A Latent Growth Curve Approach to Investigating Developmental Dynamics and Correlates of Change in Children's Perceptions of Physical Competence

Abstract

In both the physical and academic domains interest has recently grown regarding developmental change in children's perceptions of competence. Recent advances in statistical methodology, such as latent growth modeling, enable the researcher to analyze developmental trends from both an inter- and intraindividual perspective, thus serving to increase our understanding of correlates of change in perceived competence. Using latent growth modeling, the purpose of the present study was to investigate developmental change in children's perceived competence at physical skills, examining maturational factors and chronological age as possible correlates of change. Subjects were male adolescents (N = 94). Data were collected during the child's sixth, eighth, and ninth grade school years. Results revealed a good fit for the hypothesized model, which specified mean level changes in the variables over time and an interrelationship among the latent chronometric common factors. Although a significant relationship existed between maturation and perceived competence, no significant relationship was evident between chronological age and perceived competence. Findings are discussed with particular reference to the utility of latent growth curve models for assessing developmental processes at both the inter- and intraindividual level.     

Age Differences in Children's Ability to Model Motor Behavior

Abstract

In order to investigate the effects of modeling behavior for seven- and nine-year-old children, 30 seven-year-old and 30 nine-year-old females were randomly assigned within age level to three groups. These groups differed according to whether a model was presented at the beginning, midway, or not at all during 12 trials on the stabilometer. Both age groups were found to be similar in performance in the no model condition and, for both age groups, the beginning model condition was found to facilitate performance. However, the introduction of the model after six trials had a detrimental effect on the performance of younger children but facilitated older children's performance. These findings were interpreted in light of a likely increase in the processing capacity of nine year olds as well as an increase in the number of movement schemes that were previously stored in the older girls.     

Psychological and Organizational Factors Related to Burnout in Athletic Trainers

Abstract

This study investigated the relationship of five selected psychological and organizational variables to burnout in athletic trainers. Trainers (n = 332) from the Western United States completed self-report measures of burnout, role conflict, role ambiguity, locus of control and demographic variables. Regression, and follow-up canonical correlation analyses, indicated that role conflict, role ambiguity, locus of control, number of hours in direct contact with the athletes, and number of athletes in the athletic trainer's direct care were significantly related to total burnout, frequency and intensity of burnout, emotional exhaustion, depersonalization and personal accomplishment subscales. Role conflict explained the most variance on all burnout scores except personal accomplishment, which was best explained by role ambiguity. Overall, however, absolute levels of burnout were found to be low. Theoretical implications of this study include identifying variables which could be included in other studies. Practical implications include how to reduce role conflict and role ambiguity, and increase control over decision making.     

Errors in the estimation of hydration status from changes in body mass

Abstract

Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance.     

Determination of the swing technique characteristics and performance outcome relationship in golf driving for low handicap female golfers

Abstract

Previous studies on the kinematics of the golf swing have mainly focused on group analysis of male golfers of a wide ability range. In the present study, we investigated gross body kinematics using a novel method of analysis for golf research for a group of low handicap female golfers to provide an understanding of their swing mechanics in relation to performance. Data were collected for the drive swings of 16 golfers using a 12-camera three-dimensional motion capture system and a stereoscopic launch monitor. Analysis of covariance identified three covariates (increased pelvis–thorax differential at the top of the backswing, increased pelvis translation during the backswing, and a decrease in absolute backswing time) as determinants of the variance in clubhead speed (adjusted r ² = 0.965, P < 0.05). A significant correlation was found between left-hand grip strength and clubhead speed (r = 0.54, P < 0.05) and between handicap and clubhead speed (r = ?0.612, P < 0.05). Flexibility measures showed some correlation with clubhead speed; both sitting flexibility tests gave positive correlations (clockwise: r = 0.522, P < 0.05; counterclockwise: r = 0.711, P < 0.01). The results suggest that there is no common driver swing technique for optimal performance in low handicap female golfers, and therefore consideration should be given to individual swing characteristics in future studies.     

An Analysis of Playground Surface Injuries

Abstract

The purpose of this study was to examine the development of skill competence and tactical sophistication during a games unit conducted following the features of sport education provided by Siedentop (1994). One team of six players was followed through a 30-lesson season of “Ultimate.” Using Gréhaigne, Godbout, and Bouthier's (1997) formula for an efficiency index, together with a number of other measures of skill and tactical competence, it was determined that these students made significant improvements in selection and execution dimensions of the game. Furthermore, lower skilled students did not feel marginalized within their teams and believed they had equal opportunities for improvement. The key reasons for developing competence in this setting were the sufficient length of the season to allow for significant practice opportunities and the consistent team membership throughout season, which allowed all players to develop a sense of usefulness. This curriculum model provides one way students can develop skills through a system of game playing, provided sport education units are structured to prevent the more skillful players from dominating the games.     

A heuristic hierarchical scheme for academic search and retrieval

We present PubSearch, a hybrid heuristic scheme for re-ranking academic papers retrieved from standard digital libraries such as the ACM Portal. The scheme is based on the hierarchical combination of a custom implementation of the term frequency heuristic, a time-depreciated citation score and a graph-theoretic computed score that relates the paper’s index terms with each other. We designed and developed a meta-search engine that submits user queries to standard digital repositories of academic publications and re-ranks the repository results using the hierarchical heuristic scheme. We evaluate our proposed re-ranking scheme via user feedback against the results of ACM Portal on a total of 58 different user queries specified from 15 different users. The results show that our proposed scheme significantly outperforms ACM Portal in terms of retrieval precision as measured by most common metrics in Information Retrieval including Normalized Discounted Cumulative Gain (NDCG), Expected Reciprocal Rank (ERR) as well as a newly introduced lexicographic rule (LEX) of ranking search results. In particular, PubSearch outperforms ACM Portal by more than 77% in terms of ERR, by more than 11% in terms of NDCG, and by more than 907.5% in terms of LEX. We also re-rank the top-10 results of a subset of the original 58 user queries produced by Google Scholar, Microsoft Academic Search, and ArnetMiner; the results show that PubSearch compares very well against these search engines as well. The proposed scheme can be easily plugged in any existing search engine for retrieval of academic publications.     

多媒体技术在检体诊断教学中的应用

我国社会医疗水平的不断提高也对医学教学提出了更高的要求。多媒体教学是现代信息技术发展到一定阶段在医学教学界的重要应用。多媒体辅助教学作为现代信息技术的产物,也逐渐开始应用于医学检体诊断的教学工作中。本文结合笔者多年的检体诊断多媒体教学经验,对多媒体技术在检体诊断教学中的应用进行了相关探讨。只有始终坚持以教师为主导,以多媒体为辅助工具,密切联合教学实际,合理利用多媒体资源,同时注重加强多媒体环境下师生互动,才能使检体诊断教学工作达到最佳效果。     

高可用性企业网络的改造设计与实施

本文讨论了对企业网络进行高可用性改造设计。随着网络中各种应用的不断增加,企业对网络的可靠性、容错性、高可用性等的要求也不断增加,通过增加网络设备、链路及使用多生成树技术(MSTP)、虚拟路由(VRRP)、路由开销cost管理技术可实现网络链路冗余和设备冗余改造设计,实现网络高可用性的要求。