Data from numerous pathohistological, histochemical, immunohistochemical and biochemical studies of the otosclerotic tissue in the otic capsule are reviewed and correlated systematically in order to get more complete insight of the local cellular and molecular events in otosclerosis and to derive the basic knowledge from them. The following parameters are focused: sites and distribution of the otosclerotic foci, classification of the local events in otosclerosis, active and inactive otosclerotic foci, osteoid cells, enzyme activity of the otosclerotic foci and perilymph, components of the bone inorganic constituents and matrix. Characteristic morphologic changes and microscopic appearance of the otosclerotic foci are defined as well as the metabolic processes and enzyme disbalances of the disorder with respect to the phase of the otosclerotic bone resorption and formation. The authors specially stress the necessity of constant monitoring and critical evaluation of both the research data and the general concepts in the multifactorial field of otosclerosis.

We present results on numerical regulator design for sampled-data nonlinear plants via their approximate discrete-time plant models. The regulator design is based on an approximate discrete-time plant model and is carried out either via an infinite horizon optimization problem or via a finite horizon with terminal cost optimization problem. We focus on the case when the sampling period and the accuracy parameter h of the approximate discrete-time plant model are independent of each other and show that with this approach practical and/or semiglobal stability of the exact discrete-time model is achieved under appropriate conditions.