Environment

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A building is damaged in Tupelo, Miss. Monday, April 28, 2014. Tornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Ignacio Murillo)

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A building is damaged in Tupelo, Miss. Monday, April 28, 2014. Tornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Ignacio Murillo)

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A building is damaged in Tupelo, Miss. Monday, April 28, 2014. Tornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Ignacio Murillo)

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Buildings are damaged along Gloucester Street after a tornado in Tupelo, Miss., Monday, April 28, 2014.T ornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Thomas Graning)

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Buildings are damaged along Gloucester Street after a tornado in Tupelo, Miss., Monday, April 28, 2014.T ornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Thomas Graning)

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Ambulances gather outside the Winston Medical Center in Louisville, Miss., Monday, April 28, 2014 after a tornado hit the small hospital as well as several homes in the community. At least three tornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama as a massive, dangerous storm system passed over several states in the South. (AP Photo/Rogelio V. Solis)

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Buildings are damaged along Gloucester Street after a tornado in Tupelo, Miss., Monday, April 28, 2014. Tornados flattened homes and businesses, flipped trucks over on highways and injured numerous people in Mississippi and Alabama on Monday as a massive, dangerous storm system passed over several states in the South, threatening additional twisters as well as severe thunderstorms, damaging hail and flash floods. (AP Photo/The Daily Mississippian, Thomas Graning)

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Aeronautical frontier: Dassault Aviation has developed the Neuron, a stealth combat drone, through a project involving several European countries. A report predicts that Europe will spend billions of dollars in research for drones in coming years as it starts to catch up with U.S. technology. (Associated Press)