Social withdrawal in Russian youth: using the Extended Class Play to examine socio-emotional and academic adjustment

This study explored the socio-emotional characteristics and school adjustment of shy/socially withdrawn youth and examined the properties of the Extended Class Play (ECP), a common peer measure of shyness/withdrawal and other social behavior with Russian early adolescents (n =106; mean age 12.5). Associations between the ECP scores and teacher- and self-reports of adjustment (e.g. internalizing problems) provided evidence-supporting use of the ECP with Russian adolescents. Similar to North American studies, results also indicated that shy/socially withdrawn Russian youth tended to be more excluded, report greater internalizing problems and were also more asocial than a comparison group. No differences were found between shy/socially withdrawn and non-withdrawn adolescents in victimization/exclusion and academic performance. The discussion emphasizes the need for further examination of potential role of teacher-directed social interactions and classroom norms across the cultural contexts

Effects of Environment on Depressive Symptoms on Chinese Left-Behind Children

Estimates indicate that about 70 million children in China have been left behind in their hometowns by one or both parents as their parents migrate to other places for work opportunities. However, the potential impact of parental migration on the emotional well-being of left-behind children is still unclear. The purpose of this study was to examine depression levels in Chinese left-behind children and to identify potential risk factors contributing to depressive symptoms in this population. Using a nationally-representative, stratified sample from the China Family Panel Studies (CFPS) database (3019 children, ages 10-15), an HLM model was applied at 1) the child level measuring the influence of family structure and individual-level parenting practices, and 2) the county level estimating the effects of rural vs. urban differences and county-level parenting practices. Cross-level effects between child factors and county factors were also examined. The depressive symptoms were measured by the Center for Epidemiologic Studies Depression (CES-D, Radloff, 1977). Findings indicated that the left-behind children were more likely to report higher scores on depressive symptoms indices than children from intact families. Children reporting more positive parenting practices also tended to have fewer depressive symptoms. The effect of family structures on children’s depressive symptoms depended on the county-level parental behaviors. Implications for schools and parenting practices were discussed

Investigation and Optimization of Hydraulic Step-down Switched Inertance Converters with Non-uniform Inertance Tubes

In hydraulic systems with multiple actuators, difficulty can arise with matching the load requirements with the supply power from the system's pump. To get the desired performance at the individual loads, restrictive type valves are used to control pressure or flow by throttling the flow over a spool orifice, creating considerable power loss. This causes hydraulic systems powered off the same pump to be inefficient. Switched inertance hydraulic systems are a new technology in the field of fluid power that convert pressure and flow more efficiently than using restrictive type hydraulic valves. The step-down, or "buck", converter considered exclusively in this thesis has the ability to reduce pressure and increase flow rate to a load. The system is constructed using a digital hydraulic valve and check valve connected to the pressure supply and system reservoir respectfully. Following the valves, the system has an inertance tube, a long piece of uniform hydraulic line where fluid inertia is built up. The inertance tube also causes pressure wave propagation effects to occur since the length of the line is typically long. The performance of switched inertance converters are largely governed by the performance of the switching valve. An ideal switched inertance converter is 100% efficient at converting pressure and flow, however this would require the valve to actuate at extremely high frequency and switch instantaneously fast. This is not realizable as real valves operate up to a maximum of a couple hundred Hertz, and take a finite time to open and close, on the order of milliseconds. One of the main losses of a buck converter is the power loss across the switching valve as it transitions from open to closed and vice versa. This loss arises from the throttling of flow over the valve opening during actuation. The research presented in this thesis looks at mitigating this loss, as well as the viscous friction loss within the inertance tube. These losses can be reduced by using an inertance tube of variable shape, a new idea introduced very recently. A shaped inertance tube is a fluid pipeline with varying cross sectional area over its length, as compared to uniform inertance tubes which have constant cross sectional area. The current gap in the research is that the tube design is not fully optimized leaving room for potential improvements in identifying better dimensions, or perhaps finding a more optimal shape. Models for computing fluid transients in uniform lines are well developed, however modelling fluid dynamics in shaped inertance tubes is an area that has not been studied as extensively. The research presented proposes a computer model for simulating fluid transients in tapered transmission line segments using the transmission line method (TLM). The current research gap in modelling tapered transmission lines is that previous models are difficult to simulate in the time domain, have poor accuracy, and have a limited range of applicability. The proposed TLM model looks to mitigate these shortcomings. When connected in succession, the tapered TLM can model shaped inertance tubes for application to hydraulic buck converters. The proposed model shows improved agreement to a numerical solution of the Navier-Stokes equations than the previous models on the topic. Validation of the model is also gained though analysis of the dynamic response in the frequency domain. With the model now available to simulate shaped inertance tubes, a buck converter system is defined with equations presented for dynamic simulation. Initial simulations of the buck converter using parameters and design from previous research showed unoptimized performance operating at an efficiency of 47.8% for a system using a uniform inertance tube. The main objective was to optimize the shape of the inertance tube to realize increased performance using simulation studies. Genetic and pattern search algorithms were used to optimize the dimensions of the inertance tube with the goal of maximizing system efficiency while maintaining the same load. As a baseline, the uniform intertance tube design was optimized, and realized an efficiency of 64.1%, performing significantly better than the unoptimized uniform inertance tube. Further optimizations added an increasing number of tapered sections to describe the arbitrary shape of an inertance tube, up to 4 tapered segments. Significant efficiency increases were realized when using shaped inertance tubes. The best tube design increased system efficiency over 6% compared to the uniform design at a value of 70.2%. Other optimizations showed improvements in efficiency over the traditional design by reducing both valve and frictional losses in the system. The research presents a novel inertance tube design, containing a uniform section of high inertance followed by a diverging tapered section followed by another uniform section at larger diameter and low resistance. This design also proposes the idea of potential noise reduction due to the suppression of pressure fluctuations at the load

