Members of security forces secure Tahrir Square in Cairo, Egypt, November 11, 2016. Egypt imposed a big security clampdown in its cities on Friday as mass demonstrations called to protest against austerity measures failed to take place. Riot police and armored vehicles filled the otherwise empty streets of central Cairo, but most people stayed at home. (Photo by Mohamed Abd El Ghany/Reuters)

Japanese artist Mami Kiyoshi has spent 15 years creating vivid portraits of people surrounded by their belongings – from wine bottles and violins to the odd stray pet. Mami Kiyoshi’s ongoing series “New Reading Portraits” is, in part, a nod to the mise-en-scène found in traditional woodcut printing. Here: Sakura and Kazuhiro, Tokyo, 2015. (Photo by Mami Kiyoshi/Galerie Annie Gabrielli/The Guardian)

From stuffed elephants to picnics under power lines, Leipzig-born photographer Frank Herfort coaxes magical, colour-saturated tableaux from intriguing slices of everyday Russian life. Here: A lonely dog watches the mailboxes in a typical Moscow residential block. (Photo by by Frank Herfort/The Guardian)

These powerful images capture the spear-wielding tribes of Papua new Guinea who believe they are possessed with the spirit of the crocodile. They show how the Kangunaman clansmen scar their backs to resemble reptile scales while the Huli Wigmen wear elaborate headdresses to signal they are ready for battle. (Photo by Trevor Cole/Media Drum World)

In this September 30, 2017 photo, people perform “transvestite target practice” to protest the killings of transvestite prostitutes during the annual LGBQT march in Asuncion, Paraguay. Advocacy groups fear the stigma and attacks against the LGBQT community could get worse now that the country's education minister has banned classes about sexual diversity in schools and even volunteered to help burn all books related to the subject. (Photo by Jorge Saenz/AP Photo)

In this photo taken on Saturday, April 22, 2017, a drawing “King for a day” is made on the back of a muddy truck by artist Nikita Golubev in Moscow, Russia. The grimy trucks traversing the polluted and dusty streets of Moscow have inspired Golubev to use white vans and trucks as his canvas to create this ephemeral street art and signs his drawings Pro Boy Nick. (Photo by Pavel Golovkin/AP Photo)

From footballs to live fish, delivery mopeds piled high with unwieldy, unlikely goods are one of the Vietnamese capital’s most distinctive sights. As the city plans to ban motorbikes altogether, photographer Jon Enoch captured the drivers at work. (Photo by Jon Enoch/The Guardian)

Soap Bubble Structures by Kym Cox. Bubbles optimise space and minimise their surface area for a given volume of air. This phenomenon makes them a useful tool in many areas of research, in particular, materials science and “packing” – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom, which interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst. (Photo by Kym Cox/2019 Science Photographer of the Year/RPS)