1. Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
2. Department of Population and Public Health Science, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
3. Department of Rehabilitation Medicine, University of Washington, Seattle, WA 98195-2100, USA
4. Division of Plastic Surgery, University of Southern California, Los Angeles, CA 90033, USA