Many Nobel Prize winners have earlier won Gairdner Awards, Canada's top medical prize, and this year's four winners, all US researchers, must be hoping for a future call from Scandinavia.
Three awards, valued at $25 000 were presented in Toronto on October 24. Alfred Knudson Jr. of the Fox Chase Cancer Center in Philadelphia won for his contributions to cancer \Jgenetics\j, which led to the idea of \Jtumour\j-suppressor genes, Erikki Ruoslahti of the Burnham Institute, La Jolla, \JCalifornia\j, and Richard Hynes of the \JMassachusetts\j Institute of Technology shared a prize for their research on cell adhesion, and Cory Goodman of the University of \JCalifornia\j, Berkeley, earned his award for contributions to developmental neurobiology.
Knudson found in the 1960s that children who inherit a \Jmutation\j in a particular gene have a higher risk than others of developing a cancer called retinoblastoma. Knudson reasoned that a random \Jmutation\j might strike out the functional copy in the millions of dividing retinal cells, unleashing cancerous growth of the cell.
Ruslahti and Hynes discovered and characterised fibronectins and integrins, molecules responsible for making cells stick to substrates and to each other. They also recognised that cells change in response to the surrounding matrix, a fact that has clinical importance in cancer, blood coagulation, and wound healing.
Goodman has helped to shed light on how the brain wires itself during development.
#
"Ig Nobel Awards",298,0,0,0
(Oct '97)
Those who were missed by the Nobel juries, who failed to be considered for the Gairdners, can at least take comfort in the thought that they were not picked for an Ig Nobel award either. These spoof awards, issued each October, reflect the lighter-hearted side of science.
At the seventh "First" Annual Ig Nobel Prize Ceremony, ten individuals or research teams were honoured for achievements that "cannot or should not be reproduced." Unlike the Nobels, posthumous awards are available, and the \Jmeteorology\j prize went posthumously to Bernard Vonnegut of the State University of New York, Albany (novelist Kurt Vonnegut's older brother) who showed that you cannot assess wind speeds by firing a chicken into a \Jtornado\j with a cannon, as it is impossible to tell whether the chicken loses its feathers in being fired, or in the \Jtornado\j.
Vonnegut's tongue may have been in his cheek, but the medical award (for showing that the immune response is stimulated by Muzak) featured a Muzak employee and reputable workers, and appears to be a genuine piece of research.
Only one recipient turned up to receive his award, urban ecologist Mark Hostetler, who scraped dead insects off the windshields of \JGreyhound\j buses all the way from \JMassachusetts\j to British Columbia in researching his Ig Nobel-prizewinning book, \IThat Gunk on Your Car: A unique guide to insects of North America\i (Ten Speed Press, 1997), which has been garnering rave reviews. The book features colour illustrations-before and after windshield contact-as well as lots of genuine natural history. Speaking after receiving his award, Hostetler said triumphantly "At least these insects did not die in vain."
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"Former Nobel Laureates Call For Greenhouse Cuts",299,0,0,0
(Oct '97)
During late September, more than 1500 of the world's leading senior scientists, including the majority of Nobel laureates in science, signed a landmark consensus declaration urging leaders world-wide to act immediately to prevent the potentially devastating consequences of human-induced global warming. The "World Scientists' Call for Action at \JKyoto\j" was presented to the Clinton Administration at the end of September at a Science Summit on Climate Change in Washington, DC.
Nobel laureate Henry Kendall, Chairman of the Union of Concerned Scientists, and author of the scientists' statement, said it would be ". . . a grave error to believe that we can continue to procrastinate. Scientists do not believe this and no one else should either."
In December, world leaders will gather in \JKyoto\j, \JJapan\j, to negotiate final agreement on a treaty to reduce emissions of carbon dioxide and other heat-trapping gases that are altering the climate. In the run-up to that conference, political statements and political deals will become more common: as we have reported in previous months, the Australian government has been especially active in trying to avoid taking uniform action with the rest of the world. The Australian attack has been two-pronged: casting doubt on computer models that show climate problems from increased greenhouse emissions while accepting happily even the flimsiest economic computer model showing job losses if Australia does not continue on its present course.
The scientists' call represents opinions from 63 countries around the world, and a majority of the world's Nobel winners in science-98 out of 171-signed the statement, which cautiously makes the following points:
ò Global warming is under way and our overuse of \Jfossil\j fuels is partly to blame.
ò Climate change is projected to raise sea levels; increase the likelihood of more intense rainfall, floods, and droughts; and endanger human health by greater exposure to heat waves and encroachment of tropical diseases to higher latitudes.
ò Climate change is likely to exacerbate food shortages and spread undernutrition by adversely affecting \Jwater\j supplies, soil conditions, \Jtemperature\j tolerances, and growing seasons.
ò Climate change will accelerate the appalling pace at which species are now disappearing, especially in vulnerable ecosystems. Possibly one-third of all species may be lost before the end of the next century.
ò Continued destruction of forests will undermine the environment's natural ability to store carbon, thereby enhancing global warming.
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"Emissions Trading System Proposed",300,0,0,0
(Oct '97)
On October 22, President Clinton tried to look on the bright side of global warming, presenting it as a "golden opportunity" for the United States rather than a costly catastrophe, as he outlined his administration's new "flexible, market-based" plan for curbing the emission of heat-trapping gases into the \Jatmosphere\j.
He proposes an international "emissions trading system" that would allow companies in developing countries to buy the right to pollute from companies with cleaner technologies. He also said the United States should provide emissions credits and tax cuts to industries that reduce emissions early, make binding pledges to reduce its own greenhouse gas emissions early in the next century, and give a US$5 billion boost over the next 5 years to research and development aimed at using \Jenergy\j more efficiently.
This is to be the basis of the plan the US will take to \JKyoto\j in the first two weeks of December, and it may be about right, as it was immediately attacked by both the American Petroleum Institute and the Sierra Club. Unlike the Australian government, which is leading an attack on cuts because it fears crimps on economic growth, Clinton pointed out that similar objections were raised against efforts to reduce \Jacid rain\j. In fact, he says, \Jacid rain\j controls are 40% ahead of schedule and 50% below projected costs.
In anticipation of the meeting in \JKyoto\j, the President's Committee of Advisors on Science and Technology has weighed in with a proposal that the US government spend $1.1 billion more on \Jenergy\j research to foster more efficient, and renewable, technologies. Yet if the truth be known, a lot could be done, simply by avoiding appliances that lie, says one American critic of the \Jelectronics\j industry.
No, this is not a reference to artificial intelligence, just a case of "off" switches that aren't. You may think you have turned off the TV, the microwave, or the \JCD\j player, but behind the scenes, that appliance is still drawing power to operate timers, memories, or remote control sensors that will bring the appliance back to life again. More and more, the rule seems to be: if it's plugged in, it's on.
A typical first world home uses about 50 watts to power devices that supposedly aren't on, which accounts for 5 percent of the total electricity use. Such unseen consumption, often referred to as leaking current, constitutes the electric analogue of heat seeping out of poorly insulated homes. In the United States, it adds up to more than $3 billion worth of electricity annually, the output of four large generating stations. And in the European Union, leaking household electricity equals the output of two additional large generating stations.
The problem? Well, for most people, the power stations are a long way away, so electricity is seen as clean and non-polluting, but somewhere, every watt that we use has a carbon cost associated with it: even \Jalternative energy\j sources involve mining, transporting and smelting processes, so it would be worthwhile finding ways to reduce these costs. To supply the estimated amount of electricity demanded by leaking household appliances world-wide, power plants already spew some 18 million tons of carbon into the \Jatmosphere\j annually!
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"A Million Solar Roofs",301,0,0,0
(Oct '97)
Meanwhile, it may only be a start, but October also saw President Clinton announce a plan to install solar panels on a million roofs across the USA by the year 2010.
As is usual with all such claims, the solar roofs have been hailed as clean and \Jenergy\j-saving. In fact the industry tends to be a fairly dirty one in terms of polluting by-products, but the US government hopes to get this under control. Equally, large-scale production should bring in economies of scale which will reduce the \Jenergy\j costs involved in creating each solar roof. Then as long as the \Jweather\j stays fine, everything should work rather well . . .
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"El Nino Effects--Not An Ill Wind After All?",302,0,0,0
(Oct '97)
Some 70% of the world's annual \Jtuna\j harvest, around 3.2 million tonnes, comes from the \JPacific Ocean\j. Skipjack \Jtuna\j (\IKatsuwonus pelamis\i) dominate the catch. Although the skipjack are distributed in the surface mixed layer throughout the equatorial and subtropical Pacific, catches are highest in the western equatorial Pacific warm pool, a region of the ocean with low primary productivity rates that has the warmest surface waters of all the world's oceans.
Assessments of \Jtuna\j stocks indicate that western Pacific skipjack catches approaching one million tonnes annually are sustainable, but how can this be done efficiently? A report in \INature\i during October shows that the skipjack population depends on the warm pool, which is a fundamental factor in the El Ni±o Southern Oscillation (ENSO). The authors show that apparent shifts in the skipjack population distribution are linked to large zonal displacements of the warm pool that occur during ENSO events. This relationship can be used, they suggest, to predict (several months in advance) the region of highest skipjack abundance, within a fishing ground extending over 6000 km along the Equator.
Meanwhile, another report in \IScience\i journal during October suggested that an El Ni±o event or any other warm period may help temporarily slow the continual rise in atmospheric carbon dioxide due to human activity. The mechanism behind this braking appears to be a delayed burst in plant growth world-wide that appears to sop up excess levels of one of the greenhouse gases, carbon dioxide.
El Ni±o events and volcanic eruptions may send up global temperatures within just a few months, or depress them just as fast, but the impact on the \Jbiosphere\j seems to take from one to three years to appear. A global warm spell may lead to an initial surge in polar and temperate areas. At the same time, heat-stressed tropical and semiarid regions may show an initial drop in plant production. Later, plant growth leaps ahead in the regions closer to the equator, mopping up atmospheric carbon dioxide.
According to David Schimel, from the US National Center for Atmospheric Research (NCAR) in Boulder, \JColorado\j, these results highlight the usefulness of computer models that connect the \Jatmosphere\j and \Jbiosphere\j. "We were looking specifically for delayed \Jecosystem\j responses in this study because they had been predicted by the models," Schimel said.
The observed patterns of warming correlated globally with carbon dioxide levels and regionally with vegetation growth. Global carbon dioxide levels, which are steadily rising due to human activities, tended to rise more quickly over the first few months after a global \Jtemperature\j peak. The carbon dioxide levels rose at a slower pace during the one-to-three-year period after the \Jtemperature\j peak, followed by another gradual acceleration.
\BEven on the Great Lakes\b
As time passes, the world-wide effects of El Ni±o are seen to spread further afield. Scientists at the University of \JMichigan\j now believe that the phenomenon affects the centre of north America as well, with peaks in the cycle matching surges in storm strength, \Jwater\j levels and destruction on the shores of the Great Lakes.
Don't take to the hills, though-the US Geological Survey has been looking at the relationships between El Ni±o-enhanced rainfall and landslides, according to reports appearing during October.
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"New Climate Cycle",303,0,0,0
(Oct '97)
And now we have a new climate cycle. It looks like El Ni±o, it feels like El Ni±o, and if you are watching fish stocks, reservoir levels or farm production, you would say it is El Ni±o. But it isn't.
That, at least, is what University of Washington researchers are saying about the Pacific decadal \Joscillation\j, or PDO. Right now, it is positive, and this helps to explain why U. S. West Coast ocean temperatures have been warmer than average, why winters have been wetter than usual in the South, and why \JAlaska\j salmon harvests have been at historic highs, while there have been record declines in salmon catches along the West Coast.
According to one of the researchers, El Ni±o is a part of the PDO, but they are some years away from fully understanding the phenomenon. According to Nate \JMantua\j, a UW research associate, scientists probably will not have the ability to begin making accurate forecasts for at least another five years. A PDO prediction system, he says, would allow long-term planning in such areas as fisheries, \Jwater\j supplies, agriculture and \Jenergy\j production. "The science right now is more like our understanding of El Ni±o 15 to 20 years ago," says \JMantua\j.
The PDO effect was identified by combing a century of records, looking for patterns, and at first, El Ni±o emerged as the dominant recurring pattern of year-to-year climate variability on the \Jplanet\j for recent times. But when records were studied back to 1900, with the focus on the region north of Hawaii in the Pacific basin, the PDO revealed itself with positive and negative phases lasting from 10 to 30 years.
One frustrating aspect of attempting to forecast the PDO is that it develops over such a long period that a negative or a positive phase can have passed before researchers even discover it. "We can recognise the phenomenon, but we can't say what phase we're in at the time," says David Battisti, University of Washington atmospheric sciences associate professor, who was the first to show why El Ni±o recurs on an average of every four years. "But that's only because we don't yet fully understand it. After all, it has only been in recent years that we've recognised it even exists."
\BBut is it real?\b
With some scientists still doubting the reality of global warming, the \Jpermafrost\j of the Alaskan interior is melting, causing large bills for road repairs. The \JArctic\j generally has warmed by about one \JCelsius\j degree over the past thirty years, but this has been uneven, and Alaska is now about three degrees warmer than thirty years ago. Perhaps this can be related to the effects of the PDO?
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"Antibiotic Resistance in Bacteria",304,0,0,0
(Oct '97)
This is an emerging issue which is starting to attract public attention. It has almost become a regular item in the Updates section. This month, we will look at the question in more detail, but without covering issues already raised in Antibiotic-Resistant Bug Found (April), Resistant Antibiotics (July) and Bacterial Resistance (August).
The United States has recently approved the use of the antibiotic fluoroquinolone in animals intended for food in the United States. This means there will be a need for continued surveillance for quinolone-resistant \ISalmonella\i, says a report in the October issue of \IEmerging Infectious Diseases\i.
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"TB from a Contaminated Endoscope?",305,0,0,0
(Oct '97)
With resistance in tuberculosis \Jbacteria\j on the increase, a worrying new infectious pathway may just have been identified. A contaminated endoscope may have transmitted tuberculosis between two \Jhospital\j patients, according to a report in the October 1, 1997 issue of the \IJournal of the American Medical Association\i (JAMA). Researchers found identical DNA "fingerprints" in bacterial cultures isolated from two TB patients.
Since the cases were detected six months apart, no link between the two people was suspected until DNA fingerprinting revealed a perfect match. The only identifiable link between the two patients was the \Jhospital\j where they both had been bronchoscoped. While the suspicion remains no more than a suspicion, they were definitely bronchoscoped with the same instrument in the same room, and no other bronchoscopies were done between the two patients.
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"Antibiotic Resistance is Permanent",306,0,0,0
(Oct '97)
Medical logic says that antibiotic-resistant \Jbacteria\j are committing resources to resistance, and that in the absence of \Jantibiotics\j, these \Jbacteria\j will lose out in competition with normal \Jbacteria\j. In this case, the logic appears to be a little too hopeful.
A random survey last year of \IEscherichia coli\i \Jbacteria\j collected from a \Jday\j-care centre in \JAtlanta\j has indicated that these microbes will remain resistant long after doctors stop prescribing the \Jantibiotics\j which drove them to develop resistance. Experiments point to a disturbing hypothesis: a second \Jmutation\j may be blocking the resistant \Jbacteria\j from reverting to sensitivity.
Meanwhile a report in \INature\i warns that the widespread use of \Jantibiotics\j in the farming industry has selected for antibiotic-resistant \Jbacteria\j which are commonly found in food, such as soft cheeses and raw meats. Now a plasmid has been identified that may be responsible for antibiotic resistance in a strain of \ILactococcus\i bacterium present in cheese. The plasmid contains a collection of antibiotic resistance genes and genetic elements transferred from many species of \Jbacteria\j and has the potential to transfer this antibiotic survival kit to other species.
Now the trickle of warnings about resistance has started to flow out into the general public conscience. An American study indicates that by the year 2000, half of the infections caused by the bacterium responsible for 7 million cases of middle ear infection (otitis media) in children and 500,000 cases of \Jpneumonia\j in children and adults each year in the U. S. will have some resistance to \Jpenicillin\j.
The bacterium involved in middle ear infections, \IStreptococcus pneumoniae\i is a "community bug". While it is also transmitted among patients in hospitals, it is transmitted more commonly outside of hospitals, particularly among children in daycare centres.
Aside from the medical risks of antibiotic resistance, there are straightforward financial costs involved. Two strains of \IStaphylococcus aureus\i, methicillin-resistant \IS. aureus\i (MRSA) and methicillin-susceptible \IS. aureus\i (MSSA), have been identified in a Duke University study. On average, MRSA causes twelve days more hospitalisation than MSSA infections, boosting the cost due to MRSA infections to $27,082, compared with $9,661 for MSSA.
The best data available at the moment seem to come from the United States, where more than 2 million Americans each year acquire nosocomial, or in-\Jhospital\j, infections, and between 60,000 and 80,000 die. The most common cause is \IStaphylococcus aureus\i or "golden staph".
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"Engineered Bacteria To Fight Tumours",307,0,0,0
(Oct '97)
The October issue of \ICancer Research\i indicates that an engineered \ISalmonella typhimurium\i strain can be used to stunt the growth of \Jmelanoma\j tumours in mice, without causing an infection. The only problem at the moment is that the \ISalmonella\i kill the mice, so scientists are breeding weakened strains, lacking the gene for a powerful toxin called lipopolysaccharide, which can trigger an often fatal systemic infection called septic shock.
As far back as the 18th century, \Jgangrene\j was known to cure some cancers, and last century, William B. Coley of Harvard injected "Coley's mixed toxins", a brew of \ISerratia marcescens\i and other \Jbacteria\j, into cancers of the colon and uterus. It is likely that these toxins triggered the production of TNF (Tumour Necrosis Factor), a cytokine which is currently of interest to researchers around the world.
He successfully treated cancers of the uterus and prostate, and some of Coley's patients survived another thirty years, while the mice only prolonged their lives by about four weeks: the difference may have been that Coley kept on injecting his patients with \Jbacteria\j so as to keep them permanently at the feverish stage. Now today's researchers are looking at fitting the bacterium with extra cancer-fighting genes, so it will pack a real punch, but that is a side-issue to the continuing problems of controlling the \Jbacteria\j rather than having them control us.
Meanwhile, Israeli researcher, Haya Lorberboum-Galski, has been developing fusion proteins that can introduce a bacterial toxin into adenocarcinomas, the tumours found in cancers of the breast, colon, lung, \Jovary\j and prostate. The protein consists of a short chain of amino acids linked to a toxin from \IPseudomonas\i.
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"Pathfinder and Sojourner Lose Contact",308,0,0,0
(Oct '97)
The end of October may (or may not) have seen the last of NASA's Pathfinder and its Sojourner exploring machine on Mars. The batteries appear to be dead, but the \Jday\j-time solar cells may also be out of commission, or the intense (minus 100 degrees \JCelsius\j) cold of the Martian night may have cracked some key chips. Sojourner and Pathfinder may just lie there until picked up by an expedition next century and hauled back to take pride of place in a space museum, or perhaps even made key exhibits in the first Museum of Mars.
Perhaps, just perhaps, Pathfinder may come back again, and transmit yet more data, but what has been sent already will keep scientists working happily for many years. Pathfinder was last heard from on October 7, although there have been almost daily attempts to reestablish the connection. Whatever happened, the nominal lifetime had been well and truly exceeded, but whenever a machine keeps going, scientists are never backward about finding more tasks from their servants.
\BSurface rocks suggest a wet early Mars\b
Close-up images sent back by Pathfinder in early October have provided independent evidence for a benign and possibly life-supporting early climate. The images appear to show cobbles, pebbles which are several centimetres across, that may have been rounded in flowing \Jwater\j, along with conglomerates, a sedimentary rock made of rounded pebbles and sand, rushed along in a torrent.
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"Getting to Mars More Cheaply",309,0,0,0
(Oct '97)
A scheme has been proposed which would see 180 kg Mars probes being carried aloft as piggyback units during major launches of Ariane, the \JESA\j launch vehicle. Once beyond the \Jearth\j, the probes would go into a holding \Jorbit\j, ready to be launched when a launch window opens (this happens when Mars and Earth are in the right relative positions).
The probe would need 65 kg of fuel, allowing a payload of 115 kg for instrumentation, propulsion and communication equipment, and a \Jballoon\j system that would lower the probe gently through the thin Martian \Jatmosphere\j.
\B. . . and more quickly\b
If humans are ever to get to Mars, the trip will have to take less than 600 days, and scientists at the University of \JFlorida\j are working on a nuclear propulsion system they say could shorten a manned trip to Mars by more than a year.
The \Jspacecraft\j would leave \Jearth\j aboard a standard chemically fuelled rocket, and then a nuclear thermal propulsion rocket would take over. According to the developers, a small reactor about the size of a 55-gallon barrel (a standard 200 litre drum) can provide enormous power for propulsion and carry a \Jspacecraft\j at much higher speeds than can an equivalent chemical system, getting there in 200 days, rather than 600, and saving astronauts from both boredom and cosmic radiation.
Nuclear power can more than double the \Jspacecraft\j's speed. It would produce \Jhydrogen\j heated to "more than 5,000 degrees Fahrenheit" (about 2800 degrees \JCelsius\j) which would then leave the rocket nozzle and provide thrust. Like the Apollo missions of the 1960s and 1970s, these missions would \Jorbit\j Mars while sending a Mars lander down to the surface. The researchers believe that the problems of sending large amounts of fissile material are smaller than people think, but it is possible they are considering practical rather than political problems.
Those who think otherwise should look at the public reactions to the small nuclear power source which is part of the Cassini mission.
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"Cassini On Its Way",310,0,0,0
(Oct '97)
Amid controversy and protests about \Jplutonium\j, the Cassini mission is under way. Headed for Saturn, the mission will probe the \Jplanet\j's spectacular ring system, bizarre moons and atmospheric gases. After a number of delays, including wind problems, Cassini got away on October 15, well inside the launch window which allows a low-fuel trip with plenty of manoeuvring power at the end.
The mission's seven-year journey to Saturn began with the lift-off of a Titan IVB/Centaur carrying the Cassini orbiter and its attached Huygens probe, at the start of a 3.2 billion \Jkilometre\j haul. The scheduled arrival date, after several close passes of the inner planets to gain speed by \Jgravity assist\j, it will arrive at Saturn and Titan on 4 July 2004.
