1. 1University of Puerto Rico, Mayagüez, Puerto Rico, U.S.A.
2. 2University of Texas, Arlington, Texas, U.S.A.
3. 3UNAVCO, Boulder, Colorado, U.S.A.
4. 4University of Colorado-Denver, Denver, Colorado, U.S.A.
5. 5University of Oregon, Eugene, Oregon, U.S.A.