A Metro Light Rail train rolls by the Devine Legacy apartment building along Central Avenue in Phoenix. The energy-efficient complex includes 65 "urban style" apartments.
Courtesy of Mica Thomas Mulloy
House Budget Committee Chairman Paul Ryan, R-Wis., shakes hands with Federal Reserve Chairman Ben Bernanke at the close of the committee's hearing on the state of the economy in February 2011.
J. Scott Applewhite/AP
A worker on a newly constructed transmission tower near Buetzow, Germany, earlier this month. The German government plans to shut down nuclear power plants and is seeking to replace that production with power from renewable energy sources, especially wind turbines and solar parks. New power transmission lines will be needed.
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The current radar-based air traffic control system (shown here) will eventually be replaced with a new system called NextGen, which will rely on GPS. A number of computer security experts are concerned that NextGen is insecure and vulnerable to hackers.
John Moore/Getty Images