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

Drexel Siok, environmental scientist at Delaware National Estuarine Research Reserve, holds a horseshoe crab that's been tagged on Kitts Hummock Beach near Dover, Del. During the annual count volunteers make a note if they find a tagged crab. Researchers then use the information to learn where crabs are moving over time. Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR

Workers use perforating tools to create fractures in rock. An EPA study finds that "fracking" to reach and extract deep pockets of hydrocarbons has not caused widespread drinking water pollution. Brennan Linsley/AP hide caption

itoggle caption Brennan Linsley/AP

Camden County Police Officer Virginia Matias and Officer Jose Vale often walk together when on foot patrol in Camden. Matias patrols sections of the city on foot so she can strike up conversations with business owners and residents. She says this makes her more familiar with what's going on than she would be if she stayed in her patrol car all day. Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR