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

itoggle caption Allen Johnson/iStockphoto.com