FILE - This is a 2009 photo of Kris Dielman of the San Diego Chargers NFL football team. Dielman will announce his retirement Thursday, March 1, 2012, because of a series of concussions.  A nine-year NFL veteran, Dielman suffered a concussion in a loss to the New York Jets, returned to the game, then had a seizure on the flight back to San Diego. He didn't play again in 2011.   (AP Photo/File)
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