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 cat dressed in a traditional Ukrainian embroidered shirt takes part in a parade in Kiev, Ukraine on May 28, 2016. (Photo by Gleb Garanich/Reuters)

A Chinese People's Liberation Army soldier marches with members of an honor guard as they prepare for a welcome ceremony for visiting Luxembourg's Prime Minister Xavier Bettel outside the Great Hall of the People in Beijing, Monday, June 12, 2017. (Photo by Andy Wong/AP Photo)

Performers dressed as superhero characters pose with a child receiving the Pfizer-BioNtech Covid-19 vaccine for children aged 5-11 at a gym in San Juan City, suburban Manila on February 7, 2022. (Photo by Ted Aljibe/AFP Photo)

Mozambique army soldiers take a ride on a motorbike in the streets of Palma, Cabo Delgado, Mozambique, 12 April 2021. The violence unleashed more than three years ago in Cabo Delgado province escalated again about two weeks ago, when armed groups first attacked the town of Palma. (Photo by Joao Relvas/EPA/EFE)

A young woman shows off her henna tattoos at the end of Eid al-Fitr prayers in Bucharest, Romania, Wednesday, April 10, 2024. Members of the Romanian Muslim community joined prayers at the Dinamo stadium in the Romanian capital, in the largest Muslim public gathering of the year. Eid al-Fitr marks the end of the holy fasting month of Ramadan. (Photo by Andreea Alexandru/AP Photo)

United States Air Force Academy graduates cheer as the United States Air Force Thunderbirds fly over the graduation for the Class of 2021 at Falcon Stadium on May 26, 2021 in Colorado Springs, Colorado. Chairman of the Joint Chiefs of Staff General Mark A. Milley gave the commencement address to the 1,019 graduates from the academy. (Photo by Michael Ciaglo/Getty Images)

Stranded cars remain in a flooded street during an intense rainstorm in Havana, on April 29, 2015. Two people were killed, three buildings collapsed and another 24 suffered some kind of damage due to the heavy rain that affected several sectors of Havana Wednesday. (Photo by Yamil Lage/AFP Photo)