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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Video: Scales Give Sharks Their Speed
9 February 2012 3:12 pm
Shark skin may be de rigueur poolside at the 2012 Summer Olympics. A new study finds that microscopic scales known as denticles propel the predators through the water at speeds 12% faster than they would otherwise achieve without them. To fish out how this happens, researchers mounted pieces of shortfin maco (Isurus oxyrinchus) and porbeagle shark (Lamna nasus) skin on flexible robotic fins and placed them in a tank. By analyzing water flow over the skin, the team found that denticles determined the proximity of swirls of water, called vortices (visible in the video), to the fin. Intact denticles produced swirls close to the skin, the researchers report in The Journal of Experimental Biology, creating low pressure areas that pulled the fin forward. Fins with their denticles sanded off produced vortices further away from the skin, reducing fin flapping speeds. The scientists note that manufacturers of Olympic-worthy swimwear, designed with dimples to reduce drag, may want to build in little ridges instead.
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