The launch was marked by protests about the \Jspacecraft\j's main power source, which is \Jplutonium\j-fuelled. The protests about the \Jplutonium\j relate to a misunderstanding or misrepresentation of the power unit installed on board the \Jspacecraft\j. This contains about 33 kg of \Jplutonium\j 238, and the protests have been based on the assumption that the \Jplutonium\j would all be vaporised into fine dust, and breathed into human lungs, after a catastrophic accident. In reality, the \Jplutonium\j is present in a ceramic form and protected in a series of separate parcels, so the protesters' scenario is an impossible one: any accident would cause far less damage than they claim.
After its arrival in the Saturn system in 2004, the \Jspacecraft\j will spend four years orbiting Saturn and many of its 18 known moons, providing a flood of new data on what may be regarded as a miniature \Jsolar system\j. In all, Cassini is made up of an orbiter equipped with 12 scientific experiments and a probe carrying six instrument packages that will parachute into the thick \Jatmosphere\j of Titan, Saturn's largest and most intriguing moon. The earlier visits, Voyager 1, Voyager 2 and Pioneer 11, were all flybys. This longer, slower visit should reveal a great deal more to us.
Titan's \Jatmosphere\j, ten times thicker than \Jearth\j's, is likely to contain \Jnitrogen\j and a wealth of \Jhydrocarbons\j, the building blocks of life. The \Jtemperature\j is a chilly -290 degrees F (-180 degrees \JCelsius\j), but many scientists hope that Titan's surface may contain lakes of liquid \Jmethane\j and ethane, and that organic molecules may constantly be raining down from the moon's thick clouds onto its surface.
And then there are the rings of Saturn. The rings are of special interest to scientists generally, but especially to Larry Esposito, who found the F ring in 1979 from "Pioneer" photos. According to Esposito, "Saturn's rings have a very violent history. I think they were created by the break-up of a small moon perhaps 100 million years ago. The fact that we can view Saturn's rings today may be due purely to chance. I expect at some point all the ring material may reform itself into a moon or be ground into dust."
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"Uranus Has Two New Moons",311,0,0,0
(Oct '97)
At the end of October, with almost no acknowledgment in the daily press, two new moons were added to the collection circling Uranus. Moons 16 and 17 were announced on October 31 to an almost total lack of interest.
Admittedly the moons are no big deal. Described as "80 and 160 km across" (in other words, 50 and 100 miles across), they are a long way from Uranus, but amazingly, they were discovered from observations on \Jearth\j, not from the Hubble Space \Jtelescope\j or from pictures returned to us from other \Jspacecraft\j.
The discovery team used the Hale \Jtelescope\j on Mount Palomar, \JCalifornia\j, to look for slow-moving objects near Uranus that might be moons. The Voyager \Jspacecraft\j found ten moons on its 1986 flyby, but there had been no careful search for moons with modern equipment. The Hale \Jtelescope\j, a 5 metre reflector, located two moons in eccentric orbits almost immediately, making these the first moons discovered from ground-based equipment since 1948.
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"Conserving Madagascar",312,0,0,0
(Oct '97)
We reported in August on some exciting finds in Madagascar's Anjaharanibe-Sud Special Reserve, where a living \Jfossil\j had been located: now we have more good news for the island's environment. Madagascar's newest national park, Masoala National Park, was formally inaugurated by President Didier Ratsiraka on October 18. Including Madagascar's largest remaining rain forest, the park will help to retain the island's incredible \Jbiodiversity\j, currently under threat from a variety of causes.
Lying east of Africa in the Indian Ocean, Madagascar is 1600 km (1000 miles) long. It holds an estimated 5% of the world's species, and some 75% of its species are found nowhere else on \Jearth\j. There are some 14 million people living in poverty on the island, and 75% of the land has now been logged and cleared.
The park will preserve the habitats of two birds, previously thought to be extinct, \Jcoral\j reefs, and whale breeding grounds. It will also provide a continuing living for some 45 000 people who live in the area covered by the park.
Meanwhile, five captive black-and-white ruffed lemurs raised at the Duke University Primate Center were taken to Madagascar during October, with a mid-November release date scheduled, after a month of getting used to the climate in outdoor cages in the Betampona Natural Reserve. More lemurs are being prepared at Duke, and also at a Wildlife Conservation Society site on St. Catherine's Island off the coast of Georgia.
Even with these boosts to the local populations, lemurs will remain highly endangered in Madagascar, as their habitats are destroyed and they are hunted for food. The black-and-white ruffed lemurs, known for the fur that frames their faces and the lush coats of black and white fur, are among Madagascar's most \Jendangered species\j, as they can only survive in primary tropical rainforests. Significantly, meat from the black-and-white ruffed lemur is reportedly the tastier than that of any of its relatives.
Funding has come from many quarters, even from actor-producer John Cleese, who donated the proceeds from the London premier of his comedy film \IFierce Creatures\i, which featured captive lemurs in addition to its human cast.
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"Brazil's New Park",313,0,0,0
(Oct '97)
Brazil established the world's largest \Jrainforest\j reserve during October, the Ama±a Sustainable Development Reserve, which is the third of a network of protected areas in the Central Amazon Basin. Together, they cover some sixty thousand square kilometres of unbroken habitat across an area larger than Costa Rica.
The Ama±a region is known for its spectacular and untouched \Jbiodiversity\j including endangered Amazonian manatees, black caiman, river dolphins, anacondas, jaguars, black uakari monkeys, harpy eagles, and a wealth of plants and aquatic life. Residence is permitted in the protected areas, but the "locals" are encouraged to participate in the areas' conservation.
The park may be just in time: the US NOAA-12 \Jsatellite\j recorded no less than 24 000 fires in the Brazilian Amazon between early August and mid-December.
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"Breast Cancer Not Caused By PCBs",314,0,0,0
(Oct '97)
Breast cancer rates are highest in developed countries, leading some researchers to suggest that industrial \Jpollution\j could be an important cause of the condition. The main suspects have been two "environmental oestrogens", synthetic chemicals that can act like \Jhormones\j in the body, and commonly found in people's fatty tissues.
The suspects, polychlorinated biphenyls (PCBs) and DDE, a metabolic by-product of the \Jpesticide\j DDT have seemed to be connected to breast cancer, with women with high blood levels of DDE having a four times greater risk for breast cancer than women with normal levels of DDE, but a later study seemed to go against this finding. Now a large-scale study, reported in the \INew England Journal of Medicine\i during October, has dealt a heavy blow to the theory.
A team led by epidemiologist David Hunter of the Harvard School of Public Health has analysed 240 breast cancer cases that occurred in a group of nearly 33,000 women after they gave blood samples in 1989 and 1990, finding no greater incidence of breast cancer in women with higher levels of the substances.
Another report published in Toronto in October says that over the past few years, the number of women dying from breast cancer declined almost five per cent, the largest short-term decrease since 1950. Professor Judy-Anne Chapman oversaw the analytical review of 153 breast cancer studies for the National Cancer Institute of Canada, and found that data from U. S. studies revealed the incidence of breast cancer between 1940 and 1982 increasing by around 1% each year. Between 1982 and 1987, the increase was about 4% each year.
Between 1989 and 1992, the mortality rate in the USA declined 4.7%, apparently due to better detection at an earlier stage, when tumours are smaller. Another factor might be the new tests to screen women for the BRCA1 gene which leaves them predisposed to develop breast cancers. These tests catch 90% of the American women carrying mutated forms of the gene.
Dutch researchers reported several new mutations in BRCA1 during October. These discoveries may explain the standard test's failure to flag mutations in 20% to 30% of European women with a family history of breast cancer, even when their cancer could be linked to BRCA1 by damage to \Jchromosome\j 17, where the BRCA1 gene is located. Many of the faults were "deletions", where portions of the gene were missing, rather than damaged.
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"X-Ray Laser in Development",315,0,0,0
(Oct '97)
Reports appeared during October in \IPhysical Review Letters\i from a \JMichigan\j group and in \IScience\i from an Austrian group, each indicating \Jlaser\j-like behaviour, but at x-ray wavelengths. The method is called high harmonic generation, and even though it isn't technically a \Jlaser\j, it does a good job of imitating one.
The American team aimed ultrashort bursts of infrared \Jlaser\j light at a small jet of \Jhelium\j gas. Like all light, the \Jlaser\j light is made up of rapidly oscillating electric and magnetic fields. Here, though, the \Jlaser\j's electric field is so intense, and the pulse so brief, that it can strip an \Jelectron\j from a \Jhelium\j atom and slam it back in a single \Joscillation\j cycle. As it returns violently to the parent atom, the \Jelectron\j emits a high-\Jenergy\j (x-ray) \Jphoton\j. Because many nearby atoms in the gas are hit by the oscillating \Jlaser\j beam at the same time, the emitted x-rays are coherent, meaning that they oscillate in step and emerge as a remarkably \Jlaser\j-like beam.
Usually this sort of result requires huge pieces of equipment, while this achievement has come from "tabletop" apparatus. The exciting thing about this development is that coherent x-rays with a wavelength of less than 4.4 nanometre, in the "\Jwater\j window" where carbon absorbs better than \Jwater\j, will allow the imaging of living cells. So while the physics is nothing fundamentally new, the applications are likely to shake a few trees over the next few years.
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"Zebra Mussels Get A Setback",316,0,0,0
(Oct '97)
One of the greatest feral animal problems in the world right now is the zebra mussel of north America's Great Lakes. Eight years ago, zebra mussels from \JRussia\j crossed the Atlantic as stowaways in ship ballast \Jwater\j and then infested the waters of Lake Erie. Once there, they caused huge damage by "glomming" onto native clams and suffocating them. A report in \INature\i at the end of October tells us that some clams have survived by burrowing into soft mud that suffocates the zebra mussels attached to their shells.
During an ecological study before a new dyke was built, no less than 21 native species of clam were found in a haul of 7000 individuals, now in secure lodgings at Ohio State University, from which they will return to the wetland they were found in, once work is complete.
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"Pig Organs Infected",317,0,0,0
(Oct '97)
An October report in \INature\i says that pigs carry two "porcine endogenous retroviruses" (PERVs for short) in their tissues, and that these viruses may put paid to any plans to use pig organs to relieve the chronic shortage of donor organs for transplantation into people.
Tests last February showed that the viruses could infect cultured human cells, but now we know that the PERVs are found in all pig tissues, including \Jkidneys\j and hearts, and the two versions, called PERV-A and PERV-B, can both infect human cells. It appears that any advances in the use of pig organs will depend on developing a breed of pigs purged of PERVs. This, say the authors, will not be easy, with 20 to 30 copies of the virus particles in most of the cells checked.
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"X Chromosomes Mutate More",318,0,0,0
(Oct '97)
Old fathers may be a genetic liability for their offspring, according to a study, published in \INature Genetics\i at the start of October, which shows that males really do mutate more than females. A study of \Jmutation\j rates in the Y \Jchromosome\j (only found in males) and the X \Jchromosome\j (both sexes) might shed light on this, but with three X chromosomes and one Y chromosome in a mating pair of mammals, there might be variations in natural selection rates which could hide differential \Jmutation\j rates.
Luckily, birds have a "WZ system", where it is the female bird which carries the mismatched WZ pair, just as a male \Jmammal\j is XY. The answer: even in birds, the "ZZ" males mutate more than females!
The male Y \Jchromosome\j has long been called our genetic junkyard, a clutter of meaningless DNA surrounding a handful of genes, useful only for making more men. Now MIT researchers Bruce Lahn and David Page have found five genes that are used throughout the body to help keep cells working properly, all on the Y \Jchromosome\j, along with another seven genes that are unique to the Y \Jchromosome\j and seem to be expressed just in the testes. The genes lie in regions known to be involved in \Jinfertility\j: if the region is missing, the male is infertile.
#
"Genetic Transmission",319,0,0,0
(Oct '97)
Once upon a time, there was "mitochondrial Eve", the only female ancestor of us all in a direct female line. Other women of Eve's time have passed their genes on, but at some stage, those genes have passed through a male. We know this from looking at the small packets of DNA in the mitochondria, cell components that we get only from our mothers. Analysis tells us a simple story: in the direct female line, we have just one ancestor for all humans on this \Jplanet\j, and she lived in Africa, between ane and two hundred thousand years ago.
For the past ten years, people have wondered if analysis of the Y \Jchromosome\j, passed only through the male line, would reveal just one male ancestor for us all. Now two separate teams have reported just such a result. What is more, "Y-\Jchromosome\j Adam" appears to have been in Africa at about the same time, one to two hundred thousand years ago.
The genetic trail is so clear that it allows researchers to compare the migration patterns of men and women tens of thousands of years ago-and what it reveals is that most of the human genetic spread is due to women. Men, it seems, have been the less adventurous and less travelled gender of the species. In brief, the variations in the Y \Jchromosome\j have a different geographic distribution from variations in mitochondrial DNA.
#
"Upright Ancestor Gets Older",320,0,0,0
(Oct '97)
We have always assumed that it was only our crowd, the hominids, who walked upright. Now Meike K÷hler and Salvador Moyα-Solα say that a 9-million- to 7-million-year-old apelike animal called \IOreopithecus bambolii\i was two-legged as well.
This idea originally surfaced about forty years ago, but there was a lack of good anatomical evidence. K÷hler and Moyα-Solα used partial fossils and undescribed material at the Natural History Museum in \JBasel\j, \JSwitzerland\j to assemble their proof. In the \IProceedings of the National Academy of Sciences\i, they report that the lower back of the animal was arched forward like ours, and the knee joint was vertically aligned, again like ours. In a \Jhominid\j, this would be clear evidence that the owner used to walk upright.
Parts of the ancient \Jape\j's pelvis resemble corresponding areas of \IAustralopithecus afarensis\i, the \Jhominid\j species that includes the partial skeleton of the specimen known as Lucy, they add, but \IOreopithecus\i had a foot like that of no other primate. Its big toe sticks out at about 90░ from the remaining toes, probably giving the animal a short, shuffling stride.
#
"Shrinking a Genus",321,0,0,0
(Oct '97)
Students of human \Jevolution\j fall into one of two groups: lumpers and splitters. Recently, the splitters have been having a field \Jday\j, acclaiming \IHomo ergaster\i, \IHomo erectus\i, \IHomo rudolfensis\i, and \IHomo habilis\i and more, all from a set of specimens which seem to run across a continuum. Now a group of scientists from the other side has struck back, implying that all of the robust hominids are one species. Or that they may be . . .
A set of new \IAustralopithecus boisei\i specimens from Konso, \JEthiopia\j lies behind their comments. These show an unexpected combination of cranial and facial features, given what we have believed in the past. In particular, we now have a complete skull (that is, mandible or jaw and associated cranium), which is undoubtedly a 1.4 million year old specimen of \IA. boisei\i, but which has characteristics of other species: \IA. robustus\i from South Africa, and \IA. aethiopicus\i, also from \JEthiopia\j.
As usual, the turn of the splitters will come next, probably drawing attention to the well-established similarities between \IA. afarensis\i and \IA. aethiopicus\i which are striking, but which would not cause even the most hardened lumper to group the two species as one.
The problem is unlikely to go away: when you are dealing with a popluation as varied as modern humans, but where two individuals may be as much as a hundred thousand years apart, opinions will always tend to follow observers' fond beliefs.
#
"More Vitamin C Means Fewer Cataracts?",322,0,0,0
(Oct '97)
Women who took vitamin C supplements for at least 10 years are only 23 percent as likely to develop cataracts as women who received the vitamin only in their diet, a new study indicates.
In the October \IAmerican Journal of Clinical Nutrition\i, the scientists describe evidence that the human eye derives significant benefits from vitamin C. The study recruited women from the Nurses' Health Study, a \JHarvard University\j project which has been charting diet and disease in more than 120,000 women since 1972. Researchers identified some 56- to 71-year-olds who in the early 1980s had taken vitamin C supplements and others who had not. Of the women, 165 supplement users took eye tests, as did 136 women with no added vitamin C.
None of the women had been diagnosed with cataracts, but 188 showed at least early signs of the disease. Around 60% of these early cataracts appeared in the smaller group of women who had never taken supplements. More importantly, the risk of cataracts decreases when supplementation goes on for a longer period of time. The mean dietary intake of vitamin C for women not taking supplements was 130 milligrams per \Jday\j, about twice the recommended amount but less than one third the average of women taking supplements.
#
"How The Universe Will End",323,0,0,0
(Oct '97)
In short, the universe is likely to end, not with a bang, but by dissipation. This is what we learn from a study reported in \INature\i in late October, and another report, under review and likely to be published soon in \IAstrophysical Journal Letters\i. It seems that the universe's expansion rate has slowed so little so far that the universe's own gravity will never be enough to pull everything back together again into a Big Crunch, a reversal of the original Big Bang.
Two separate groups of astronomers have analysed the light from distant exploding stars to reach a preliminary verdict on the fate of the expanding universe, and both verdicts are the same. One group is led by Saul Perlmutter of Lawrence Berkeley National Laboratory and the University of \JCalifornia\j, Berkeley, and the other by Brian Schmidt of Mount Stromlo and Siding Spring Observatory in \JAustralia\j.
The two studies looked at exploding stars called type Ia supernovas, which make good standard candles, dotted through the universe. Stars further away can be examined for their red shift, an aspect of the Doppler effect, and this should flush out any subtle variations in the speed of travel, or in the force due to gravity, which \Imay\i not be constant. The variations would tell us that the universe has been changing over time, under the force of its own gravity.
We would be able to detect this because the supernovas further away actually exploded earlier, and their light has just taken longer to reach us. The supernovas have equivalent brightness, wherever they are, the only variation being a result of their distance, since brightness is controlled by the inverse square law, so this allows us to be certain of just how far away they are. Then all we have to do is plot the distance against the pattern of their red shifts. If everything is constant, the plot will be a \Jstraight line\j, otherwise, it will be a curve.
The result is now shown to be a \Jstraight line\j. Hence, we will end by being dispersed into thinness.
#
"Tiniest Transistor",324,0,0,0
(Oct '97)
In simple terms, a transistor acts to control voltage or current in such a way as to achieve gain or switching action. At some point, transistors will have to stop getting smaller, because at a certain limiting gate size, electrons will start to leak through, even when the transistor is off. Standard wisdom says the limiting gate size is around 30 nanometres.
This limit on size then acts to limit the amount of circuitry on a chip of a given size, and to limit the operational power of central processing units or CPUs, the "chips" which are at the centre of every computer. Now a team at NEC has found a way of halving that limit with clever design, producing transistors which are a mere twentieth of the standard size currently found on the most crammed commercial chips.
The NEC team built their working mini-transistor adding a second gate, shaped something like a top hat with the crown above the first gate and brims above both sides of the channel. This second gate allowed them to leave insulating gaps between the channel and the doped source and drain regions.
A differing view, reported in \INature\i during October, is that we still have a long way to go. The authors suggest that the answer may lie with colloidal crystals, periodical arrays of suspended colloidal particles which may arise in a colloidal suspension where the particles are al identical in size, shape and interactions. The American researchers report measurements of electrical transport in a single-\Jelectron\j transistor made from a colloidal nanocrystal (a crystal of nanometre dimensions) of cadmium selenide.
#
"Neurochip Development",325,0,0,0
(Oct '97)
A "neurochip," a silicon rectangle about 4 centimetres wide immersed in a Petri dish, may be the sign of things to come, the forerunner of bionic eyes or machine-mind interfaces, moulded from combinations of silicon and living neurons. The first silicon chip equipped with living nerve cells is now a reality.
The neurochip was reported to a meeting of the Society for Neuroscience in \JNew Orleans\j, late in October, but the purpose of this possible "ancestor" is just to allow us better to understand how nerve cells grow and communicate with each other.
Jerome Pine is a neurophysicist at the \JCalifornia\j Institute of Technology in Pasadena. Together with a team of electrical engineers and biologists, he has formed up a finely etched silicon landscape that confines individual neurons. While confining them, the silicon surface also allowed them to establish connections. The surface has sixteen tiny wells, each about 1/40 of a \Jmillimetre\j in diameter, with short tunnels leading to the surface.
The researchers placed an embryonic rat brain cell in each well. As the cells grew, they sent out long dendrite arms through the tunnels toward neighbouring wells. Wires in the underlying silicon monitored the electrical behaviour of the neurons. This is a development to watch . . .
#
"Collagen Brought Low",326,0,0,0
(Oct '97)
Collagen is one of those handy things to hang as a label on beauty products. As a beauty treatment, collagen is probably about as useful as diseased warthog liver, but it sells stuff. Now here is a hint for the advertising people: collagen was used around the Dead Sea, 8000 years ago!
Unfortunately, these people, who were still not able to make simple pots, used collagen as a glue. It was a protective lining on rope baskets, containers and embroidered fabrics, as a crisscross-patterned decoration on tops of sculptured skulls and as an adhesive holding together tools and utensils.
Dr Arie Nissenbaum from Israel's Weizmann Institute of Science at first thought the material on various archaeological finds was \Jasphalt\j, but chemical analysis revealed that it was collagen. The chemistry of the samples, along with \Jelectron\j \Jmicroscope\j studies, showed that it was probably collagen derived from animal skin. Carbon 14 dating tells us that the collagen is about 8100 years old. So if collagen does not stop you ageing, at least you know that it can last a very long time . . .
#
"Sparrows Not Dinosaurs After All",327,0,0,0
(Oct '97)
One of the accepted models of \Jevolution\j for many biologists has been that the dinosaurs did not die: they just sprouted feathers. This belief saw its most memorable presentation in the line from \IJurassic Park\i which reads "I think they're flocking this way" as a stampede of small dinosaurs flees a hunting party of \IT. rex\i.
Now it looks as though the model may need to be reconsidered, after comparative "hand" studies. The theropod dinosaurs, widely believed to be the pre-birds, are generally considered to have preserved digits I, II, and III, while a new study of the hands and feet of developing embryos of birds, alligators, and turtles shows that their hands develop to preserve digits II, III, and IV.
In other words, all of these animals have lost the digits that we would call the little finger and the thumb, and retained the other three. The theropods retain their versions of the ring finger and little finger, as tiny bumps, so there can be no real doubt about this. And if the facts are as stated, there can be no plausible route for the theropods or their immediate ancestors to have become birds.
Given that the theropods first appear in the \Jfossil\j record at least 30 (and perhaps 80) million years after the first birds, perhaps this should not really be so surprising, but it seems a shame. "The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact", said T. H. Huxley.
There is hope yet, though: a recent \INature\i report describes a v-shaped wishbone from the shoulder region of a \IVelociraptor\i (the small nasty ones in \IJurassic Park\i). The author, Mark Norell, says it is a very convincing wishbone, and in just the right place.
#
"Discovering More About Ozone Holes",328,0,0,0
(Oct '97)
It is very difficult to study the "ozone hole" over the Antarctic in the southern winter, and it has always been assumed that the hole was a summer phenomenon. A paper in \IScience\i during October indicates that data gathered at \JFaraday\j (65░S) throughout the winters of 1990, 1991, and 1994, shows that ozone depletion starts in June, at the height of the southern winter.
