Science and technology

Associated Press
In this Wednesday, April 24, 2013 photo, traffic signals are seen on Wilshire Boulevard in Los Angeles. The nation's most congested city has become a model for traffic control. With the flip of a switch earlier this year, Los Angeles became a worldwide leader by synchronizing all of its nearly 4,400 stoplights, making it the world's first major city to do so. (AP Photo/Reed Saxon)

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