1. Department of Aerospace and Mechanical Engineering, University of Arizona, P.O. Box 210119, Tucson, Arizona 85721, United States
2. Department of Urology, Stanford University, 300 Pasteur Drive, S-287, Stanford, California 94305-5118, United States
3. Veterans Affairs Palo Alto Health Care System, Palo Alto, California 94304, United States
4. Biomedical Engineering and Bio5 Institute, University of Arizona, Tucson, Arizona 85721, United States