1. Departments of Mechanical Engineering and
2. Biomedical Engineering, Northwestern University, Evanston, Illinois 60208;
3. Marquette University and Medical College of Wisconsin, Milwaukee 53201;
4. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin 53295;
5. Department of Surgery, University of Michigan Medical Center, Ann Arbor, Michigan 48109;
6. Department of Physiology, Technion, Israel Institute of Technology, Haifa, Israel, and
7. Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109