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)

Giant Olympic rings are towed on The River Thames past The Tower of London on February 28, 2012 in London, England. (Photo by Peter Macdiarmid/Getty Images)

Visitors attend a press preview of the 2012 Whitney Biennial at the Whitney Museum of American Art on February 27, 2012 in New York City. The contemporary art exhibition includes sculpture, photography, painting, installations, dance, theater, film and music and runs from March 1 through May 27. (Photo by Mario Tama/Getty Images)

In this combination image visitors to the London Super Comic Convention dress as their favourite Marvel comic characters at ExCel on February 25, 2012 in London, England. Visitors to the Comic Convention are encouraged to wear a costume of their favourite character. (Photo by Peter Macdiarmid/Getty Images)

A model walks down the runway at the 13th China International Young Fashion Designers Contest during China Fashion Week on March 25, 2005 in Beijing, China. (Photo by China Photos/Getty Images)

Singer Kevin Lyttle (C) performs during the Premier Beverage: Jocktails 2012 Orlando at the Orlando Magic Experience Center on February 24, 2012 in Orlando, United States. (Photo by Gerardo Mora/Getty Images for Premier Beverage Company)

An activist in a Guy Fawkes mask adjusts a skull and crossbones flag during a demonstration against the Anti-Counterfeiting Trade Agreement (ACTA) on February 25, 2012 in Berlin, Germany. (Photo by Adam Berry/Getty Images)

Kenny Wallace, driver of the #09 Family Farmers Toyota, spins into Justin Allgaier, driver of the #31 Brandt Chevrolet, who is lifted into the air by Reed Sorenson, driver of the #52 Means Racing Chevrolet, as Michael Annett, driver of the #43 Pilot Flying J. Ford, tries to avoid the wreckage during the NASCAR Nationwide Series DRIVE4COPD 300 at Daytona International Speedway on February 25, 2012 in Daytona Beach, Florida. (Photo by John Harrelson/Getty Images for NASCAR)