6 августа 2002 г.
|
Новости науки и техники в "Scientific American"
6 августа 2002 г. |
NEW FINDINGS FAN DEBATE OVER ORIGIN OF VINLAND MAPEver since it surfaced in 1957, the Vinland Map has been controversial. Some experts purport that it was drawn in the 15th century and that it chronicles the Vikings' travels to the New World, prior to Christopher Columbus's 1492 journey. Others argue that it is instead the work of a 20th-century counterfeiter. Now the results of two new studies are adding further fuel to the debate. One report concludes that the map's ink has modern roots; a second group of researchers says that the parchment dates back to 1434.MONSOON INTENSITY INCREASING AS EARTH WARMSDumping untold gallons of rain on 65 percent of the earth's population each year, the Asian southwest monsoon is one of the most important climate systems in the world. Scientists have long wondered how changes in the earth's temperature affect monsoon intensity. Recent findings may provide some answers. Using historical abundances of a fossilized marine microorganism called Globigerina bulloides, researchers have pieced together a 1,000-year record of monsoon intensity.BOOKSTORE: SAKHAROV: A BIOGRAPHY by Richard LourieA pillar of Soviet science - father of that nation's hydrogen bomb - becomes an outspoken dissident of the regime and wins the Nobel Peace Prize for his efforts. That is the unusual story of physicist Andrei Sakharov (1921-1989). Lourie, a biographer and translator of contemporary Russian and Polish authors, tells that story well and enriches the picture with accounts of Sakharov's family life and friendships. "It is not false modesty," Sakharov said of himself, "but the desire to be precise that prompts me to say that my fate proved greater than my personality. I only tried to keep up with it."NEW LIGHT ON BREAST CANCERNo one would argue that mammograms have saved countless lives since their introduction. But they are not a cure-all. Indeed, recently it seems that some mammography problem or other makes the headlines almost weekly. In addition to being uncomfortable experiences for women to undergo, mammograms can be difficult to read and interpret, sometimes leading to missed cancers. Two new scanning methods, CT laser mammography and Computerized Thermal Imaging, may help as adjuncts for more reliable testing of early breast cancers.LOBSTER SHELL COLOR SHIFT EXPLAINEDThe blush of a lobster's shell during cooking is extraordinary by any measure. Exactly why the shift from purplish-blue to fiery crimson occurs has long eluded explanation. But new research is at last revealing the molecular mechanism underlying the phenomenon.CANNABIS-LIKE BRAIN CHEMICALS BLOCK OUT BAD MEMORIESSome memories, particularly those evoking fear or pain, are best forgotten. But just how the brain squelches unpleasant recollections is unclear. New findings suggest that natural chemicals similar to the active ingredient in marijuana help mice wipe out traumatic memories.ASK THE EXPERTS: WHY DO STARS TWINKLE?John A. Graham, an astronomer with the Carnegie Institution in Washington, D.C., explains.