Catálogo de publicaciones - revistas

<jats:p> <jats:bold>PARIS</jats:bold> —Fabrication methods for computer memory chips are reaching the physical limit of how small they can create circuits, and energy consumption of chips is becoming excessive. Designers are now looking around for new ways to store information on a chip, and this challenge is the focus of a new $3.7 million research program announced last week by the European Union. Its aim: to build a chip capable of storing a terabit of information with each bit recorded by a single electron. </jats:p>

<jats:p>Cell biologist Mikulas Popovic, who was cleared of scientific misconduct by an appeals board in 1993, has filed a $5 million lawsuit against the United States and one of its employees, fraud investigator Suzanne Hadley, for pursuing a “baseless” investigation that caused him “severe emotional stress” and resulted in his “de facto forced exile from science for 4 years.” On 31 January, the government submitted its formal response to the suit, arguing that it should be dismissed on technical grounds.</jats:p>

<jats:p>Adding Russia as a partner in the international space station put the controversial orbiting laboratory on firmer footing. But now the multibillion-dollar effort is being threatened by Russia's failure to come up with money to build critical portions of the station, and U.S. legislators say they won't be left holding the bag.</jats:p>

<jats:p> <jats:bold>OTTAWA</jats:bold> —The Canadian government, like its neighbor to the south, has been trying to forge stronger links between the nation's private companies and universities. But a new report on one such program warns that these efforts could falter unless universities relax their grip on technologies with commercial potential. One research manager in the middle of disputes over intellectual property rights calls the issue a “ticking time bomb.” </jats:p>

<jats:p> <jats:bold>BOSTON</jats:bold> —The Human Genome Project already studies such organisms as yeast, roundworms, and mice; if an intrepid band of biologists has their way, the zebrafish—which is very useful for developmental biology but has an almost unknown genome—will be the next species to hitch a ride on the mammoth project. </jats:p>

<jats:p> What triggered the collapse of the medieval Norse colony on Greenland? Theories have ranged from a cold climate to warring Thule hunters, ancestors of the modern Inuit. <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://maxweber.hunter.cuny.edu/anthro/nabo.html" xlink:type="simple">New studies</jats:ext-link> combine data from ice cores, archaeological digs, and fossil flies to create a picture of desperation and disaster in the final days of one settlement—and finger climate as well as culture as causes of the settlers' demise. </jats:p>

<jats:p> In autoimmune diseases, such as diabetes and rheumatoid arthritis, the immune system goes awry and turns on the body's own tissues. But researchers do not know which of the immune system's several types of killer T cells carries out the attack, nor why killer cells are scarce at the site of tissue destruction in many autoimmune diseases. New results published in this issue ( <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="960" related-article-type="in-this-issue" vol="275" xlink:href="10.1126/science.275.5302.960" xlink:type="simple">p. 960</jats:related-article> ) suggest that in at least one autoimmune disease, the immune system itself may not carry out the final act: Instead, the target cells commit suicide through a process called apoptosis. </jats:p>

<jats:p>Conventional methods for predicting the next peak in the sun's magnetic cycle, due around 2000, suggest it will be the most intense in history. That could be bad news for space agencies and satellite operators, because the flares and magnetic storms of a solar maximum are a threat to spacecraft. But a new technique, based on the physics of the solar cycle, says that the sun's current magnetic state foreshadows only a modest peak, the lowest in decades.</jats:p>

<jats:p> Cells that divide repeatedly, such as cancer cells, germ-line cells, and microorganisms such as yeast, have to take good care of their telomeres, the specialized stretches of repetitive DNA at the ends of their chromosomes. Because of a quirk in the enzymes that replicate the DNA, the chromosomes shorten a little with each cell division, and for cells to keep dividing they have to add back the telomere DNA. Otherwise, essential genes could be lost. New results appearing on pages <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="973" related-article-type="in-this-issue" vol="275" xlink:href="10.1126/science.275.5302.973" xlink:type="simple">973</jats:related-article> and <jats:related-article xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="doi" page="986" related-article-type="in-this-issue" vol="275" xlink:href="10.1126/science.275.5302.986" xlink:type="simple">986</jats:related-article> now show that one way yeast cells keep track of how long their telomeres are is by counting the copies of a protein called Rap1 bound to the telomere DNA. </jats:p>

<jats:p> <jats:bold>SAN DIEGO</jats:bold> —Far from being simple on-off switches, neurons can “rewire” themselves, changing the way they respond to incoming signals as the properties of their membranes change. But which properties are important for which responses? Answers are emerging from a synapse between two disciplines: mathematical analysis of differential equations describing this activity. </jats:p>