"This July 28, 2014 photo shows Clive Pai, a University of Illinois-Chicago physical therapy professor, left, and graduate student Emma Wang, right, hooking Mary Kaye, 81 into a safety harness before she demonstrates a treadmill balance session at the school in Chicago. Once in the harness, Kaye walks on a lab-built walkway that causes people to unexpectedly trip and can teach them quickly how to catch themselves and avoid falling. Falls in the elderly cost $30 billion yearly to treat and can send them spiraling into poor health and disability. Pai who came up with the idea calls it ""a vaccine against falls"" and says his research shows that older people's brains can learn and adapt much more quickly than previously thought. (AP Photo/M. Spencer Green)"
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