RESUMEN
The distributed optimization problem (DOP) of Takagi-Sugeno (T-S) fuzzy cyber-physical systems is studied under the framework of weight-balanced graphs and quasistrongly connected characteristics. The objective is to drive the outputs of all agents to the optimal solution of a given global objective function regarded as the desired output, based on the partial information of the local objective functions. To this end, distributed optimal coordinators (DOCs) are used to generate optimal solutions of local objective functions that converge to the desired output, and fuzzy reference-tracking controllers are designed to ensure that all agents can track the optimal solutions. As novel technical results, two Lyapunov-based fuzzy input-to-state stability (ISS) small-gain theorems are proposed for the T-S fuzzy interconnected system. Thus, the overall closed-loop system is an interconnected system involving the modules of optimal coordinators and fuzzy tracking controllers with T-S fuzzy subsystems. The fuzzy ISS cyclic-small-gain theorem is applied to analyze the system stability. The DOP of T-S fuzzy cyber-physical systems is solved using the DOCs and fuzzy reference-tracking controllers through the fuzzy small-gain approach. A numerical example is presented to demonstrate the effectiveness and superiority of the proposed method.
RESUMEN
Graves' disease is an autoimmune disease of the thyroid gland mediated by T cells. CD28, a member of costimulatory molecules, plays a pivotal role in regulating T-cell responses. Plasma-soluble CD28 is one form of CD28 in peripheral blood. To investigate the concentrations of soluble CD28 in patients with Graves' disease, we used a sensitive dual monoclonal antibody sandwich enzyme-linked immunosorbent assay (ELISA) to detect the soluble form of CD28. Our results suggested that mean concentrations of soluble CD28 in plasma of patients with Graves' disease were 1.79 ±1.52 ng/ml, and levels of soluble CD28 in healthy subjects were only 0.83 ±1.35 ng/ml. Concentrations of soluble CD28 detected in patients with Graves' disease were significantly higher than those of healthy subjects (p < 0.01). Moreover, there was a significant positive correlation between the concentrations of soluble CD28 in plasma and levels of FT3 (r = 0.663), FT4 (r = 0.624) and TRAb (r = 0.728) in serum, but a negative correlation was found between sCD28 levels and TSH (r = -0.726). Through in vitro experiments we observed that engagement of soluble CD28 protein and B7-1/B7-2 molecules expressed on dendritic cells could exert the secretion of cytokine IL-6, which may promote the production of autoantibody and aggravate Graves' disease. Therefore, aberrant elevation of plasma-soluble CD28 in patients with Graves' disease may reflect the dysregulation of immune system, and may serve as a useful biomarker in Graves' disease diagnosis.