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Neil Johnson, a University of Miami physicist, developed this mathematical formula to predict insurgent attacks in war zones. Courtesy of Neil Johnson hide caption

African Union and Somali troops launch an attack on al-Shabaab, a militant group linked to al-Qaida, in Mogadishu, Somalia, on Thursday in an effort to protect famine relief efforts, officials said. The World Food Program says it cannot reach 2.2 million people in need of aid in the militant-controlled areas in southern Somalia because of insecurity. AP hide caption

A drone takes its first flight at Edwards Air Force Base in California in February. In the near future, drones could be used outside of the military for things like traffic helicopters or flying jumbo jets. Alan Radecki/AP hide caption

Israa Saad Diab lifts the cover from her son Hamza's face, while her husband, Ibrahim Muhammad, watches, after the traditional Sebou ceremony in Mansoura, Egypt, on May 27. Holly Pickett for NPR hide caption

News International executive James Murdoch testified at a parliamentary hearing that he was unaware of a wider problem of cell phone hacking until a lawsuit in 2010. Warren Allott/AFP/Getty Images hide caption

In this photo taken July 6, rebel forces chief commander Abdel Fattah Younes speaks during a rally in the rebel-held city of Benghazi, Libya. Libya's rebel leadership council announced the death of Younes on Thursday, hours after he was arrested by the rebels for questioning about suspicions his family still had ties to Moammar Gadhafi's regime. Sergey Ponomarev/AP hide caption

People gather outside Oslo City Hall on Monday to participate in a "rose march" in memory of the victims of Friday's twin attacks in Norway. Anders Behring Breivik, who admitted to the attacks but entered a plea of not guilty, said he wanted to save Europe from Muslim immigration. Emilio Morenatti/AP hide caption