1. Department of Environmental and Molecular Toxicology, North Carolina State University, Campus Box 7633, Raleigh, North Carolina 27695 USA
2. Department of Statistics, North Carolina State University, Raleigh, North Carolina 27695 USA
3. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, Georgia 30602 USA
4. Department of Biology, Missouri State University, Springfield, Missouri 65897 USA
5. US Environmental Protection Agency, Chicago, Illinois 60604 USA