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BackgroundProblematic Internet Use (PIU) is a growing problem in Chinese adolescents. There are many risk factors for PIU, which are found at school and at home. This study was designed to investigate the prevalence of PIU and to investigate the potential risk factors for PIU among high school students in China.Methodology/Principal FindingsA cross-sectional study was conducted. A total of 14,296 high school students were surveyed in four cities in Guangdong province. Problematic Internet Use was assessed by the 20-item Young Internet Addiction Test (YIAT). Information was also collected on demographics, family and school-related factors and Internet usage patterns. Of the 14,296 students, 12,446 were Internet users. Of those, 12.2% (1,515) were identified as problematic Internet users (PIUs). Generalized mixed-model regression revealed that there was no gender difference between PIUs and non-PIUs. High study-related stress, having social friends, poor relations with teachers and students and conflictive family relationships were risk factors for PIU. Students who spent more time on-line were more likely to develop PIU. The habits of and purposes for Internet usage were diverse, influencing the susceptibility to PIU.Conclusions/SignificancePIU is common among high school students, and risk factors are found at home and at school. Teachers and parents should pay close attention to these risk factors. Effective measures are needed to prevent the spread of this problem.

The leader-member exchange (LMX) literature argues that leaders develop different quality dyadic relationships with members in the same team (i.e., LMX differentiation). Research has generally not found support for a linear (i.e., main effect) relationship between LMX differentiation and team performance; rather, moderators typically determine whether the relationship is significantly positive or negative. Examining linear effect moderators alone, however, does not account for (a) potential curvilinear (i.e., inverted U-shaped) effects, (b) explanatory mechanisms of how LMX differentiation influences team performance, or (c) moderators of curvilinear effects. Integrating social identity theory with LMX differentiation research, we propose inverted U-shaped relationships between LMX differentiation and both team coordination (as a mediator) and team performance (as an outcome), and we examine both team size and team power distance orientation as moderators. Using data from 928 employees in 145 teams in 3 organizations, we found an inverted U-shaped relationship between LMX differentiation and team coordination, which, in turn, partially mediated LMX differentiation's inverted U-shaped relationship with team performance. Larger teams, or those with higher team power distance orientation, benefit more from LMX differentiation. By integrating social identity theory with LMX differentiation research, we enhance the understanding of the processes by, and conditions under, which LMX differentiation affects team performance both positively and negatively.Leader-member exchange (LMX) theory is one of the most prominent frameworks for understanding leadership in organizations. Even though

BackgroundThe MSM (Men who have sex with men) population suffers from very high rates of concurrent psychosocial problems. Together, these problems comprise a syndemic that increases the risk of HIV infection for this community. The precise mechanisms through which this syndemic can raise the likelihood of HIV infection warrant further exploration.Methodology/Principal FindingsA total of 522 MSM were enrolled via a multiframe sampling approach and were asked to report psychosocial problems, risky sexual behaviors and HIV test results. A count of psychosocial health problems was calculated to test the additive relationship of these factors on HIV risk. Adjusting analysis and restriction analysis were used to determine a proposed intermediate pathway. Psychosocial health problems are highly concurrent and intercorrelated among urban MSM. Greater numbers of health problems are significantly and positively associated with HIV infection, which is mediated, at least partially, by risky sexual behaviors.Conclusions/SignificanceMSM experience concurrent psychosocial health problems that correlate with HIV infection in this community. We recommend the development of coping strategies for this population to deal with these psychosocial problems, both in prevention research and health policy.