Pre-school contributions to future achievements

This paper provides recent evidence about the beneÖts of attending preschool on future performance. A non-parametric matching procedure is used over two outcomes: math and verbal scores at a national mandatory test (Saber11) in Colombia. It is found that students who had the chance of attending preschool obtain higher scores in math (6.7%) and verbal (5.4%) than those who did not. A considerable fraction of these gaps comes from the upper quintiles of studentís performance, suggesting that preschool matters when is done at high quality institutions. When we include the number of years at the preschool, the gap rises up to 12% in verbal and 17% in math.

A grouped P2P network for scalable grid information services

Information services play a crucial role in grid environments in that the state information can be used to facilitate the discovery of resources and the services available to meet user requirements, and also to help tune the performance of a grid system. However, the large size and dynamic nature of the grid brings forth a number of challenges for information services. This paper presents PIndex, a grouped peer-to-peer network that can be used for scalable grid information services. PIndex builds on Globus MDS4, but introduces peer groups to dynamically split the large grid information search space into many small sections to enhance its scalability and resilience. PIndex is subsequently modeled with Colored Petri Nets for performance evaluation. The simulation results show that PIndex is scalable and resilient in dealing with a large number of peer nodes.

Short-time behaviour of demand and price viewed through an exactly solvable model for heterogeneous interacting market agents

We introduce a stochastic heterogeneous interacting-agent model for the short-time non-equilibrium evolution of excess demand and price in a stylized asset market. We consider a combination of social interaction within peer groups and individually heterogeneous fundamentalist trading decisions which take into account the market price and the perceived fundamental value of the asset. The resulting excess demand is coupled to the market price. Rigorous analysis reveals that this feedback may lead to price oscillations, a single bounce, or monotonic price behaviour. The model is a rare example of an analytically tractable interacting-agent model which allows LIS to deduce in detail the origin of these different collective patterns. For a natural choice of initial distribution, the results are independent of the graph structure that models the peer network of agents whose decisions influence each other. (C) 2009 Elsevier B.V. All rights reserved.

Homofobia e sexualidade em adolescentes: trajetórias sexuais, riscos e vulnerabilidades

Esta pesquisa é um estudo transversal realizado junto a 2282 estudantes de ambos os sexos que cursavam as três séries do ensino médio em três cidades do interior do oeste paulista. O instrumento de coleta de dados empregado foi um questionário autoaplicável com 131 questões. Neste artigo, abordamos as trajetórias sexuais de adolescentes de ambos os sexos que mantêm práticas sexuais homoeróticas ou não. Discutimos as relações desses adolescentes com seus familiares e grupos de pares e a questão de sair do armário como ferramenta política. Tendo como base as concepções de Sedgwick, analisamos os momentos em que sair do armário pode ser uma entre tantas maneiras de manifestação das diferentes sexualidades em relação à heteronormatividade. Apoiando-nos nas colocações de teóricos pós-estruturalistas, abordamos também as construções teóricas e as produções discursivas sobre a adolescência, apontando novas manifestações da juventude na contemporaneidade. Por fim, percebemos a existência de amplos fatores que afetam as decisões de jovens não heterossexuais quanto a sair (ou não) do armário para além da homofobia: eventos pessoais, histórias de vida e mesmo a revelação de sua sexualidade aos pais e/ou a outras pessoas.

O consumo de bebidas alcoólicas por estudantes do ensino médio e características do grupo de pares

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Selbstbereicherung an kollektiven Ressourcen. «Eigennutz» als Leitmotiv politischer und sozialer Skandalisierung in der vormodernen Eidgenossenschaft

