Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

Women perform under black fabric during a street performance in Pristina on October 6, 2017 against sexual harassments in Kosovo. (Photo by Armend Nimani/AFP Photo)

Magbola Alhadi, 20, and her three children pose for a portrait in Jamam refugee camp in Maban County, South Sudan on August 11th, 2012. Magboola and her family weathered aerial bombing raids for several months, but decided it was time to leave their village of Bofe the night that soldiers arrived and opened fire. With her three children, she travelled for 12 days from Bofe to the town of El Fudj, on the South Sudanese border. The most important thing that Magboola was able to bring with her is the saucepan she holds in this photograph. It wasn't the largest pot that she had in Bofe, but it was small enough she could travel with it, yet big enough to cook sorghum for herself and her three daughters (from left: Aduna Omar, 6, Halima Omar, 4, and Arfa Omar, 2) during their journey. (Photo by Brian Sokol/Panos Pictures)

People pass by a vehicle almost completely submerged on a street covered with mud due to heavy floods in Tekija village September 17, 2014. One person died in Serbia and authorities scrambled to evacuate hundreds of people from villages threatened by rising rivers, officials said on Tuesday, in scenes recalling the devastating May flooding that killed dozens. (Photo by Djordje Kojadinovic/Reuters)

Diesel is poured into a container at theArea 10 shopping centre in Abuja, Nigeria May 25, 2015. Nigerian fuel marketers agreed to resume distribution on Monday after weeks of disruption led to chronic fuel shortages, bringing phone companies, banks and airlines to a standstill days before the inauguration of the country's new president. (Photo by Afolabi Sotunde/Reuters)

Men sleep at a 24-hour McDonald's restaurant in Hong Kong, China November 10, 2015. A large number of homeless people sleeping on the street has long been been a problem in Hong Kong mainly due to its high rent and soaring property. In recent years, McDonald's 24-hour fast food shops opening all over the city have become popular alternatives for people, know as McRefugees or McSleepers, to spend the night in a safer and more comfortable way than on the street. (Photo by Tyrone Siu/Reuters)

A person stands near the “Untitled” installation of miniature elevators by Maurizio Cattelan at a preview of the Postwar and Contemporary Art Evening Sale at Christie's auction house on November 4, 2011 in New York City. The 33-inch functioning elevator installation is expected to realize $400,000-$600,000 at the November 8 auction. (Photo by Mario Tama/Getty Images)

A boy carries empty sacks after bringing different types of plastic materials to a recycling station in Khartoum North April 16, 2015. People bring bottles and other plastic materials to the station for recycling, and get paid in return. (Photo by Mohamed Nureldin Abdallah/Reuters)