And now there is an \JArctic\j ozone hole as well. In recent years, the \JArctic\j "hole" has been getting worse, according to a letter to \INature\i during October. Worst of all was the unusually cold winter of 1995/96, when the \JArctic\j \Jozone layer\j fell from about 450 Dobson units to about 300. This change appears to be due to longer stratospheric winters, which allow nitric acid, a "preserver" of ozone, to fall from the \Jstratosphere\j on the surface of ice particles.
#
"Antimatter Disproved?",329,0,0,0
(Oct '97)
Science fiction authors appear to have just lost another range of sub-plots, with the news that no antimatter galaxies lurk in the far corners of the universe. The report revealing this is still to be published by Andy Cohen of \JBoston\j University, Alvaro de R·jula of CERN, and Sheldon Glashow of \JHarvard University\j, but it was released in early October. To appear in print in the February 1998 \IAstrophysical Journal\i, the report reminds us once again of the unfairness of the Big Bang in favouring matter over antimatter.
The universe that the \Jbig bang\j made should have contained equal parts of matter and antimatter, but we have long known that our cosmic neighbourhood is all matter. We were restricted to hypothesising about antimatter in a Galaxy Far Far Away, or that some of the blobs of matter collided with some of then blobs of antimatter, turning into gamma radiation. Given a few constraints, you can predict how much of this radiation there will be.
The three scientists tested their idea by computing the spectrum of diffuse photons from matter-antimatter annihilation in the early universe. They conclude that even in the most conservative analysis, matter-antimatter annihilation should produce a signal five times as large as the observable diffuse gamma ray background. From this, it looks as though the antimatter just isn't out there.
Nonetheless, a \Jspace shuttle\j study is scheduled for May 1998, led by physicist Sam Ting of the \JMassachusetts\j Institute of Technology and CERN, which will look for antimatter cosmic rays, such as nuclei of anticarbon, coming from distant antigalaxies. While that study now seems less likely to turn up a result, perhaps the \Jscience fiction\j fans can keep on hoping for a bit longer.
#
"No Successor To Clementine Mission",330,0,0,0
(Oct '97)
The proposed successor to the Clementine mission (see No Ice on the Moon After All, June) has been dropped. The plan, which would have fired probes into several \Jasteroids\j, will not now go ahead. Some Republicans in Congress had backed it as a high-tech attempt to learn more about intercepting objects in space while gathering useful scientific data, but the program was not supported by the Defense Department.
#
"Tsunamis Prediction",331,0,0,0
(Oct '97)
These giant seismic sea waves, sometimes as high as a five-storey building when they reach shallow \Jwater\j, are produced by undersea earthquakes, landslides or volcanic eruptions. Hard to detect at sea, the tsunamis give little warning to human populations living on the shores of the Pacific, but that may be about to change. Plans are in place for a network of instruments to be deployed and placed on the ocean floor, giving humanity a precious tool to predict and track tsunamis in real time.
The tsunamis travel at speeds close to 600 miles an hour (about 1000 km/hr) in the open ocean and at 100 miles an hour (around 150 km/hr) closer to the shore, so if they are identified near their sources, which may be on the other side of the \JPacific Ocean\j, a huge loss of life could be prevented. A 1960 tsunami, resulting from an undersea \Jearthquake\j near \JChile\j, killed 5000 people near the quake site. The tsunami set off by the tremor killed 61 people in Hawaii and caused millions of dollars in property damage. Then after Hawaii, the tsunami continued for nine more hours, finally striking \JJapan\j and killing another 150 people.
Bottom-pressure recorders (BPR's) and seismic instrument arrays for real-time monitoring of tsunamic development will be deployed by 1998, and more theoretical studies will be undertaken. For example, if the sea floor shakes from side-to-side, then the tsunami that follows will be minimal. But, if there is an up-and-down motion, a tsunami develops. That at least, is the theory, though more work is needed to work out the full dynamics.
At the end of October we learned of a major \Jearthquake\j on the Northwest coast of the United States around 1700 hours, which caused a tidal wave that hit the Japanese island of \JHonshu\j on 26 January 1700 hours. The \Jgeology\j has always suggested that there could have been such a quake, but now this has been confirmed, and located around the Cascadia fault zone.
Gordon Jacoby and his colleagues took core samples from 33 \Jsitka\j spruce trees, each at least 300 years old, that stand along a 100-\Jkilometre\j stretch of Washington and Oregon coastline, and they report in the November issue of \IGeology\i, that they found signs of waterlogging or trauma that had disrupted many of the trees. The evidence came from tree rings dated to around 1699. These signs include changes in ring width; the presence of "traumatic \Jresin\j canals" (sap-conducting tubes formed by altered cells); and "reaction wood," (dense cells formed in response to tilting).
More importantly, a report in \INature\i at the end of October describes dead \Jcedar\j trees along the Washington coast, still standing in what are now salt marshes. These trees last added cells to their timber in the northern growing season of 1699.
Based on the size of the \Jtsunami\j, as recorded in Japanese records, researchers had previously estimated the \Jearthquake\j at \Jmagnitude\j 9, even though no \Jearthquake\j in the area identified, the Cascadia fault region, with a \Jmagnitude\j 5 or above has ever been recorded by seismologists. The \INature\i article points out that the tree dates mean the northwestern United States and adjacent Canada are plausibly subject to earthquakes of \Jmagnitude\j 9.
#
"New World-Record Prime Number",332,0,0,0
(Oct '97)
Back in January 1997 (Mathematics update), we reported the discovery of the largest Mersenne prime so far known, the 35th found, a number derived from n = 1398269, discovered in the Great \JInternet\j Mersenne Prime Search.
We advised you then that anybody can now join in adding to the list of Mersenne primes by contacting George Woltman's Great \JInternet\j Mersenne Prime Search at http://www.mersenne.org/prime.htm and reading what they find there.
Well, if you wanted to find Mersenne prime number 36, you are too late. There are 1700 participants in the hunt now (all you need is a moderately powerful computer and some software provided by Woltman), and Gordon Spence has just found that one of the numbers that he happened to pick to test is the latest record-breaking prime.
The largest number yet identified that is evenly divisible only by itself and 1 is 2^2,976,221 - 1. This number would contain 895,932 digits if written out in full. Spence used a very ordinary Pentium-based desktop computer to find the record-breaking prime. It took 15 days of calculation to obtain the result, which was later verified independently on a supercomputer. Woltman, who organised GIMPS more than a year ago, and who wrote the software that searchers use, announced the discovery during October.
So will one of our readers be the proud discoverer of Mersenne prime number 37?
#
"South-East Asian Smoke Clouds",333,0,0,0
(Oct '97)
The fires of \JIndonesia\j continued through October, with forests still being cleared by fire during the developing El Ni±o \Jdrought\j. What was once 36 million square kilometres of dense virgin forest, two centuries ago, is now down to 4 million square kilometres across the SE Asian region.
Malaysia has borne the brunt of the smoke \Jpollution\j, and this has produced some strong reactions, ranging from a millennialist fervour among Islamic fundamentalists in \JKelantan\j to proposals to limit motor traffic in Kuala Lumpur. Malaysia's ironically named Air Pollution Index or API (\Iapi\i is the Malay and Indonesian root word for "fire") has been placed under question. Measuring five chemical pollutants: ozone, \Jnitrogen\j dioxide, sulphur dioxide, carbon monoxide, and particulate matter, the API has given results that lay observers felt did not match their personal experiences.
Each pollutant is scored on a range from 0 to 500, where 500 denotes "very hazardous", but this is merely a linear addition, and takes no account of interactions between components. As a result of public the protests, the Malaysian government has now redefined the safe limits for API values: where 500 was previously "hazardous", the 300-500 range is now "hazardous", 200-300 is "very unhealthy", and 100-200 is "unhealthy".
Meanwhile, the smoke clouds kept pouring into the skies.
#
"How Second-Hand Smoke Kills",334,0,0,0
(Oct '97)
A report in the \IBritish Medical Journal\i during October looks at the mystery whereby 20-\Jcigarette\j-a-\Jday\j smokers have a 78% increased risk of \Jheart disease\j over the general population, a risk elevation which is only three times that of passive smokers, even though active smokers inhale roughly 100 times as much smoke. It seems that even a relatively small amount of smoke causes clotting factors in the blood to become significantly stickier, and even passive smoking causes enough aggregation to explain the \Jheart disease\j risk.
#
"Aspirin and Heart Disease",335,0,0,0
(Oct '97)
If more people would take an aspirin when they experience chest pain or other symptoms of a severe heart attack, five to ten thousand lives could be saved in the United States each year, according to an American Heart Association scientific statement published in the association's journal \ICirculation\i during October.
#
"Obituary for October 97",336,0,0,0
(Oct '97)
The death was reported in October of Hans Eysenck, one of the most stimulating and controversial psychologists of this century.
#
"Latex Allergy",337,0,0,0
(Nov '97)
With AIDs and hepatitis risks causing concern among health workers, \Jlatex\j \Jallergy\j has become a serious concern, and was the subject of an article and an editorial in the \INew England Journal of Medicine\i during November.
Most of the people with problems fall into clearly defined groups with high exposure: health care workers, \Jrubber\j industry workers, and children with spina bifida (meningomyelocele) and urogenital abnormalities. Latex \Jallergy\j is fairly rare in members of the general population. Avoidance of \Jlatex\j products is the only measure that can avert a serious allergic reaction to \Jlatex\j.
A survey of all active-duty dental officers in the US Army in 1990 suggested a prevalence of \Jlatex\j \Jallergy\j of about 8.8%, indicating how serious the problem may become, but in spina bifida bases, the rates appear to lie in the 20% range, although one study showed that 37% (35/93) had \Jlatex\j-specific IgE in blood tests.
Natural \Jrubber\j is a processed plant product that has found widespread use since the second half of the nineteenth century. Today, almost all natural \Jrubber\j comes from the \Jlatex\j, or milky sap, of the commercial \Jrubber\j tree \IHevea brasiliensis\i. Over 200 other species of plants produce \Jrubber\j, but only \IH brasiliensis\i and the guayule bush, \IParthenium argentatum\i (a metre-tall desert plant that grows in the Southwest US and Northern Mexico) are used to produce \Jrubber\j in commercially significant quantities.
The allergic reaction appears to be caused by a protein fraction in the \Jrubber\j, a portion which can be removed by washing, heat treatment, chlorination, and \Jenzyme\j digestion of the \Jrubber\j. Rubber derived from guayule contains very little of this protein, and seems to cause no problems in people who react to \IHevea\i \Jrubber\j.
Interestingly, cross-reactivity has shown up for certain foods, at least for health workers. In one study, 17 people (36%) had clinical reactivity to at least one food. Some 53% were positive to prick testing with avocado, and a smaller number were reactive to \Jpotato\j, banana, \Jtomato\j, chestnut and kiwi fruit.
One of the problems with \Jrubber\j gloves is that they are commonly dusted with corn starch powder, which is a potent carrier of \Jlatex\j proteins, but in one extreme case, a physician's skin or clothing was apparently tainted with \Jlatex\j \Jantigen\j, as his wife began to show allergic responses which disappeared when the husband washed carefully and changed his clothes after work.
Most health care workers with \Jlatex\j \Jallergy\j can remain at work by switching to non-\Jlatex\j gloves and asking colleagues to use powder-free gloves. Latex condoms have been associated with problems in both males and females, and a documented life-threatening reaction in a female has been reported. Polyurethane condoms are now available.
In short, says the \INEJM\i article by Dr. Jay Slater , \Jlatex\j \Jallergy\j is rare, but can have devastating effects. High risk groups should be educated regarding potential risks and tested if they have reported symptoms of \Jlatex\j \Jallergy\j. This view is backed up in the editorial, which points out that the extreme allergic reaction, \Janaphylaxis\j to \Jlatex\j, can be fatal.
#
"Cochineal An Allergen",338,0,0,0
(Nov '97)
Cochineal, a food colouring agent, was once a valuable dye-stuff, the sort of thing that \Jbuccaneers\j like William Dampier regarded as valuable booty. To historians, \Jcochineal\j is the dye which gave us the uniforms of the "redcoats" and tinted the "thin red line" of the British Army. Now \Jcochineal\j, or carmine, as it is also called, seems to be an allergen.
The colouring is "natural", being made from female \Jcochineal\j bugs, which are harvested in Central and \JSouth America\j and the Canary Islands specifically to be made into dye. It is common in a variety of foods, and some cooks even add it to gravy. Because it is natural, the dye is commonly not listed as a separate ingredient, but after a report in the November issue of the peer-reviewed journal \IAnnals of Allergy, Asthma & Immunology\i, this may need to change. Only one case has been recorded so far, where a patient went into "life-threatening anaphylactic shock" (allergic reaction) in a patient after she ate a popsicle containing the colour, but other cases of mild \Janaphylaxis\j and hives may also have been caused by the additive, without anybody making the connection to the dye.
The woman in question had previously suffered from allergic reactions after applying a blush which also contains carmine. Two other patients have since been found with allergic reactions to the dye.
#
"Polyunsaturated Oils No Guarantee",339,0,0,0
(Nov '97)
Olive oil, is one of the dietary "good guys", polyunsaturated, and widely recommended. That is to say, it was-now a study in Denmark, reported in the journal \IArteriosclerosis, \JThrombosis\j and Vascular Biology\i, has found that one high-fat meal almost doubles the peak concentration in the blood of a known risk factor for heart attack and stroke. This is irrespective of whether the fat is-monounsaturated, polyunsaturated, or saturated.
So why are people who feed on "Mediterranean" diets, high in olive oil, so much healthier? Nobody is sure, but the test subjects in the study, all Danes, are in the habit of eating high-fat diets, so further tests are to be carried out, using other Danes who have been "starved" of fats for three weeks before the new study begins.
#
"Saccharin Cancer Causing?",340,0,0,0
(Nov '97)
Saccharin is back in the news again. With some medical scientists arguing that rat evidence is not sufficient to say that \Jsaccharin\j will cause cancer in humans, others still say that the risk is too great, especially if the substance ends up in children's drinks.
The evidence is equivocal at best: \Jsaccharin\j \Imay\i cause more bladder cancers in non-smoking women, and it does cause cancers in male rats, but that is hardly damning evidence. But to play safe, an advisory panel to the National Toxicology Program (NTP) in the USA voted on October 31 to keep \Jsaccharin\j in the federal Report on Carcinogens, which has listed the sweetener as an "anticipated human carcinogen" since 1981.
#
"Pathogens In Food",341,0,0,0
(Nov '97)
As if that was not enough for most Americans, November saw a major report on food-borne diseases from the Centers for Disease Control and Prevention, \JAtlanta\j. Written by Robert V. Tauxe, the report looks at a wide range of bacterial infections, and basically seems to offer more gloom than hope as we approach the festive season.
\IVibrio vulnificus\i, \IEscherichia coli\i O157:H7, and \ICyclospora cayetanensis\i are examples of newly described pathogens that are often food-borne, while other older \Jbacteria\j are able to flourish as food preparation and storage patterns change around the world, providing desirable ecological conditions for the pathogens. Whatever you eat, there is probably something deadly lurking there, in among the succulent juices.
#
"Oral Vaccine Against Botulism",342,0,0,0
(Nov '97)
Botulism is poisoning from the by-products of the anaerobic \IClostridium botulinum\i. The bacterium thrives in sealed tins of food, where it produces botulin, or botulinum toxin, which is usually described as nature's deadliest poison.
Now two Philadelphia scientists have reported in the November edition of the journal \IInfection and Immunity\i the development of an oral vaccine against the toxin. Even more importantly, the vaccine may show the way to developing vaccines against other diseases such as \Jdiphtheria\j, whooping cough and tetanus which also do their harm through toxin production. The researchers' long-term aim is to produce a range of oral vaccines which could be inserted into ordinary foods.
Lance Simpson, Nikita Kiyatkin, and Andrew Maksymowych used the complex tools of molecular \Jbiology\j to create a modified and non-toxic version of botulin. When somebody eats food tainted with botulin, the toxin passes through the digestive system and enters the blood circulation unaltered. When it reaches the central \Jnervous system\j, it causes general paralysis.
The new oral vaccine is similar to the active toxin, and able to pass through the intestinal tract, but it does not attack the central \Jnervous system\j, though it is sufficiently similar to cause the body to make \Jantibodies\j that will attack the real toxin, if it should appear. So far, the vaccine has only been successfully used to protect mice against \Jbotulism\j, but even that much is a healthy start. The next step may be to use the vaccine on horses and chickens, both likely to die from the effects of \Jbotulism\j if they come in contact with it.
The principle could also be useful against other diseases which produce toxins, and the researchers are already toying with the interesting notion of producing a banana which carries a gene that produces the vaccinating compound, providing cheap and effective protection in Third World countries.
Where our usual antibiotic defences provoke \Jbacteria\j into mutating into resistant forms, it is hard to see how \Jbacteria\j could work their way around this defence. Those few \IClostridium\i \Jbacteria\j which attack humans are lost to the reproductive future of their species, once the can is opened and air gets in. Of course, at the moment, the \Jbacteria\j cannot live on humans. If we became immune to the bacterium we now know and fear, and if we could suddenly carry and nurture the presently toxic \Jbacteria\j without harm, this could even favour the preservation of the toxic form, to the benefit of humans and \Jbacteria\j alike.
In other words, this could be an interesting development to watch, for a number of reasons.
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"Test Tube Vaccine",343,0,0,0
(Nov '97)
A team of chemists from Birmingham University has succeeded in making a completely synthetic vaccine. Using no biologically-derived components, the vaccine may be the first of a new range of vaccines, virtually free of side-effects.
The synthetic vaccine was produced by a team led by Dr Geert-Jan Boons. While the first real synthetic vaccines are probably several years away, the present work shows that the approach is feasible. Pathogens carry specific molecules on their surfaces, called epitopes, and it is these which trigger the immune response.
Vaccination involves setting off this immune response in the absence of pathogens, and this was originally done with whole cells which have been "crippled". Later vaccines concentrated on providing just that part of the cell which contained the epitope, but other materials are often included in the vaccine, and these can cause complications.
Epitopes are often oligosaccharides, molecules made up of a small number of sugar sub-units. By studying the human pathogen \INeisseria meningiditis\i, the team focused on the crucial portion of the epitope. They arranged the specific sugar sub-units correctly in relation to one another, and managed at the same time to get the whole molecule's three-dimensional shape correct. They then attached this molecule to a synthetic \Jpeptide\j and a lipid, two other essential components of a vaccine.
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"DNA as a Vaccine?",344,0,0,0
(Nov '97)
DNA can be injected as a vaccine, and this is generally seen as one of the most exciting new approaches in disease protection. Now 1996 Nobel laureate, Rolf Zinkernagel, suggests that animals may gain lifelong immunity to some viral infections by retaining a bit of viral DNA inside their cells like a souvenir.
In a November paper in \INature\i, Zinkernagel and his colleagues (P Klenerman and H Hengartner) describe studies they have carried out on mice which remain immune to lymphocytic choriomeningitis virus (LCMV), long after the virus has completely disappeared from their bodies. This is unusual, as the immune system normally begins to lose its "memory" of an invader as soon as the attack fades away.
Zinkernagel's team undertook an odd search, looking for traces of viral-looking DNA. Even Zinkernagel described it as "a crazy idea," because LCMV contains RNA, not DNA. Like many other viruses, it does not use DNA for its genetic information.
Until at least 225 days after infection, they were still able to find DNA "copies" of viral RNA in the mouse cells. These copies were clearly made from RNA by the \Jenzyme\j reverse transcriptase (RT), since azidothymidine (AZT), an RT inhibitor, blocked viral DNA production in infected cells. (AZT is probably better known in its role as a treatment against \JHIV\j/AIDS infection.)
Hamsters, which can be infected by LCMV showed the same traces, but human, monkey, dog, or cow cells, all of which are not susceptible to the virus, showed no signs of the "viral DNA". But does the DNA actually cause the mice to be immune to LCMV, or is it just a coincidence? That remains to be proven, but if anybody can show that the "viral DNA" is translated into a protein, which in turn can trigger an immune response, this fascinating observation may suddenly become very important as well.
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"Acupuncture Proven Effective",345,0,0,0
(Nov '97)
All over the western world, people have accepted \Jacupuncture\j as an alternative treatment for some diseases. Scientists have remained rather sceptical, because "Yin and Yang" explanations do not fit well into the western scientific tradition. Now that attitude is beginning to change. During November, an expert panel assembled by the US National Institutes of Health (NIH) reported that \Jacupuncture\j is effective treatment for nausea and some forms of pain.
Scientific theories about acupunctures cures tended to be about notions like the possibility that acupuncture triggers the production of many different chemicals, including pain-killing \Jendorphins\j, calming endogenous benzodiazepines, and mood-lifting \Jserotonin\j.
The panel found most studies on \Jacupuncture\j, used to treat everything from nausea and ovulatory problems to paralysis and drug abuse, to be flawed. Nonetheless, the panel found "clear evidence" that needle \Jacupuncture\j can relieve nausea from operations and \Jchemotherapy\j, and possibly also morning sickness. They also found some support for using \Jacupuncture\j for postoperative dental pain, and signs of pain relief for other conditions.
But is it the power of the mysterious East? The sceptics still seem to have an answer: if the treatment does not release chemicals, then electrical stimulation, either with needles or conductive pads, is "a very simple technique" for stirring up a storm of \Jhormones\j that act on nerves, and which have the potential to create the cures confirmed so far. But does it cure viruses?
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"Can Computers Develop Immunity To Viruses?",346,0,0,0
(Nov '97)
The average computer anti-virus package will often claim to defend your computer against 8000 or more viruses. This number will always be a bit rubbery, as many viruses use a standard piece of code to deliver a different message, and are really the same computer virus. In any case, these "viruses" are generally made by pimply wannabes, who lack any real programming skills, and whose "products" will never be a real problem. The real worry is with viruses that mutate, whether they are the viruses that cause disease in living things, or the viruses that attack computers. Now a unique study is combining both of those virus types.
It began with doctoral student Derek Smith, working closely with Associate Professor Stephanie Forrest and Los Alamos Laboratory Fellow Alan Perelson to build a computer model of the human immune system and doing experiments \Iin machina\i (in machine) to see how different vaccine strategies might work on mutating viruses. Traditionally, studies have been \Iin vitro\i (in the test tube-literally "in glass") or \Iin vivo\i through experiments on live animals.
The computer immune system model they developed simulates a virus on a computer by breaking it down into its basic components and modelling only the patterns where the components bind molecularly. By looking at these patterns, the researchers can work out how the immune system responds to viruses that mutate-and make estimates about the effectiveness of potential vaccines.
