A pedestrian crosses in front of a vehicle as part of a demonstration at Mcity on July 20, on the University of Michigan campus in Ann Arbor, Mich. Paul Sancya/AP hide caption

itoggle caption Paul Sancya/AP

Eric Pennucci of Horizon Air Services, a Boston trucking firm, does not like the idea of 18-year-olds behind the wheel of a tractor-trailer. Chris Arnold/NPR hide caption

itoggle caption Chris Arnold/NPR

The Japanese supercomputer K, pictured in June 2012 at the RIKEN Advanced Institute for Computational Science in Kobe, western Japan. The K computer is currently ranked No. 3 on a list of the 500 fastest supercomputers. Kyodo/Landov hide caption

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A piece of a wing, apparently from a Boeing 777, has been found on Reunion, an island in the Indian Ocean. It's not clear yet whether the debris is from the Malaysia Airlines jet that disappeared from radar during a flight last year. Yannick Pitou/AFP/Getty Images hide caption

itoggle caption Yannick Pitou/AFP/Getty Images