In a study of 1.3 million women, ages 40 to 74, having a false positive on a screening mammogram was associated with a slightly increased chance that the woman would eventually develop breast cancer. The extra risk seemed to be independent of the density of her breasts. Lester Lefkowitz/Getty Images hide caption

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Max Chan Zuckerberg's parents are marking her birth by promising to give most of their Facebook shares to good causes over their lifetimes. The family is pictured in this photo provided by Mark Zuckerberg. Uncredited/AP hide caption

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This sea wall protects the Quinault Indian Reservation at the mouth of the Quinault River. In March, a state of emergency was declared by the tribe when waves crashed over the wall. Larry Workman/KUOW/EarthFix hide caption

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David Vawter (left), project manager at LPCiminelli and Steve James, senior vice president of Operations at SolarCity, on the roof of the factory in South Buffalo. Joel Rose/NPR hide caption

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A conference attendee looks at a projection of the Earth on Monday, the opening day of the COP 21 United Nations conference on climate change, in Le Bourget, on the outskirts of Paris. Alain Jocard/AFP/Getty Images hide caption

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