Comandos de Salvamento rescuers Maria Martinez (L) and Ana Chichilla attend to a wounded homeless man in San Salvador, El Salvador July 16, 2016. The man was attacked with a machete by suspected gang members. In 2015, El Salvador registered a record 103 homicides per 100,000 habitants, making it one of the most dangerous countries in the world outside a war zone. But for many young people who have few chances to distance themselves from rivalries between so-called maras in their schools and neighbourhoods, a civil-society organisation called the Comandos de Salvamento, or Rescue Corps, has been a refuge. (Photo by Jose Cabezas/Reuters)

Ivanelis Jimenez, front, and Veronica Barreto pose for the camera wearing Puerto Rican flag dresses as they welcome passengers exiting Carnival's Mardi Gras cruise ship, docked in the bay of San Juan, Puerto Rico, Tuesday, August 3, 2021, marking the first time a cruise ship visits the U.S. territory since the COVID-19 pandemic began. (Photo by Carlos Giusti/AP Photo)

Ocean Beach after a rain storm in San Francisco, California, US, on Thursday, January 5, 2023. A powerful storm with hurricane-force gusts has begun to wind down after ripping across California, leaving behind power outages, flood threats and road closures just hours before another drenching is set to wash over the state. (Photo by Shelby Knowles/Bloomberg)

Competitors take part in the 8th annual World Gravy Wrestling Championships at the Rose n Bowl Pub in Bacup, north west England on August 31, 2015. Contestants must participate in fancy dress and wrestle in a pool of Lancashire Gravy for 2 minutes whilst being scored for a variety of wrestling moves. (Photo by Oli Scarff/AFP Photo)

People will spout about impermanence of digital records, but books are really fragile, too. Alexis Arnold from San Francisco wanted to illustrate that with her project The Crystallized Book: collecting books and growing Borax crystals on them. Books range from literature classics to magazines, and there’s even a mysterious and arcane tome called “Linux: The Complete Manual”.

Nova Scotia Duck Tolling retriever Torrey competes in the 10th annual Petco Unleashed surfing dog contest at Imperial Beach, California August 1, 2015. Proceeds raised at the event go to benefit the San Diego Humane Society. (Photo by Mike Blake/Reuters)

Sharon Beals is a San Francisco based photographer who has photographed nest and eggs specimens collected over the last two centuries at The California Academy of Sciences, The Museum of Vertebrate Zoology, and The Western Foundation of Vertebrate Zoology. While few nests are collected today, these nests and eggs are used for research, providing important information about their builder’s habitats, DNA, diseases and other survival issues.

Terence Chang's (aka exxonvaldez) long exposure photographs, capturing only streaks of light as airplanes arrive and depart from the San Francisco airport, certainly are stunning. There's just something so magical about seeing the various patterns created in the sky, even over a relatively short amount of time.