16 июля 2002 г.
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Новости науки и техники в "Scientific American"
16 июля 2002 г. |
MEET THE OLDEST MEMBER OF THE HUMAN FAMILYAfter more than a decade of digging, researchers working in Chad, Central Africa, have made the fossil discovery of a lifetime: a nearly complete skull of the oldest and most primitive member of the human family yet known. Nicknamed Toumaп - or "hope of life" in the local Goran language - it belongs to an entirely new genus and species of hominid, Sahelanthropus tchadensis. And at almost seven million years old, it has taken scientists several crucial steps closer to the point in time at which humans and chimpanzees diverged. Yet as is the case for most spectacular finds, this one raises as many questions, if not more, than it answers.SCIENTISTS SAY MASS VACCINATION IS BEST RESPONSE TO A SMALLPOX ATTACKSmallpox was eradicated from humans in 1979. But in light of last fall's terrorist attacks, it has returned to the forefront of public consciousness as a potential bioweapon. Because of the uncertainty surrounding both the chances of an assault involving the virus and the availability of vaccine stockpiles, the response policy to such an attack is continually evolving. Now a mathematical analysis suggests that mass vaccination after a smallpox attack would save thousands more lives than the government's current plan of action.MACHINE TRANSLATIONSure, you can download free software from the Internet that will translate a document in, say, Italian, into English. But these programs are generally only about 70 percent accurate. Moreover, they are generally available only for certain languages. Although it's relatively easy to get a translation from Italian to English, it may not be to get a translation from Urdish to English - or Urdish to Russian. For these reasons, reliable translations have always required the services of a human. Now the tide may be changing. A company called Fluent Machines has developed software that conducts a statistical analysis of large volumes of translated documents to improve the likelihood of translating correctly. Is it a real solution? Only time will tell, but the idea seems promising.BOOKSTORE: SENSORY EXOTICA: A WORLD BEYOND HUMAN EXPERIENCE by Howard C. HughesCan a dog sense in advance that its owner is about to have an epileptic seizure? A dog described in a recent news report does that, evidently by detecting certain chemicals associated with the onset of a seizure. It is an example of a sensory capability beyond the human range. Many animals can sense things that people are unaware of or sense weakly. Such animals are the subject of the story recounted by Hughes, who is a professor of psychology at Dartmouth College. He describes sonar in bats and dolphins, biological compasses (based on the sun or stars or geomagnetism) in birds and insects, electricity sensing in fish, and pheromones (chemical signals) in insects and apparently in people. And he takes pains to pin down the mechanism of the sensory capability in each case.RESEARCHERS IDENTIFY GENE ASSOCIATED WITH ASTHMARacking up some $14.5 billion in annual U.S. costs and resulting in more than 5,000 American deaths each year, asthma is becoming an increasingly worrisome epidemic. Recent research has emphasized the condition's strong environmental triggers, such as diesel-powered truck emissions or dust mite-infested carpets, but scientists have long known that heredity also plays a significant role in disease onset. Now a new study has identified a gene linked to increased asthma susceptibility.ASTRONOMERS SPY SIGNS OF GAS GIANT PLANET IN THE MAKINGAstronomers have long wondered how giant gas planets like Jupiter and Saturn form. Now scientists say that they may have caught this development in action. Recent detection of the hydrogenic ion (a hydrogen molecule with an additional proton) around a distant star may signal the presence of a gas-giant protoplanet.ASK THE EXPERTS: WHY IS SPIDER SILK SO STRONG?Biologist William K. Purves of Harvey Mudd College explains.