The other side of this picture comes when you model a computer virus or intrusion detection system after the human immune system. There is a strong analogy between the way natural immune systems protect animals from dangerous foreign pathogens, including \Jbacteria\j, viruses, parasites and toxins, and the way we would like intelligent software to protect our computers. Immune systems will respond to an entirely novel virus, and learn from the encounter, and it would be nice to have computer virus protection which does the same thing.
Our immune system stores its information in proteins: what is the equivalent of a protein in computers? A Ph.D. student, Anil Somayaji has come to the conclusion that a computer program's system calls are the missing link. He suggests that a "normal" profile of a computer program's pattern of system calls can be created. This profile can then be monitored, with changes to the norm readily detected. The aim is to distinguish "self" from dangerous "other" (or "non-self") and then eliminate the dangerous non-self. Non-self might be any of an unauthorised user, a foreign code in the form of a computer virus, or even corrupted data.
In cyberspace, people like to talk about convergence, the way in which all of the media are coming together, absorbing \Jtelevision\j, radio, mail, newspapers and more. From this work, it looks as though there may soon be a second convergence, where cyberspace and meatspace begin to converge.
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"Immunity To Student Plagiarism?",347,0,0,0
(Nov '97)
Teachers frequently ask about ways of stopping students who lift wholesale from \JCD\j-ROMs. With certain products, the simple style of the writers can make it hard for teachers to be sure whose work they are reading.
The same problem of authorship can arise in training exercises for people learning to work in the computer industry. One of the major tasks for somebody going into software production is to write a compiler, a collection of code which takes a set of instructions written in human terms, and converts it into bug-free code that a computer can run. If a student has lifted this from another student, perhaps in another institution, or from another year, how can the examiners tell? There are just too many other versions around to check them all.
Alex Aiken, an associate professor of computer science at UC Berkeley, has developed a reliable and easy-to-use piece of software that lets anyone check within minutes whether a student in the class has plagiarised their programming assignment. The software also automatically eliminates matches to code that are expected to be shared, such as code libraries or instructor-supplied code, and so eliminating false positives that arise from legitimate sharing of code.
The software, which Aiken calls MOSS for Measure Of Software Similarity, looks for similar or identical lines of code sprinkled throughout a program, then creates a web page where the instructor can see the top 40 matches. Aiken has now posted MOSS on the \JInternet\j, so others can use it as well. MOSS automatically determines the similarity of programs written in any of several computer languages, most commonly C, C++ and Java, but also Pascal, Ada, ML, Lisp and Scheme.
There is still some distance to go: this story has three sentences quoted verbatim from a press release, put out by Aiken's university. So far, there is no way that MOSS or any other program can identify "lifts" of this sort, for which many working journalists (who usually lift far more than three sentences from any given press release) will give hearty thanks.
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"Tuberculosis in the News",348,0,0,0
(Nov '97)
A curious study on tuberculosis, reported in the \IProceedings of the National Academy of Sciences\i during November sheds some interesting light on the human immune system. More than half of the Yanomami people of \JBrazil\j who had been vaccinated against TB do not produce a regular immune response to the tuberculosis bacterium. This seems to suggest that because previous generations of Yanomami had never been exposed to TB, their immune systems had not evolved a mechanism for mounting an immune response to it.
Europeans, on the other hand, lived with tuberculosis for centuries, so that there was strong selection for resistance, in some form or another, to TB. The Yanomami Indians, isolated from the outside world until the 1920s, are in a situation similar to the first time Europeans were exposed to the disease. The disease was first noted among the Yanomami in 1992, having come with gold miners in the 1970s and 1980s. By then, 6% of the population had TB, and even though they had been vaccinated in 1989, 58% of the Indians had a weakened or nonexistent immune reaction in skin tests that measure cell response to the tuberculosis bacterium.
In other words, a majority had poor defences, and only 29% had \Jantibodies\j that could activate T cells-a necessary part of a strong immune response. The Brazilian government closed the Yanomami Reservation to outsiders from 1993 until last year, but now it is open again, and doctors who are helping the Yanomami are also recording the progress of the disease and the victims' responses, in the hope of knowing more about how humans are affected by new epidemics.
In more experienced populations, where drug-resistant TB is on the rise, a major problem is still the delay in diagnosing TB and in obtaining drug susceptibility results which allow physicians to provide the most suitable treatment. The normal procedure is to obtain a sputum specimen, culture it, identify the \Jbacteria\j present, and test them for drug susceptibility.
Most laboratories still use slow methods, even though the use of rapid diagnostic methods for \IMycobacterium tuberculosis\i, a combination of solid medium and radiometric broth cultures, nucleic acid probes for identification, and radiometric broth drug-susceptibility testing, substantially decreases the time to diagnosis.
If the rapid methods were used, says a November Harvard (USA) School of Public Health report, the time to diagnosis would drop from an average 38.5 days to 23 days, while the time to appropriate therapy would drop from an average of 6.6 days to 2.0 days, and mortality would be 22 to 33% lower, in addition to decreasing the average health care costs per patient, which would be 9 to 22% lower in the USA).
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"Wine Good For The Heart?",349,0,0,0
(Nov '97)
"Drink no longer water, but use a little wine for thy stomach's sake . . .", said St Paul in his first epistle to Timothy. He goes on to add that wine will also treat Timothy's "often infirmities". Now a report in mid-November to the American Heart Association says that wine is good for the heart. Could this have been Timothy's "often infirmity"?
Whether it was or not, this hardly detracts from the proposal that drinking moderate amounts of alcohol-about one drink a \Jday\j-cuts the risk of a deadly heart attack in men who already had one heart attack or stroke. There was a clear reduction in the risk of death when light to moderate drinkers were compared with total abstainers, according to Michael Gaziano, M.D., director of cardiovascular \Jepidemiology\j at \JBoston\j's Brigham and Women's Hospital, leader of the study.
The study investigated 4797 male physicians who had suffered a previous heart attack and 953 who had experienced a stroke. Men who drank one or two alcoholic drinks reduced their risk of premature death and the risk of a fatal heart attack by 20 to 30 percent. These men were drawn from among the more than 90,000 doctors who filled out a questionnaire to enter the Physicians' Health Study, a trial designed in part to learn if low doses of aspirin reduce the risk of a first heart attack. The physicians in Gaziano's study were rejected for the aspirin trial because of their previous heart and stroke problems.
The study only examined men, so women will have to wait for further investigation. Now doctors will face a real dilemma: whether to encourage their patients to drink, knowing that uncontrolled and heavy drinking can lead to avoidable deaths, or whether to avoid them to shy away from any alcohol drinking at all. Gaziano believes all physicians should discuss alcohol intake with their patients first and identify and counsel problem drinkers. However, for patients with previous heart attack or stroke who are light to moderate drinkers, this behaviour appears to be safe and may confer modest benefits, he said.
And the real crunch: it may even be that drinking two or more drinks a \Jday\j is even more effective-so few of the doctors in the study fell into this category that nobody can really tell, one way or the other.
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"Ethanol Increases Toxin Levels",350,0,0,0
(Nov '97)
If alcohol is good for the heart, it seems that it is more of a problem for the lungs. Used as an \Jautomobile\j fuel additive to make gasohol, \Jethanol\j improves air quality by reducing hydrocarbon and carbon monoxide emissions, but it also causes increased levels of toxins called aldehydes and peroxyacyl nitrates (PAN), according to a report from U.S. Department of Energy's Argonne National Laboratory and published in \IEnvironmental Science & Technology\i during November.
Aldehydes are much more reactive in the \Jatmosphere\j than the alcohols they are made from. They react with other chemicals in urban atmospheres to set off chemical reactions leading to PAN, and once created, they can last for days if the conditions are right.
PAN is highly toxic to plants and is a powerful eye irritant. This pollutant has been measured in many areas of the world, indicating that it can be carried by winds throughout the globe. The Albuquerque study was particularly appropriate as federal regulations require cars to use \Jethanol\j-\Jgasoline\j fuel blends and to ban wood-burning in order to maintain air quality during the winter months. More than 99 per cent of the vehicles in the area use blended fuels containing 10 percent alcohol in the winter, while blended fuel use declines substantially during the summer.
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"Digital X-Rays Cheaper",351,0,0,0
(Nov '97)
Just as ordinary photography is being revolutionised by digital cameras, now x-ray technology looks set to be changed forever by digital methods. This method has the potential to replace the current film X-ray technology, while reducing health care costs and improving patient care.
Around 70% of all x-rays now are stored on film, but this is an indirect method, because fluorescent materials must first absorb the X-ray \Jenergy\j and convert it into light during the exposure process. Then the light must be converted to electronic signals. During this second step, the emitted light scatters and can reduce the sharpness of the image.
With digital radiography technology, X-ray \Jenergy\j is captured and converted into electronic signals that form a precise digital image on a video screen. These images can be duplicated and transmitted electronically with no loss of quality, making it easier to consult with distant experts via the \JInternet\j. There is also software available that would allow a radiologist to focus on or enhance a specific area of interest on the digital X-ray.
The system has been under development for some time, and was unveiled at the end of November at the 83rd Scientific Assembly and Annual meeting of the Radiological Society of \JNorth America\j meeting (RSNA) in \JChicago\j, where two papers on the technique were read by Gary S. Shaber, M.D., research professor of Radiology, Jefferson Medical College, Philadelphia.
The X-rays can also be stored in the computer for easy and quick access by physicians, and the digital X-ray technology would also allow \Jhospital\j radiology departments to see more patients and cut down on repeat examinations. In the longer term, this sort of system could even allow more rapid reporting to the primary care physician who referred the patient for x-rays. And if that isn't enough, digital technology also offers a significantly lower dose of radiation than conventional imaging.
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"Anticancer Drugs Making Liver Transplants Stick",352,0,0,0
(Nov '97)
Liver transplants are extremely difficult, as the organs will fail if they are not transplanted within 24 hours. Now a lucky observation has led to the discovery that a powerful anticancer drug, interferon, can double the lifetime of donor livers. This could greatly improve the supply of donor livers and relieve some of the pressure on the complicated transplant procedure.
The main problem is preserving cells called hepatocytes. This is done best by immersing fresh donor livers in a chilled solution of electrolytes and sugars. The hepatocytes \Jpump\j out something like 5000 different proteins which are involved in everything from blood clotting to detoxification. At the cold temperatures usually used, the liver's sinusoidal cells become bloated and cover the blood vessels. Then after transplantation, these bloated cells detach from the hepatocytes and die, weakening the blood vessels and starving the liver of blood.
When a Duke University team began looking at this problem in 1995, one of the team members had a relative who had just been diagnosed with breast cancer, leading the unnamed researcher to brush up on the subject. What the researcher saw was a "striking similarity" between the earliest stages of \Jtumour\j development and the injuries to refrigerated livers. A report in the November issue of \IGastroenterology\i says that the key observation was that liver sinusoidal cells were bloated just like their counterparts, endothelial cells, when blood vessels grow into a \Jtumour\j, a process called angiogenesis.
Tests on rats suggest that a single dose of interferon, given a few hours before the liver is removed, could make donor livers last perhaps 48 hours, at least in rats: human results will still need to be obtained.
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"Growing Smarter Cotton",353,0,0,0
(Nov '97)
A genetically altered form of cotton, highly resistant to the \Jherbicide\j glyphosate, is now growing well in \JFlorida\j, according to Raymond Gallaher, agronomy professor at the University of \JFlorida\j Institute of Food and Agricultural Sciences.
Typical \Jherbicide\j spraying of unaltered cotton may need up to five applications. The savings from fewer sprayings-to both the environment and the farmers' bank balances, are significant. Cotton and weeds cannot co-exist, so the weeds must go, in order to save the cotton plants from competition, but the problem has always been to do this as cheaply as possible.
The resistance gene was first identified in 1984, and it was incorporated into soy beans in 1989, with the first field trials of the "gene beans" in 1992. The same gene is expected to be field tested in corn during the 1998 growing season.
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"Frogs Deformed By Chemicals?",354,0,0,0
(Nov '97)
The frogs of \JFlorida\j and other parts of the United States may welcome the introduction of more resistant corn. Frogs in an Ohio pond have been turning up with too many legs, and while nobody is sure of the reasons why, one possibility is run-off from a neighbouring cornfield.
A report released in mid-November considers herbicides, a naturally occurring parasite, and other possible causes, indicating that it will be 1998 at the earliest before the cause is known with any certainty. All over the world, frogs are dying out, and it is just possible that the deformities may be related in some way.
The expected background level for deformities is about 1%, but on this site, the level has reached 5%. The deformities have been reported as far back as the 1700s, but reports have increased dramatically in number since 1995. The largest deformed frog populations have been found in \JWisconsin\j, \JMinnesota\j and parts of Canada, where anywhere between 10 and 75 percent of specific species of frogs have deformities.
The problem may have trematodes as the direct cause. Best known to humans as the cause of bilharzia, these can alter limb development by burrowing into the limb buds of tadpoles, though it is improbable that trematodes are the only cause, especially as some of the problems are facial deformities, less likely to be caused by trematodes. In the pictured example, an extra leg is growing from the frog's \Jsternum\j, or breast-bone, and this is most certainly not a trematode problem.
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"Jumping Gene",355,0,0,0
(Nov '97)
Jumping genes were discovered Nobel Laureate Barbara McClintock in the 1940s, and recognised properly only in 1983, when she received her Nobel Prize. McClintock's genes can "jump" from one \Jchromosome\j to another. These so-called transposable elements, or transposons, squeeze themselves into host chromosomes.
In simple terms, a transposon is just a gene for an \Jenzyme\j called a transposase. The transposase has just one mission: to cut its own gene free from a \Jchromosome\j and insert it into another \Jchromosome\j or at another site on the same \Jchromosome\j. The transposase recognises its own gene by the special stretches of DNA, the "recognition sequences", on either side of the gene. The transposase cuts the gene, recognition sequences and all, and moves the whole package to a new location.
McClintock found her jumping genes in the \Jmaize\j \Jgenome\j, and the genes have close counterparts in fruit flies. In 1994, the first vertebrate transposons were discovered in that popular genetic animal, the zebra fish, but the genes were inactive and appeared to have been silenced millions of years ago, given the number of mutations that appeared to have occurred since then.
Perry Hackett, together with Zoltan Ivics, Zsuzsanna Izsvak, and Ronald Plasterk, examined the salmon \Jgenome\j, looking for signs of transposons which might have been active more recently. They found recurring base sequences in salmon which suggested that the ancestors of these fish had possessed transposons, but that both the transposase genes and their recognition sequences had mutated to the point where they were no longer functional. From the extent of the mutations, they estimated that it was some 15 million years since the salmon "jumping genes" last leapt.
After searching for inactive transposons and eliminating mutations in the genes, they patched together a sequence, based on observations and knowledge of such sequences in other organisms. The work was written up in \ICell\i during November. Their new construction, a newly-revived gene which they have called "Sleeping Beauty," can not only slip into chromosomes, but a small test gene spliced into the transposon was also imported into the DNA of both zebra fish and human cells. When they combined "Sleeping Beauty" with lipids to deliver genes to cells, the transposon showed a 20-fold increase in efficiency in getting genes into chromosomes.
This work could overcome a stumbling block for gene therapy by providing a way of ensuring that a gene is actually inserted into a target cell's \Jchromosome\j, where it will order the production of useful proteins. There are still problems, though. "Sleeping Beauty" inserts itself almost randomly into the host cell's chromosomes, and so could land in the middle of an important or essential gene, causing a harmful \Jmutation\j. It will also have to be adapted to carry genes large enough to code for many therapeutic proteins.
Up until now, the only way to get material into cells was to use viruses, or to inject DNA into cells directly. The viruses are often destroyed by the host's immune system, and the injection method gives patchy results at best. In any case, the viruses used most often can only get into the cell nucleus when the cell is getting ready to divide.
The fact that Sleeping Beauty can carry genes into both zebra fish and humans suggests that it will work on most vertebrates, making the gene a potentially exciting tool to work with. With further development, Sleeping Beauty might be used to transport normal genes into cells containing defective forms of the genes that cause conditions such as haemophilia or cancer.
The researchers are also considering using the transposon as a new and better way to create mutants to study embryonic development, since the gene inactivated by having "Sleeping Beauty" poked into its middle can also be "tagged" using a short DNA sequence inserted by the transposon. So experimenters can throw tagged transposons at a developing embryo, check to see which gene is not working, and then use the position of the tag to find where on the \Jchromosome\j that gene lies.
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"How Plague Kills Macrophages",356,0,0,0
(Nov '97)
In early November, Olaf Schneewind and colleagues at the University of \JCalifornia\j School of Medicine in Los Angeles, announced to the world through the pages of \IScience\i that they had found the signal that the plague bacterium, \IYersinia pestis\i, uses to release a powerful toxin that attacks and destroys the macrophages which are the front line of our immune defences.
Under attack, the \Jbacteria\j inject a toxin that rapidly paralyses the macrophages. The toxin proteins, called \IYersinia\i outer proteins (Yops), had no apparent amino acid signal calling for secretion. A possible gene was found, but even when this was drastically mutated, the toxin proteins were still secreted. It seems that the bacterium uses a novel signal, a piece of messenger RNA (mRNA), the template for assembling the protein in question.
So far so good: we now know what switches on the reaction. Now scientists can start to look for novel ways of combatting the bacterium, simply by attacking this pathway. More interestingly, it may be possible to use these \Jbacteria\j as miniature factories for injecting proteins directly into human cells. In the long term, bubonic plague may be rather more welcome than it was when we called it the \JBlack Death\j.
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"Phosphate Problems Ahead",357,0,0,0
(Nov '97)
Plants rely on several key \Jnutrients\j: \Jpotassium\j, \Jnitrogen\j and \Jphosphorus\j being the main ones. There is no shortage of \Jpotassium\j, and \Jnitrogen\j can be added to the soil from "fixed" atmospheric \Jnitrogen\j, but \Jphosphorus\j is likely to be a problem at the end of the 21st century, when the available rock phosphate deposits run out.
The farmers of next century are going to need to guard their \Jphosphorus\j reserves jealously, and that means we need to know more about how \Jphosphorus\j is taken up by plants. The first steps in working this out were announced during November in the \IProceedings of the National Academy of Science\i. K. G. Raghothama, Purdue assistant professor of \Jhorticulture\j, describes in that journal how he has isolated the genes that help plant roots take up phosphate, a common form of \Jphosphorus\j.
The problem of phosphate extraction is made worse by the way in which soils hold on to \Jphosphorus\j. This is especially severe in the very acid soils of the tropics, which are rich in iron and \Jaluminium\j, which both latch onto and tie up nearly all available \Jphosphorus\j. And in some alkaline soils, \Jcalcium\j reacts with the \Jphosphorus\j and essentially fixes it, although the hold is less tight than in acid soils.
Plants have a variety of strategies to get at \Jphosphorus\j. Some plants develop more roots, while others may produce and release organic acids and enzymes that can pry the nutrient away from the attraction of the soil clay and organic matter. In others again, the plants flip a genetic switch that changes certain molecules in roots and makes plants better at acquiring phosphate.
Studies with yeast and fungi have already identified protein molecules called "phosphate transporters" which actively take up phosphate, and the responsible genes are also known. So Raghothama, in collaboration with Jose Pardo from Instituto de Recursos Naturales y Agrobiologia in \JSpain\j, set out to find the mechanism which makes plants better at \Jphosphorus\j uptake, then track down the genes that turn on that mechanism.
Their aim was to identify phosphate transporter genes in higher plants. They did this by studying \IArabidopsis\i plants: this is a member of the mustard family, and a popular experimental plant. Raghothama and postdoctoral researcher U. Muchhal "starved" their \IArabidopsis\i plants to activate any phosphate-scavenging mechanisms, and then probed the DNA libraries of the starved plants for genes that produce phosphate transporter proteins.
They found the genes and identified them, and also noted that the phosphate-starved plants sent out significantly more messages calling for production of phosphate transporter proteins. In this way, they have advanced our understanding of the way in which \Jphosphorus\j is taken up by plants. It is quite likely that their names will be revered by the farmers of the late 21st century.
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"Moon a Part of Earth?",358,0,0,0
(Nov '97)
Two hundred years ago, the only sort of story we could read around rocks was that engraved on the surfaces by other humans, but even that had to wait on people learning to decipher \Jrunes\j and \Jhieroglyphics\j. Now we can read the stories written inside the rocks just as well, almost all the way back to the \Jearth\j's formation, and certainly back to the moon's formation. All we had to do was learn how to decipher the tale that was waiting there for us.
Tungsten \Jisotopes\j have shown up as the key item in dating the moon, working out where it came from. Writing in \IScience\i, early in November, a group of researchers explained how they analysed \Jisotopes\j of \Jtungsten\j in rock samples from the lunar surface to unlock the secrets of the moon's origin.
"Our data indicate the moon formed within the time window of 4.52 billion to 4.50 billion years ago. The tungsten isotopic composition of the moon is consistent with the hypothesis that the moon was derived from the Earth itself, or from a large object colliding with the Earth which had a similar chemical composition," said Alexander Halliday, one of the authors, in a press release.
As they see it, using simulations, the collision produced temperatures of 10 000 kelvin, mixing and melting the rocks of the young Earth. The researchers dated 21 lunar samples, studying very small amounts of \Jtungsten\j-182, formed from the decay of hafnium-182 in the rocks.
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"Mars Wet and Liquid Because of Dry Ice",359,0,0,0
(Nov '97)
Nothing we see in daily life seems as cold as dry ice, or as dry as dry ice. The name, once a trade mark for commercially supplied frozen carbon dioxide, is now our standard everyday name for that product, but on Mars, it seems as though the substance may have been responsible for keeping the Red \JPlanet\j both warm and wet.
University of \JChicago\j Professor of Geophysical Sciences Raymond Pierrehumbert and his colleague Franτois Forget, from the Laboratoire de MΘtΘorologie Dynamique du CNRS in Paris, believe they can explain why there are deep channels to be seen in surface photographs from Mars, created by surface \Jwater\j on a young Mars, some four billion years ago. The answer, they say in a November article in \IScience\i, is reflective carbon-dioxide ice clouds that retain thermal radiation near the \Jplanet\j's surface, clouds made of dry ice.
People have tried atmospheric models involving CO\D2\d before, but if you have enough of the gas to warm the \Jplanet\j, there is enough carbon dioxide present for it to condense out, and this should have produced thick clouds that would reflect sunlight back to space and actually cool the \Jplanet\j. The carbon dioxide ice clouds, unlike the \Jwater\j ice clouds found on Earth, are made up of particles which are large enough to scatter infrared light more effectively than visible light coming from the sun.
