Dr. Mark Harper, MD, PhD, is a consultant anaesthetist at Brighton and Sussex University and a leading expert in the prevention of hypothermia in surgical patients. He serves as an expert adviser to organisations studying the therapeutic uses of cold-water adaptation and open-water swimming, and his work studying the mental-health benefits of cold-water immersion was featured in the BBC documentary The Doctor Who Gave Up Drugs. Dr. Harper is a co-creator of Chill UK, a nonprofit committed to improving access to cold-water swimming for those who suffer from anxiety and depression. He lives in England.

David Edward Byrd is one of the world’s most renowned graphic artists. His acclaimed music art includes work for the Rolling Stones, the Who, and the Grateful Dead, as well as the original poster for the 1969 Woodstock festival. His 1968 poster for Jimi Hendrix is now in the collection of the Museum of Modern Art in New York.

He then moved on to Broadway, where he created iconic posters for Follies, Godspell, and Little Shop of Horrors, among others. He was later the art director for Advocate magazine and the senior illustrator at Warner Bros. Consumer Products for twelve years. He has had retrospective shows in Los Angeles, New York, Sarasota, and Seattle. David lives in Los Angeles with his husband, Jolino Beserra, who is a renowned mosaic artist, and their six four-legged street thugs.