South Korean soldiers participate in a winter river crossing operation in preparation for a possible North Korean attack on February 8, 2012 in Yeoju, South Korea. The Korean peninsula is the world's last Cold War frontier as stalinist North Korea and pro-western South Korea have been technically at war since the 1950-53 conflict. (Photo by Chung Sung-Jun/Getty Images)

Characters from Star Wars pose for a photocall to promote the release of Star Wars: Episode 1 – The Phantom Menace 3D at The London Eye on February 8, 2012 in London, England. (Photo by Dave J. Hogan/Getty Images)

A new 3D IMAX screen is installed at IMAX Darling Harbour on February 9, 2012 in Sydney, Australia. The new 3D screen at 29.5 metres by 35.7 metres will replace the former screen at IMAX Darling Harbour as the largest in the world. (Photo by Matt King/Getty Images)

A Chinese couple take pictures in an interactive installation art work named “You and Me” on Valentine's Day at 798 Art Zone on February 14, 2012 in Beijing, China. (Photo by Feng Li/Getty Images)

The walls of Sydney's Town Hall Station are bedecked to resemble a Woolworths' supermarket shelf in Australia's first virtual supermarket, at Town Hall Station on February 19, 2012 in Sydney, Australia. (Photo by Marianna Massey/Getty Images for Woolworths)

A sculpture entitled “Powerless Structures, Fig.101” designed by Danish artist Michael Elmgreen and Norwegian artist Ingar Dragset is unveiled on the Fourth Plinth in Trafalgar Square on February 23, 2012 in London, England. (Photo by Oli Scarff/Getty Images)

German kickboxer Christine Theiss (L) hits challenger Olja Zerajic of Bosnia during their WKA middleweight title fight at Postpalast on March 2, 2012 in Munich, Germany. (Photo by Alexandra Beier/Bongarts/Getty Images)

Encyclopedia Britannica editions are seen at the New York Public Library on March 14, 2012 in New York City. Encyclopedia Britannica announced it will be ceasing its print edition of reference books for the first time in its 244-year history to focus solely on digital versions. (Photo by Mario Tama/Getty Images)