Many people with sleep apnea wear a CPAP machine mask in bed to help them breathe. Amy Walters/ hide caption

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The regulation of medical devices bears a passing resemblance to this giant version of the Rube Goldberg-style game Mouse Trap. Bill Ward/Flickr hide caption

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Doctors perform a kidney transplant operation in Spain in 2010. One in three people with kidney failure has antibodies that make it hard to receive a transplant, but a new treatment can get rid of them prior to transplant. Xurxo Lobato/Cover/Getty Images hide caption

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