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41.
A new approach to study ergodicity of filtering processes is presented. It is based on the vanishing discount approach to discounted functional of filtering process. We show that limit superior of the Cesaro averages of the functionals is the same for all initial conditions from which the uniqueness of invariant measures of filtering processes follows. The approach is based on certain assumption for which we provide a sufficient condition using concavity arguments. In addition we show the existence of solutions to the Poisson equation corresponding to filtering process with concave functional. The assumptions are then extended to the controlled case and using similar concave arguments we obtain the existence of solutions to the Bellman equation corresponding to partially observed average cost per unit time problem. 相似文献
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The complete mechanism by which pathogenic mtDNA mutations cause cellular pathophysiology and in some cases cell death is unclear. Oxidant stress is especially toxic to excitable nerve and muscle cells, cells that are often affected in mitochondrial disease. The sensitivity of cells bearing the LHON, MELAS, and MERRF mutations to oxidant stress was determined. All were significantly more sensitive to H2O2 exposure than their nonmutant cybrid controls, the order of sensitivity was MELAS > LHON > MERRF > controls. Depletion of Ca2+ from the medium protected all cell lines from oxidant stress, consistent with the hypothesis that death induced by oxidant stress is Ca(2+)-dependent. A potential downstream target of Ca2+ is the mitochondrial permeability transition, MPT, which is inhibited by cyclosporin A. Treatment of MELAS, LHON, and MERRF cells with cyclosporin A caused significant rescue from oxidant exposure, and in each case significantly greater rescue of mutant than control cells. The pronounced oxidant-sensitivity of mutant cells, and their protection by Ca2+ depletion and CsA, has potential implications for both the pathophysiological mechanism and therapy of these mitochondrial genetic diseases. 相似文献
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The early phases of T-cell development require both cell-cell interactions and soluble factors provided by stromal cells within the thymic microenvironment. Still, the precise nature of the signals delivered in vivo by cytokines (resulting in survival, proliferation or differentiation) remains unclear. Recent studies using mice deficient in cytokines or in their receptors have helped to identify essential signaling pathways required for the development of intrathymic precursors to mature alpha beta and gamma delta T cells. In addition, cytokine requirements for the development of natural killer cells were revealed in such mutants. The results obtained demonstrate that the development of all classes of lymphocytes (natural killer, gamma delta T cells and alpha beta T cells) is cytokine dependent, but the specific requirements differ for each lineage. 相似文献
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This paper investigates the stability analysis and antiwindup design problem for a class of discrete-time switched linear systems with time-varying norm-bounded uncertainties and saturating actuators by using the switched Lyapunov function approach.Supposing that a set of linear dynamic output controllers have been designed to stabilize the switched system without considering its input saturation,we design antiwindup compensation gains in order to enlarge the domain of attraction of the closed-loop system in the presence of saturation.Then,in terms of a sector condition,the antiwindup compensation gains which aim to maximize the estimation of domain of attraction of the closed-loop system are presented by solving a convex optimization problem with linear matrix inequality(LMI)constraints.A numerical example is given to demonstrate the effectiveness of the proposed design method. 相似文献
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弓网接触压力作为接触网的重要参数之一,对确保受流质量具有重要意义.针对供电段的实际情况,开发了一套采用AVR作为控制器的接触网弓网压力动态检测系统,实现了弓网压力的检测.设备的使用表明:系统运行稳定,检测效果好、测量数据准确,具有一定的应用前景. 相似文献