A protester jumps on the table in front of the European Central Bank President Mario Draghi during a news conference in Frankfurt, Germany April 15, 2015. (Photo by Kai Pfaffenbach/Reuters)

Wearing his new prosthetic legs Hero gets a taste of shrubbery Wednesday, May 21, 2014, in Houston. The abandoned calf rescued from a Virginia farm a year ago and brought to Texas after it nearly died is getting permanent prosthetics to replace back hooves that had to be amputated because of frostbite. (Photo by Pat Sullivan/AP Photo)

A woman poses for a photograph in front of a 3D painting at HK 3D Museum in Hong Kong June 26, 2014. (Photo by Tyrone Siu/Reuters)

A man dressed as Hindu goddess Kali, the goddess of power, performs with a burning camphor tablet on his tongue during a religious procession ahead of the “Kumbh Mela”, or Pitcher Festival, in the northern Indian city of Allahabad January 6, 2013. During the festival, hundreds of thousands of Hindus take part in a religious gathering at the banks of the river Ganges. The festival is held every 12 years in different Indian cities. (Photo by Jitendra Prakash/Reuters)

“A robot suit that can help the elderly or disabled get around was given its global safety certificate in Japan on February 27, 2013, paving the way for its worldwide roll-out”. Photo: Robot suit “Hybrid Assistive Limb (HAL)” worn by a man developed by University of Tsukuba is seen lifting a 30kg weight during 2005 International Robot Exhibition on November 30, 2005 in Tokyo, Japan. By wearing the power suit, it makes it easier to move and lift heavy things. (Photo by Koichi Kamoshida)

Student protestors, including one girl with a camera, struggle with soldiers from the Chinese Army, the PLA. Tiananmen Square, 1989. (Photo by Jeff Widener/Associated Press)

A pro-democracy demonstrator fights with a Soviet soldier on top of a tank parked in front of the Russian Federation building on August 19, 1991, after a coup toppled Soviet President Mikhail Gorbachev. The same day, thousands in Moscow, Leningrad, and other cities answered Russian Republic President Boris Yeltsin's call to raise barricades against tanks and troops. (Dima Tanin/AFP/Getty Images)