Angemessen historisiert kann der «Skandal» auch für die Vormoderne als produktive Forschungskategorie genutzt werden, um nach fundamentalen Wertehaltungen und zugehörigen Konfliktmodi zu fragen. Während Skandale in heutiger Zeit über massenmedial verbreitete Enthüllungen befeuert werden, adressierte Skandalisierung in der Vormoderne unterschiedliche Kommunikationsräume wie etwa Familie, Peer Groups, politische Gremien und Versammlungen, die als ständisch gerahmte, ineinander verschachtelte und miteinander interagierende Teilöffentlichkeiten fungierten. Eigentliches Skandalon stellte der Vorwurf des Eigennutzes bzw. die Schädigung des gemeinen Nutzens dar. Angeprangert wurden Selbstbereicherung, undurchsichtige Machenschaften oder übermässige Profite aus Amtstätigkeiten. Skandalen kam dabei die Funktion von Läuterungsritualen zu, welche lokalen Gesellschaften und ständischen Gruppen die ungeschriebenen Gesetze ihres Zusammenlebens in Erinnerung riefen.

The Effects of Social Anxiety on the Development of Romantic Relationships in Adolescence

The present study sought to investigate the ways in which social anxiety impedes the development of romantic relationships across adolescence. Previous research has demonstrated a natural progression for romantic associations during adolescence in which teens transition from same- to mixed-sex peer groups, and finally to dyadic relationships with romantic partners (Connolly, Furman, Konarski, 2000; Dunphy, 1963). This model of development was the basis for the present investigation. Social anxiety was examined in terms of how it impacted affiliations at the same- and mixed sex peer group levels, and ultimately the formation of romantic relationships. This project involved administering a series of questionnaires and rating scales to students enrolled in the 9th through \2l grades. Participants included 457 adolescents (196 males, 261 females) recruited from public high schools in the state of Maine. The questionnaires assessed social anxiety, peer acceptance, heterosocial competence, gender composition of adolescent peer networks, dating history, and relationship quality with significant others in the adolescent's life. Higher levels of social anxiety were expected to be associated with impairment at each of these three levels. Given the proposed developmental progression, the effects of anxiety were theorized to be most pronounced within the older cohort of adolescents. Moreover, gender was expected to affect the pattern of results. Social anxiety is most prevalent among females (LaGreca, 1998; LaGreca & Lopez, 1998), who are also thought to progress along the proposed developmental trajectory more quickly than their male counterparts. Therefore, social anxiety was expected to impact the females to a greater degree at each of the three levels. Correlation coefficients, multivariate analyses of variance, and regression analyses were used to evaluate the data. Overall, despite some discrepant findings, the results supported the hypotheses. Social anxiety was affiliated with problems in the same-sex peer group, the mixed-sex clique, and, for older adolescents, romantic relationships. As expected, social anxiety affected females the most at each level. There seems to be a maladaptive pathway that socially anxious teens are following that is markedly different than their non-anxious counterparts.

Applied Research “Specializers”Versus “Samplers” in Youth Sport: Comparing Experiences and Outcomes

The purpose of the current study was to examine two different trajectories of sport participation and explore any similarities or differences that may result regarding per­sonal development and sport outcomes. Seventy-four youth athletes (40 “specializ­ers” and 34 “samplers”) were recruited for the current study and four measures were employed to assess sport experiences and outcomes. Discriminant function analyses revealed no differences between groups in asset possession or sources of enjoyment however, differences were reported in sport experiences and burnout. The “samplers” reported more experiences regarding the integration of sport and family as well as linkages to the community. Although the “specializers” reported higher levels of physical/emotional exhaustion than did the “samplers,” they also reported more expe­riences related to diverse peer groups. The differences highlight the importance of examining specific pathways of development in sport to gain a deeper understanding of youths’ experiences in sport.

