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)

People stand in queue keeping social distance beside a Covid-19 awareness scarecrows placed by Chennai municipality at a market during a government-imposed nationwide lockdown as a preventive measure against the COVID-19 coronavirus, in Chennai on April 11, 2020. (Photo by Arun Sankar/AFP Photo)

Alejandro Ccasa prays after waiting three days next to an empty oxygen tank for his uncle who has COVID-19 outside a refill shop where he is the first in line before it opens in Callao, Peru, early Tuesday, February 2, 2021. Ccasa said his family has one large tank and it gives about four hours of oxygen therapy. (Photo by Martin Mejia/AP Photo)

Nursery plants are seen placed in people's seats during a rehearsal as Barcelona's Gran Teatre del Liceu opera reopens its doors with a concert for plants, to raise awareness about the importance of an audience after the coronavirus lockdown, in Barcelona, Spain on June 22, 2020. The Gran Teatre del Liceu reopens its doors, in which the 2,292 seats of the auditorium will be occupied on this occasion by plants. It will be on 22 June, broadcast live online, when the UceLi Quartet string quartet performs Puccini's “Crisantemi” for this verdant public, brought in from local nurseries. (Photo by Nacho Doce/Reuters)

Beautician Alex Smith, 26, does the nails of Jules Aspen, 40, at the Madame Beauty salon in Chirton, North Tyneside, UK on July 13, 2020. Nail bars, beauty salons, tattoo and massage studios, physical therapy businesses, spas and piercing services are able to reopen in the latest lifting of restrictions in England. (Photo by Owen Humphreys/PA Images via Getty Images)

American fashion model Karlie Kloss attends the 2021 Met Gala benefit “In America: A Lexicon of Fashion” at Metropolitan Museum of Art on September 13, 2021 in New York City. (Photo by Stephen Lovekin/Rex Features/Shutterstock)

Members of the Knights Guard clean the ice during the Vegas Golden Knights' game against the Anaheim Ducks at T-Mobile Arena on January 14, 2021 in Las Vegas, Nevada. The Golden Knights defeated the Ducks 5-2. (Photo by Ethan Miller/Getty images/Profimedia)

A torch bearer poses for photographs during the Olympic Torch Relay Celebration event on July 21, 2021 in Tokyo, Japan. As the Olympic torch relay makes its way around Tokyo, public relays have been cancelled in favour of daily ceremonies held behind closed doors, as authorities act to avoid large gatherings while the country endures a fourth wave of coronavirus. (Photo by Yuichi Yamazaki/Getty Images)