Ordinary, Earth-type clouds would absorb heat from the \Jplanet\j's surface and re-emit it both back to the surface and to outer space, losing half of the heat in the process. The carbon dioxide clouds act like a one-way mirror, so while only a small amount of sunlight gets through to the \Jplanet\j's surface, what does reach the \Jplanet\j is converted to heat, which the clouds then reflect back to the surface, according to Pierrehumbert.
Working from this, Pierrehumbert suggests that this may tell us what sorts of life forms are possible on Mars. "If we're going to be looking for analogues of terrestrial life forms on Mars," he said, "then we should be looking for the kinds of organisms that might evolve in extreme environments, like the bottoms of oceans or in caves. The conditions on early Mars were a little more like the conditions at the bottom of the ocean than like a \Jrainforest\j. It would have been dark, warm enough for liquid \Jwater\j, but without a large \Jenergy\j source for \Jphotosynthesis\j."
The researchers' model extends the habitable zone on extrasolar planets and increases the likelihood that life exists outside our \Jsolar system\j. Previously, scientists thought that only planets orbiting within 1.37 astronomical units (one AU is the distance between Earth and the Sun) of a \Jsun\j-type star could have \Jwater\j above the freezing point. But if the planets have carbon-dioxide ice clouds, they could have liquid \Jwater\j as far away as 2.4 AU. Mars is 1.52 AU from the Sun.
Despite his name, Pierrehumbert is not a strong speaker of French, so they wrote in English, and the question of how to express some of the terms they use in language acceptable to the Academie Francaise did not arise. It was, however, something of a problem for Forget, who recently had to translate "runaway \Jgreenhouse effect\j" into French. A check of the literature showed that "\Jgreenhouse effect\j" translates to a straightforward "effet-serre," though there was no clear translation for the "runaway" part. So, Forget had to coin a term himself, and wound up writing about "effet-serre gallopant." "Dry ice", says Pierrehumbert, is easy: it is just "glace carbonique".
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"Einstein's Frame Dragging",360,0,0,0
(Nov '97)
Every science eccentric likes to target Einstein, explaining confidentially that he (it is usually a "he") has been able to show that Einstein got it wrong. Somehow, these "proofs" never seem to impress mainstream scientists, who are more interested in the evidence gained from observations.
Real scientists are especially interested in observations which bear out Einstein's views, because so much of our modern science seems to be perfectly explained by Einstein's ideas. And at least the observations serve to keep the "crackpots" at bay.
Einstein predicted an effect, called "frame dragging," 80 years ago. Like many other aspects of Einstein's famous theories of relativity, it is so subtle that no conventional method could measure it. In simple terms, frame dragging results in space and time get pulled out of shape near a rotating body. In an extreme case, a rotating Tipler machine may even interfere with the causality principle through frame dragging.
Using recent observations by X-ray \Jastronomy\j satellites, including NASA's Rossi X-ray Timing Explorer, a team of astronomers reported in November that they had found evidence of frame dragging in discs of gas swirling around a black hole.
Drs Wei Cui, Nan Zhang, and Wan Chen began with Einstein's prediction that the rotation of an object would alter space and time, dragging a nearby object out of position compared to predictions by the simpler math of Sir Isaac Newton. This effect had not been observed in the eighty years since Einstein predicted it. In this, it was unlike the other, more familiar Einsteinian predictions, such as the conversion of mass into \Jenergy\j (as seen in atomic bombs and stars) and back, the Lorentz transformations that make objects near the speed of light grow thinner and heavier and stretch time, and the warping of space by gravity (as seen when light is bent by a massive object)
And no wonder: the effect is incredibly small, about one part in a few trillion, which means that you have to look at something very massive, or build an instrument that is incredibly sensitive and put it in \Jorbit\j. Cui, Zhang, and Chen took the first option, and studied radiation coming from around black holes in binaries with other visible stars. Over time, the black hole strips material from the star, producing an \Jaccretion\j disc of material which gets hotter as it approaches the event horizon of the black hole, and gives off radio waves, visible light, and-just before it disappears-x-rays.
They found that the discs precessed, wobbling like a child's toy top. By studying the radiation from supraluminal jets in two black holes, called GRS 1915+105 and GRO J1655-40, they found that the rate of precession was far greater than could be explained by the sorts of effects seen in children's toys. Conclusion: Einstein's frame-dragging is real.
The sensitive instrument option will follow next: NASA is developing it as Gravity Probe B, described in the entry on \Jgeneral relativity\j. This is a \Jsatellite\j containing precision gyroscopes inside a liquid \Jhelium\j bath. Gravity Probe B will point at a selected star, and sensitive instruments will measure how much the gyros precess after conventional effects are nullified. The leftover effects should provide a precise measure of frame dragging. Because the Rossi \Jsatellite\j observations are somewhat uncontrolled, the final proof of frame dragging will come when Gravity Probe B points at a known star of known mass, and turns in consistent results.
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"Einstein Cleared of Plagiarism",361,0,0,0
(Nov '97)
Meanwhile, Einstein was cleared of a charge of plagiarism during November. Many people have long believed that the mathematician David Hilbert completed the theory of General Relativity five days before Albert Einstein in November 1915, but it now seems unlikely that Einstein copied the correct field equations of General Relativity from Hilbert, even though his paper is dated five days after Hilbert's.
Proofs of Hilbert's key paper (dated November 20, 1915), have been found which are dated December 6, 1915, after Einstein had completed his paper. These proofs contain only an immature version of General Relativity, without the explicit field equations. These equations must have been inserted only later, after 6 December and before the published version appeared in 1916.
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"Cost of El Nino",362,0,0,0
(Nov '97)
The importance of understanding the \Jweather\j comes home best when you are in a small country in central or \JSouth America\j, and relying on hydro-electric power. A new computerised forecasting model designed to predict the financial impact of El Ni±o \Jweather\j patterns could save millions of dollars in \Jenergy\j costs, according to its developers.
More than half the electric power for \JColombia\j, Panama and Costa Rica comes from hydroelectricity. During a normal year in this region of \JLatin America\j, the heavy rainy season from June through October feeds the reservoirs that supply the nations' power sources. During an El Ni±o year, however, the rains are reduced. Then the only other option is to import oil.
Even the USA gets 13% of its \Jenergy\j from hydro power, which translates to 500 million barrels of oil annually. A tiny 1% increase in the US efficiency in hydro power would mean a saving of some 4.9 million barrels of oil, costing around US$90 million.
With rainfall in Panama down by 39 percent compared to the yearly average, the government there has already tried to reduce electricity consumption and outflow of \Jwater\j from the reservoirs by 30 percent so they don't run out by January, 1998.
\BThe health cost of El Ni±o\b
The costs go beyond simple economic costs. Doctors in \JPeru\j blamed climate changes caused by El Nino for an increase in diarrhoea and \Jdehydration\j in infants and young children. Unusually high temperatures in Lima and along the north-central coast have corresponded with the rise in childhood illness and doctors are preparing for even worse to come.
In a letter to the \ILancet\i, they pointed to the coming southern summer as a problem time, and suggested that the changing \Jweather\j patterns will burden financially strapped health services and lead to an outbreak of \Jcholera\j. This is because higher temperatures support blooms of plankton which provide a perfect breeding ground for the \IVibrio\i \Jbacteria\j which cause the disease.
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"Global Warming: Could We Lose The Conveyor?",363,0,0,0
(Nov '97)
A great cost of global warming might come about if we lost a giant ocean current called the conveyor. This system, which among other things drives the Gulf Stream, is all that prevents Ireland from having a climate like Spitsbergen (Svalbard), 600 miles north of the \JArctic\j Circle.
This Doomsday scenario is no mere piece of \Jscience fiction\j. Worked out by Wallace S. Broecker, Newberry Professor of Earth and Environmental Sciences at Columbia University's Lamont-Doherty Earth Observatory, it was published in the journal \IScience\i at the end of November. In something of an understatement, Broecker describes the results as devastating, saying that Dublin could encounter a fall of 20░F (about 11░C) in just ten years, even as the rest of the world was heating up.
The Conveyor is delicately balanced and vulnerable, and it has shut down or changed direction many times in Earth's history, according to Broecker. Each change has produced massive climatic variation in a matter of decades, causing large-scale wind shifts, fluctuations in atmospheric dust levels, glacial advances or retreats, and other changes as the Conveyor jumps from one stable mode to another.
So while the current warming from the enhanced \Jgreenhouse effect\j may be a slow one, it may well be all that is required to take us "over the hump", and into a new climatic regime. Right now, the system is driven by cold salty \Jwater\j sinking to the bottom of the North \JAtlantic Ocean\j. This then pushes waters through the world's oceans, a flow 16 times greater than the flow of all the world's rivers combined.
The waters of the equatorial Indian Ocean are too warm to sink, while the north Pacific is too diluted by the snow and rains of the western United States and Canada. If the north Atlantic warms by just a few degrees, or if it gets a bit more rain, the whole flow could stop, and once stopped, who can say if it will start again?
Ice core evidence tells us that when a climatic change comes, it happens over a short period, geologically speaking, with just a few decades of transition. Broecker believes that the Conveyor is the key factor that we need to watch and worry about. And who is Broecker? Just one of the world's leading authorities on global climate change. He has won nearly every major geological award, including the Vetlesen Prize, considered by many to be the equivalent of the Nobel Prize in \Jearth\j sciences. Last year he was awarded the National Medal of Science and the Blue \JPlanet\j Prize, for achievements in global environmental research. When people like Broecker are worried, it is time to be worried too.
Coincidentally, evidence appeared in nature, just two weeks before that, giving us the same message. A 53-metre-long sediment core, retrieved from the \JBermuda\j Rise in the western North Atlantic, now gives us the most detailed picture yet of events during the previous interglacial. The key feature: "its termination seems to have been marked by a sudden reduction in the ocean 'conveyor' circulation which today carries ocean heat north from the tropics and warms much of Europe." In this case, the blip took less than four hundred years to throw the world back into a severe \JIce Age\j.
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"Earth's 1500-Year Rhythm",364,0,0,0
(Nov '97)
Another sea core finding in November, reported in the November 14 issue of the journal \IScience\i, indicates that the Earth's climate cools significantly and abruptly every 1,500 years or so in a persistent, regular rhythm. Or so a team led by scientists at Columbia University's Lamont-Doherty Earth Observatory would have us believe.
As this is written in early December, more information is coming in to support this claim, which will be dealt with more fully next month. The main points: the cycle has continued uninterrupted for 32 thousand years, with a period of 1470 years, plus or minus 500 years. The last such cycle may have taken place 300 years ago, and the cycle appears to persist when the \Jplanet\j is in the grip of an \JIce Age\j or when it is in an interglacial as we are now.
The finding throws new light on historical events, such as the Little \JIce Age\j, a cold spell that gripped the world in the 17th and 18th centuries and might prove to be the most recent manifestation of the phenomenon. The evidence for their theory is in the form of tiny particles of rock and volcanic glass, carried by glacial icebergs and \Jsea ice\j to the North Atlantic, deposited on the sea floor and buried by subsequent sediments. In the cold snaps, the number of particles doubled or tripled in ocean sediments on both sides of the north Atlantic, indicating that the amount of floating ice had both increased and extended further south. This is borne out by the study of the abundance of cold-\Jwater\j-loving plants, which increased, and the amount of warmer-\Jwater\j plankton, which decreased in the same 1500-year cycle.
In each cycle, cold, ice-bearing waters, which today circulate around southern \JGreenland\j, pushed as far south as \JGreat Britain\j. The cold waters penetrated a warm North Atlantic current that prevails today, and may have disrupted the global ocean circulation pattern that keeps the North Atlantic region warm. The ocean circulation disruption may well have had far-flung, world-wide effects, say the researchers.
For the moment, the findings only go back 32 thousand years, as this is the effective limit of \Jradiocarbon dating\j in the sea-floor sediments. The next step will be to see if the cycles persisted even before the last \Jice age\j began, as far back as the Eemian Period, more than 115 thousand years ago, when the Earth was relatively warm, as it is today.
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"More Arctic Change",365,0,0,0
(Nov '97)
It seems that the \JArctic\j is quite capable of changing its climate, even without human effects. A study published in \IScience\i during November reveals that the \JArctic\j experienced its highest temperatures in 400 years between the mid-19th and mid-20th centuries.
A team of 18 north American researchers used a whole range of palaeoenvironmental data, including information from glaciers, tree rings and marine, lake and pond sediments. As an example, one researcher focused on diatoms, a type of \Jalgae\j known to respond in a measurable way to environmental change, in \JArctic\j ponds. In this way, she was able to reconstruct past environmental conditions using the diatom assemblages that are preserved in lake and pond sediments. The data from the various sources were all consistent in the story they told.
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"Ancient Eruptions Caused Global Warming?",366,0,0,0
(Nov '97)
There is some evidence to suggest that multiple massive volcanic eruptions occurred roughly 55 million years ago in the Caribbean Basin. The evidence, based on drill cores from the sea floor south of \JHaiti\j, points to an abrupt inversion of ocean waters, triggering one of the most dramatic climatic changes ever. It was published in the November issue of the journal \IGeology\i. It covers cores taken by the 470-foot \IJOIDES Resolution\i, the world's largest scientific drill ship, in late 1995 and early 1996.
The inversion would have caused release of massive amounts of sea floor \Jmethane\j into the \Jatmosphere\j, presumably leading to global warming and possibly speeding the \Jevolution\j of countless new plant and animal species, including many primates and carnivores. At the same time, close to half of all deep-sea animals went extinct, asphyxiated in the suddenly warmer and stagnant deep waters.
Who beats whom in the carbon dioxide emission leagues? Here is a table which will let you compare absolute production levels with per capita outputs. Notice how \JAustralia\j, singled out for special leniency at \JKyoto\j in December, scores.
On a per capita basis, the United States retains first place, but \JAustralia\j leaps up the ladder to take second place, just ahead of Canada in third place, followed by North Korea, \JKazakhstan\j, \JRussia\j, \JGermany\j and \JJapan\j, with the rest of the world trailing behind.
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"Filtering Spam",368,0,0,0
(Nov '97)
Spam, apart from being a nutritious meat product invented by George A. Hormel, and a long running Monty Python joke, is nuisance mail which arrives as e-mail. As more and more losers try to make a profit by scattering their get-rich-quick schemes and unsolicited offers of unwanted services across the \JInternet\j, so e-mail users around the world become more and more annoyed.
There are a number of ways of dealing with Spam mail. You can try writing back to the sender, but they have usually lost their account privileges by the time you react, so your mail will simply bounce back to you. Or if the account has not been closed, it may have never existed: spammers are quite good at "forging" the origin address -- at least on the surface. Usually a determined person can uncover the real address that the Spam came from, and then write to the service provider, but by then the damage is done, as most spammers need only to trawl their announcement, with a phone number, past as many users as possible. After that, the \JInternet\j account is of no further use, and it is abandoned, with the damage done.
There are also more complex approaches, involving single-minded pursuit of the spamming enemy. The information you need can be found easily on the \JInternet\j. The Sendmail Anti-spam site is at http://www.sendmail.org/antispam.html, and this provides a numbers of links, one of the best being http://spam.abuse.net/
Spam Hater is free Windows software which works with many mail readers: it analyses the Spam, and does most of the heavy work of preparing a letter of complaint to the relevant Postmaster. Downloads of Spam Hater can be obtained from http://www.compulink.co.uk/~net-services/spam/
Useful advice is available at http://kryten.eng.monash.edu.au/gspam.html. On the other hand, if you want a scholarly (warning: that means "heavyweight") paper on Spam, turn to http://server.berkeley.edu/BTLJ/articles/11-2/carroll.html but be warned that this single Web page is more than 170k long, and contains more than 200 footnotes. A check at the end of November revealed that the footnote numbers are still there, but the actual footnotes have gone.
As an alternative, you may prefer to turn to the new service that Lucent's Bell Laboratories are offering. People using Lucent's proxy server, Lucent Personalized Web Assistant, to give each site a personal user alias, password, and email address. Then, if that site sells your address, you will know who is doing it, and you will also be able to filter out the offending calls. This service, only announced during November, has not been widely reviewed yet, but it may be worth watching out for.
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"Future of Security",369,0,0,0
(Nov '97)
Security staff in casinos around the world have computer-stored mugshots of banned customers, and screen-savers running on the computer to cycle through those who are unwanted, to make their faces more familiar. "Mugspot", a computer program that can recognise a face in a crowd, may take some of the pressure off.
The system spots a person, tracks them, and then selects the nearest to a full-face shot, which is then passed on to the software. This sophisticated software is able to see through superficial changes such as moustaches, beards, changed hair-styles and spectacles.
The Mugspot system can scan eight video frames per second in real time, and takes about 13 seconds to select the best view, process it for identification, compare it to the several hundred faces in its memory and decide whether it has found a match. This will do to identify wanted suspects fleeing the law, but will it be fast enough to identify known bank robbers before they can produce their guns?
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"Mars Express To Go Ahead",370,0,0,0
(Nov '97)
The European Space Agency (\JESA\j) has decided to go ahead with a fast-track plan to launch a new Mars mission, Mars Express, in mid-2003. The \Jspacecraft\j will include an orbiter and several landers, one of which will search for traces of past or present life on Mars. The \JESA\j will provide about $175 million for the orbiter and launch; participating countries will pay for the landers and instruments.
This plan is intended to regain the impetus that was lost when a launcher for a Russian-led mission carrying the Mars '96 \Jspacecraft\j exploded a year ago over the \JPacific Ocean\j. But in addition to instruments developed for Mars '96, Mars Express will carry a subsurface-penetrating radar that can look for signs of conditions that might support life, such as evidence of \Jwater\j.
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"Laser Surgery a Step Closer",371,0,0,0
(Nov '97)
The same computer models which predict how lasers pound fuel pellets to trigger nuclear fusion have now shown that high-power lasers can also destroy bone, and do it without endangering nearby nerves. Given this, it now seems possible that surgeons in the future could treat chronic back pain by vaporising the bone away from pinched nerves with lasers.
Laser fusion involves high-intensity \Jlaser\j pulses heating a tiny pellet of \Jhydrogen\j \Jisotopes\j to tens of millions of degrees, while squeezing it to high density, so as to spark a nuclear reaction. While thermonuclear fusion is not yet a way of generating useful \Jenergy\j, scientists have created detailed computer simulations of exactly how the \Jlaser\j light is absorbed in the fusion process.
Richard London of the Lawrence Livermore National Laboratory in \JCalifornia\j told the American Physical Society Division of Plasma Physics Meeting about this at a November meeting. The calculations suggested that a burst of very intense \Jlaser\j light, lasting less than one-trillionth of a second, would ionise atoms in the bone and turn it into a hot gas called a plasma. And since the plasma is an electrical conductor, the \Jlaser\j light only penetrates a short distance, removing just a micrometre of bone.
Researchers have already used a \Jtitanium\j-sapphire \Jlaser\j on pig bones from a slaughterhouse, and they have demonstrated that they can target just the bone. When the \Jlaser\j zaps bone, the \Jcalcium\j atoms in the bone tissue emit photons at a certain wavelength, so all they had to do was set the \Jlaser\j to shut itself off if those wavelengths disappear - the sort of effect that might happen if the \Jlaser\j struck a nerve, which is low in \Jcalcium\j.
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"Chronic Diseases and PTSD",372,0,0,0
(Nov '97)
US Vietnam veterans who saw heavy combat, and who were later diagnosed with post-traumatic stress syndrome (PTSD) are significantly more likely than other veterans to suffer from a variety of chronic diseases 15 to 20 years later. Using soldiers who saw little combat in Vietnam and did not develop PTSD as a control group, these former soldiers are 50% to 150% more likely to develop \Jheart disease\j, weakened immune systems, infections, \Jarthritis\j, and respiratory and digestive problems, according to a report in \IPsychosomatic Medicine\i.
Author Joseph Boscarino, an epidemiologist and social psychologist, suggests that the problem arises from a high state of nervous arousal induced by the post-traumatic stress. Previous studies have shown less obvious signs of medical problems, since it is only when heavy-combat PTSD and light-combat PTSD groups are studies that the medical effects show up in analysis.
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"Instant Memory Recall Limit",373,0,0,0
(Nov '97)
Somewhere back in the 1950s, a psychologist called Miller proposed "The Magic Number Seven Plus or Minus Two" in the \IPsychological Bulletin\i. This is now so lost in the mists of antiquity, that most people take it as \Jfolklore\j, but it was Miller who originated the idea.
What he suggested was that people can keep track of approximately seven plus or minus two separate categories or situations at any one time. Wine judges who are very well-trained may be able to divide wines into nine quality groups, teachers may be able to assign pupils into seven distinct groups in terms of their skills, and so on.
Now it appears that for some tasks, we may only be able to keep track of four distinct categories at any one time. Steven Luck and Edward Vogel reported in \INature\i during November that humans can instantly recall the details of only four different objects. They say that a better understanding of this memory limit could have practical applications, such as improving the design of dashboard displays in cars or road signage.
Their work relates only to the subsystem of short-term memory that stores visual information, but it is often this that we rely on most, especially in situations like driving, where verbal memory is almost unused.
They used a simple test, flashing several squares, each one a single colour, onto a screen for one tenth of a second. After 1 second of darkness, they showed their subjects the squares again for 2 seconds, sometimes with one colour altered. As is traditional in \Jpsychology\j, the subjects were \Jpsychology\j students, ten of whom were repeatedly tested to see if they could recall if there had been a change.
With three or fewer squares, the students answered almost perfectly, but their success rate began to drop away when there were four or more squares. Next, the researchers made the task more difficult by asking the students to remember multiple features such as colour, orientation, size, or the presence or absence of a gap in rectangles. And once again, they noted a drop in accuracy when more than four rectangles were on the screen during the test.
Interestingly, they could remember a total of 16 features, as long as they were associated in only four objects: it looks as though some "chunking" was going on, of the sort we see when people remember words rather than collections of letters. There is almost certainly a message here for people who are designing things as diverse as road signage and \Jaircraft\j and \Jautomobile\j displays.
Or as the researchers put it, "the capacity of visual working memory must be understood in terms of integrated objects rather than individual features, which places significant constraints on cognitive and neurobiological models of the temporary storage of visual information".
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"Herpes Virus a Trigger For MS",374,0,0,0
(Nov '97)
A strain of reactivated herpes virus may be associated with multiple sclerosis (MS), an autoimmune disorder in which the body attacks its own tissues. More than 70% of the American patients studied with the relapsing-remitting form of MS showed an increased immune response to human herpes virus-6 (HHV-6) and approximately 35% of all MS patients studied had detectable levels of active HHV-6 in their serum, according to a report announced in November, and appearing in December's issue of \INature Medicine\i. Only 18% of a control group showed an increased immune response to the virus.
