An undercover police officer, who had been marching with anti-police demonstrators, aims his gun at protesters after some in the crowd attacked him and his partner in Oakland, California December 10, 2014. Police said more than 100 demonstrators marched in Berkeley, California, which has a history of social activism. Under cloudy skies, turnout was smaller than earlier in the week, when demonstrators in the area threw rocks at police and shut down a major freeway. (Photo by Noah Berger/Reuters)

French actress Frederique Bel arrives for the NRJ Music Awards ceremony at the Festival Palace in Cannes December 13, 2014. (Photo by Eric Gaillard/Reuters)

The Kremlin's Spasskaya (Saviour) Tower, covered by scaffolding, is seen behind the mausoleum of Soviet state founder Vladimir Lenin at the Red Square in Moscow, December 23, 2014. The restoration works will last until the spring of 2015, according to local media. (Photo by Sergei Karpukhin/Reuters)

A person dressed as an astronaut walks past a man stopping traffic on a pedestrian crossing outside the Sydney Exhibition Centre September 13, 2014 where the science-fiction convention called “Oz Comic-Con” is currently being held. The two-day convention showcases “pop culture”, and includes appearances by actors from science-fiction movies and television shows. (Photo by David Gray/Reuters)

A picture made available on 17 September 2014 shows extreme athletes resting in hammocks on webbings stretched between rocks during the International Highline Meeting in Monte Piana, near Misurina, in the northern Italian Alps, Italy, 08 September 2014. (Photo by Balazs Mohai/EPA)

A doctor performs surgery on an injured man with a part of an aluminium alloy fence through his chest after a car accident in Zhumadian, Henan province, China, September 15, 2014. The doctor managed to surgically remove the piece. (Photo by Reuters/Stringer)

BASE jumper Luke Denniss of Australia gestures as he dives in the air from the Kuala Lumpur Tower during the KL Tower International Jump in Kuala Lumpur, Malaysia, Saturday, September 27, 2014. BASE stands for the places such jumpers usually jump from: buildings, antennas, spans (bridges) and earth (cliffs). (Photo by Lai Seng Sin/AP Photo)

Italian disabled dancer Simona Atzori (top) performs, before a special audience with disabled athletes led by Pope Francis, in Paul VI hall at the Vatican October 4, 2014. (Photo by Tony Gentile/Reuters)