1. Contribution from the Center for Bio/Molecular Science and Engineering, U.S. Naval Research Laboratory, Washington, D.C. 20375, The Center for Biomedical Genomics, George Mason University, Fairfax, Virginia 22030, Department of Virology and Immunology, Southwest Foundation for Biomedical Research, 7620 N.W. Loop 410, San Antonio, Texas 78227-5301, Division of Optical Sciences, U.S. Naval Research Laboratory, Washington, D.C. 20375, and Laboratory for the Structure of Matter, U.S. Naval Research...