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)

Participants in the Grelka Fest at the Sheregesh resort in Tashtagolsky District of Kemerovo Oblast, Russia on April 22, 2017. Russian girls marked the end of the ski season with a record-breaking bikini ski festival at Siberia’s top winter resort, Sheregesh. Some 1,498 skiers and snowboarders undressed to impress in the annual event as they took to the pistes under blues skies and sunshine in a bracing temperature of just 5°C. (Photo by Grelka Fest/The Siberian Times)

Students training to be flight attendants hold books on their heads, chopsticks in their mouths, and papers in between their knees, as they take part in a standing posture practice at a vocational school in Shijiazhuang, Hebei province, China May 4, 2017. (Photo by Reuters/Stringer)

Girls rest on stairs at the China Digital Entertainment Expo and Conference (ChinaJoy) in Shanghai, China July 27, 2017. (Photo by Aly Song/Reuters)

Law enforcement officers clash with protesters, Wednesday, July 20, 2016, in Cleveland, during the third day of the Republican convention. (Photo by John Minchillo/AP Photo)

A girl washes the body paint off her arm on the shore of Lake Balaton during the coinciding Strand Festival and B.My.Lake Festival in Zamardi, 110 kms southwest of Budapest, Hungary, 24 August 2016. (Photo by Zoltan Balogh/EPA)

A protesting student runs past a burning bus off campus outside the University of the Witwatersrand in Johannesburg, South Africa on Monday, October 10, 2016. Tear gas and water cannon were fired as hundreds of students protested at the university amid a bitter national dispute with university managers and the government over demonstrators' demands for free education, forcing student into the neighbouring city streets. (Photo by AP Photo)

Spain fans react during the penalty shootout during 2022 FIFA World Cup football match between Morocco v Spain in Qatar as they watch the match on a big screen in Barcelona, December 6, 2022. (Photo by Nacho Doce/Reuters)