1. Department of Physical Medicine and Rehabilitation, University of Texas Health Science Center at Houston, 7000 Fannin St., Houston, TX, USA
2. TIRR Memorial Hermann Research Center, 1333B Moursund St., Houston, TX, USA
3. Biomedical Engineering Program, University of Science and Technology of China, Hefei, P. R. China
4. Division of Biomedical Engineering, Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, P. R. China
5. Guangdong Work Injury Rehabilitation Center, 68 Qide Rd., Guangzhou, P. R. China