Abortion opponents demonstrate outside Mississippi's only abortion clinic in Jackson. Rogelio V. Solis/AP hide caption

itoggle caption Rogelio V. Solis/AP

Pretty to look at, almost, but Klebsiella pneumoniae bacteria these are a common cause of infections in hospitals. CDC hide caption

itoggle caption CDC

Brian Lawson rolls a marijuana cigarette at the BC Marijuana Party Headquarters in Vancouver, British Columbia. Vancouver is in the marijuana-friendly corner of Canada. Jae C. Hong/AP hide caption

itoggle caption Jae C. Hong/AP

An American Cancer Society Relay for Life event at the University of Texas-Dallas in 2006. The events are meant to "celebrate the lives of people who have battled cancer, remember loved ones lost, and fight back against the disease," according to the organization. Josh Berglund/via Wikimedia Commons hide caption

itoggle caption Josh Berglund/via Wikimedia Commons

Timothy Ray Brown, widely known in research circles as the Berlin patient, was cured of his HIV infection by bone marrow transplants. Now scientists are trying to make sense of the traces of HIV they've found in some cells of his body. Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

A woman pours two tablets into her hand from a pill bottle. iStockphoto.com hide caption

itoggle caption iStockphoto.com