1. a Professor of Geography , Arizona State University , Tempe, AZ, 85287-0104
2. b Associate Professor of Geography and Regional Planning , Pennsylvania State University , University Park, PA, 19802
3. c Geographer-in-Residence at the National Geographic Society , 1145 17th Street NW, Washington, DC, 20036-4688
4. d Professor and Head of the Department of Geography and Regional Development , University of Arizona , Tucson, AZ, 85721
5. e Professor of Geography , University of Cincinnati , Cincinnati, OH, 45221-0131
6. f Associate Professor and Chair in the Department of Geography and Earth Systems Science , George Mason University , Fairfax, VA, 22030-4444