The implication from this is that it may be possible to use currently available antiviral treatments like acyclovir to treat MS. Curiously, HHV-6 is found in about 90% of the US population, where it causes the common childhood illness, roseola. So now we need to know why such a common virus causes this major change at such a low level-the 250 million Americans include only about 350 thousand with MS.
Significantly, magnetic \Jresonance\j imaging detected numerous lesions in the \Jmyelin\j in the brain of a recently deceased MS patient, and an autopsy revealed HHV-6 in the lesions, but not in the adjoining normal tissues.
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"Identifying Habitats",375,0,0,0
(Nov '97)
We brought you last month a report on the new 840-square-mile (2000 square \Jkilometre\j) Masoala National Park, officially dedicated in October by the people of the \JMalagasy\j Republic (Madagascar). This month, a brief account of the methods used to identify the habitats which needed to be protected.
Claire Kremen, a research associate with Stanford's Center for Conservation Biology (CCB), has described some of her methods early in November. She led the planning team that designed the park for an international consortium that includes the Madagascar government, the WCS, CARE International, the Peregrine Fund and the people of Masoala.
In consultation with local communities, Masoala's planners sought to preserve natural habitats while respecting the traditional boundaries of villages. A long-term management plan is being implemented for the park and its surrounding waters. To help villagers better their lives yet sustain the forest, work is under way to build markets for renewable resources, such as ecotourism, butterfly farming and the sale of individually cut trees to buyers of high-value "certified sustainable" wood.
Conservation agents, specially-trained members of the local population, visited scores of villages on the Masoala Peninsula to learn about the population and what villagers considered to be the local forest necessary for their use. A Global Positioning System receiver would then be used to determine the latitude and longitude of each village.
The two teams (biologists and village surveyors) began with topographic maps and \Jsatellite\j imagery provided by the Missouri Botanical Garden and the U.S. Geological Survey, to chart the rugged terrain and the vegetation of the 1500-square-mile (4000 square \Jkilometre\j) peninsula.
After the teams had established the "ground truth" of these maps, they were able to establish a scientific basis for choosing which parts of the peninsula to set aside as most crucial to support the peninsula's rich diversity of species, and how much forest to leave outside the preserve as a functional buffer and support zone in which to develop sustainable economic alternatives to forest destruction.
The \Jbiology\j team had to conduct \Jbiodiversity\j inventories of birds, mammals, selected insect taxa and one of the world's most diverse collection of palms. They assessed the potential influence on diversity of gradients in rainfall, elevation, soil type, distance along the peninsula and distance from the forest's edge into the forest.
In the end, butterflies showed the way. Kremen and her colleagues at the Natural History Museum in London had earlier studied a group of brown "wood nymph" butterflies that have differentiated into more than 60 different species across Madagascar. Each species occupies its own niche, so the butterflies are an indicator that different types of soil, moisture and other conditions support a different mix of plants and animals in each of those habitat types. It was the first time that this application of butterflies as an "indicator species" was used to design a nature preserve.
And then to find out how large an area should be protected, the scientists assessed the ranges needed by wide-foraging animals like red-ruffed lemurs and the Madagascar serpent eagle, a species feared extinct, but rediscovered by the Peregrine Fund during the surveys.
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"Lemurs Are Doing Well",376,0,0,0
(Nov '97)
The Duke University lemurs, released on Madagascar last month, are starting to move further afield, though they have do not seem to have had any interactions with wild lemurs in the release area. After their arrival in Madagascar three weeks ago, the animals-Janus, Letitia, \JPraesepe\j, Sarph and Zuben'ubi-had spent time in an outdoor cage in the reserve, under the care of \JSan Francisco\j Zoo veterinarian Graham Crawford. During that time, all began eating fruits harvested from the forest, supplemented with commercial monkey food.
Before release on November 10, the lemurs' tail hair was trimmed to give each a distinctive pattern, so they could be better identified as they were tracked through the forest. After a brief ceremony, the doors were opened, and within five minutes, the lemurs were moving off.
Unfortunately, three animals immediately headed for the project's base camp and had to be recaught and released to ensure they would stay away from the familiar comforts of "home", while another moved too close to the territory of a wild group of ruffed lemurs, a contact which the researchers wanted to discourage early in the animal's adjustment to the wild. So, he had to be recaptured and freed near the release site.
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"Cassini, Last Glimpse For Now",377,0,0,0
(Nov '97)
Joseph Montani and colleagues at the University of \JArizona\j's Lunar and Planetary Lab in Tucson pointed their 36-inch Spacewatch \Jtelescope\j toward Cassini, which was 1 week into its mission to Saturn, late in October, and managed to detect the craft.
Cassini was moving at about three times the speed of an asteroid in the main belt, making the study a useful test. Certainly the observers had the advantage of a detailed \Jorbit\j to search along, but it was still a victory when the CCD (charge-coupled device) on the \Jtelescope\j registered the object, then nearly 5 million kilometres from Earth. We will have one more chance to see Cassini when it flies past Earth to gain some more speed on its trip to Saturn.
#
"Neutrinos Have a Cycle Too.",378,0,0,0
(Dec '97)
Science research is largely about designing better "models", simple descriptions of how things work and behave. Advances in science come when somebody finds a flaw in an existing model, or a better and simpler model that explains all of the same things.
The \Jsun\j has a large number of cycles associated with it, like the eleven-year cycle of \Jsunspot\j activity. Any model which explains the sun's operation has to take these cycles into account, and explain them as well.
Apart from the \Jsunspot\j cycle, there is a 157-\Jday\j periodicity that Eric Rieger of the Max Planck Institute in \JGermany\j found in the intensity of solar flares, and a 780-\Jday\j "quasi-biennial" periodicity that Kunitomo Sakurai from Kanagawa University reported finding in neutrino data from the Homestake neutrino detector in South Dakota. Now data from the same detector have yielded a new and rather more important cycle in the sun.
A December report in the \IAstrophysical Journal\i by Peter Sturrock, Guenther Walther, and Michael Wheatland, describes how Homestake data, collected over a 24-year period, show a 28.4 \Jday\j cycle in neutrino flux. The cycle has been dissected out using a complex statistical analysis, but it has only a 3% chance of being just a random pattern.
Neutrinos are not very exciting things to the casual observer. They are small, they have no charge, no rest mass, according to the "standard model", and the \Jsun\j does not seem to be producing enough of them. They are also very hard to detect, which could explain why we do not see enough of them, or maybe something happens, somewhere between the core of the \Jsun\j, where neutrinos form, and when they get here.
The three Stanford researchers favour a model for the \Jsun\j which involves magnetic fields that disrupts the neutrino flow, but if they are right, then our model for the neutrino is wrong. That is no great problem: the new model might help to explain the "missing mass" of the universe, and the shortage of solar neutrinos as detected at the \Jearth\j's surface as well.
As we understand the \Jsun\j now, light takes as much as a hundred thousand years to ooze and bounce its way from the solar core to the surface, and then it leaps across space, travelling the last 150 million kilometres in 500 seconds.
This slow travel to the surface would smear and hide most pulsations inside the \Jsun\j, burying them under layers of random "noise". Neutrinos, however, travel straight up from the centre of the \Jsun\j, passing through ordinary matter as if it did not exist, so any internal fluctuations would be preserved in the rate of neutrino arrivals at the \Jearth\j.
This same disdain for ordinary matter is what makes it hard to detect neutrinos, which is probably just as well, seeing something like a million billion (10\U15\u) solar neutrinos pass through your body each second. Occasionally, a neutrino passing through a vat of carbon tetrachloride (tetrachloromethane to the chemists, dry cleaning fluid to the old-fashioned) will change a single \Jchlorine\j atom into an \Jargon\j atom. If you have a large enough tank (around a hundred thousand gallons, half a million litres), and if the tank is deep enough below ground, so cosmic rays are blocked off, you may just be able to detect the odd neutrino now and then.
The Homestake gold mine became the first such home to a neutrino detector, a mile (1.6 km) below the ground. It only detects one "neutrino event" every two days, about a third of the predicted level, but this is in accordance with the results obtained at two other detectors, Kamiokande in \JJapan\j, and Gran Sasso in \JItaly\j.
One way of explaining the shortfall in the detection rate is to assume that the \Jsun\j is cooler than expected at its centre, but measurements of sound waves travelling inside the \Jsun\j imply a \Jtemperature\j of 15.6 million degrees \JCelsius\j, so that rules out any "cool \Jsun\j" explanation. This leads some physicists to assume that the neutrinos have a tiny but non-zero rest mass, and this is the favoured solution for the Stanford group.
Neutrinos come in three varieties, each associated with a different elementary particle (\Jelectron\j, muon and tau). According to some new theories, if neutrinos have mass, then they may cycle between the three different neutrino types (see Neutrinos--Do they have a mass?, June 1997). While the proposed neutrino mass is far too small to measure directly, if this \Jcycling\j can be demonstrated, then we would have a clear idea of why the shortfall occurs. Only one of the three types, the \Jelectron\j neutrino, is detectable, so if the neutrinos are \Jcycling\j through the three types, this would explain rather elegantly why only one third of the expected neutrinos are detected (except that there is no good reason why the three types should occur in equal amounts!).
With so few events, the Homestake data have normally been taken around four times a year, apparently making it impossible to detect a cycle as short as 28 days, but because the times are irregular, statistical analysis can be used to drag out the underlying pattern. Their first analysis, reported in 1996, claimed a 21.3-day cycle, but when this analysis was presented to a peer-reviewed journal, one of the reviewers was unable to duplicate their results, which eventually drew their attention to a transcription error in the Homestake data.
The 21.3-\Jday\j cycle disappeared, once this error was corrected, to be replaced by a 28.4-\Jday\j cycle which corresponds closely to the \Jsun\j's perceived rate of rotation, as observed from the \Jearth\j's \Jorbit\j around the \Jsun\j. As this rotation is a property of the outer "radiative zone", this suggests that whatever is causing the \Jcycling\j may be found not in the core of the \Jsun\j, but in the outer layers.
Each solution brings a problem-and perhaps a grain more truth. If the neutrinos are being affected by something in the \Jsun\j's outer layers, this must be tied up with magnetic fields in the \Jsun\j. But magnetic fields can only affect neutrinos if they have a \Jmagnetic moment\j, and standard model neutrinos do not have a \Jmagnetic moment\j. Not unless they also have mass, that is.
Neutrinos can spin in either direction, and these directions are called, by convention, left-handed and right-handed. Nuclear reactions produce left-handed neutrinos only, and only the left-handed neutrinos take part in nuclear reactions such as converting \Jchlorine\j into \Jargon\j. If different parts of the Sun have different strength magnetic fields, the flux of left-handed neutrinos will vary as they travel in different directions from the Sun. That would lead to a detection rate on Earth that varies with the Sun's rotation period.
This one will be worth watching.
#
"Space Junk A Hazard",379,0,0,0
(Dec '97)
Outer space is by no means as empty as we once believed, and near-\Jearth\j space is even worse. Our \Jplanet\j has a thickening layer of drifting debris such as small metal fragments and paint chips. Taken together, these bits and pieces can almost double the accident risk faced by some shuttle crews.
Radar surveys reveal that space junk is now a serious problem, with a fifty-year collection of abandoned satellites, nuts, bolts and fragments, all whirling around the \Jearth\j. These travel at about 7.5 kilometres a second (17 thousand miles an hour) in all sorts of elliptical orbits in all sorts of directions. Yet when the \Jspace shuttle\j was designed and built, there were many fewer bits and pieces up there, so the shuttles are only lightly protected.
At that sort of speed, a piece just 2/10" (5 mm) across can vaporise metal and send hypervelocity waves through the shuttle as it punches a fist-sized hole in whatever it hits. Radar systems on the ground can track the larger pieces of debris, but 95% of what is there is too small to be radar-visible from the \Jplanet\j's surface, and that 95% adds up to literally millions of odds and ends.
So now NASA is looking at ways of reducing the risk of damage from debris. During December, a report from the US National Research Council suggested that the risk of damage is as great as the risks from all other sources. Now NASA will be looking at changes in procedures, and also adding extra shielding to the shuttle's most vulnerable areas.
#
"How the Planets Influence Us",380,0,0,0
(Dec '97)
It looks as though the planets do influence our lives after all, though not quite in the way that astrologers would have us believe, and certainly not on the time scale of a single human life. University of Toronto physicist Jerry Mitrovica and Allessandro Forte of the Institut de Physique du Globe de Paris reported in \INature\i during December on their numerical simulations which show the connection between Earth's changing shape and the gravitational effects of other bodies in the \JSolar System\j, particularly Jupiter and Saturn.
The \Jearth\j's rotational axis precesses (precession of the equinoxes), turning slowly over a 26 000 year cycle. The obliquity of the \Jecliptic\j, the tilt of the Earth's axis, varies over a period of 40 000 years. As the precession and obliquity vary, so too does the \Jearth\j's climate, mainly because the pattern of the sunshine that falls on the Earth has been altered.
The researchers' simulations show that the obliquity and precession have been affected by the gravitational attraction of Saturn and Jupiter. At some time during the last 20 million years, the Earth passed through a gravitational \Jresonance\j associated with the orbits of Jupiter and Saturn, which in turn influenced the way the Earth's axial tilt changed during the same period. This gravitational pull would have had a much greater impact on the Earth millions of years ago when the Earth was shaped differently, says Mitrovica in a press release sent out on the \JInternet\j.
"To understand climate on Earth it's clear that we need to consider the Earth as this dynamic deforming system," Mitrovica added. "But we also need to understand, more than we thought we did, the Earth's place in the solar system."
#
"Mars News (Dec '97)",381,0,0,0
With more than 9500 pictures sent back by the Pathfinder mission, it took scientists into early December to complete their full analysis of the information. In the journal \IScience\i for December 5, the Mars Pathfinder imaging team reported that surface photographs provide strong geological and geochemical evidence that fluid \Jwater\j was once present on the red \Jplanet\j.
The 9669 pictures appear to confirm that a giant flood left stones, cobbles and rocks throughout \JAres\j Vallis, the Pathfinder landing site. More importantly, the researchers found evidence for a mineral known as maghemite-a very magnetic iron oxide. This forms in \Jwater\j-rich environments on Earth and could probably have been formed the same way on Mars.
So where did the \Jwater\j go? Did it evaporate into space, disappear into sub-surface aquifers as a liquid or freeze into ice below the surface or at the Martian \Jpoles\j? For now, nobody knows, but answering this question will be a major challenge for the next mission in 2001.
The images also reveal a dustier and more active \Jatmosphere\j than anybody had expected. There were even wispy, blue clouds, possibly made of carbon dioxide crystals (dry ice), travelling through Mars' salmon-coloured sky. White cirrus-like clouds, made of icy \Jwater\j vapour, also circulate throughout the thin Martian \Jatmosphere\j.
While the \Jweather\j is more active than expected, it is still puny by \Jearth\j terms. Some of the named Martian rocks like Yogi, Barnacle Bill and Scooby Doo must have been on the surface for millions of years to be carved and sandblasted by the weak winds of Mars.
Other reports in the same issue of \IScience\i identified a number of major finds. The better estimates of Mars' rotation rate and the wobble of the polar axis point to the \Jplanet\j having a dense, iron-rich core. The daytime \Jtemperature\j proved to be slightly warmer than that recorded by Viking I, and there was evidence for "dust devils" occurring. The Alpha Proton X-ray Spectrometer (APXS) on Pathfinder completed about a dozen chemical analyses and determined that the sampled rocks are high in \Jsilica\j, unlike the Martian meteorites, and probably represent a differentiated crust.
The Viking soil analyses and information from the twelve meteorites assumed to be of Martian origin pointed to a rather primitive surface composition, but this new evidence suggests that the Martian crust is probably as highly differentiated as the Earth's crust.
The sampled soils have a different composition from the rocks, and these soils may have formed by the addition of \Jmagnesium\j and iron from mafic rocks, like the Martian meteorites, to the locally eroded rocks during weathering. All of the observations and analyses suggest that Mars was indeed a warmer and wetter place a long time ago. Each of the five soil analyses gave similar results, and these were consistent with results obtained by Viking I.
Taken together, the evidence from the soils and from rocks such as Barnacle Bill (a felsic rock, low in \Jmagnesium\j, high in silicon and \Jaluminium\j) tells us that Mars must have a wide variety of geological types, just as our own \Jplanet\j does. This means that future expeditions will need to be highly mobile, in order to assess as many areas as possible.
#
"Jupiter News (Dec '97)",382,0,0,0
Meanwhile on Jupiter, there is oxygen at Callisto's surface, and there are sulphur dioxide sources on Io. In either case, you would be well-advised to hold your breath. The ultraviolet spectrometer on \JGalileo\j has detected \Jhydrogen\j atoms escaping from Callisto, which implies that the Mercury-sized moon has oxygen locked up in its ice and rocks. In 1996 \JGalileo\j detected evidence of oxygen on the surface of Callisto's neighbouring moon, Ganymede.
Ganymede's oxygen probably comes from collisions between charged particles from Jupiter's plasma torus and the icy surface of the moon. On Callisto, the main cause appears to be ultraviolet sunlight striking the icy surface, but the levels of oxygen present are going to be extremely low. So hold your breath, if you ever get there.
While Io's volcanic activity appears to be rather variable, the sulphur dioxide levels are maintained when SO\D2\d ice sublimes on the moon's surface.
#
"Gravitational Waves May Be Detectable",383,0,0,0
(Dec '97)
Dutch physicists, working in what is usually called the Grail Project, have concluded that a resonant antenna to detect gravitational waves is feasible. Gravitational waves have never yet been detected, but the workers believe a solid sphere of a copper-\Jaluminium\j alloy with a diameter of more than three metres, weighing more than a hundred tonnes, and held almost at \Jabsolute zero\j, may just be what they need to succeed. They hope to have their first successful results in 2002.
Gravitational waves should occur when several masses are accelerated with respect to each other. If you jump from a ladder, you are accelerated with respect to the \Jearth\j, and should create a gravitational wave, which will then spread out into space. But just as a small pebble only makes a small splash, serious gravitational waves will only be found when a massive star collapses to form a neutron star, or when material is pulled into a black hole.
The massive copper sphere will vibrate when the waves from such an event reach it. The spherical shape of the antenna means that each direction will be equally favoured, a vibration-free suspension will protect the antenna from other rumblings, and sensitive microphones will detect any signal and magnify it.
The instrument will be so sensitive that cosmic particles might set it off, so it will probably need to be located deep underground, and its extreme cold, between .01 and .02 kelvin, should guarantee that thermal interference is avoided or ruled out. The instrument will measure a range of frequencies between 100 and 150 hertz wide, centred on 700 Hz.
The alloy was chosen to have no residual magnetism, and a thermal \Jconductivity\j which will allow rapid cooling of the entire sphere. The anticipated degree of movement will be of the order of 10\U-21\u metre, and this will require the use of five examples of a superconducting quantum interference device (SQUID). For more information, look to www.nikhef.nl/pub/projects/grail/grail.html
#
"Teleportation A Tiny Step Closer",384,0,0,0
(Dec '97)
That long-standing dream of Star Trek fans, particularly the ones who have to commute, the teleportation device, came a tiny step closer during December. But so far, it only works on single photons, so there is a way to go before this is a successful commuting method.
Anton Zeilinger and his team at the University of Innsbruck in \JAustria\j have shown that part of the spin orientation of a \Jphoton\j of light can be transferred instantaneously to another \Jphoton\j, no matter how far away it is. This appears to be the first experimental demonstration of quantum teleportation, the transfer of a quantum state from one particle to another, which was first proposed as a thought experiment by \JIBM\j's Charles Bennett and his collaborators in 1993.
Before that, Albert Einstein knew of the basic concept, but rejected it, calling this notion of action at a distance spooky. All the same, this was a process that was due to appear about now: a second research group in \JRome\j has achieved similar results, which will be published soon in another journal.
In the future, this process might help physicists build superfast quantum computers, by providing a safe way to communicate delicate quantum information. The trick relies on creating a pair of photons that are intimately related. When \Jlaser\j light is fired into certain crystals, individual photons can split into two identical twins, with a special property: they are "entangled" in the terms of a quantum physicist. In plain terms, the sum of the two offspring photons has to equal the original quantum state.
This means that when you measure, say, the spin of one \Jphoton\j, and find that its spin is up, the entangled twin is instantly forced into the opposite state-spin down-no matter how far it has travelled. As Bennett describes it, suppose a sender called Alice makes a combined measurement of the "message \Jphoton\j" and one member of the entangled pair. This forces the two photons measured by Alice to have opposite states. At the same time, the second member of the entangled pair is forced into a specific state.
Now the recipient, Bob, makes a measurement specified in advance by Alice, and he finds that the entangled \Jelectron\j has a state which is identical to that of the original message \Jphoton\j. One of the limitations of the method is that only information flows from Alice to Bob, being transferred from one \Jphoton\j to another. "It's more like faxing than teleportation", said one physicist.
Charles Bennett commented that we were so far away from teleporting even a bacterium that it was not worth thinking about. Zeilinger believes we might be able to teleport atoms within a few years, and molecules within a decade or so. But if the whole concept seems difficult, don't worry too much. Zeilinger says he does not really understand how it works either.
#
"Finding Landmines",385,0,0,0
(Dec '97)
The recent Nobel Peace Prize award to Jody Williams and ICBL (see October), coupled with the death of Diana, Princess of Wales, has made the public far more aware of land mines. The guerrilla fighter's dream: mines can cost as little as a dollar, they are easy to make, they are often lethal and they cannot be detected by current technology. But that last qualification may be about to blow away.
Research which will be published in the February 1998 issue of \IPhysical Review E\i, indicates that weak shock waves sent into granular beds like soil, will cause acoustic signals containing critical information to be reflected off buried objects, such as land mines. Surajit Sen, who has been working and publishing on this topic for several years, believes that his work will lead to an accurate and inexpensive detection method effective for land mines in either plastic or metal casings.
It was only after his first publication that Sen watched a \Jtelevision\j news report about land mines and realised that his work might be able to be applied in this way. The shock waves are able to detect the shape and size of the object they bounce off, and also to provide information about the density of the object they are reflecting from. Sand, for example, has a density of around 2700 \Jkilogram\j per metre cubed, while plastic is lighter, with a density of around 1100 kg/m\U3\u.
Sen envisages a "special microelectromechanical device that would send weak acoustic shock waves deep into soil and detect the pulses that are returned after hitting an object". The bad news: the system has worked well, so far, but only in simulation. The next step will involve testing in sand and soil boxes, before going on to field trials.
