Prevalence of internet addiction and its association with stressful life events and psychological symptoms among adolescent internet users

Internet addiction (IA) among adolescents is a serious public health problem around the world. However, there have been few studies that examine the association between IA and stressful life events and psychological symptoms among Chinese adolescent internet users. We examined the association between IA and stressful life events and psychological symptoms among a random sample of school students who were internet users (N = 755) in Wuhan, China. Internet addiction, stressful life events, coping style and psychological symptoms were measured by self-rated scales. The prevalence rate of internet addiction was 6.0% among adolescent internet users. Logistic regression analyses indicated that stressors from interpersonal problem and school related problem and anxiety symptoms were significantly associated with IA after controlling for demographic characteristics. Analyses examining the coping style with the IA revealed that negative coping style may mediate the effects of stressful life events to increase the risk of IA. However, no significant interaction of stressful life events and psychological symptoms was found. These findings of the current study indicate a high prevalence of internet addiction among Chinese adolescent internet users and highlight the importance of stressors from interpersonal problem and school related problem as a risk factor for IA which mainly mediated through negative coping style.Published versio

Sexual Knowledge, attitudes and behaviors among unmarried migrant female workers in China: a comparative analysis

<p>Abstract</p> <p>Background</p> <p>In recent years, many studies have focused on adolescent's sex-related issues in China. However, there have been few studies of unmarried migrant females' sexual knowledge, attitudes and behaviors, which is important for sexual health education and promotion.</p> <p>Methods</p> <p>A sample of 5156 unmarried migrant female workers was selected from three manufacturing factories, two located in Shenzhen and one in Guangzhou, China. Demographic data, sexual knowledge, attitudes and behaviors were assessed by self-administered questionnaires. Multivariate logistic regression analysis was conducted to examine the factors associated with premarital sexual intercourse.</p> <p>Results</p> <p>The average age of the unmarried female workers included in the sample was 20.2 years, and majority of them showed a low level of sex-related knowledge. Females from the west of China demonstrated a significant lower level of sex-related knowledge than those from the eastern or central provinces (<it>p </it>< 0.05). Approximately 13% of participants held a favorable attitude towards premarital sexual intercourse, and youths from the east/central were more likely to have favorable attitudes compared with those from the west (<it>p </it>< 0.05). About 17.0% of the unmarried female workers reported having engaged in premarital sexual intercourse, and females from the east/central were more likely to have experienced premarital sexual intercourse than those from the west (<it>p </it>< 0.05). Multivariate analysis revealed that age, education, current residential type, dating, sexual knowledge, attitudes, and pattern of communication were significantly associated with premarital sexual intercourse.</p> <p>Conclusion</p> <p>The unmarried migrant female workers lack sexual knowledge and a substantial proportion of them are engaged in premarital sexual behaviors. Interventions aimed at improving their sexual knowledge and related skills are needed.</p

Structural Design Methodology Based on Concepts of Uncertainty

In this report, an approach to damage-tolerant aircraft structural design is proposed based on the concept of an equivalent "Level of Safety" that incorporates past service experience in the design of new structures. The discrete "Level of Safety" for a single inspection event is defined as the compliment of the probability that a single flaw size larger than the critical flaw size for residual strength of the structure exists, and that the flaw will not be detected. The cumulative "Level of Safety" for the entire structure is the product of the discrete "Level of Safety" values for each flaw of each damage type present at each location in the structure. Based on the definition of "Level of Safety", a design procedure was identified and demonstrated on a composite sandwich panel for various damage types, with results showing the sensitivity of the structural sizing parameters to the relative safety of the design. The "Level of Safety" approach has broad potential application to damage-tolerant aircraft structural design with uncertainty

Effects of loading history on fracture properties of concrete

A static fracture process zone (FPZ) model, which describes the nonlinear relationship between the crack-closure stress and the coexisting crack-opening displacement, was used to predict the effects of sustained and cyclic loading on crack propagation and fracture for concrete in tension. This study found that when plain concrete was subjected to an incremental tensile displacement loading, microcracks continued to grow for more than 1 hr after that increment was first applied. Such a process of slow damage accumulation is the cause of increases in deformation and crack length for concrete in the tensile zone of specimens subject to cyclic or sustained loadings. This conclusion is consistent with the results for previous studies on concrete fracture under compressive loading

The Electronic Transport Properties in Boron-Doped Armchair Graphene Nanoribbon Junctions

An electronic component using individual molecules is one of the ultimate goals in nanotechnology. In this work, by performing non-equilibrium Green's functions in combination with density-functions theory, the transport properties of armchair graphene nanoribbon (AGNR) devices are investigated, in which one lead is undoped AGNRs and the other is Boron (B)-doped AGNRs. The current voltage (I V) characteristic of B-doped AGNRs devices depends on their width and exhibits three distinct family (3n, 3n +1, 3n +2) behaviors. It was found that the 3n+2 system exhibits a metallic property and 3n and 3n +1 systems exhibit semi conductive property. Moreover, it shows rectifying behavior for W7 system

Research on Technological Innovation as Seen through the Chinese Looking Glass

The rapid development of the Chinese economy during the 1990's has intensified research on technological innovation. Recent policy emphasis on innovation as a path to sustainable economic growth will only accelerate work on this important topic. The work by individuals and groups at various research institutes and universities has mainly been published in leading Chinese scholarly journals. In this paper, we develop a framework and do a substantive review of the literature to characterize the state of knowledge about technological innovation in China, with special emphasis on: 1) conceptual contributions, 2) empirical results, and 3) connections between innovation and performance