1. Massachusetts College of Pharmacy and Health Sciences, 179 Longwood Avenue, Boston, Massachusetts 02115, The Laboratory for the Structure of Matter, Naval Research Laboratory, 4555 Overlook Avenue, Washington, D.C. 20375, and Department of Veterans Affairs Medical Center and Methamphetamine Abuse Research Center, Oregon Health and Science University, 3710 Southwest U.S. Veterans Hospital Road, Portland, Oregon 97239