Princeton University professor John Nash speaks during a news conference at the university in Oct. 1994 after being named the winner of the Nobel Prize for economics. Charles Rex Arbogast/AP hide caption

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Greek Prime Minister Alexis Tsipras (center) gestures next to Deputy Prime Minister Yannis Dragasakis (left) and Interior and Administrative Reconstruction Minister Nikos Voutsis. Voutsis says Greece may miss its next debt payment. Alkis Konstantinidis/Reuters/Landov hide caption

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Panama's former President Ricardo Martinelli answers questions during an interview at a hotel in Guatemala City in January. Moises Castillo/AP hide caption

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Mourners attend the May 14 funeral of Hezbollah fighter Ahmad al-Amin in Babliyeh, Lebanon. Hezbollah is fighting alongside the Syrian army and Amin was killed while fighting in Syria's Qalamoun mountains against Nusra Front, al-Qaida's branch in Syria. The Syrian army has suffered multiple setbacks recently, but Hezbollah did help dislodge rebel fighters along the Syria-Lebanon border. Mohammad Zaatari/AP hide caption

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A statue of Olympias, mother of Alexander the Great, depicts her as pregnant with her famous son. It's part of a monument to Alexander's family in Skopje, the Macedonian capital. Joanna Kakissis/NPR hide caption

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Gloria Steinem and South Korean peace activists march along a military fence at a checkpoint after crossing the border separating North and South Korea. Jung Yeon-Je/AFP/Getty Images hide caption

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The Bank of England in London in a photograph taken in March. The central bank inadvertently revealed that it was planning for a possible withdrawal of the U.K. from the European Union. Suzanne Plunkett/Reuters/Landov hide caption

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Former Defense Secretary Robert Gates at the Boy Scouts of America's annual meeting in 2014. "There's no certainty about any of this," he says of the situation in Iraq. Mark Zaleski/AP hide caption

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Vehicles burn, that authorities say caught fire during a gunbattle, in a warehouse at Rancho del Sol, near Ecuanduero, in western Mexico, on Friday. At least 43 people died Friday in what authorities described as a fierce, three-hour gunbattle between federal forces and suspected drug gang gunmen. Oscar Pantoja Segundo/AP hide caption

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