Number 315 (Story #1), April 3, 1997 by Phillip F. Schewe and Ben Stein THE WORLD'S SMALLEST FOCUSED BEAM OF LIGHT is a 50-nm-diameter x-ray beam created at the Brookhaven National Synchrotron Light Source in New York. At the APS March Meeting Janos Kirz and Chris Jacobsen at SUNY-Stony Brook reported that they and their colleagues had for the first time produced images showing the distribution of DNA and protein in sperm from bulls and other mammals. Using a 5-micron-diameter x-ray beam at the Brookhaven synchrotron, Slade Cargill at Columbia reported the first real-time measurements of the stresses that occur when electric current traveling through an aluminum wire displaces atoms in the wire; this "electromigration" effect is expected to be a problem in the ever- shrinking aluminum-based wires of future-generation computer chips. (Associated graphics can be seen at Physics News Graphics.)