Michelle Obama eats lunch with school children at Parklawn Elementary School in Alexandria, Va., in 2012. The first lady unveiled new guidelines Tuesday aimed at cracking down on the marketing of junk food to kids during the school day. Saul Loeb/AFP/Getty Images hide caption

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Sophia Jarvis, 4, of Berkeley, Calif., is one of the few children diagnosed with the polio-like disease, which left her arm paralyzed. She attended a press conference Monday at Stanford University with her dad, Jeff. Martha Mendoza/AP hide caption

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Joscelyn Benninghoff, 10, goes over the results of her cholesterol test with her mother Elizabeth Duruz (right) and Dr. Elaine Urbina at Cincinnati Children's Hospital in 2011. Al Behrman/AP hide caption

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In the Institute for the Unsalvageable in Sighetu Marmatiei, Romania, shown here in 1992, children were left in cribs for days on end. Tom Szalay hide caption

itoggle caption Tom Szalay

When schools close for bad weather, some kids miss out on much-needed nutritious meals. "It's hard to be a hungry person, and it gets harder when the weather is like this," Nancy Roman, president of the Capital Area Food Bank in Washington, D.C., says of severe cold and snow. Jessica Glazer/NPR hide caption

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A 13-year-old girl gets an HPV vaccination at the University of Miami in 2011. The vaccine protects against the human papillomavirus, which can cause cervical cancer. Joe Raedle/Getty Images hide caption

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A nurse attaches the low-cost breathing machine (far left) to an infant at The Queen Elizabeth Central Hospital in Blantyre, Malawi. Jocelyn Brown/Rice University hide caption

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The CDC would be happy with these guys, who were playing in Birmingham, Ala., in July 2013. Teenage boys say basketball is their favorite activity. Mark Almond/AL.COM /Landov hide caption

itoggle caption Mark Almond/AL.COM /Landov

Palestinian girls read the Koran at a camp in Gaza City, June 2012. In poor countries, boys are 20 percent more likely than girls to enroll in school, UNICEF says. Mahmud Hams/AFP/Getty Images hide caption

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