A security exercise takes place along the River Thames on January 19, 2012 in London, England. The exercise including around 44 police officers, 94 military personnel, 15 boats and a Royal Navy Lynx helicopter was conducted by both the Metropolitan Police and the Royal Marines and designed to test their joint capability ahead of the 2012 London Olympic Games. (Photo by Dan Kitwood/Getty Images)

Baraa Melhem plays on her sisters bike at her mothers house on February 2, 2012 in Qalandia, near Ramallah, West Bank. Baraa Melhem was held in captivity in a bathroom by her father for over nine years, and was finally rescued by Palestinian security forces after a family member notified police. (Photo by Ilia Yefimovich/Getty Images)

Casey Stoner of Australia and Repsol Honda Team rounds the bend during the third day of MotoGP testing at Sepang Circuit on February 2, 2012 in Kuala Lumpur, Malaysia. (Photo by Mirco Lazzari gp/Getty Images)

Hooded torch bearers lead the winter procession through the snow on February 4, 2012 in Huddersfield, England. Imbolc is a pagan festival that marks the half way point between the winter solstice and the spring equinox. Imbolc festivals celebrates the awakening of the land and the growing power of the Sun. (Photo by Bethany Clarke/Getty Images)

In this handout image provided by Carnival Australia, captain of the Queen Mary 2 Christopher Rynd poses on the desk of the Queen Mary 2 on February 8, 2012 in Perth, Australia. (Photo by James Morgan/Carnival Australia via Getty Images)

(L-R) Models Lindsay Ellingson, Adriana Lima, and Doutzen Kroes attend the Victoria's Secret Angels Valentine's Day Event at Victoria's Secret, SoHo on February 8, 2012 in New York City. (Photo by D. Dipasupil/Getty Images)

Commuters walk up the redesigned subway stairs at the Tanjong Pagar subway station on August 23, 2011 in Singapore. The subway stairs have been repainted in bright colours and slogans encouraging people to take the stairs, by way of promoting fitness in the city. (Photo by Chris McGrath/Getty Images)

Grinders are on display for sale during the HempCon 2011 Medical Marijuana Expo at the Los Angeles Convention Center on August 26, 2011 in Los Angeles, California. The three-day event includes exhibits, evaluation services, legal services, equipment, and accessories. (Photo by Kevork Djansezian/Getty Images)