Minimum Time Synchronization of Chaotic Systems via Numerical Optimal Control Techniques

Chaos synchronization has attracted much attention in recent decades since it has not only brought theoretical challenges but also could be applied to many real-world applications, such as digital communication, complex networks, and semiconductor lasers communication systems. We consider the minimum time problem of chaos synchronization via optimal control computation. The general synchronization scheme consists of identical/non-identical drive and response chaotic systems. We propose a novel computational approach to compute the minimum synchronization time of the drive-response chaotic systems and the corresponding optimal controls in a finite time horizon. By the control parametrization technique, the minimum-time chaos synchronization problem is transformed to an optimal parameter selection problem in two stages. A computational synchronization algorithm is hence devised to compute the minimum synchronization time and the optimal controls. For illustration, an exemplary scheme of Lorenz–Rossler chaotic systems is given to demonstrate the effectiveness of the proposed algorithm

Partner Violence and Psychosocial Distress among Female Sex Workers in China

BACKGROUND: Despite recognized vulnerability of female sex workers (FSW), most data on this population are focused on their HIV and STI prevalence; studies on their experience of partner violence and psychosocial distress are limited, especially FSW in China. METHODS AND FINDINGS: A cross-sectional survey was administered among 1,022 FSW recruited from 9 different types of commercial sex venues in Southwest China. Partner violence scales were adapted from WHO's Women's Health and Domestic Violence scale and psychosocial distress was measured by five indicators, including alcohol intoxication, drug use, suicidal behavior, depression, and loneliness. Random effects modeling was used to control for cluster effects. Findings: About 58% of FSW ever experienced violence from their stable partners, and 45% suffered it from their clients. Partner violence was strongly associated with each of the five measures of psychosocial distress, even after controlling for potential confounders. CONCLUSION: This study is one of the first to examine the association between partner violence and psychosocial distress among FSW in China. The high prevalence of violence experience and distress in this population suggests urgency for intervention. The public health programs targeting FSW should go beyond the focus on HIV/STI prevention and care for the fundamental health and human rights of millions of FSW in China