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)

Injured horses huddle together in Oklahoma City on Monday. (Photo by Chris Landsberger/The Oklahoman)

Participants dressed as Santa Claus take part in the Great Edinburgh Santa Run on December 11, 2011 in Edinburgh, Scotland. Around a thousand people took part in the annual fundraising event, with all money raised being donated to the charity “When You Wish Upon a Star”. (Photo by Jeff J. Mitchell/Getty Images)

Getting it done. Felicity, an athlete at an amateur weightlifting competition in a small local gym. (Photo by Clinton Bradbury/Women in Sport Photo Action Awards 2021)

Miss Georgia USA Emanii Davis, Miss Kentucky USA Kyle Hornback and Miss North Carolina USA Devin Gant competes in the swimsuit competition during the 2016 Miss USA pageant preliminary competition at T-Mobile Arena on June 1, 2016 in Las Vegas, Nevada. The 2016 Miss USA will be crowned on June 5 in Las Vegas. (Photo by Ethan Miller/Getty Images)

The sun rises over the River Brue on the Somerset Levels as temperatures in parts of the south west drop below freezing, on January, 20, 2015. (Photo by Ben Birchall/PA Wire)

Supporters of US President Donald J. Trump gather for a rally in Freedom Plaza to protest Congress's upcoming certification of Joe Biden as the next president in Washington, DC, USA, 05 January 2021. Various groups of Trump supporters announced rallies on 06 January 2021 as Congress meets to certify the results of the 2020 US Presidential election. (Photo by Shawn Thew/EPA/EFE)

In this Sunday, June 17, 2018, file photo, an Indonesian resident walks past graffiti on a downtown street in Hong Kong. There are 370,000 foreign domestic helpers in the Chinese territory and about 49.4 percent from Indonesia. (Photo by Vincent Yu/AP Photo)