Social withdrawal in Russian youth: using the Extended Class Play to examine socio-emotional and academic adjustment

This study explored the socio-emotional characteristics and school adjustment of shy/socially withdrawn youth and examined the properties of the Extended Class Play (ECP), a common peer measure of shyness/withdrawal and other social behavior with Russian early adolescents (n =106; mean age 12.5). Associations between the ECP scores and teacher- and self-reports of adjustment (e.g. internalizing problems) provided evidence-supporting use of the ECP with Russian adolescents. Similar to North American studies, results also indicated that shy/socially withdrawn Russian youth tended to be more excluded, report greater internalizing problems and were also more asocial than a comparison group. No differences were found between shy/socially withdrawn and non-withdrawn adolescents in victimization/exclusion and academic performance. The discussion emphasizes the need for further examination of potential role of teacher-directed social interactions and classroom norms across the cultural contexts

Review of \u3ci\u3eOrdinary Magic: Resilience in Development\u3c/i\u3e by Ann S. Masten

The notion of risk has been a mainstay of research in child development for decades. Studying and understanding risk have led to important discoveries that have informed policy and practice, particularly for children living in situations where risk is abundant. More recently, there has been attention to cumulative risk, or the idea that single indicators of risk – for example, poverty, hunger, and home insecurity – tend to co-occur. Individuals and families facing higher levels of cumulative risk are thought to have compounded problems, regardless of the risks themselves, because these multiple stressors together wear down a family’s resources and ability to combat the forces of risk

Review of \u3ci\u3eOrdinary Magic: Resilience in Development\u3c/i\u3e by Ann S. Masten

The notion of risk has been a mainstay of research in child development for decades. Studying and understanding risk have led to important discoveries that have informed policy and practice, particularly for children living in situations where risk is abundant. More recently, there has been attention to cumulative risk, or the idea that single indicators of risk – for example, poverty, hunger, and home insecurity – tend to co-occur. Individuals and families facing higher levels of cumulative risk are thought to have compounded problems, regardless of the risks themselves, because these multiple stressors together wear down a family’s resources and ability to combat the forces of risk

Childhood peer relationships in context

Gifford-Smith and Brownell (2003) have provided an extensive critical review of the current state of the art in peer relations research. Their thorough review of the basic research in these areas clearly illustrates the complexity of the task of understanding these aspects of children’s social development and how they navigate the interrelated relational ecologies. Our purpose is to extend the discussion by suggesting implications for intervention work and related research

Shyness and engagement: Contributions of peer rejection and teacher sensitivity

This study tested a longitudinal model of mediated moderation for the role of temperament and shyness in the development of young children’s (n = 960, aged 54 mos. to 1st grade [SD = 1.08 at 54 mos.]) peer relationships at school and linkages to subsequent academic engagement. Teacher sensitivity was examined as a parallel predictor of peer relationship effects and subsequent engagement, and we examined whether or not adverse effects of shyness on peer relationships and adjustment were stronger in classrooms where teachers displayed lower sensitivity. Findings indicated that peer rejection mediated the association between children’s shyness at preschool age and engagement in first grade and that teacher sensitivity, although not directly related to peer rejection, was positively related to engagement. Finally, teacher sensitivity moderated the association between shyness, peer rejection, and classroom engagement. Results suggested that teacher sensitivity plays a role in linkages between shyness and peer rejection. Teacher sensitivity may moderate effects on engagement and function as an important aspect of supportive contexts for shy children

Influence of Peer Pressure and Self-Efficacy for Alcohol Self-Regulation on Chinese University Physical Education Students’ Drinking Behaviors

This study examined peer group influence on university student drinking in China and the indirect effects of peer pressure and self-efficacy for alcohol self-regulation. A total of 951 undergraduate university students (first, second and third year) from a university in central China completed questionnaires asking about perceived peer pressures, self-efficacy for alcohol self-regulation, and drinking frequency. Analysis of their answers showed that the drinking frequency among physical education (PE) students was higher than among the comparison group (History students). The PE students perceived greater peer pressure, and had lower self-efficacy for alcohol self-regulation, both of which contributed directly to drinking frequency. Path analysis indicated indirect effects of peer pressure and self-efficacy for alcohol self-regulation on the association between peer group membership and drinking frequency. This suggested that skills training to increase self-efficacy for alcohol self-regulation in culturally-specific settings have the potential to both directly and indirectly lower drinking rates in peer groups with high peer pressure and higher than normal drinking

Child Temperamental Regulation and Classroom Quality in Head Start: Considering the Role of Cumulative Economic Risk

There is growing recognition that cumulative economic risk places children at higher risk for depressed academic competencies (Crosnoe & Cooper, 2010; NCCP, 2008; Sameroff, 2000). Yet, children’s temperamental regulation and the quality of the early childhood classroom environment have been associated with better academic skills. This study is an examination of prekindergarten classroom quality (instructional support, emotional support, organization) as a moderator between temperamental regulation and early math and literacy skills for children at varying levels of cumulative economic risk. The sample includes children enrolled in Head Start programs drawn from the FACES 2009 study. Three main findings emerged. First, for lower and highest risk children, more instructional support was associated with better math performance when children had high levels of temperamental regulation but poorer performance when children had low temperamental regulation. Second, among highest risk children, low instructional support was protective for math performance for children with low temperamental regulation and detrimental for those with high temperamental regulation. Third, for highest risk children, high classroom organization predicted better literacy scores for those with high temperamental regulation. Children with low temperamental regulation were expected to perform about the same, regardless of the level of classroom organization. Implications are discussed