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<jats:p>The National Science Foundation (NSF) has decided to concentrate its $65 million a year supercomputing program at two university-based megacenters and phase out support for two other centers. That is good news for scientists at the University of Illinois and the University of California, San Diego, which have ambitious plans to develop the next generation of high-end computing hardware and applications with partners around the country, and bad news for officials at the Pittsburgh Supercomputing and Cornell Theory centers, which have 2 years to plug the hole left by NSF's departure.</jats:p>

<jats:p> <jats:bold>HOUSTON</jats:bold> --Scientists studying putative microbes in a martian meteorite are finding it surprisingly hard to prove or deny the idea that life once existed on the Red Planet. Researchers at the recent Lunar and Planetary Science Conference dueled to a stalemate on such questions as the temperature of formation of carbonate in the meteorite and whether grains of magnetite might be masquerading as “nanobacteria.” But they also suggested how new studies may settle the question in coming months. </jats:p>

<jats:p>The Hubble Space Telescope took its sharpest image ever of the planet Mars last month, in part to scout out what the Pathfinder spacecraft will find when it lands on Mars on 4 July. A martian dust storm could play havoc with the Pathfinder lander and the small rover it will place on the surface, both of which depend on full sunlight falling on their solar power panels. The image, however, shows nary a dust storm in sight.</jats:p>

<jats:p>Who were the first toolmakers? For years, scientists pondering which hominid species were capable of making tools have relied on a simple test based on anatomical traits in the human thumb. Now new work reported at the annual meeting of the American Association of Physical Anthropologists in St. Louis suggests that data from the whole hand are needed to identify toolmakers--and that the human hand was evolving to accommodate tool use as far back as 3.3 million years ago.</jats:p>

<jats:p> Mention particulate pollution, and most people think of soot from smokestacks and diesel buses. But another source of particles--which are linked to respiratory-disease deaths in many cities--is just as important: gases from evaporated gasoline, solvents in paints, and other sources that condense onto bits of dust. Scientists have been hard pressed to figure out how these particles form and interact. But now, on <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="96" related-article-type="in-this-issue" vol="276" xlink:href="10.1126/science.276.5309.96" xlink:type="simple">page 96</jats:related-article> , a team of researchers describes a mathematical model that predicts how these gases are transformed into particles. The model should help the U.S. Environmental Protection Agency--which is planning to issue its first fine-particle standards this summer--figure out how to reduce levels of these tiny killers. </jats:p>

<jats:p> Living organisms come in a vast range of sizes--from microbes to whales, they span at least 21 orders of magnitude. For more than a century, biologists have been trying to figure out how body size and physiology are related, but so far they have come up with a big conundrum. Now, on <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="122" related-article-type="in-this-issue" vol="276" xlink:href="10.1126/science.276.5309.122" xlink:type="simple">page 122</jats:related-article> , a team of researchers reports a new mathematical model--a unique combination of the dynamics of energy transport and the mathematics of fractal geometry--that may finally help solve the puzzle. </jats:p>

<jats:p>Mammalian DNA contains redundant genes that might, in a pinch, be capable of standing in for their counterparts. Now, scientists are trying to use one of those genes to treat a currently incurable human genetic disease: Duchenne type muscular dystrophy. Each year, about 21,000 boys worldwide are born with a genetic defect that renders them incapable of making a key muscle-strengthening protein called dystrophin. Recent work in mice suggests that it may be possible to correct this defect by enticing muscle cells to make more of a very similar protein, called utrophin.</jats:p>

<jats:p> <jats:bold>IRVINE, CALIFORNIA</jats:bold> --New observations described at a National Academy of Sciences colloquium here suggest that giant walls of galaxies, hundreds of millions of light-years long, may have crisscrossed the universe when it was just 15% of its present age. Such structures are similar to what we see today, which raises a problem for theorists: If gravity hasn't radically resculpted the universe over time, that implies that it may have far less mass than theorists prefer. That is in line with evidence of a scarcity of mass in the nearby universe but at odds with one measurement of how fast the cosmic expansion rate is changing, which hints at a much higher density of matter ( <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="37" related-article-type="in-this-issue" vol="276" xlink:href="10.1126/science.276.5309.37" xlink:type="simple">see p. 37</jats:related-article> ). </jats:p>

<jats:p> By studying Type Ia supernovae, exploding stars visible at distances so vast that they represent earlier epochs of cosmic history, astronomers are getting a look at the ultimate fate of the universe. By comparing the brightness of these beacons--an indicator of their distance--with the rate at which cosmic expansion is carrying them away, two groups of observers are now closing in on the rate at which cosmic expansion has changed over time. Early results suggest that high matter density is slowing the universe's expansion, and that the cosmos contains hundreds of times more mass than can be seen as stars and galaxies--a conclusion that may conflict with other clues suggesting a low-density universe ( <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="36" related-article-type="in-this-issue" vol="276" xlink:href="10.1126/science.276.5309.36" xlink:type="simple">see p. 36</jats:related-article> ). </jats:p>

<jats:p>Researchers at Case Western Reserve University and Athersys Inc., both in Cleveland, report constructing the first wholly synthetic, self-replicating, human “microchromosomes,” which are one-fifth to one-tenth the size of normal human chromosomes. Although the team hasn't yet found an efficient way of transplanting microchromosomes’ self-assembling components into new cells--a crucial step before researchers can exploit them fully--human artificial chromosomes could eventually be used to study chromosomal functions and to ferry “repair genes” into target cells in gene therapy.</jats:p>