I retired from teaching at the Mathematics Department of The Royal Institute of Technology in Stockholm in 1996, but I continue to work there with research in biomathematics. My main concern has been with stochastic models in population biology. A list of my publications is found here.
The stochastic version of the classical so-called SIS model is dealt with in a 2011 monograph with the title "Extinction and Quasi-stationarity in the Stochastic Logistic SIS Model", Springer Lecture Notes in Mathematics #2022. Access to a Maple module used for numerical evaluations, and a list of corrigenda are given here.