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)

Afghan police officers secure a transportation headquarters that was besieged for two days last weekend, on May 14, 2011 in Kandahar, Afghanistan. Taliban gunmen and suicide bombers unleashed a major assault May 7, 2011 on locations in Kandahar that included the governor's compound, the mayor's office, police stations, and an intelligence agency headquarters. (Photo by Majid Saeedi/Getty Images)

Lady officers of the Philippine National Police force show the taped muzzle of their guns at a police camp in Taguig City, south of Manila, Philippines, 22 December 2014. Law enforcement units all over the country held a ceremonial taping of firearms as a counter measure against cases of indiscriminate firing and illegal discharge of service weapons during the upcoming Christmas and New Year celebrations. (Photo by Francis R. Malasig/EPA)

Singer Stacy “Fergie” Ferguson of the Black Eyed Peas appears with her wax figure after it was unveiled at Madame Tussauds Las Vegas at The Venetian September 22, 2011 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

“The Sloan Digital Sky Survey III (SDSS-III) has released the largest-ever three-dimensional map of massive galaxies and distant black holes, which will help astronomers explain the mysterious “dark matter” and “dark energy” that scientists know makes up 96 percent of the Universe”. – SDSS-III

“Belarus riot police detained scores of demonstrators at a protest rally against President Alexander Lukashenko. Rallies against Lukashenko's rule are rare in the tightly-policed ex-Soviet republic, but protest calls on social networking sites have multiplied in recent weeks as a severe currency crisis has brought economic hardship. Demonstrators gathered peacefully, simply applauding in a coordinated act of protest”. – Af.Reuters.com (Photo by Anton Motolko; Belarus, Minsk; June 22, 2011)

Rio de Janeiro's state military policemen aim their guns during a violent protest in a favela next to Copacabana, Rio de Janeiro on April 22, 2014. Violent protests broke out in Rio's landmark beachfront district, Copacabana, following the death of a resident last weekend during clashes with the Army in a nearby favela. (Photo by Christophe Simon/AFP Photo)

A policeman kick in the door of a residence next to the Black Panther headquarters in New Orleans as they moved in following a shootout, September 15, 1970. Other heavily armed policemen stand at ready. (Photo by Jack Thornell/AP Photo)