One of the year's most popular posts examined the evolutionary pull of running and high-aerobic activities on our brains. Above, a man runs past the Sydney Harbour Bridge in April.
Ryan Pierse/Getty Images
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Researchers at the U.S. Geological Survey National Wildlife Health Center in Madison, Wis., use eggs to see if the Asian strain of the H5N1 bird flu virus has entered the U.S. in this photo from 2006.
Andy Manis/AP
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Mosquitoes like this one can carry the virus that causes dengue fever, which may become a bigger problem in some regions as biodiversity is lost.
James Gathany/CDC Public Health Image Library
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Kathy Del Tonto (far right) participates in a class that teaches school cafeteria workers how to prepare meals from scratch.
LiveWell Colorado
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Photographer Freya Najade journeys into the weird sci-fi world of Europe's agricultural production. In one cow-milking facility she visited, "two people are needed to milk twice a day 300 cows," she writes.
Freya Najade
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John Kelly and Dr. Marcia Angell were advocates on opposing sides of a Massachusetts measure to legalize physician-assisted suicide.
Jesse Costa/Jesse Costa/WBUR
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Dr. Jame Abraham used positron emission tomography, or PET, scans to understand differences in brain metabolism before and after chemotherapy.
Dr. Jame Abraham
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Brain scans using Amyvid dye to highlight beta-amyloid plaques in the brain. Clockwise from top left: a cognitively normal subject; an amyloid-positive patient with Alzheimer's disease; a patient with mild cognitive impairment who progressed to dementia during a study; and a patient with mild cognitive impairment.
Slide courtesy of the journal Neurology
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