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6 March 2014 1:04 pm ,
Vol. 343 ,
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
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Video: Self-Lubrication Speeds Avalanches
8 December 2011 12:15 pm
In September 2002, roughly 100 million cubic meters of rock and ice crashed down onto the Kolka and Maili glaciers in Russia’s Kazbek Massif, sending both glaciers sliding toward the Genaldon River valley. The avalanche reached blistering speeds of more than 150 miles per hour. How did the ice and rock flow so quickly? In a new study, reported in an upcoming issue of Physical Review Letters, a researcher tested the idea that surface melting in colliding ice particles might be playing a role. She created an avalanche in the laboratory by half-filling a hollow wheel of clear plastic with frozen water droplets and rotating it so that the surface of the ice balls became a slope. As ice bounced and slipped down that slope (shown in video), the amount of water in the mixture increased. Even at -4°C, enough liquid water formed at the surface of the ice particles to enhance the speed of the flow by more than 10%. The water lubricates the ice, and the higher speeds mean more collisions and melting—so the speed of an avalanche is, in part, due to this snowball effect.
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