4 июня 2002 г.
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Новости науки и техники в "Scientific American"
4 июня 2002 г. |
MARS ODYSSEY'S MEASUREMENTS REVEAL A WET, RED PLANETDry valleys, channels, and networks of gullies scar the arid Martian landscape. Along with other evidence, these physical vestiges of conditions on ancient Mars suggest a planet once saturated with liquid water. According to new data, large deposits of water ice may in fact exist under just tens of centimeters of soil on the Red Planet.BOOKSTORE: SEMICONDUCTOR SPINTRONICS & QUANTUM COMPUTATION Edited by D. D. Awschalom, D. Loss and N. SamarthRecent studies of spin-dependent phenomena in semiconductors open the door to technologies that harness the spin of the electron in semiconductor devices. In addition to providing spin-dependent analogies that extend existing electronic devices into the realm of semiconductor "spintronics," the spin degree of freedom also offers prospects for fundamentally new functionality in the quantum domain, ranging from storage to computation. This is likely to play a crucial role in the information technologies in the 21st century. Written by a team of experts, this book provides an overview of emerging concepts in this rapidly developing field. The topics range from spin transport and injection in semiconductors and their heterostructures to coherent processes and computation in semiconductor quantum structures and microcavities.NEW DRUG STOPS DIABETES IN ITS TRACKSType I, or juvenile, diabetes occurs when the body's own immune system attacks the insulin-producing islet cells in the pancreas, preventing the formation of insulin and thus hindering the regulation of sugar in the blood. Now the results of a clinical trial show that patients taking a new drug, called hOKT3g1(ala-ala), continued to make their own insulin and did not need externally created protein. This treatment has allowed diabetics to live shot-free for at least a year without any serious side effects.SCIENTISTS DISCOVER A NEW AMINO ACIDA tiny methane-producing microbe has revealed the existence of a new amino acid, researchers report. The nonstandard amino acid, pyrrolysine, is encoded in the RNA of bacteria-like members of the group Archaea. The findings suggest that the genetic code may be more adaptable than previously believed.NEW MATERIAL COULD FORM BASIS FOR NOVEL ELECTRONIC DEVICESMany feats of engineering boil down to a material's ability to switch between two different states. More complex devices can arise if the so-called bistable material undergoes changes in more than one physical property as it switches between states. Now scientists have succeeded in making a material that exhibits bistability involving three physical properties and that holds promise for new electronic devices.ASK THE EXPERTS: HOW DO GPS DEVICES WORK?Alfred Leick, a professor in the department of spatial information science at the University of Maine, explains.