1. a NorthShore University HealthSystem , Evanston , IL , USA
2. b University of Chicago, Pritzker School of Medicine , Chicago , IL , USA
3. c National Rehabilitation Hospital , Washington , DC , USA
4. d University of St. Thomas , Minneapolis , MN , USA
5. e Minneapolis Veterans Affairs Medical Center , Minneapolis , MN , USA
6. f University of Pennsylvania School of Medicine , Philadelphia , PA , USA