1. VA Nebraska-Western Iowa Health Care System , Omaha, NE, USA
2. University of Nebraska Medical Center , Omaha, NE, USA
3. University of Pennsylvania & Corporal Michael J. Crescenz VA Medical Center , Philadelphia, PA, USA
4. VA Puget Sound Health Care System & University of Washington , Seattle, WA, USA
5. VA Salt Lake City & University of Utah , Salt Lake City, UT, USA
6. Washington DC VA, Howard University, & Georgetown University , Washington, DC, USA
7. Pittsburgh VA & University of Pittsburgh , Pittsburgh, PA, USA
8. Boston VA , Boston, MA, USA
9. Dallas VA & University of Texas Southwestern , Dallas, TX, USA
10. University of Alabama at Birmingham , Birmingham, AL, USA