Number 179 (Story #1), May 17, 1994 by Phillip F. Schewe and Ben Stein THE RELAXATION OF A SINGLE DNA MOLECULE has been studied by attaching to it a 1- micron latex bead which then can be manipulated in a special configuration of lasers known as an "optical tweezers." Lit up by an infrared laser and viewed in a microscope, the DNA molecule can be sent through a series of maneuvers (including spelling out the letters "DNA") designed to measure the molecule's mechanical properties. Stanford physicist Steven Chu and his colleagues were also able to corroborate a theory of 1991 Nobel-laureate Pierre-Gilles de Gennes, who asserted that the movement of single polymer strand among other strands was analogous to one snake crawling past other snakes. (Thomas T. Perkins et al., Science, 6 May.)