JoAnne Dahl, PhD , is professor of psychology at Uppsala University, Sweden. JoAnne is a clinical psychologist specializing in behavior medicine. She is coauthor of the The Art and Science of Valuing in Psychotherapy , Acceptance and Commitment Therapy for Chronic Pain, Living Beyond Your Pain, and ACT and RFT in Relationships.
Ian Stewart's recent books include (with Terry Pratchett and Jack Cohen) The Science of Discworld IV and (published by Profile) 17 Equations that Changed the World, The Great Mathematical Problems, Professor Stewart's Casebook of Mathematical Mysteries and Calculating the Cosmos. His app, Incredible Numbers, was published jointly by Profile and Touch Press in 2014.