Science and technology

Associated Press
In this April 25, 2013 extended time exposure photo, stoplights shine like stars at top right, and traffic, seen as streaks, flows along 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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