Nonfragile Exponential Synchronization of Delayed Complex Dynamical Networks With Memory Sampled-Data Control.

This paper considers nonfragile exponential synchronization for complex dynamical networks (CDNs) with time-varying coupling delay. The sampled-data feedback control, which is assumed to allow norm-bounded uncertainty and involves a constant signal transmission delay, is constructed for the first time in this paper. By constructing a suitable augmented Lyapunov function, and with the help of introduced integral inequalities and employing the convex combination technique, a sufficient condition is developed, such that the nonfragile exponential stability of the error system is guaranteed. As a result, for the case of sampled-data control free of norm-bound uncertainties, some sufficient conditions of sampled-data synchronization criteria for the CDNs with time-varying coupling delay are presented. As the formulations are in the framework of linear matrix inequality, these conditions can be easily solved and implemented. Two illustrative examples are presented to demonstrate the effectiveness and merits of the proposed feedback control.

Non-fragile H∞ filtering for nonlinear discrete-time delay systems with randomly occurring gain variations.

In this paper,the problem of H∞ filtering for a class of nonlinear discrete-time delay systems is investigated. The time delay is assumed to be belonging to a given interval, and the designed filter includes additive gain variations which are supposed to be random and satisfy the Bernoulli distribution. By the augmented Lyapunov functional approach, a sufficient condition is developed to ensure that the filtering error system is asymptotically mean-square stable with a prescribed H∞ performance. In addition, an improved result of H∞ filtering for linear system is also derived. The filter parameters are obtained by solving a set of linear matrix inequalities. For nonlinear systems, the applicability of the developed filtering result is confirmed by a longitudinal flight system, and an additional example for linear system is presented to demonstrate the less conservativeness of the proposed design method.

Efficacy of swim-up versus density gradient centrifugation in improving sperm deformity rate and DNA fragmentation index in semen samples from teratozoospermic patients.

PURPOSE: To compare the efficacy of swim-up and DGC in improving sperm deformity and DNA fragmentation and to determine which method is better in teratozoospermic patients requiring artificial reproduction. METHODS: The present study compared the effects of swim-up and density gradient centrifugation (DGC), the two most commonly used semen preparation methods, on sperm deformity rate and DNA fragmentation index (DFI) in semen samples from teratozoospermic patients. RESULTS: The results demonstrated that both swim-up and DGC yielded a significantly lower sperm deformity rate and DFI in comparison to unprocessed whole semen, with DGC having more favorable results. Sperm deformity rate in unprocessed whole semen samples was significantly lower in the 20-29 age group than in the 40-49 age group, but no significant difference was observed in DFI between different age groups. There was no significant correlation between sperm deformity rate and DFI. CONCLUSIONS: Our findings suggest that enrichment of sperm with normal morphology and intact DNA in teratozoospermic patients could be achieved by both DGC and swim-up procedures, and that DGC is a better method.

A state dependent pulse control strategy for a SIRS epidemic system.

With the consideration of mechanism of prevention and control for the spread of infectious diseases, we propose, in this paper, a state dependent pulse vaccination and medication control strategy for a SIRS type epidemic dynamic system. The sufficient conditions on the existence and orbital stability of positive order-1 or order-2 periodic solution are presented. Numerical simulations are carried out to illustrate the main results and compare numerically the state dependent vaccination strategy and the fixed time pulse vaccination strategy.

A note for the global stability of a delay differential equation of hepatitis B virus infection.

The global stability for a delayed HIV-1 infection model is investigated. It is shown that the global dynamics of the system can be completely determined by the reproduction number, and the chronic infected equilibrium of the system is globally asymptotically stable whenever it exists. This improves the related results presented in [S. A. Gourley,Y. Kuang and J.D.Nagy, Dynamics of a delay differential equation model of hepatitis B virus infection, Journal of Biological Dynamics, 2(2008), 140-153].

[Teratozoospermia affects in vitro fertilization outcome].

OBJECTIVE: To analyze the possible causes of total fertilization failure (TFF) in conventional in vitro fertilization (IVF). METHODS: We included in this study 552 couples who accomplished the first conventional IVF cycle in our center from January 2007 to August 2008. All the males met the Kruger/Tygerberg criteria, with the teratozoospermia rate < 96% in the previous 12 months and the postwash motile sperm > 1 million on the day of egg retrieval. The eggs were fertilized totally by conventional IVF. RESULTS: Of the total number, 515 couples got zygotes by conventional IVF, with a fertilization rate of 78.67%, and 37 suffered TFF. The rates of primary infertility and teratozoospermia were significantly higher in the TFF group than in the fertilized group (P < 0.05). There were no statistically significant differences between the two groups in the number of controlled ovarian hyperstimulation (COH) days, the number of oocytes retrieved, the dose of gonadotropin (Gn) used, the age of the couples, the length of protocols and the rate of oligoasthenozoospermia. CONCLUSION: Intracytoplasmic sperm injection (ICSI) can be considered for at least some of the oocytes to avoid unnecessary fertilization failure in teratozoospermia patients by Kruger/Tygerberg strict criteria.