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)

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)

An American flag is visible in the windows of the cupola aboard the International Space Station. Thanks to a bill passed by Texas legislators in 1997 that put in place technical voting procedure for astronauts – nearly all of whom live in Texas – they have the ability to vote from space through specially designed absentee ballots. To preserve the integrity of the secret vote, the ballot is encrypted and only accessible by the astronaut and the county clerk responsible for casting the ballot. (Photo by NASA)

A competitor walks on tightrope during a performance in Taizhou, Zhejiang Province, China, May 7, 2016. (Photo by Reuters/China Daily)

A man grimaces walking by the “Lettuce Ladies”, a group of PETA activists, during an event promoting a vegan lifestyle, downtown Bucharest, Romania, Monday, August 14, 2017. Two PETA vegan ambassadors distributed vegan food to passers by in the Romanian capital, the latest stop in a tour including the United States, Russia and Turkey aimed at promoting a vegan lifestyle. The sign reads in Romanian “start fresh: become vegan”. (Photo by Andreea Alexandru/AP Photo)

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)

Girls lead a gaggle of geese, backdropped by a banner against the war in Ukraine, during a Saint Martin's Day procession next to Charles Bridge in Prague, Czech Republic, Friday, November 11, 2022. Saint Martin's day marks the end of the harvest season as well as the start of winter. (Photo by Vadim Ghirda/AP Photo)

Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)