The Benefits of Sampling Sports During Childhood

Sampling may promote prolonged engagement in sport by limiting physical injuries (Fraser-Thomas et al., 2005). Overtraining injuries are a concern for young athletes who specialize in one sport and engage in high volumes of deliberate practice (Hollander, Meyers, & Leunes, 1995; Law, Côté, & Ericsson, 2007). For instance, young gymnasts who practice for over 16 hours a week have been shown to have higher incidences of back injuries (Goldstein, Berger, Windier, & Jackson, 1991). A sampling approach in child-controlled play (e.g. deliberate play) rather than highly adult-controlled practice (e.g. deliberate practice) has been proposed as a strategy to limit overuse and other sport-related injuries (Micheli, Glassman, & Klein, 2000). In summary, sampling may protect against sport attrition by limiting sport related injuries and allowing children to have early experiences in sport that are enjoyable. Psychosocial Benefits of Sampling Only a small percentage of children who participate in school sports ever become elite athletes. Therefore, the psychosocial outcomes of sport participation are particularly important to consider. Recent studies with youth between the ages of 11 to 17 have found that those who are involved in a variety of extracurricular activities (e.g. sports, volunteer, arts) score more favourably on outcome measures such as Grade Point Average (GPA; Fredricks & Eccles, 2006a) and positive peer relationships (Fredricks & Eccles, 2006b) than youth who participate in fewer activities. These patterns are thought to exist due to each extracurricular activity bringing its own distinct pattern of socialization experiences that reinforce certain behaviours and/or teach various skills (Fredricks & Eccles, 2006b; Rose-Krasnor, Bussen, Willoughby, & Chambers, 2006). This contention is corroborated by studies of children and youths' experiences in extracurricular activities indicating that youth have unique experiences in each activity that contribute to their development (Hansen, Larson, & Dworkin, 2003; Larson, Hansen, & Moneta, 2006). This has led Wilkes and Côté (2007) to propose that children who sample different activities (through their own choice or by virtue of parental direction), have a greater chance of developing the following five developmental outcomes compared to children who specialize in one activity: 1) life skills, 2) prosocial behaviour, 3) healthy identity, 4) diverse peer groups and 5) social capital.

Implementation guide for establishing a youth traffic safety council.

National Highway Traffic Safety Administration, Washington, D.C.

Program overview for establishing a youth traffic safety council.

National Highway Traffic Safety Administration, Washington, D.C.

Motivating anti-DWI behavior using existing values. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

55 mph - Interstate Communications Project. Task 3: preliminary communications concept test. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Field assessment of social learning approach to teaching adolescents about alcohol and driving. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Are diagnosis specific outcome indicators based on administrative data useful in assessing quality of hospital care?

Background: Hospital performance reports based on administrative data should distinguish differences in quality of care between hospitals from case mix related variation and random error effects. A study was undertaken to determine which of 12 diagnosis-outcome indicators measured across all hospitals in one state had significant risk adjusted systematic ( or special cause) variation (SV) suggesting differences in quality of care. For those that did, we determined whether SV persists within hospital peer groups, whether indicator results correlate at the individual hospital level, and how many adverse outcomes would be avoided if all hospitals achieved indicator values equal to the best performing 20% of hospitals. Methods: All patients admitted during a 12 month period to 180 acute care hospitals in Queensland, Australia with heart failure (n = 5745), acute myocardial infarction ( AMI) ( n = 3427), or stroke ( n = 2955) were entered into the study. Outcomes comprised in-hospital deaths, long hospital stays, and 30 day readmissions. Regression models produced standardised, risk adjusted diagnosis specific outcome event ratios for each hospital. Systematic and random variation in ratio distributions for each indicator were then apportioned using hierarchical statistical models. Results: Only five of 12 (42%) diagnosis-outcome indicators showed significant SV across all hospitals ( long stays and same diagnosis readmissions for heart failure; in-hospital deaths and same diagnosis readmissions for AMI; and in-hospital deaths for stroke). Significant SV was only seen for two indicators within hospital peer groups ( same diagnosis readmissions for heart failure in tertiary hospitals and inhospital mortality for AMI in community hospitals). Only two pairs of indicators showed significant correlation. If all hospitals emulated the best performers, at least 20% of AMI and stroke deaths, heart failure long stays, and heart failure and AMI readmissions could be avoided. Conclusions: Diagnosis-outcome indicators based on administrative data require validation as markers of significant risk adjusted SV. Validated indicators allow quantification of realisable outcome benefits if all hospitals achieved best performer levels. The overall level of quality of care within single institutions cannot be inferred from the results of one or a few indicators.