Science and technology

Associated Press
In this April 25, 2013 photo, stoplights shine red and green at top right as traffic flows 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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