President Barack Obama pedals bicycle-powered emergency water-sanitation station for Payton Karr, 16, left, and Kiona Elliott, 18, center, both from Oakland Park, Fla., to help demonstrate their

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President Barack Obama pedals bicycle-powered emergency water-sanitation station for Payton Karr, 16, left, and Kiona Elliott, 18, center, both from Oakland Park, Fla., to help demonstrate their invention, Monday, April 22, 2103, in the East Garden of the White House in Washington, where the president hosted the White House Science Fair to celebrate the student winners of a broad range of science, technology, engineering and math (STEM) competitions from across the country. The bicycle filters E. Coli and other harmful pathogens from contaminated water. (AP Photo/Pablo Martinez Monsivais) less 

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Associated Press
Tue, Apr 23, 2013 1:57 PM EDT