A study published in the journal Science last December suggested that a bacterium found in California's Mono Lake was able to substitute arsenic for phosphorous. But that conclusion has many critics. Miss Bliss 55 via Flickr hide caption

itoggle caption Miss Bliss 55 via Flickr

Amy Womack and her daughter, Alexis Nelson, sit on the front steps of her parents' house in Cleveland, Tenn., in late April. Womack says her father urged her and 13 relatives and friends into the basement before a tornado hit; she credits him with saving their lives. Wade Payne/AP hide caption

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Residents of Joplin, Mo. salvage items from their home on Monday, a day after a devastating tornado struck the town. University of Oklahoma meteorologist Howie Bluestein says this could be be the last major tornado of the season, or "it could continue to be crazy." Charlie Riedel/AP hide caption

itoggle caption Charlie Riedel/AP

Learning juicy details about someone can change the way you see them — literally, according to a new study. August Darwell/Getty Images hide caption

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1st Lt. Fred Simpson considers a computerized mental exercise designed to improve focus and memory. Simpson was knocked unconscious by a grenade blast in Afghanistan and now receives treatment at Walter Reed Army Medical Center in Washington. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR

A patient participates in a brain-computer interface study. By placing an array of sensors directly on the brain and connecting them to a computer, researchers are able to decode brain signals into meaningful information, including some words. American Museum of Natural History Science Bulletins hide caption

itoggle caption American Museum of Natural History Science Bulletins

In a town in South Korea, one out of every 38 children tested had autism. Two thirds of these were undiagnosed and untreated, and seemed to be doing okay in school. Lee Jin-man/AP hide caption

itoggle caption Lee Jin-man/AP

Residents survey the destruction after a tornado hit Pratt City, Ala., on April 27. Short-term forecasting of twisters like the ones that swept the South this week has grown increasingly accurate, but long-term forecasting remains highly unreliable. Butch Dill/AP hide caption

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The placenta, the nutrient-rich organ shown in this model as the layer above the baby's feet, makes its own serotonin. Mark Evans/iStockphoto.com hide caption

itoggle caption Mark Evans/iStockphoto.com

Manholes poke out from the ground in Urayasu, Japan, due to the liquefaction triggered by the 9.0 magnitude earthquake. The phenomenon, which allows sand and water to rise following ground shaking, was particularly pronounced in this area as a result of the long duration of the March 11 quake. Koki Nagahama/Getty Images hide caption

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A Tokyo tuna wholesaler adds slices of fish to his stall on March 23. Fish prices have plummeted in Japan amid fears that radioactive material leaking from the damaged Fukushima Dai-ichi nuclear power plant may have contaminated the animals. But experts say there's no risk right now and that fish is safe to eat. Lee Jin-man/AP hide caption

itoggle caption Lee Jin-man/AP

Japan Self-Defense Force officers in radiation protection suits hold a blue sheet over patients who were exposed to high levels of radiation at the Fukushima Dai-ichi nuclear power plant on March 25. A team of experts at Japan's National Institute of Radiological Sciences have helped treat injured workers. Jiji Press/AFP/Getty Images hide caption

itoggle caption Jiji Press/AFP/Getty Images