1. Applied Biomathematics; 100 North Country Road Setauket NY 11733 U.S.A.
2. United States Army Engineer Research and Development Center; Environmental Laboratory; 3909 Halls Ferry Road Vicksburg MS 39180 U.S.A.
3. Department of Biology; University of St. Louis; 1008 South Spring Avenue St. Louis MO 63110 U.S.A.