1. Department of Physical Medicine & Rehabilitation, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
2. Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
3. Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146, USA
4. TIRR Memorial Hermann Hospital, Houston, TX 77030, USA