1. Mathematics, Statistics, and Computer Science, Macalester College, Saint Paul, MN 55105, USA
2. Department of Mathematics, NYC College of Technology, Brooklyn, NY 11201
3. Department of Mathematics, University of California Davis, Davis, CA 95616
4. Department of Mathematics, University at Buffalo, Buffalo, NY 14260
5. Department of Mathematics and Department of Biology, Duke University, Durham, NC 27708
6. Department of Mathematics and Center for Mathematical Biology, University of Pennsylvania, Philadelphia, PA 19104
7. Department of Mathematics, Purdue University, West Lafayette, IN 47907