Thisisthefourthvolumeintheseries TutorialsinMathematicalBiosciences. These lectures are based on material which was presented in tutorials or developed by visitors and postdoctoral fellows of the Mathematical B- sciences Institute (MBI), at The Ohio State University. The aim of this series is to introduce graduate students and researchers with just a little ba- ground in either mathematics or biology to mathematical modeling of biol- ical processes. The ?rst volume was devoted to mathematical neuroscience, which was the focus of the MBI program 2002 2003. The second volume dealt with...

In this new century mankind faces ever more challenging environmental and publichealthproblems, suchaspollution, invasionbyexoticspecies, theem- gence of new diseases or the emergence of diseases into new regions (West Nile virus, SARS, Anthrax, etc.), andtheresurgenceofexistingdiseases(in?uenza, malaria, TB, HIV/AIDS, etc.). Mathematical models have been successfully used to study many biological, epidemiological and medical problems, and nonlinear and complex dynamics have been observed in all of those contexts. Mathematical studies have helped us not only to better understand these...