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)

Activists from the climate action group Ocean Rebellion perform a stunt outside The Baltic Exchange building, in London, Britain on November 16, 2020. (Photo by Henry Nicholls/Reuters)

An illuminated Christmas tree leans against the window of a damaged house in Mayschoss in the Ahrtal valley, southern Germany, Tuesday, December 14, 2021. The region was hit by floodings exactly five months ago, causing the death of about 180 people. Amid the mud and debris still clogging the streets from last summer's devastating floods, residents of the Ahr Valley in western Germany are trying to spark some festive cheer with Christmas trees. (Photo by Michael Probst/AP Photo)

A woman wearing in face mask to curb the spread of COVID-19 passes street's cafe in Kyiv, Ukraine, Friday, October 22, 2021. Coronavirus infections and deaths in Ukraine have surged to all-time highs amid a laggard pace of vaccination, which is one of the lowest in Europe. (Photo by Efrem Lukatsky/AP Photo)

Tactics reminiscent of the early American frontier days are now being used in Vietnam. Lieutenant Commander Donald D. Sheppard, UBN, of Coronado, California, aims a flaming arrow at a bamboo hut concealing a fortified Viet Cong bunker on the banks of the Bassac River, Vietnam on December 8, 1967. (Photo by AP Photo)

Friends of Li Guojun drive a homemade tank-shaped vehicle in Kangping county, China. Li, a farmer who is a fan of tanks, spent six months with help from his friends to construct the almost 20-foot vehicle which weighs 2.5 tons. (Photo by Sheng Li/Reuters)

Bogdana, 17, laughs with her boyfriend, Ivan, 19, in Brovary, Ukraine, Sunday, March 20, 2022. Russian forces pushed deeper into Ukraine's besieged and battered port city of Mariupol on Saturday, where heavy fighting shut down a major steel plant and local authorities pleaded for more Western help. (Photo by Vadim Ghirda/AP Photo)

Shakira and Jennifer Lopez perform onstage during the Pepsi Super Bowl LIV Halftime Show at Hard Rock Stadium on February 02, 2020 in Miami, Florida. (Photo by Mike Blake/Reuters)