1. Princeton Univ. (United States)
2. National Institute of Standards and Technology (United States)
3. Univ. of Michigan (United States)
4. Cornell Univ. (United States)
5. Univ. of Pennsylvania (United States)
6. Univ. of Toronto (Canada)
7. Pontificia Univ. Católica de Chile (Chile)
8. NASA Goddard Space Flight Ctr. (United States)