
Cover image: Geckos bear millions of dry, adhesive hairs (setae) on their feet that allow them to stick to nearly every surface. Each seta branches into 100-1,000 flat tips that adhere by using van der Waals forces. These chemical bonds temporarily rearrange electrons and create an electrodynamic attraction. Photo courtesy of Paul D. Stewart. See article by Autumn et al. on pages 12252–12256.