1. Department of Biomedical Engineering Columbia University 351 Engineering Terrace, 1210 Amsterdam Avenue New York NY 10027 USA
2. Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
3. Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
4. Department of Bioengineering George Mason University 4400 University Drive Fairfax VA 22030 USA