U.S. Park Police officers arrest demonstrators in front of the While House on Thursday. They were protesting against a proposed 1,700-mile-long pipeline that would carry oil from the tar sands in Alberta, Canada, to the U.S. Gulf Coast.
A screen grab of Syrian Attorney General Anan Bakkor, during a video he made where he resigned from his post and revealed that he was forced to cover up deaths related to the popular uprising in the country.
Former Utah Gov. Jon Huntsman, shown speaking at an American Legion Post in Nashua, N.H., last month, is campaigning again in the state this week. The Republican White House hopeful so far hasn't run any TV ads in the state.
A lab technician prepares blood samples from volunteers for viral genotyping at a government-run health center in Bagamoyo, Tanzania, in 2009. Tanzania is currently hosting the final stages of a human trial of a pioneering vaccine against malaria. The vaccine is one of many medical innovations to emerge from Walter Reed over the decades.
Tony Karumba/AFP/Getty Images