1. Johns Hopkins School of Medicine, Baltimore, Maryland, USA
2. RAND Corporation, Santa Monica, California, USA
3. University of Memphis, Memphis, Tennessee, USA
4. University of Minnesota, Minneapolis, Minnesota, USA
5. Fenway Health, Boston, Massachusetts, USA
6. Tufts University, Boston, Massachusetts, USA
7. University of Miami, Coral Gables, Florida, USA
8. Brown University, Providence, Rhode Island, USA