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 woman is assisted while crossing a flooded street after the Huayco river overflooded its banks sending torrents of mud and water rushing through the streets, in Huachipa, Peru on March 17, 2017. Muddy water spilled onto streets and into homes on Thursday in a new round of unusually heavy rains that has killed at least a dozen people in Peru and now threatens flooding in the capital. (Photo by Guadalupe Pardo/Reuters)

A foreign passenger wearing a protective suit poses as they prepare for their flight at Manila's International Airport, Philippines, Monday, January 18, 2021. Coronavirus infections in the Philippines have surged past 500,000 in a new bleak milestone with the government facing criticisms for failing to immediately launch a vaccination program amid a global scramble for COVID-19 vaccines. (Photo by Aaron Favila/AP Photo)

N.C. Dezendorf, wife of the general manager of the Electro-Motive division of General Motors, christens the new lightweight “Aerotrain” at the company's locomotive works in La Grange, Ill. on August 22, 1955. (Photo by Edward Kitch/AP Photo)

A kite flying contest is held in Nantong, east China's Jiangsu featuring various kites of different shapes on December 20, 2017. (Photo by SIPA Asia/Pacific Press/Barcroft Images)

A sewer cleaner of Dhaka City Corporation cleaning out the city's sewers on May 03, 2017 in Dhaka, Bangladesh. Despite a rise in the number of deaths of manhole workers every year, workers regularly go into the manholes without any protective gear. (Photo by Zakir Chowdhury/Barcroft Images)

Monumental landscape artwork “Hush” by installation artist Steve Messam hangs in the moors of Teesdale on July 18, 2019 in Barnard Castle, England. The outdoor installation is inspired by the geology, mining history and landscape of the area. It hangs over Bales Hush, a deep gauge in the terrain created when miners flushed the area with water to reveal the geological riches below. Hundreds of metres of recyclable saffron yellow fabric blow in the wind. (Photo by Christopher Thomond/The Guardian)

A squid swims underwater off the shore of the coastal city of Qalamun, north of the Lebanese capital Beirut, on September 24, 2019. (Photo by Ibrahim Chalhoub/AFP Photo)