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 Ukrainian Army liaison officer Vira, 22, plays with her rat Malyi (Tiny) at her positions near a frontline, in Donetsk region, Ukraine, on March 8, 2024. (Photo by Inna Varenytsia/Reuters)

A staff of the Beijing 2022 Winter Olympic Games holds a placard reading “Mask on” as USA's players react after their defeat in the women's gold medal match of the Beijing 2022 Winter Olympic Games ice hockey competition between Canada and USA, at the Wukesong Sports Centre in Beijing on February 17, 2022. (Photo by Kirill Kudryavtsev/AFP Photo)

Figure skater Alexandra Trusova of Team ROC practices during a training session at the 2022 Winter Olympic Games, at the Capital Indoor Stadium in Beijing, China on February 19, 2022. (Photo by Valery Sharifulin/TASS)

A Syrian rebel walks past Sham 2, a homemade armored vehicle, in Bishqatin, Syria, on December 8, 2012. From a distance it looks rather like a big rusty metal box but closer inspection reveals a homemade armored vehicle waiting to be deployed. Sham II, named after ancient Syria, is built from the chassis of a car and touted by rebels as “100 percent made in Syria”. (Photo by Herve Bar/AFP Photo)

Belarusian villagers celebrate the Christmas carol rite (Kalyady) in the village of Danilevichy, some 320 km south of Minsk on January 7, 2020. Kalyady is an ancient pagan holiday originally celebrated on winter solstice. Dressed-up people walk from house to house singing, dancing, eating and drinking with their neighbours. (Photo by Sergei Gapon/AFP Photo)

Dancers prepare before a performance in the backstage area of the Buick exhibition during the “Auto China 2014” Beijing International Automotive Exhibition in Beijing on April 21, 2014. Leading automakers have gathered in Beijing for the kickoff of China's biggest car show, but lackluster growth and environmental restrictions in the world's largest car market have thrown uncertainty into the mix. (Photo by AFP Photo)