House Republicans leave the White House Wednesday after meeting with President Obama about the debt ceiling. Charles Dharapak/AP hide caption

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A newborn gets a hearing test. Cytomegalovirus is a major cause of hearing loss in babies. hide caption

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An image of 13-year-old Hamza al-Khateeb is surrounded by candles in this photo from a Facebook page in his memory. From hide caption

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Clashes erupted between security forces and students demanding political change at a protest in Algeria's capital, Algiers, on May 2. Small protests in the city are quickly put down by well-equipped riot police. Farouk Batiche/AFP/Getty Images hide caption

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After a sperm fertilizes an egg, cells divide in a stage called a blastocyst. Doctors say pregnancy doesn't start until the blastocyst implants into the woman's uterus. hide caption

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The confluence of the Baker and Chacabuco rivers in the remote Patagonian region of Aysen in Chile, as seen on Jan. 20, 2008. The plan to build five new hydroelectric dams in the region has sparked protests in Chile. Jorge Uzon/AP hide caption

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Secretary of Defense Robert Gates. Alex Brandon/AP hide caption

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