1. Department of Mechanical Engineering, Vanderbilt University, VU Station B 351592, 2301 Vanderbilt Place, Nashville, TN 37235-1592, USA
2. Department of Biomedical Engineering, Vanderbilt University, VU Station B 351631, 2301 Vanderbilt Place, Nashville, TN 37235-1631, USA
3. College of Engineering, Virginia Polytechnic Institute and State University, 333 Norris Hall, Blacksburg, VA 24061-0217, USA