A new control problem, which arises in active control of variable speed horizontal axis wind turbines for electric power generation, is discussed. Feedback control of a linear plant, which is persistently disturbed, must cause the plant output to track a linear function of the disturbance. Theory, which will guarantee stable disturbance tracking, is developed using the method of aggregation. These results are related to the better known Disturbance Accommodating Control Theory and applied to create a tip speed ratio tracking controller for a horizontal axis wind turbine generator.

To evaluate the incidence of autoimmune disorders and organ-specific autoantibodies in Korean vitiligo patients, antibodies to nuclear, mitochondrial, smooth muscle, gastric parietal cell, thyroglobulin, and microsomal antigens were screened in 226 vitiligo patients and 120 controls. Of the 226 vitiligo patients, three (1.3%) had thyrotoxicosis and two (0.8%) had diabetes mellitus. The vitiligo patients had an increased incidence of antinuclear (12.4%), antimicrosomal (7.1%), and antismooth muscle antibodies (25.7%). The increased incidence of antismooth muscle antibody was correlated with early onset (less than 15 years), a positive family history of vitiligo, and long duration of vitiligo. These results support an autoimmune origin of vitiligo and suggest that the high incidence of antismooth muscle antibody is a distinctive feature of laboratory findings in Korean vitiligo patients.

No abstract

The control problems associated with the linear periodic time-varying system (LPTS) are quite challenging because the time-varying eigenvalues of the periodic matrix can not determine the stability of the system. In this paper, a new approach is developed to design time-varying controllers for LPTS. For this purpose, the well known Liapunov-Flcquet transformation theory is utilized and time-varying feedback gains are calculated based on a transformed time-invariant system. The effectiveness of the proposed technique is demonstrated through numerical simulation.varying feedback gains is discussed. Section 4 discusses the numerical test of this algorithm with a simple example. Background : Floquet Theory

Mature dendritic cells (DCs) were generated by culturing human peripheral blood monocytes for 7 days and, then, treating them with a cytokine cocktail for 2 days. The viability of the mature DCs (Day 9) obtained was approximately 60-70%, and this gradually declined when they were recultured in X-VIVO 15 media containing 2% human plasma (40% viability after 3 days of reculture). DC death accelerated on withdrawing plasma from the culture (20% viability after 3 days). However, the addition of tumor necrosis factor-alpha (TNF-alpha) to the medium completely restored DC viability in the absence of plasma. Such a protective effect was not afforded by other cytokines, such as granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-1alpha (IL-1alpha), IL-4, IL-6 and prostaglandin E2 which are used for the maturation of DCs. These results indicate that TNF-alpha is specifically required to maintain the viability of mature DCs. The withdrawal of plasma rapidly (within 15 min) elevated cellular levels of reactive oxygen intermediates (ROIs), which have been proposed to regulate the ability of DCs to control inflammatory reactions. The possibility that ROIs act as mediators of DC death was eliminated by the observation that scavengers of ROIs, such as catalase, N-acetylcysteine, glutathione, failed to prolong DC life span in the absence of plasma. Interestingly, TNF-alpha was found to almost completely abolish the production of ROIs induced by plasma withdrawal. To summarize, our results suggest that TNF-alpha controls not only the inflammatory functions of DCs but also their survival.