258 research outputs found

    Purpose and enactment in job design: An empirical examination of the processes through which job characteristics have their effects

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    Job characteristics are linked with health, safety, well-being and other performance outcomes. Job characteristics are usually assessed by their presence or absence, which gives no indication of the specific purposes for which workers might use some job characteristics. We focused on job control and social support as two job characteristics embedded in the well-known Demand-Control-Support model (Karasek & Theorell, 1990). In Study 1, using an experience sampling methodology (N = 67) and a cross-sectional survey methodology (N = 299), we found that relationships between the execution of job control or the elicitation of social support and a range of other variables depended on the purposes for which job control was executed or social support elicited. In Study 2 (N = 28), we found that it may be feasible to improve aspects of well-being and performance through training workers on how to use job control or social support for specific purposes

    Relationship between advanced maternal age and timing of first developmental evaluation in children with autism

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    Objective: Mothers of advanced maternal age (AMA) at childbirth (age ‡35 years) may have different perceptions of autism spectrum disorder (ASD) risk, independent of sociodemographic factors, that may affect ASD identification. We aimed to estimate associations between AMA and both age of a child's first evaluation noting developmental concerns and time from first evaluation to first ASD diagnosis. Methods: We used data for 8-year-olds identified with ASD in the 2008 to 2012 Autism and Developmental Disabilities Monitoring Network. We estimated differences in age at first evaluation noting developmental concerns and time to first ASD diagnosis by AMA using quantile and Cox regression. Results: Of 10,358 children with ASD, 19.7% had mothers of AMA. AMA was associated with higher educational attainment and previous live births compared with younger mothers. In unadjusted analyses, AMA was associated with earlier first evaluation noting developmental concerns (median 37 vs 40 mo) and patterns in time to first evaluation (hazard ratio: 1.12, 95% confidence interval: 1.06-1.18). Associations between AMA and evaluation timing diminished and were no longer significant after adjustment for socioeconomic and demographic characteristics. Children's intellectual disability did not modify associations between AMA and timing of evaluations. Conclusion: Advanced maternal age is a sociodemographic factor associated with younger age of first evaluation noting developmental concerns in children with ASD, but AMA was not independently associated likely, because it is a consequence or cofactor of maternal education and other sociodemographic characteristics. AMA may be a demographic factor to consider when aiming to screen and evaluate children at risk for ASD

    Selected Topics in Three- and Four-Nucleon Systems

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    Two different aspects of the description of three- and four-nucleon systems are addressed. The use of bound state like wave functions to describe scattering states in NdN-d collisions at low energies and the effects of some of the widely used three-nucleon force models in selected polarization observables in the three- and four-nucleon systems are discussed.Comment: Presented at the 21st European Conference on Few-Body Problems in Physics, Salamanca, Spain, 30 August - 3 September 201

    PEACH™ Queensland program improved child eating behaviours and reduced BMI z-score for overweight children (pilot study)

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    Background/Aims: Parenting, Eating and Activity for Child Health (PEACH™) Queensland is a 6-month family-focussed child weight management program currently targeting 1400 Queensland children. This study aims to investigate changes in child BMI and eating behaviours during the pilot phase. Methods: From 2013 – 2014, 251 overweight children (US-CDC BMI percentile ≥ 85th) were enrolled in the pilot phase of PEACH™ Queensland, using pre-defined inclusion criteria which included having a child above a healthy weight for their age (5 – 11 years). Baseline and follow-up data were collected from parents by questionnaire and included child eating behaviours, measured by core food intake and Children’s Dietary Questionnaire (CDQ). Children attending sessions were weighed and measured by a trained facilitator. Results: Children attending sessions were 80% obese (IOTF cut-points), 60% female, with average age of 9.0 ± 1.9 years. For the subset of children with complete anthropometry (n = 69), we observed significant decreases in US-CDC z-scores for weight and BMI, 2.3 ± 0.7 to 2.2 ± 0.7 (p < 0.001) and 2.2 ± 0.5 to 2.1 ± 0.7 (p < 0.0001), respectively. This reduction in BMI z-score was accompanied by increases in the proportion meeting recommendations for serves of fruit and vegetables, and significantly lower scores for sweetened beverages and discretionary food intake as measured by CDQ. Conclusions: The PEACH™ Queensland pilot reduced child weight and BMI z-scores, and improved eating behaviours (increased fruit and vegetable intake, decreased intake of discretionary foods and sweetened beverages) although there is need for further improvement

    Solid-state additive manufacturing for metallized optical fiber integration

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    The formation of smart, Metal Matrix Composite (MMC) structures through the use of solid-state Ultrasonic Additive Manufacturing (UAM) is currently hindered by the fragility of uncoated optical fibers under the required processing conditions. In this work, optical fibers equipped with metallic coatings were fully integrated into solid Aluminum matrices using processing parameter levels not previously possible. The mechanical performance of the resulting manufactured composite structure, as well as the functionality of the integrated fibers, was tested. Optical microscopy, Scanning Electron Microscopy (SEM) and Focused Ion Beam (FIB) analysis were used to characterize the interlaminar and fiber/matrix interfaces whilst mechanical peel testing was used to quantify bond strength. Via the integration of metallized optical fibers it was possible to increase the bond density by 20–22%, increase the composite mechanical strength by 12–29% and create a solid state bond between the metal matrix and fiber coating; whilst maintaining full fiber functionality

    Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles

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    publisher: Elsevier articletitle: Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles journaltitle: Carbon articlelink: http://dx.doi.org/10.1016/j.carbon.2017.04.018 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved.publisher: Elsevier articletitle: Mechanical properties and fracture patterns of graphene (graphitic) nanowiggles journaltitle: Carbon articlelink: http://dx.doi.org/10.1016/j.carbon.2017.04.018 content_type: article copyright: © 2017 Elsevier Ltd. All rights reserved.This work was supported in part by the Brazilian Agencies CNPq, CAPES and FAPESP. The authors would like to thank the Center for Computational Engineering and Sciences at Unicamp for financial support through the FAPESP/CEPID Grant 2013/08293-7. N.M.P. is supported by the European Research Council PoC 2015 “Silkene” No. 693670, by the European Commission H2020 under the Graphene Flagship Core 1 No. 696656 (WP14 “Polymer Nanocomposites”) and under the Fet Proactive “Neurofibres” No. 732344

    Random Convex Hulls and Extreme Value Statistics

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    In this paper we study the statistical properties of convex hulls of NN random points in a plane chosen according to a given distribution. The points may be chosen independently or they may be correlated. After a non-exhaustive survey of the somewhat sporadic literature and diverse methods used in the random convex hull problem, we present a unifying approach, based on the notion of support function of a closed curve and the associated Cauchy's formulae, that allows us to compute exactly the mean perimeter and the mean area enclosed by the convex polygon both in case of independent as well as correlated points. Our method demonstrates a beautiful link between the random convex hull problem and the subject of extreme value statistics. As an example of correlated points, we study here in detail the case when the points represent the vertices of nn independent random walks. In the continuum time limit this reduces to nn independent planar Brownian trajectories for which we compute exactly, for all nn, the mean perimeter and the mean area of their global convex hull. Our results have relevant applications in ecology in estimating the home range of a herd of animals. Some of these results were announced recently in a short communication [Phys. Rev. Lett. {\bf 103}, 140602 (2009)].Comment: 61 pages (pedagogical review); invited contribution to the special issue of J. Stat. Phys. celebrating the 50 years of Yeshiba/Rutgers meeting

    Prevalence of intellectual disability among eight-year-old children from selected communities in the United States, 2014

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    Background: Children with intellectual disability (ID), characterized by impairments in intellectual functioning and adaptive behavior, benefit from early identification and access to services. Previous U.S. estimates used administrative data or parent report with limited information for demographic subgroups. Objective: Using empiric measures we examined ID characteristics among 8-year-old children and estimated prevalence by sex, race/ethnicity, geographic area and socioeconomic status (SES) area indicators. Methods: We analyzed data for 8-year-old children in 9 geographic areas participating in the 2014 Autism and Developmental Disabilities Monitoring Network. Children with ID were identified through record review of IQ test data. Census and American Community Survey data were used to estimate the denominator. Results: Overall, 11.8 per 1,000 (1.2%) had ID (IQ ≤ 70), of whom 39% (n = 998) also had autism spectrum disorder. Among children with ID, 1,823 had adaptive behavior test scores for which 64% were characterized as impaired. ID prevalence per 1,000 was 15.8 (95% confidence interval [95% CI], 15.0–16.5) among males and 7.7 (95% CI, 7.2–8.2) among females. ID prevalence was 17.7 (95% CI, 16.6–18.9) among children who were non-Hispanic black; 12.0 (95% CI, 11.1–13.0), among Hispanic; 8.6 (95% CI, 7.1–10.4), among non-Hispanic Asian; and 8.0 (95% CI, 7.5–8.6), among non-Hispanic white. Prevalence varied across geographic areas and was inversely associated with SES. Conclusions: ID prevalence varied substantively among racial, ethnic, geographic, and SES groups. Results can inform strategies to enhance identification and improve access to services particularly for children who are minorities or living in areas with lower SES

    Family Composition and Stability for Orphans: A Longitudinal Study of Well-Being in 5 Low- and Middle-Income Countries

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    Objectives: Many orphaned children in low- and middle-income countries live with family. Yet, their household composition and its stability are not well-characterized, nor is impact of stability on longer-term outcomes. Methods: We used the longitudinal, multi-country Positive Outcomes for Orphans cohort to describe adult family living with orphans. Stability was measured by changes in presence of six familial relations over time, and related to three outcomes: 1) incident abuse, 2) cognitive functioning, 3) emotional difficulties. Associations were estimated using generalized linear models fit with generalized estimating equations. For abuse, Poisson regression estimated risk ratios. For continuous scores of cognitive functioning and emotional difficulties, linear models estimated mean differences (MDs) with 95% confidence intervals. Results: Among 1,359 orphans, 53–61% reported living with their mother each year; 7–13% with father; nearly 60% reported ≥1 change in composition over follow-up. Compared to 0 changes, difficulties increased with 1 change [MD: 0.23 (−0.33, 0.79)], 2 changes [MD: 0.57 (0.00, 1.16)] and ≥3 changes [MD: 0.73 (0.18, 1.29)]. No associations were found with abuse or cognitive functioning. Conclusion: Orphan well-being may be improved through supports stabilizing household composition or targeting emotional resilience
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