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6 March 2014 1:04 pm ,
Vol. 343 ,
Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
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...
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Video: Grains Shape the Songs of Sand Dunes
25 October 2012 5:12 pm
When plagued by whipping desert winds, sand dunes signal their displeasure with haunting moans that reverberate across the arid landscape. Some emit single-note songs while others mimic a jumbled chorus—but no one knew why they sang these different songs until now. New research published online this week in Geophysical Research Letters finds that the size of sand grains shapes a dune's song. Scientists collected sand from a singing dune in Morocco that moans at around 105 hertz (Hz)—or, to a musician, that's G-sharp two octaves below middle C. They compared those grains to sand collected from a dune in Oman, which produces notes ranging from 90 Hz to 150 Hz (F-sharp to D). By creating mini-dune avalanches in the lab, scientists recreated these desert songs, finding that different layers of sand aren't necessary to produce the moans, as previous researchers contended. They also found that when they sieved the Omani sand so that the grains were similarly sized, the resulting "avalanche" produced a single-note song. The synchronized movement of sand grains, they conclude, produces the famed moaning, while grain size determines the notes contained in the song.
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