The core of the RBT-3 reactor at the Research Institute of Atomic Reactors in Dimitrovgrad, Russia. Some scientists suspect the institute's work on medical isotopes might explain radioactivity detected over Europe.
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The Centers for Medicare and Medicaid Services — and its controversial center for innovation — is part of the U.S. Department of Health and Human Services, and has its headquarters outside D.C., in Woodlawn, Md.
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A technician examines the mirror on the Large Synoptic Survey Telescope. Scientists at two national laboratories are currently building the components for an enormous digital camera that will capture images from the telescope.
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Martha (right), the last known passenger pigeon, died in 1914. Her preserved body is now on display at the Smithsonian's National Museum of Natural History in Washington, D.C.
A farmer plows his field with an ox-pulled plow in China's Guangxi province. Archaeologists think that domesticated farm animals increased inequality in some ancient societies.
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