The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.     

Influences on Student Cognitions About Evaluation

Interviews on two occasions with 71 Grade 2, 4 and 6 students in a multi-ethnic setting in Toronto, Canada, found that student cognitions about evaluation mediated the relationship between evaluation and achievement. Parents, peers and student characteristics influenced student cognitions about evaluation. Parents identified the evaluation dimensions their children should attend to, raised student aspirations, stated how well student work attained standards and recommended actions children should take in response to the evaluation. Peer interpretations influenced whether a given performance was viewed as superior or inferior. Older student peers focused attention, to a greater extent than parents, on specific aspects of student performance that could be ameliorated through self-remediation. Children became more sophisticated evaluation consumers as they grew older. Females processed evaluation data more productively than males. There were few cultural differences in response to evaluation. Students responded to traditional and alternate evaluation in very similar ways.     

技术支持的"非正规学习"研究新进展

对大部分人来说,当我们讨论学习时,我们会不可避免地将其与正规的教育系统联系起来。但任何关于ICTs在儿童学习中角色的研究都使我们认识到,在校外情景中,儿童非常容易沉浸于ICTs相关的活动中,这就迫使我们必须用更广阔的视角来审视包括学校、家庭、休闲、图书馆、博物馆等在内的"教育生态学"。本综述首先对"非正规学习"进行了界定,指发生在学校环境之外,数字技术支持或与数字技术交互的非正规学习;接着讨论了本研究所依据的学习的核心理论以及在ICTs支持的关于学习的研究中不断产生的新的学习理论;勾勒出儿童在校外获取和使用数字技术的情景;然后基于已有的关于技术支持的非正规学习的案例,总结提炼出技术支持的非正规学习的关键特征;最后对这些研究的理论和政策含义进行了深入的研究和剖析。     

Do allegations of emotional maltreatment predict developmental outcomes beyond that of other forms of maltreatment?

OBJECTIVES: To understand the features of child abuse/neglect (CA/N) allegations in cases with emotional maltreatment (EMT) allegations, as well as the features of the EMT allegations themselves, and to describe any associations of EMT with distinct impairments of children's behavior, emotion and functioning. METHOD: The sample consisted of 806 high-risk children, 545 with one or more maltreatment reports to CPS. The Maltreatment Classification System was used to record the number and severity levels of maltreatment allegations, which compared cases with and without EMT. Multiple regression analyses were conducted using 10 outcome scales from the Child Behavior Checklist, Vineland Screener, and Trauma Symptom Checklist. Successive blocks of predictor variables included demographics, maltreatment classification variables, maternal and family characteristics, and study site. RESULTS: When there were allegations of EMT as well as CA/N in a CPS case-record (by age 8), the CA/N allegations tended to be either more frequent or less severe than those kinds of allegations in cases without EMT. When neglect was alleged to occur with EMT, neglect allegations outnumbered allegations of EMT. However, when sexual abuse allegations were accompanied by EMT allegations, there were more EMT allegations than sexual abuse allegations in the cases. Higher severity ratings for EMT allegations than for physical abuse occurred when cases included any abuse. Distinctive effects of EMT subtypes were found between problems of safety/restriction and self-reported anger symptoms, and between problems of self-esteem/autonomy and posttraumatic stress. CONCLUSION: Differences exist between the CA/N allegations in cases with and without EMT. Having few cases containing only EMT allegations made it difficult to assess distinctive harm associated with EMT. Certain types of EMT allegations were associated with increases in children's anger and posttraumatic stress.