Pulse-modulated feedback in mathematical modeling and estimation of endocrine systems

The research field of systems biology has gained a lot of interest during the last decades. Systems biology can be seen as the systematic study of complex interactions in biological systems, mainly by methods from dynamical systems theory. This thesis mainly deals with the testosterone (Te) regulation in the human male, but techniques developed here might be useful for studying other parts of the endocrine system too. The contribution of the thesis can be divided into two parts: one covering mathematical models of Te regulation and another suggesting and validating identification techniques for those models. Regarding modeling, existing models of testosterone regulation have been extended with time delays and nonlinear dynamics, with the purpose of achieving better fit to clinical data. The identification part treats the estimation of unknown model parameters, and estimation of signals that cannot be measured in a noninvasive way