The Penn State University campus in State College, Pa. A new state law requires university professors to get a background check every three years and have their fingerprints taken. Gene J. Puskar/AP hide caption

itoggle caption Gene J. Puskar/AP

Alachua County Sheriff Sadie Darnell (left) and Dr. Nancy Hardt, University of Florida. Bryan Thomas for NPR hide caption

itoggle caption Bryan Thomas for NPR

Silvester Fullard fixes dinner for his 11-year-old son Tavestsiar. When Tavestsiar first came to live with his dad in 2010, he was closed off, Silvester says; "he didn't want to be around other kids." Charles Mostoller for NPR hide caption

itoggle caption Charles Mostoller for NPR
Vidhya Nagarajan for NPR
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Using Tor, or The Onion Router, enables users to hide their online activities. Advocates say the network protects the privacy of activists. But prosecutors say it's used extensively by criminals — and is making it harder for law enforcement to do its job. Daniel Acker/Bloomberg via Getty Images hide caption

itoggle caption Daniel Acker/Bloomberg via Getty Images

Girls are particularly vulnerable to brain changes caused by stress or trauma, researchers say. Allen Johnson/iStockphoto.com hide caption

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