Molecular biologist Randy Sheckman, who shared the 2013 Nobel Prize in physiology or medicine, acknowledges applause after receiving his prize during the ceremony in Stockholm last December. Pascal Le Segretain/Getty Images hide caption

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New York City police officers stand guard in Times Square earlier this month after a blog affiliated with the so-called Islamic State militants mentioned the area as a target for bombing. Andrew Burton/Getty Images hide caption

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Biohazard suits used to handle dangerous microbes hang in a laboratory at the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Md. Patrick Semansky/AP hide caption

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The French enjoy horse meat — here's a horse meat butcher in Paris. But even the French were angry that they had been paying beef prices for it last year. Thomas Coex/AFP/Getty Images hide caption

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This grocery store packet of porcini mushrooms contained a surprise: three species of fungi never before named or described. Bryn Dentinger/Royal Botanical Gardens, Kew hide caption

itoggle caption Bryn Dentinger/Royal Botanical Gardens, Kew

No amount of training can undo the violence someone experienced at home as a child, but it can help break the cycle. Pamela Albin Moore/iStockphoto hide caption

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Mammuthus columbi, the Columbian mammoth, used to be common in America, but went extinct about 10,000 years ago. The specimen found south of Dallas is estimated to be 20,000 - 40,000 years old. Illustration by Karen Carr/Perot Museum of Nature and Science hide caption

itoggle caption Illustration by Karen Carr/Perot Museum of Nature and Science