In this May 14, 2016 photo, children wearing their school backpacks climb on a cliff using a bamboo ladder on their way home from school in Zhaojue county, southwest China's Sichuan province. A village in China's mountainous west where schoolchildren must climb an 800-meter (2,625-foot)-high bamboo ladder secured to a sheer cliff face may get a set of steel stairs to improve it's safety. (Photo by Chinatopix via AP Photo)

Costume details featuring Joao Candido, a black sailor who led a revolt against the physical punishment of Brazilian Navy soldiers at the beginning of the 20th century, lie inside the Paraíso do Tuiuti Samba school at the Samba City complex in Rio de Janeiro, Brazil, Tuesday, January 16, 2024. Samba schools are gearing up for this year's Carnival, scheduled from Feb. 9-17. (Photo by Bruna Prado/AP Photo)

Elementary school sumo wrestlers compete in the sumo ring during the Wanpaku sumo-wrestling tournament in Tokyo, Japan July 30, 2017. (Photo by Kim Kyung-Hoon/Reuters)

Ketula Melo from the Imperatriz Leopoldinense samba school performs during Carnival celebrations at the Sambadrome in Rio de Janeiro, Brazil, Friday, April 22, 2022. (AP Photo/Bruna Prado)

A girl receives Covid-19 vaccine as Nepal Government begins vaccinating children aged 5-12 at a school in Kathmandu on June 23, 2022. (Photo by Aryan Dhimal/ZUMA Press Wire/Rex Features/Shutterstock)

Elementary school sumo wrestlers compete in the sumo ring during the Wanpaku sumo-wrestling tournament in Tokyo, Japan on October 29, 2022. (Photo by Kim Kyung-Hoon/Reuters)

Members of Tom Maior Special Group samba school perform during the carnival parade at the Anhembi Sambadrome in Sao Paulo, Brazil, 22 Febr​uary 2020. Carnival is the biggest and most popular celebration in Brazil. (Photo by Sebastiao Moreira/EPA/EFE)

Mr. Zhong Hua, of Johns Hopkins University School of Medicine, took this image of the peripheral nerves (those outside of the brain) in an 11.5-day-old mouse embryo, magnified five times. (Photo by Zhong Hua)