Google's self-driving prototype car can be found cruising the streets near the Internet company's Silicon Valley headquarters to test programming responses to a variety of situations. Tony Avelar/AP hide caption

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A surgical team at Sooam Biotech in Seoul, South Korea, injects cloned embryos into the uterus of an anesthetized dog. Rob Stein/NPR hide caption

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Alan Schein Photography/Corbis

Journalist Brian Williams hosts The Lincoln Awards: A Concert For Veterans & The Military Family on Jan. 7 at John F. Kennedy Center for the Performing Arts in Washington. Recent reports suggest the suspended NBC anchor may have embellished several of his stories. Paul Morigi/Getty Images Entertainment hide caption

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When combined with results of other neurological tests, and in the context of a thorough medical history, atrophy of the brain (shown here in an MRI scan) sometimes indicates Alzheimer's. Simon Fraser/Science Source hide caption

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