Biomathematics Unit, Department of Zoology, Faculty of Life Sciences, Tel-Aviv Uniersity, P.O Box 39040, Tel-Aviv 69978, ISRAEL Tel: 972-3-6409806 Fax: 972-3-6409403 e-mail address: lewi_(at)_post.tau.ac.il Scientific intrests: # Theoretical Ecology # Mathematical Biology # Population Models of Disease Spread # Nonlinear Dynamics