President Barack Obama and first lady Michelle Obama unveiled the Let Girls Learn program at the East Room of the White House on Tuesday. Chip Somodevilla/Getty Images hide caption

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The ParaGuard IUD, which releases copper into the uterine cavity, can last up to 10 years. In clinical studies, the pregnancy rate among women using the device was less than 1 pregnancy per 100 women annually. Mark Harmel/Science Source hide caption

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Research into how the human brain develops helps explain why teens have trouble controlling impulses. Leigh Wells/Ikon Images/Corbis hide caption

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Researchers say that aggressive people tend to interpret ambiguous faces as reflecting hostility. iStockphoto.com hide caption

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Members of the boys basketball team from Dimond High School in Anchorage, Alaska, celebrate their 2012 state championship victory. Psychological research shows that sports camaraderie improves teenagers' mental health. Charles Pulliam/AP hide caption

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