#
"Free Supercomputer Anyone?",386,0,0,0
(Dec '97)
After the Stone Age came the Silicon Age, and after the Silicon Age, came the Age of the Stone Souper. "Stone Soup" is a \Jfable\j about a soldier who persuades villagers to help him make soup from a stone, each villager contributing something small to the pot to "make the stone soup better". In the computing world, the best-known application of the Stone Soup principle has probably been the development of Fractint, a fractal program for PCs of many flavours, although the \JInternet\j owes its existence to a similar process.
Now the term may take on an entirely new meaning as people emulate Forrest Hoffman and Bill Hargrove of Oak Ridge National Laboratory (ORNL) in \JTennessee\j. They were refused funding to build a parallel supercomputer, a machine made by wiring together a collection of individual PCs, which divides massive calculations into small chunks, farming out each one to a single PC that sends a crunched number back to a central processor to be integrated with the rest.
They managed to scavenge 48 PC 486s and strung them together in an empty floor of an ORNL computer building. Their Stone Souper, which carries out 1.5 million calculations per second, is only one-seventh as fast as a "real" parallel computer built with state-of-the-art components. All the same, it performed the cumbersome statistics that Oak Ridge environmental researchers needed to make a US map, with four soil variables plus elevation, showing which regions are best suited for growing certain plants.
And the best news? People are starting to discard Pentium computers, and just so long as people continue to discard and upgrade, there will be people there, ready and willing to use their leftovers to make a tasty pot of Stone Soup.
#
"Making the Net Faster",387,0,0,0
(Dec '97)
Next to making a faster computer, there can be no greater joy than making the Net faster. On December 22, computer scientists at Washington University in St. Louis announced that they have patented two major inventions that should make \JInternet\j applications like e-mail, the World Wide Web and electronic commerce 10 times faster than they are now.
It now takes 1.2 microseconds to look up an \JInternet\j address: the new system will allow this to be done in just 100 nanoseconds, a better than tenfold increase in speed. This will increase the throughput of every packet of data passing across the \JInternet\j.
While links between computers are getting ever faster, the routers that pass messages on are not getting faster, leading to the risk that they will cause bottlenecks. The number of computers on the \JInternet\j is tripling every two years, and more complex messages and files are sent as people add multimedia, audio and video to their Web pages and transmissions.
When a router receives a message you have sent, it reads the \JInternet\j (IP) address, and determines which of many links it will pass the message along to. If it is a large message, your e-mail may be in a number of separate packets, and each needs to be examined separately.
In simple terms, it would help if the router had a lookup table that gave the correct links for every \JInternet\j address in the world, but this would make for a huge \Jdatabase\j, so the trick is to take the IP address in chunks. This keeps the \Jdatabase\j size down, but makes the lookup task more complex.
Real \JInternet\j addresses are not those odd little "me@myISP.com" addresses we all know and use, but sets of numbers, read in binary form by computers. We each have one of the approximately four billion IP addresses ranging from 0.0.0.0 to 255.255.255.255-these are the so-called 32-bit addresses, to be replaced at some point in the future by 128-bit addresses. While there are enough addresses available for all the world's literate people, if you want your toaster and washing machine to be controlled over the \JInternet\j next century, they will need their own IP address as well!
Routers today carry a \Jdatabase\j of about 40,000 prefix entries only, and use this to pass data packets along, but because there are 32 possible lengths for prefixes, processing is still too slow. Eight companies have now signed non-disclosure agreements, and are looking more closely at the methods developed by George Varghese, Venkatachary Srinivasan, Jonathan S. Turner and Marcel Walgvogel, and their university hopes soon to enter into licensing agreements.
December saw a redating of the northern Australian sediments at a site where humans may have been present more than 100 000 years ago. The previous dates, using thermoluminescence, had been recognised as having a possible flaw: a few old grains would raise the average age of the deposit considerably. Now individual grains have been dated, and it appears that the site was only some 40 000 years old, with contaminating grains in the deposit.
In the same month, the date for the arrival of the first "native Americans" (who were then Asian immigrants) has been pushed back to about the same date of 40 000 years ago. This was reported in December's \IAmerican Journal of Human Genetics\i. This finding may help to reconcile the disagreement between geneticists who believe that Native Americans descended from a single wave of immigrants, and the archaeologists who believe that the great cultural diversity of the new arrivals' descendants points squarely to a settlement that came as multiple waves.
Mitochondrial DNA is always passed from mother to child, and never from the father. Some parts of the mitochondrial DNA have no function, and so are free to mutate. In a large population, this happens almost as regularly as clockwork, explaining why mtDNA is sometimes referred to as a biological clock.
Over time, groups which began with the same ancestry, will diverge. From the number of mutations between two groups, we can estimate how far back they separated from each other. All Native American groups share four typical mutation patterns, resembling those seen in some modern Asians, suggesting that a single group of Asians gave rise to all Native Americans. Using the characteristic patterns found in short sections of mtDNA suggested an arrival date of around twenty to thirty thousand years ago.
Now Sandro Bonatto of the Universidade Federal do Rio Grande do Sul in \JBrazil\j, working with Francisco Salzano, has looked at the DNA sequences of more than 700 individuals from 20 Native American groups. The results point to modern Native Americans sharing a single group of ancestors who lived in \JNorth America\j at least 25 000 years ago, and more probably between thirty and forty thousand years ago.
Of course, this difference could have arisen before the various groups crossed the Bering land bridge which joined \JAlaska\j to \JRussia\j, but it is also possible that the first immigrants arrived in north America forty thousand years ago, split up, and began to develop the different cultures which seem to have been in place by ten thousand years ago.
#
"Artificial Life By Way of Symbiosis",389,0,0,0
(Dec '97)
On December 14, 1967, biochemists Arthur Kornberg and Mehran Goulian announced the creation of an artificial copy of DNA that was biologically active and could infect cells. On December 11, 1997, D H Lee, K Severin, Y Yokobayashi & M R Ghadiri reported in Nature on a set of two self-replicating molecules with a symbiotic relationship. The two \Jpeptide\j chains or proteins might be seen as competitors for resources, but each catalyses the formation of the other.
It began last year when chemist Reza Ghadiri of The Scripps Research Institute in La Jolla, \JCalifornia\j, announced the discovery of the first protein that could reproduce itself. When this was present in a system, it made the assembly of other fragments happen faster, but that did not make the molecule "alive". Ghadiri wanted to see a "molecular \Jecosystem\j," in which several molecules interact to promote each other's survival.
So far, Ghadiri's laboratory has come up with about eight replicating protein fragments. Two of these, called R-one and R-two, have a common segment, called \Jpeptide\j E, and slightly different versions of a second piece. Because each replicator needed the same resource, \Jpeptide\j E, they might be regarded as competitors, when they were together, the two types grew five times as fast.
This form of reproduction, termed a symbiotic hypercycle, was proposed by Nobel laureate Manfred Eigen in 1971, but now the theory has turned into reality. The big surprise for chemists, though, is that it turned up among peptides, rather than among nucleic acids.
#
"South American Fossils in Madagascar and India",390,0,0,0
(Dec '97)
A group of mammals, the Gondwanatheria, previously known only as fossils from Argentina, have now been located in both Madagascar and India. The 65-70 million year old mammals, dating from the Late Cretaceous period, are not related to any groups living today and are known commonly as gondwanatheres.
The fossils have been identified as teeth, but these are highly distinctive. Finding them so widely dispersed is going to require some rethinking of the main ideas of \Jplate tectonics\j. Their name, which literally means "Gondwana mammals" now looks a little suspect, though it is more likely to represent independent support for a recent revision of plate tectonic theory, which has India and Madagascar attached to eastern \JAntarctica\j in the late Cretaceous.
No gondwanathere remains have been found in Africa so far, supporting the \Jfossil\j evidence from dinosaurs, which implies that Africa was isolated at that time.
#
"Water Trapped In Earth As Crystals",391,0,0,0
(Dec '97)
While some people think the \Jearth\j's surface \Jwater\j comes from small comets in space, Professor Joseph Smyth told a American Geophysical Union meeting in \JSan Francisco\j during December that the \Jearth\j's interior may contain three to five times the \Jearth\j's surface \Jwater\j locked within billions of crystals. He suspects that this trapped \Jwater\j could help regulate the level of \Jwater\j on the surface of the \Jplanet\j.
Ten years ago, Smyth discovered that a mineral called wadsleyite, located 250 miles to 350 miles below the \Jearth\j's surface, could contain \Jwater\j, not as a liquid, but as the elements needed to make \Jwater\j, bound into the solid crystals, giving the crystals a 3.3% \Jwater\j content.
The wadsleyite is found in the \Jearth\j's mantle, and when convection brings some of the mineral to the surface at the volcanic vents of mid-ocean ridges, the \Jwater\j might be released, says Smyth. He is currently trying to make wadsleyite in the laboratory to study it: in its own environment, wadsleyite is stable at a pressure of about 3 million pounds per square inch (20 million kPa) and a \Jtemperature\j of about 3000░F (1650░C).
#
"Big Quakes May Be Gentler",392,0,0,0
(Dec '97)
The \JMexico City\j \Jearthquake\j of 1985, the Newcastle \JAustralia\j \Jearthquake\j of 1989, and the Kobe \Jearthquake\j of 1995 all had one thing in common. Buildings on unconsolidated sediment were badly shaken by an effect which causes structures built on soil shake harder than those perched on bedrock. Under some conditions, the shaking can be three times as great on loose sediments such as sand, landfill, and loose soil.
A report in \INature\i this month indicates that for larger earthquakes, the \Jmagnification\j may be less than for small earthquakes. This had been predicted from laboratory studies, and even incorporated into building codes, but many seismologists expressed concern about extending lab simulations to the real world.
Now they need worry no more. A careful analysis of the records of the 1994 Northridge \Jearthquake\j provided Edward Field of the University of Southern \JCalifornia\j in Los Angeles and his colleagues with the data they needed to resolve the question. Data from 21 seismic stations for the 6.7-\Jmagnitude\j main shock of the Northridge quake and 184 aftershocks provided the answer: while aftershock \Jmagnification\j ranged from a factor of 1.4 to 3.1, during the main event, ground shaking in sediment was never more than 1.9 times higher.
#
"Genome of Tuberculosis",393,0,0,0
(Dec '97)
\IMycobacterium tuberculosis\i has 4.41 million base pairs, and now we know them all. The chemical composition of the \Jgenome\j made it one of the most challenging yet to sequence. This is because the DNA is packed with stretches rich in two bases, \Jcytosine\j and \Jguanine\j, which tend to stick together, turning a DNA strand into a nasty knot.
Tuberculosis kills some 3 million people in the world each year, and is becoming increasingly dangerous (See Antibiotic-Resistant Bug Found, April, and Tuberculosis in the News, November), so this information will be an important addition to our medical armoury. Apart from anything else, this knowledge should allow researchers to develop tests which will quickly distinguish lethal TB strains from innocuous "cousins".
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"Genome of a Spirochaete",394,0,0,0
(Dec '97)
The \Jgenome\j of the bacterium \IBorrelia burgdorferi\i B31, the cause of Lyme disease, has been reported in \INature\i during December. The \Jgenome\j contains a linear \Jchromosome\j of 910,725 base pairs and at least 17 linear and circular plasmids with a combined size of more than 533 000 base pairs. The \Jchromosome\j contains 853 genes encoding a basic set of proteins for DNA replication, transcription, translation, solute transport and \Jenergy\j \Jmetabolism\j.
This is the first spirochaete \Jgenome\j to be sequenced, and the first procaryotic \Jgenome\j to contain several genetic elements. Lyme disease is the most common vector-borne disease in Europe, the United States and parts of Asia, while it is also becoming more common in \JAustralia\j.
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"Genome of an Archaebacterium",395,0,0,0
(Dec '97)
The Archaebacteria are a group of bacteria regarded as ancient when compared with other bacterial kingdoms. They usually exist in extreme environments, and include not only the methanogens, but also the "salt-loving" or halophilic bacteria, and the sulphur-acid tolerant thermoacidophilic bacteria.
\IArchaeoglobus fulgidus\i is a sulphur-metabolising archaebacterium. A group of 51 authors at three USA institutions reported the determination of the complete \Jgenome\j sequence of \IA. fulgidus\i in \INature\i in late November. The bacterial \Jgenome\j has 2,178,400 base pairs.
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"Dog Genome Gets Closer",396,0,0,0
(Dec '97)
At the same time, scientists have produced a rough map of the genetic blueprint of dogs, which has just been published in the journal \IGenomics\i. A map like this, while less than a complete base-pair \Jgenome\j, identified a set of molecular signposts along the gene. So researchers, rather than searching for a needle in a haystack, can now search for the same needle in a cup of hay.
There are more than 300 distinct breeds of dogs with a range of genetically defined shapes, sizes, and temperaments, many of which carry a predisposition to certain diseases, many of which also occur in people. By comparing the genes found in different breeds which do or don't get a particular disease, the "needle", a gene causing the problem, can then be spotted. Problems ranging from hip problems to \Jepilepsy\j to \Jblindness\j may be open to attack in this way.
The map for dogs has a marker every 14 million bases-for comparison, the human map now has markers at every one million base pairs. This is like having a map with states and cities on it, but no detail of the streets in the cities just yet.
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"Tubulin Unveiled",397,0,0,0
(Dec '97)
The protein that makes up the cell's internal rail system, transporting everything from proteins to DNA, has now had its structure revealed. Announced just before Christmas, with publication due in \INature\i on January 8, the new knowledge may help researchers design such things as better anti-cancer drugs and fungicides.
The structure reveals how the two parts of the molecule interlock. It also shows the binding site of taxol, an important anti-cancer drug that works by setting up "roadblocks" on the microtubule highway. That information might allow researchers to design a family of microtubule disrupters. (An unrelated report, a few days earlier, indicates that taxol may also be useful in combatting Alzheimer's disease.)
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"Chicken Flu Virus Scare",398,0,0,0
(Dec '97)
"A brave family ate a large chicken as part of traditional Chinese celebrations of the winter solstice yesterday with more than 10 friends and relatives", reported the \ISouth China Morning Post\i. A cluster of illnesses due to infection with avian influenza A (H5N1) virus seized the imagination of the world's media as Christmas approached. With no evidence that there is any risk of a major outbreak, each death from the "new virus" was reported breathlessly, and Hong Kong's "school zoos" and pet corners faced a loss of all the children's feathered friends.
The "brave family" was not really taking any risk, not if the chicken was properly cooked. The new virus was easily identified from a number of tests in Rotterdam, \JAtlanta\j, and London. It is a known strain which causes influenza in birds, which now seems to have acquired the ability to transfer from birds into humans, but until it acquires the ability to transfer from human to human, it represents no great threat to the world.
Although evidence of person to person transmission has not been found so far, scientists are researching possible vaccines against this virus, "just in case".
The first case surfaced as far back as May, 1997, when a three-year-old boy died of Reye's Syndrome (a rare disease involving the liver and central \Jnervous system\j, which can be assosiated with influenza B, influenza A or \Jchickenpox\j). The boy was later found to be carrying the H5N1 virus. The second case did not arise until November. By the end of the year, four people had died, and sixteen cases were known, but in the absence of any evidence of human to human transmission, no quarantine or travel restriction recommendations appeared necessary, according to the World Health Organisation.
Before the May case, the disease was known to occur in chickens and ducks, although it was first isolated in terns in South Africa as far back as 1961. In the northern spring of 1997, thousands of chickens died of the disease in Hong Kong. In 1983, H5 influenza outbreaks in poultry farms in the USA killed many birds, and cost $61 million to bring under control, but there were no cases of human infection at that time.
More cases were anticipated for January, if only because medical authorities are now on the lookout for the disease, and will be testing 'flu victims more carefully. In fact, it is likely that the new cases reported in December were more a result of better surveillance of Hong Kong's 6.5 million people, rather than a sign of a "flare-up".
There was one reported "family cluster", and work was still going on to identify what appeared to be a common cause as this report was being prepared. While live chickens are the prime suspects, rats, mice, dogs, cats and other domestic and wild birds, in Hong Kong and the vicinity are also under investigation.
Usually, bird influenza only transfers into humans after it has become established in another \Jmammal\j first. And because the affected humans have never encountered the new influenza variety before, they have no resistance to it. Flu viruses commonly change their surface proteins, the parts that our immune systems recognise, through a process called "drift". The real worry is whether we are going to see a "shift", when major changes happen in the proteins. A shift is believed to occur when two different strains of virus come together in the same host.
The WHO Collaborating Centre at CDC (Centers for Disease Control, \JAtlanta\j) has also prepared a kit of reagents which will be despatched shortly to 110 National Influenza Centres in 82 countries for diagnosis of H5N1, and at the end of December, more than a million chickens were condemned to death as the first reports of confirmed human to human transmission were heard.
Meanwhile, During 1997, Djibouti had 41 deaths from \Jcholera\j, \JKenya\j 55, \JSomalia\j 248, \JTanzania\j 1720 and Zanzibar 122 deaths, with another 70 deaths in \JKampala\j. In Sierra Leone, a respiratory illness similar to influenza affected 2000-3000 people and killed 36 between September and December, and some 2.5 million people died of AIDS in 1997.
These outbreaks, however, did not seem to rate the same media prominence. It would be unkind to suggest that the difference might arise from Hong Kong being a major trading point and well-connected to the western world which owns and consumes those media.
No doubt they were remembering the 20 million killed by the 1918 flu epidemic, caused by a virus derived from swine (pig) flu, or the "Asian flu" of 1957-58 and the "Hong Kong flu" of 1968-69, both avian (bird) flu, which killed thousands of westerners. The symptoms of influenza were first described by \JHippocrates\j in 412 BC. The first well-described pandemic of influenza-like disease occurred in 1580. Since then, 31 possible influenza pandemics have been documented.
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"Why Red Wine is Good For The Heart",399,0,0,0
(Dec '97)
Red wine is good for the heart (Wine Good For The Heart?, November), but now we know why. A December report reveals that resveratrol, described as a form of oestrogen, is highly concentrated in the skin of grapes and is abundant in red wine.
Resveratrol protects grapes and some other plants against fungal infections. It has been shown previously to have a number of potentially beneficial properties, including antioxidant, anticoagulant, anti-inflammatory and anti-cancer effects. It has a molecular structure similar to that of diethylstilbestrol, a synthetic oestrogen.
A study reported in the December 9 issue of the \IProceedings of the National Academy of Sciences\i confirms that the substance has oestrogen-like properties, and interestingly, the authors indicate that resveratrol could replace oestradiol in supporting the proliferation of certain breast cancer cells that require estragon for growth.
Strictly speaking, there is no compound called "oestrogen": it is a category of substances defined by their biological effect. Originally named for their ability to induce oestrus ("going into heat") in animals, oestrogens act on cells by binding to a protein called "oestrogen receptor", which then causes certain genes to be expressed, or "turned on."
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"Immunoglobulin E a Killer?",400,0,0,0
(Dec '97)
Immunoglobulin E, or IgE, the antibody responsible for hayfever, appears also to be involved in \Jmalaria\j. At an \Jimmunology\j conference in Britain during December, Dr Marita Troye-Blomberg of Stockholm University, Sweden explained why she thinks that IgE could be a killer.
Malaria kills between 1.5 and 3 million people a year, of the estimated 300-500 million people who are infected with \Jmalaria\j. The most common deadly form is cerebral \Jmalaria\j, in which blood clots form in the brain, and cerebral \Jmalaria\j patients have higher levels of IgE type \Jantibodies\j in their blood than people with milder forms of the disease..
IgE is produced in response to the mouse parasite \IPlasmodium chabaudi\i, which is related to the malarial parasite, \IPlasmodium falciparum\i. The IgE \Jantibodies\j stimulate the immune system to produce a messenger molecule called \Jtumour\j necrosis factor, or TNF. While TNF helps the body fight malaria, people who produce excessive amounts of TNF have an increased risk of dying from cerebral malaria.
Studies of twins reveal that identical twins produce very similar amounts of IgE whereas non-identical twins do not, suggesting that the amount of IgE produced by an individual is genetically controlled, and there seems also to be a genetic link to the amount of TNF an individual produces in response to IgE. The implication: if researchers try to make immunoregulatory drugs against \Jmalaria\j, they will need to tread carefully, to make sure they do not do more damage than good.
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"Genetic Mutation Responsible For Allergies?",401,0,0,0
(Dec '97)
A December report in the \INew England Journal of Medicine\i says that some \Jallergy\j-prone people seem to have a genetic flaw that makes them more susceptible. A group of researchers have identified a gene which appears to be found in patients with either severe skin allergies or hyper-IgE syndrome, a rare condition in which the body produces too much IgE. They found an identical genetic \Jmutation\j in seven of their 10 patients.
When they tested fifty healthy adults for both the \Jmutation\j and for above-average IgE levels, they found the \Jmutation\j in 13 of 20 people with elevated IgE levels, but only in five of 30 people with normal IgE levels.
#
"Asbestos Transformed",402,0,0,0
(Dec '97)
According to scientific \Jfolklore\j, one insurance company, as early as 1917, refused to insure the lives of people working in the \Jasbestos\j industry. In 1971, your reporter was called a dangerous troublemaker for barring \Jasbestos\j mats from a school laboratory: just a few years later, the mats were entirely banned, and schools were being closed when \Jasbestos\j was found in them. Today, we all know that \Jasbestos\j is a very dangerous substance, but what do you do with it?
Removing \Jasbestos\j throws small fibres into the air, fibres which can be breathed into people's lungs to cause later damage. So in some cases, the safest thing is to immobilise the \Jasbestos\j that was once used to fireproof homes, schools, and offices, by painting it or covering it in cement, but this reduces the fireproofing properties. Now a new \Jfoam\j has been announced which also breaks down the \Jasbestos\j fibres. This \Jfoam\j transforms \Jasbestos\j to a harmless silicate compound while leaving the fireproofing intact.
The \Jasbestos\j eater, announced by the chemical company W. R. Grace and the Brookhaven National Laboratory in December, contains acids and \Jfluoride\j ions that convert the cancer-causing the fibres of \Jasbestos\j to become an amorphous form which seems to be just as useful as the original fibres, while losing the carcinogenic properties.
#
"Kyoto Environmental Conference Report",403,0,0,0
(Dec '97)
The \JKyoto\j conference on greenhouse emissions has finally taken place, and cuts have been agreed for carbon dioxide emissions, with the European Union reducing its emissions by 8% below 1990 levels by 2010, \JRussia\j, \JJapan\j and the USA reducing their emissions by 5%, and \JAustralia\j and \JNorway\j being allowed a 5% increase, with other countries falling somewhere between, according to the proposals of Raul Estrada-Oyuela of Argentina, who chaired the meeting.
