A girl joins other novice nuns for a lunch at the Sathira-Dhammasathan Buddhist meditation centre in Bangkok April 21, 2013. A group of Thai girls are choosing to spend part of their school holidays as Buddhist nuns, down to having their heads shaven at the meditation centre. The centre, founded in 1987, is a learning community for peace and harmony that has programs open to people regardless of age and gender. (Photo by Damir Sagolj/Reuters)

Gers, traditional Mongolian tents, are seen on a hill in an area known as a ger district in Ulan Bator June 26, 2013. Approximately 60 percent of the population of Ulan Bator live in settlements known as ger districts and in many cases residents have limited access to basic services such as water and sanitation. According to a 2010 National Population Center census, every year between thirty and forty thousand people migrate from the countryside to the capital Ulan Bator. Ger districts in the city have been expanding rapidly in recent years. Mongolia is the world's least densely populated country, with 2.8 million people spread across an area around three times the size of France. (Photo by Carlos Barria/Reuters)

Celebrities including singer Nicole Scherzinger and actor Simon Pegg have been snapped by top photographer Rankin for an Oxfam campaign. All in all, a dozen well-known faces have been captured in various poses to highlight the charity's Lift Lives for Good campaign. The fundraising drive, launched at the start of the year, aims to shine a light on the work done by the charity to help poor people around the world. Photo: Undated handout photo issued by Oxfam of Caroline Flack who took part in a photo shoot with top photographer Rankin for Oxfam's Lift Lives for Good campaign. (Photo by Rankin/PA Wire)

In this Wednesday, March, 5, 2014 photo, Afghan female boxers practice at the Kabul Stadium boxing club, Afghanistan. The women, who are 18 and older, don't have much more than determination, and a trainer who runs them through their paces, watches as they spar, corrects their technique, tells them when to jab, how to protect themselves, when to power through with a left and then a right. (Photo by Massoud Hossaini/AP Photo)

A woman attends a boxing class at Princess Women's Boxing Club in Shanghai December 3, 2014. Women have boxed as long as the sport has existed but for years they were relegated out of national and international competitions in many countries around the world. Female boxers entered the ring in an exhibition match at the 1904 Olympic Games, but it was more than a century later when they were given the green light to make their Olympic debut in London in 2012. (Photo by Carlos Barria/Reuters)

A follower shows a ring of La Santa Muerte (The Saint of Death), a cult figure often depicted as a skeletal grim reaper, near at the saint's altar at Tepito neighborhood, in Mexico City January 1, 2015. Followers gather at the saint's altar at the start of the new year to leave offerings of apples, flowers, cigarettes, coloured candles and tequila to thank the saint for favours that have been granted and to ask for new ones in the new year. (Photo by Edgard Garrido/Reuters)

In this October 15, 2014 file photo, Katsu Nakamura, sky division manager for Yamaha USA, moves the RMax unmanned helicopter into position before a demonstration of its aerial application capabilities at the University of California, Davis' Oakville Station test vineyard in Oakville, Calif. Researchers at UC Davis have been studying the effectiveness of the drone's ability for spraying pest control and nutritional materials on the test vineyard in California's Napa Valley. (Photo by Rich Pedroncelli/AP Photo)

A bird is cleaned at the International Bird Rescue in Fairfield, California January 20, 2015. A gooey, unknown material discovered on the eastern shores of San Francisco Bay is clinging to the feathers of birds, and more than 100 birds, mostly species of oceangoing, diving ducks, have died after their feathers were fouled by the viscous substance now undergoing testing at state labs in Sacramento. (Photo by Robert Galbraith/Reuters)