A military police officer patrols in the Roquette Pinto shantytown, part of the Mare slum complex in Rio de Janeiro, Brazil, Wednesday, April 1, 2015. The Brazilian army has begun to pull out of one of Rio de Janeiro's most violent slums, with police assuming responsibility for security in the area. (Photo by Felipe Dana/AP Photo)

A giant Rubber Duck created by Dutch artist Florentijn Hofman is towed along Hong Kong's Victoria Habour Thursday, May 2, 2013. Since 2007 the 16.5-meter (54 feet)-tall Rubber Duck has traveled to various cites including Osaka, Sydney, Sao Paulo and Amsterdam. (Photo by Vincent Yu/AP Photo)

Touching and dramatic portraits and landscape shots have won prizes at Australia's prestigious photography prize. Photo: Winner of the NSW (New South Wales) prize: Peter Solness said: “I wanted to re-imagine the lost waterways, so I got my light-painting tools to work. In this image, water is being released from the top of the historic Centennial Park No. 2 Reservoir, which was built in 1925 and holds 90 megalitres of water. After 89 years of incarceration these waters now run free!”. (Photo by Peter Solness/Head On)

Number 10. BELL H-13 SIOUX was a two-bladed, single engine, light helicopter built by Bell Helicopter. Westland Aircraft manufactured the Sioux under license for the British military as the Sioux AH.1 and HT. In 1947, the United States Air Force ordered the improved Bell Model 47A. Most were designated YR-13 and three winterized versions were designated YR-13A. The United States Army first ordered Bell 47s in 1948 under the designation H-13. These would later receive the name Sioux. The Bell-built H-13 B is seen airborne in this April 29, 1951 photo. The helicopter is equipped with a 173 horsepower engine, cruises at 85 miles per hour, climbs 900 feet in a minute and has a service ceiling of 11,500 feet. (Photo by AP Photo)

Indian authorities hold a tiger skin as they set fire to a stockpile of illegal wildlife parts at the Delhi Zoo in New Delhi, India, Sunday, November 2, 2014. A stockpile of tiger skins, elephant tusks, rhino horns and other illegal animal parts were burned Sunday in an effort to discourage wildlife smuggling in South Asia. (Photo by Tsering Topgyal/AP Photo)

Medics carry a wounded person at the scene after an attack at a popular nightclub in Istanbul, early Sunday, January 1, 2017. Istanbul Governor Vasip Sahin said that an armed assailant has opened fire at a nightclub in Istanbul during New Year's celebrations. Turkish authorities have banned distribution of images relating to the Istanbul attack within Turkey. (Photo by IHA via AP Photo)

Ultra- trailers compete at sunrise on September 2, 2017 in Courmayeur, Italy, during the 15 th edition of the Mount Blanc Ultra Trail (UTMB), a 170 km race around the Mont Blanc crossing France, Italy and Switzerland. The 15 th Ultra- Trail du Mont- Blanc (UTMB) is a mountain ultramarathon with numerous passages in high altitude (>2500 m) and in difficult weather conditions (night, wind, cold, rain or snow). (Photo by Jeff Pachoud/AFP Photo)

The work entitled “Trip 1, Trip II, Trip III” by April Pine is pictured before dawn at Sculpture By The Sea at Bondi Beach on October 19, 2017 in Sydney, Australia. This year the outdoor exhibition celebrates its 21st birthday with 104 exhibiting artists from Australia and around the world and runs from the 19th October-5th November 2017. (Photo by Brook Mitchell/Getty Images)