The proposals cover only CO\D2\d, \Jmethane\j and nitrous oxide: HFCs, PFCs and SF\D6\d will need to be argued over at the next meeting, at Buenos Aires, in 1998. The question of countries such as the USA, Canada and \JRussia\j forming a carbon "club" to trade emissions will also need to be discussed at that meeting. In summary, the conference achieved, at best, a modest gain for the world.
#
"Global Warming Confirmed",404,0,0,0
(Dec '97)
A new 300-site survey of borehole temperatures spanning four continents and five centuries has confirmed what most scientists already believe-the Earth is getting warmer and the rate of warming has been accelerating rapidly since 1900. Subsurface rock temperatures confirm that the average global surface temperature has increased about 1░C. (1.8░F.) over the last five centuries with half of that warming taking place in the last 100 years. And 80% of the rise occurred after 1750, when people began making a serious use of \Jcoal\j as a fuel.
The boreholes were in Europe, \JNorth America\j, \JAustralia\j and South Africa, and the data were presented to the American Geophysical Union at a \JSan Francisco\j meeting during December. Sensitive thermometers were lowered into boreholes drilled from the surface to obtain the data. Because subsurface rocks preserve a record of actual surface \Jtemperature\j changes over time, boreholes are an important data source for scientists studying global climate change. Short-term changes, such as seasonal variations, penetrate only a few metres underground. Long-term changes on scales of hundreds of years are preserved at greater depths.
#
"African Weather",405,0,0,0
(Dec '97)
Over the past 25 thousand years, Africa's climate has varied wildly, with the continent's rainfall and average temperatures suddenly plunging or rising, dozens of times. The evidence for this claim is based on core samples taken by the Ocean Drilling Program's drill ship, the \IJOIDES Resolution\i, from about 10 miles (15 kilometres), at 20 degrees north latitude and 18 degrees west longitude, off the coast of \JSenegal\j. Rapid \Jsedimentation\j means that a 2.5 cm (1 inch) layer of sediment represents about eighty years of history, and in that core, dust from desert dust storms and plankton remains, reflecting past ocean temperatures, told a clear story of rapid change.
There were literally dozens of periods when the climate shifted drastically within the space of a century. It has been normal to assume that climate shifts were slow and gradual, but future climate changes in Africa could be just as rapid, they warn.
Interestingly, the study offers further confirmation of the 1500-year cycle in the \Jearth\j's climate, reported last month (The Earth's 1500-Year Rhythm, November). According to Peter deMenocal, a palaeoclimatologist at Columbia University's Lamont-Doherty Earth Observatory, Africa becomes dramatically colder and wetter every 1,500 years, and stays that way for centuries. And this cycle of cold-wet, then warm-dry periods exactly matches a pattern of dramatic, abrupt changes in the North Atlantic region reported last month, which was the work of another Lamont-Doherty researcher.
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"Cold Snap 8200 y.a.?",406,0,0,0
(Dec '97)
A team of palaeoclimatologists in America told the American Geophysical Union in \JSan Francisco\j how, 8200 years ago, the world climate suddenly got colder and stayed that way for a few hundred years before temperatures returned to normal. They have dubbed this the "8k event", and they say that it was short, compared to other, more distant events, lasting only about 200 years.
In the cold snap, temperatures dropped 11░F (6░C), and is clearly shown in the temperature record from the \JGreenland\j ice cores, but also in ice accumulation, in the indicators of forest fires and in the amounts of \Jmethane\j found in the \Jatmosphere\j. The researchers believe that the event may be linked to the shutdown of the ocean conveyor system (see Global Warming: Could We Lose The Conveyor?, November) which drives, among other things, the Gulf Stream.
#
"New Toxin To Combat Insect Pests",407,0,0,0
(Dec '97)
\IBacillus thuringiensis\i, or Bt to its farmer (and other) friends, has been a pest-control mainstay for the past thirty years. It has had close to a monopoly of the role during that time. Now a new bacterium, \IPhotorhabdus luminescens\i, has been found to contain a toxin which has proven effective against a broad array of insect pests, from household cockroaches to the boll weevil pest of American cotton farmers..
\IPhotorhabdus\i is a widely-dispersed, multiple strain bacterium that lives inside of, and in symbiosis with, soil-dwelling called \Jnematode\j roundworms. The nematodes invade the insects, release the \Jbacteria\j, which then turn the insects into a protein-rich "soup", suitable food for large numbers of nematodes.
The genes of Bt have since been transferred to a number of plants, and 1998 will see an estimated 3 million to 5 million acres of Bt transgenic corn planted in the Midwest of the USA alone. The genes responsible for the Photorhabdus' toxin have already been sequenced, and may well be seen in plants within the next three to five years.
#
"Pill To Combat Mosquitoes",408,0,0,0
(Dec '97)
An American researcher, Dov Borovsky, wants to put mosquitoes on a diet, to turn them into whining anorexics which starve to death. He has developed a mosquito "diet pill" which alters mosquito digestion, making it impossible for them to feed, lay eggs or survive.
There are more than 3000 species of mosquitoes. Worldwide, mosquito-borne diseases infect about 700 million people each year and kill at least 3 million. Borovsky's pill will work on all of them, and he is even willing to share his "recipe", which has a certain resemblance to lines written by W. Shakespeare when he was developing what actors call "the Scottish play".
See if you think the three witches would like this recipe: first, take a hundred thousand mosquito ovaries, dry and crush them into a powder that contains their digestive control hormone. From the nearest pool or pond, scrape off the green scum, also known as \IChlorella\i, an alga. Insert the hormone into the \IChlorella\i, make it into a pill, then place the pill into any \Jwater\j body where mosquitoes are known to breed. Then watch the larvae feast on the \IChlorella\i. Famine follows.
"Fortunately, now we can synthesise the hormone, so we don't have to use 100,000 ovaries for each batch any more," Borovsky says. The synthesised hormone is inexpensive, as is \IChlorella\i, which is found and produced worldwide. \IChlorella\i, in fact, turns out to be the perfect ride for the mosquito hormone, because it can be freeze-dried and stored for long periods and then brought back to life as the deadly diet pill.
Better still, the \IChlorella\i stops producing the hormone within three weeks, making it safe to use in the environment, and this is a deliberate design feature, since mosquitoes continually exposed to the poisoned \IChlorella\i might develop resistance to it. As the hormone gene sits outside \IChlorella\i's \Jgenome\j, and after the third cell division, it is no longer detectable.
Of course, as Borovsky points out, if mosquitoes become resistant to their own reproductive hormone that could have unknown adverse consequences for them as well. It seems to be a lose-lose situation for the mosquitoes..
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"Gorilla Census",409,0,0,0
(Dec '97)
A new count of mountain gorillas in \JUganda\j's Bwindi Impenetrable Forest National Park has found almost 300 of the giant apes, bringing the total to around 600 for this most endangered gorilla sub-species. There were 292 gorillas in 28 groups, as well as seven lone silverbacks (adult males).
The researchers followed trails and counted nests. Each night, gorillas build a new nest, and researchers can tell the age of the animal that slept there by the size of dung piles left behind, and if it is a female by the presence of infant dung. In addition, silvery hairs found in the nest can reveal the presence of adult males. Researchers collected hairs from every nest for DNA fingerprinting, to confirm that no groups were counted twice.
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"Japan Prize Results",410,0,0,0
(Dec '97)
A Japanese physicist and two Belgian geneticists have won the 1998 Japan Prize, one of the world's richest science awards, announced on December 19. Physicist Leo Esaki will receive 50 million yen, about US$391,000, and geneticists Jozef Schell and Marc Van Montagu will each get 25 million yen, about US$196,000.
Esaki, 72, was awarded the prize for the category "Generation and Design of New Materials Creating Novel Functions." His work was on superlattice crystals, which are composed of layered thin films. These crystals exhibit a number of novel electronic properties, such as the ability to carry current at discrete voltages. The technology is at the heart of semiconductor lasers used in optical telecommunications systems, sensors in wireless communications devices, and in devices that read stored data in the coming generation of computer hard disks.
Schell, 62, of the Max Planck Institute in Cologne, \JGermany\j, and Van Montagu, 64, of the Flanders Interuniversity Institute for Biotechnology in \JGhent\j, \JBelgium\j, are to share the prize in the category "Biotechnology in Agricultural Sciences." They were honoured for developing a method of inserting foreign genes into a plant, leading to transgenic plants which can resist insects or diseases.
The prizes will be conferred in April 1998. The 1999 categories for the \JJapan\j Prize have just been announced: "Information Technologies" and "Molecular Recognition and Dynamics in Bioscience."
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"Top Ten Scientific Breakthroughs (1997)",411,0,0,0
In the 19 December 1997 issue, the editors of Science offered what they saw as the year's top ten scientific breakthroughs. We thought it would be interesting to see how we fared: we scored about eight out of ten, not bad, considering we were picking the stories up as they broke, rather than having the benefit of hindsight. Here are the selections made by the editors of \IScience\i:
\B1. The \Jcloning\j of Dolly, the world's first cloned adult \Jmammal\j.\b
We brought you that story in February, with follow-ups later in the year - and another follow-up this month-see the next story.
\B2. The Mars Pathfinder mission.\b
We brought you reports on Pathfinder and its mission, every month since July, with a summary report this month.
\B3. Synchrotron light\b
While we did not cover these giant light sources during the year, we described one of the key discoveries made with \Jsynchrotron\j light, the structure of the nucleosome core particle, in September.
\B4. Clock genes\b
We left that one out. A report in the October 2, 1997 issue of \INature\i from Dr Hajime Tei of the University of \JTokyo\j, \JJapan\j and colleagues, identified the mouse and human versions of the \IDrosophila\i gene period. These genes share several structural features with the fly gene, suggesting that they work in broadly similar ways. In other words, the homeobox gene concept gets further support.
\B5. Single-walled nanotubes\b
We looked at fullerenes last December and again in June, but we have not featured nanotubes in detail. Nanotubes are small tubes made of carbon atoms joined in a lattice arrangement, rather like \Jgraphite\j. The reports of new findings have been constant all year, but never quite big enough to rate a special article. There are still a lot of "maybes" around nanotubes, but we will keep you posted in 1998.
\B6. Microbial genomes\b
Over the past twelve months, we have brought you news of the identification of the genomes of a yeast, \ISaccharomyces cerevisiae\i (May), \IBacillus subtilis\i in July, \IHelicobacter pylori\i in August, \IEscherichia coli\i in September, with no less than three new reports this month!
\B7. Gamma ray bursts\b
See Small Galaxy Disappears (March). Gamma-ray bursts (GRBs) drew the attention of astronomers and physicists this year, as it became clear that these immensely violent astronomical events are occurring at cosmological distances, and not, as might have been the case, in our Galaxy.
\B8. Neandertal DNA\b
See Neandertal Man Partly Cloned (July) for full details. According to the evidence of mitochondrial DNA, isolated from Neandertal remains, the Neandertal people were not "us". (Incidentally, a January report indicates that one Neandertal man, whose skeleton was found at La Ferrassie in the Dordogne in 1909, has scars on the bones which tell us that he died of lung cancer, so even the bones have some stories still to tell.)
\B9. Neurological disease developments\b
The main developments relate to Parkinson's disease and Alzheimer's disease, both of which we have covered fully in a number of articles over the year.
\B10. Europa's ocean\b
We did well there: we brought you the first news in December 1996, with a follow-up in January and a detailed account (Europa's Ocean) in April.
#
"First Transgenic Cloned Sheep",412,0,0,0
(Dec '97)
Dolly may have been the world's first cloned sheep, but now she is followed by Polly, the world's first transgenic cloned sheep. Polly was produced from a fetal cell, which is easier to clone than an adult cell. Before the nucleus was inserted into an empty \Jovum\j, the Roslin researchers injected the human gene that controls the production of Factor IX into the fetal cell. This factor is used as a treatment for human haemophilia B. Factor IX is now produced by extracting it from human blood, or in some cases, by genetically engineered organisms.
The new sheep produces Factor IX in its milk, which means haemophiliacs can now obtain Factor IX in large amounts from a source free of the disease risks associated with human blood. Because Polly has been grown from a fetal cell, she is a clone, and because she carries a human gene, she is transgenic. (In fact, "Polly" is one of six sheep, three of which express the human gene, while the other three are misses.)
The cell used to produce Polly is now being cloned repeatedly to produce a flock of identical sheep, in the hope that when Polly is old enough, her milk will contain Factor IX in commercially and medically useful amounts. Next target for the researchers: transgenic pigs, to act as a source of organs which can be transplanted into humans.
(In early January, a physicist named Richard Seed announced his intention to go ahead on \Jcloning\j human babies for childless couples. There will be more on this next month.)
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"Prion Chaperone Identified",413,0,0,0
(Dec '97)
As we indicated in our report on the 1997 Nobel Prize in Physiology or Medicine (October), Stanley Prusiner was of the opinion that a "chaperone" molecule might be needed to help a prion convert proteins from one shape to another, causing prion disease.
Now, even before Prusiner can collect his award, a chaperone protein has been isolated in years, and this protein has been shown also to affect mammalian prion proteins. These findings suggest prions are far more widespread than suspected.
Meanwhile, a December \INature\i report implicates B cells, a type of immune cell carried in the blood, in prion diseases like scrapie. According to the report, mice lacking B cells are resistant to infection with scrapie, a sheep condition similar to mad cow disease, when they are inoculated with infectious material in areas outside the brain. Defects affecting only T lymphocytes had no apparent effect, but all mutations which disrupted the differentiation and response of B lymphocytes prevented the development of clinical scrapie. The conclusion is that white blood cells may be involved in the transmission of diseases such as "mad cow disease" (BSE) and CJD.
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"Small Comets in Doubt Again",414,0,0,0
(Dec '97)
Louis Frank believes that the \Jearth\j is being bombarded with small watery comets (Controversy in Space, May) while others disagree vehemently (No Watery Comets After All?, July). The debate continues, with a paper in \IGeophysical Research Letters\i in which George Parks and colleagues claim to demonstrate that dark spots in instrument records of the ultraviolet glow in the Earth's upper \Jatmosphere\j can be produced as artefacts of the ultraviolet camera instrumentation. Louis Frank, on the other hand, claims that their methods are flawed, and that 20- to 40-ton cosmic snowballs, the size of houses, are still pelting the Earth at the rate of 30,000 a \Jday\j.
Parks says that at first he was "agnostic" towards Frank's data, but later became suspicious when he saw the data. It was simply unlikely, he says, that the clusters of spots on the images could have been caused by snowballs in space. Parks began an analysis of his own images taken with the Ultraviolet Imager (UVI) on the NASA Polar \Jsatellite\j. There he found the same dark spots that Frank had found on his images. The "comets", says Park, are just random blobs of "noise", and he claims that this is borne out by a statistical analysis of the "blips".
Against this, Frank notes that the number of atmospheric holes in the images drops by about 80% when the \Jsatellite\j is farther from Earth. This is just what you would expect from real impacts, he says, adding that instrument noise would show the same pattern at low or high altitudes. We will keep you posted, but please recall what this random noise on screens is called-snow!
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"Mathilde Pictures Released",415,0,0,0
(Dec '97)
Pictures of the C-class asteroid, 253 Mathilde (see Mathilde--Not Your Average Asteroid?, July) were released in \IScience\i during December.
The main surprise is in finding so many large craters packed so tightly on the relatively small surface of Mathilde. This means that large objects have been able to strike the asteroid's surface without destroying it, leading scientists to suggest that hitting the asteroid is a bit like throwing things at Styrofoam. Whatever the asteroid is made of, it does not seem to be too rigid. But why this should be is anybody's guess. Another mystery, still to be explained: Mathilde rotates once every 17.4 days. Only two other known \Jasteroids\j rotate more slowly: 288 Glauke and 1220 Crocus.
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"Martian Life Gets More Distant",416,0,0,0
(Dec '97)
One of the top stories of 1996 is fading in interest. Three scientists, Ralph Harvey, John Bradley, and Hap McSween, have dismissed the claim that Martian \Jmeteorite\j ALH84001 contains small fossils. They say that most of the "microfossils" are nothing more than narrow ledges of mineral protruding from the underlying rock that under certain viewing conditions can masquerade as fossil \Jbacteria\j.
Unusually, \INature\i published not only their views in its December 4 issue, but also a rebuttal of their claims, by some of those who still believe that the \Jmeteorite\j offers evidence of Martian life. Web reference: http://www.cwru.edu/artsci/geol/ansmet/index.html
#
"Royal Greenwich Observatory Closed",417,0,0,0
(Dec '97)
Britain's Particle Physics and Astronomy Research Council rejected a proposal to privatise the Royal Greenwich Observatory in early December. The business plan drawn up by the staff of the RGO appeared too risky and costly. It also threatened to turn the RGO into an unwelcome competitor for the new Astronomy Technology Centre, which PPARC is setting up at the Royal Observatory, Edinburgh (ROE).
The RGO's duties, which are now mainly in \Jtelescope\j design, will go to Edinburgh, but RGO staff, outraged at the loss of their historic institution, set about preparing a rescue package that would involve setting up a company to provide astronomical services not being transferred to Edinburgh, such as data archiving. They also planned to establish a \Jtelescope\j-building business with John Moores University in Liverpool, and to carry out some PPARC-funded astronomical research.
Now the institution which created Greenwich Mean Time, and which has been home of the Astronomer Royal since 1675 when John Flamsteed filled the post, will be no more.
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"High X-Ray Bursts Detected Over Sweden",418,0,0,0
(Dec '97)
A 1996 \Jballoon\j flight over Sweden, designed to study the aurora borealis, the "northern lights", detected x-ray bursts with energies as high as a million \Jelectron\j volts-enough to penetrate an inch (2.5 cm) of \Jaluminium\j. Ten times higher than the usual energies at 35 km, where the observations were made, the x-rays are a complete mystery.
The x-rays probably came from particles spiralling in through the \Jearth\j's magnetic field, but their exact nature remains a mystery, especially as the \Jearth\j's magnetic field was quiet at the time. NASA has made funds available for a fortnight-long \Jballoon\j flight in June 1998 to explore the phenomenon further.
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"End of a Star",419,0,0,0
(Dec '97)
A week before Christmas, NASA released pictures of a dying star, a "planetary nebula" of the sort our \Jsun\j will form in some 5 billion years. These were named in the 18th century by astronomers who thought the stars looked planet-like.
This sort of nebula forms when a midsized star runs out of fuel, and blasts out its outer layers, leaving a superheated white dwarf behind. The surface of the white dwarf radiates off ultraviolet which ionises the expanding shells of gas, creating colourful "sculptures in the sky".
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"Death of a Planet--Or Many Planets?",420,0,0,0
(Dec '97)
A new analysis of solar data has led Max-Planck scientist K. Scherer, his colleagues H. Fichtner from the University of \JBonn\j and John Anderson and E. Lau from JPL to conclude that an apparent \Jplanet\j around Pulsar PSR B1257+12 may be an artefact of solar rotation. The report was published in \IScience\i.
Pioneer 10, one of four deep space probes in the heliosphere, the circumsolar region dominated by the \Jsolar wind\j plasma, recorded data while moving between 40 and 60 AU (6 to 9 billion km) from the Sun. Measuring Doppler shifts in two-way radio signals to accuracies of 1 mHz (millihertz), the researchers found an \Jelectron\j density fluctuation of a particle stream (\Jsolar wind\j) from the Sun, with a main period of 25.3 days. If the \Jsun\j shows this sort of variation, say the researchers, then Doppler shifts in radio signals from distant stars may be caused in the same way, rather than being generated by planets.
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"Switzerland: The Gene Protection Initiative",421,0,0,0
(Dec '97)
A referendum under this name will be voted on during 1998 in \JSwitzerland\j. If the proposal is approved by the referendum, it will result in a constitutional prohibition of gene manipulation, a prohibition on the use and patenting of gene-modified animals (including those standard genetic animals, worms and flies), and a prohibition on the cultivation of gene-modified plants.
While the initiative is opposed by both houses of the Swiss parliament and scientists, its supporters are busily warning the public that genetically modified organisms cause allergies, shine \Jlaser\j light from their eyes, spit venom, read your thoughts, are one step from super-monsters and worse. If the initiative is passed, it will mean the end of Swiss biotechnology and molecular \Jbiology\j. Swiss scientists now find themselves challenged to explain complex science to the scientifically illiterate, to demonstrate that they are ethically and morally responsible. This won't be easy, given that this area of study is so close to the bleeding edge of science.
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"Green Tea Kills Cancer",422,0,0,0
(Dec '97)
In September, we reported (A soothing cup of tea) on the cancer-fighting properties of green tea. The substance in green tea which kills cancer cells, while leaving healthy ones alive, has now been isolated. It is epigallocatechin-3-gallate, which has now been tested on cancerous human and mouse cells of the skin, \Jlymph\j system, and prostate, and on normal human skin cells. In the test tube, it led to apoptosis, or programmed cell death, in the cancer cells, but left the healthy cells unharmed.
Epigallocatechin-3-gallate is a major constituent of the polyphenols found in green tea. A typical cup of green tea contains 200 mg of the compound. Tea consumption in the world ranks second only to \Jwater\j consumption, and around 20 percent of tea consumed is green; with the rest being black tea.
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"Pine Cone Intelligence",423,0,0,0
(Dec '97)
The scales on pine cones open when the \Jweather\j is dry, favouring seed dispersal, and stay shut when it is damp. Strangely, the mechanism by which the female pine cone responds to changes in relative \Jhumidity\j has never been explained-until now. A December report explains that the scale contains a "bilayer system", rather like a bimetallic strip, but reacting to \Jhumidity\j, not heat.
For botanists, the inner surface of the ovuliferous (\Jovule\j-bearing) scale is made up of sclerenchyma fibres, grouped in cable-like bundles, with microfibres aligned along the scale and resistant to any stretching. The outer surface consists of sclereids with microfibrils wound around the cell allowing for \Jelongation\j when it is damp, closing the scale down.
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"Obituary for December 97",424,0,0,0
David Schramm, 52-year-old astrophysicist and the research vice president at the University of \JChicago\j, died on 19 December, after the private \Jaircraft\j he was piloting crashed outside \JDenver\j.
Schramm was a leading authority on the birth of the universe, who helped explain the process by which the three lightest elements--\Jhydrogen\j, \Jhelium\j, and \Jlithium\j--were created immediately after the \Jbig bang\j. He and his collaborators also calculated the amount of ordinary matter in the universe, which helped demonstrate that the universe is dominated by invisible "\Jdark matter\j".
