Egyptians attend a rally calling for a rapid transition from military to civilian rule following the February ouster of president Hosni Mubarak in Cairo's Tahrir Square. Mahmud Hams /AFP/Getty Images hide caption

The ideas of John Maynard Keynes, seen here around 1940, had great influence over the economic policies that followed the Great Depression and World War II. Walter Stoneman/Getty Images hide caption

Egyptians are seen working in a bakery in Cairo. The U.S. has been working on ways to help revive the economies of nations in transition, like Egypt, Tunisia and Libya, while having limited resources available during tough economic times. Mahmud Hams /AFP/Getty Images hide caption

Windmills and solar panels in Atlantic City, N.J., power a wastewater treatment plant, with surplus energy going to the area power grid. Solar and wind energy companies receive $370 million in federal subsidies annually, which is less than 1 percent of what oil and gas industries receive. Mel Evans/AP hide caption

President Richard Nixon faced television cameras in the Oval Office on April 30, 1973 to announce the departure of his two closest assistants in the deepening Watergate scandal. CBS/AP hide caption

Patricia Maisch, one of the people who helped halt the Tucson shooting that killed six and wounded 13, including Arizona Rep. Gabrielle Giffords, holds up a photograph of victim John Roll, a federal judge, while testifying before a Senate subcommittee on Tuesday. Maisch testified in support of legislation that would strengthen federal power over the states' handling of background checks. Chip Somodevilla/Getty Images hide caption

Fishermen and visitors gather at the beach in the village of Popotla, Mexico, some 15 miles south of the U.S.-Mexico border, in July 2010. Illegal immigrants are increasingly looking to the ocean, as they consider crossing overland more risky. Guillermo Arias/AP hide caption

Police clash with workers of American mining company Freeport-McMoRan during a protest in Timika, Papua province, Indonesia, Oct. 10. Indonesian security forces fired on striking workers at Freeport-McMoRan's Grasberg gold and copper mine after a protest turned deadly. Anonymous/AP hide caption

Then-Penn State head coach Joe Paterno gets out of the way during warm-ups before an NCAA college football game in State College, Pa., last month. Gene J. Puskar/AP hide caption