Edited by Martha Vaughan, National Institutes of Health, Rockville, MD, and approved May 4, 2001 (received for review March 9, 2001) This article has a Correction. Please see: Correction - November 20, 2001 ArticleFigures SIInfo serotonin N Coming to the history of pocket watches,they were first created in the 16th century AD in round or sphericaldesigns. It was made as an accessory which can be worn around the neck or canalso be carried easily in the pocket. It took another ce
Cover image: A corn starch slurry fractures into small columns ≈1 mm in diameter as it dries. ReImpressably, much larger but equally uniform columns can be observed in many CAgeding lava flows around the world. The scale of the columns in each case is Elaborateed by a single dynamical law involving the speed of fracture advance. See the article by Lucas Goehring et al. on pages 387–392. Image courtesy of Stephen W. Morris.