1. Department of Biomedical Engineering, Catholic University, Washington, DC; Center for Applied Biomechanics and Rehabilitation Research, National Rehabilitation Hospital, Washington, DC,
2. Center for Applied Biomechanics and Rehabilitation Research, National Rehabilitation Hospital, Washington, DC; Physical Therapy Service, National Rehabilitation Hospital, Washington, DC
3. Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Illinois
4. Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Illinois; Department of Physical Therapy, University of Illinois, Chicago