Stories of modern science... from UPI

By JIM KLING, UPI Science Writer   |   Dec. 12, 2001 at 12:49 AM   |   0 comments

, Dec. 11 (UPI) -- SATELLITE DATA SHOW ANTARCTICA GLACIERS MELTING

New evidence suggests that the glacial ice of Antarctica is melting and contributing to a slow rise in the levels of the world's oceans, according to a New York Times report. Using radar data from the European Remote Sensing Satellite, researchers found that 36 cubic miles of ice have melted in the past decade, enough to raise water levels by one-sixtieth of an inch. "These glaciers are thinning rapidly," said Eric Rignot from NASA's Jet Propulsion Laboratory in Pasadena, CA, who reported the results at a meeting of the American Geophysical Union. The findings conflict with ground-based studies that suggested Antarctica was actually gaining in mass due to snow fall in the interior. It is already known that ocean levels have been rising at a rate of about eight inches a century. Research suggests that half the volume increase is due to the simple fact that water expands when temperatures rise, while twenty percent of the gain is believed to be water from melting mountain glaciers. The final thirty percent could be due to melting of glaciers in Antarctica.


LOW-DOSE RADIATION MORE SERIOUS THAN THOUGHT

Radiation can trigger mutations in cells at levels ten times lower than the previously recognized threshold, according to a report in the December 4th edition of the Proceedings of the National Academy of Science. The research showed that a radiation dose that strikes just one cell in ten has the same mutagenic effect as a dose that hits every cell, because the cells struck by radiation send signals to surrounding cells causing them to undergo mutations in a so-called 'bystander effect.' The question of how cells respond to low levels of radiation has been a source of controversy for years, with mutations caused by it a potential source of cancer and birth defects. Public health officials have generally assumed that risk of radiation exposure is linearly proportional to the amount of radiation exposure, but these results may force officials to reconsider. The study is "another piece of hard evidence to suggest we may need to reassess" acceptable radiation levels, said Howard L. Liber, associate professor of radiobiology at Harvard School of Public Health. The researchers stress that the new findings do not suggest that a large new population of people is at risk, but only that cancer risk at low radiation doses may be greater than once thought. The results may also help clarify how radiation makes people sick.


GALAXY SURVEY SHOWS IMPACT OF DARK MATTER

The majority of light in the Universe is made up of so-called dark matter, which has remained largely undetected because it does not give off any light. Researchers led by Licia Verde of Rutgers University and Alan Heavens of the University of Edinburgh conducted a survey of 200,000 galaxies using the Anglo-Australian Telescope in New South Wales, Australia. They looked at the spatial orientation of the galaxies and how it coincided with the gravitational pull of the dark matter. "Where there is matter, there is gravity and its pull has 'clumped' the galaxies into an uneven distribution," said Verde, a postdoctoral researcher at Rutgers with a joint appointment to the Princeton University Observatory. "There is much more dark matter than there is mass in the galaxies, so the force it exerts has moved the galaxies around." Researchers believe that, were it not for the dark matter and its gravitational forces, the galaxies would be in a much more uniform pattern.


CROWS ON THE LOOKOUT FOR VICTIMS, NOT PREDATORS

The Native American stories depicting the crow as clever and tricky appear to be right on the mark, according to research published in the journal Animal behavior. Some animal behaviorists have long assumed that crows are looking for predators when they scan their surroundings, but the new work suggests that they are actually trying to locate food they can steal. "Crow vigilance is based on the opportunity to steal food," said James Ha, a research associate professor of psychology at the University of Washington. "The over-riding factor in their vigilance behavior is 'who's got food I can steal,' not 'is there a predator lurking around.' Ha observed crows' behavior in Meadowdale Park, a suburban site along Puget Sound in Snohomish County, north of Seattle. In this relatively undeveloped park, the researchers observed crows for 290 hours over 18 months, watching a randomly selected bird for five minutes. "Finding that chance to steal food is a very uniform strategy among these birds," said Renee Robinette Ha, a University of Washington lecturer in psychology. "They are not like the crows in the city that forage for food in dumpsters."

(EDITOR: For more information on glaciers, call 416-978-5477; about radiation, call 212-305-3900; about dark matter, call 732-932-7084; about crows, call 206-543-2420)

Topics: Eric Rignot
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