Slowed driving-reaction time following concussion-symptom resolution

Background: Concussed patients have impaired reaction time (RT) and cognition following injury that may linger and impair driving performance. Limited research has used direct methods to assess driving-RT post-concussion. Our study compared driving RT during simulated scenarios between concussed and control individuals and examined driving-RT''s relationship with traditional computerized neurocognitive testing (CNT) domains.MethodsWe employed a cross-sectional study among 14 concussed (15.9 ± 9.8 days post-concussion, mean ± SD) individuals and 14 healthy controls matched for age, sex, and driving experience. Participants completed a driving simulator and CNT (CNS Vital Signs) assessment within 48 h of symptom resolution. A driving-RT composite (ms) was derived from 3 simulated driving scenarios: stoplight (green to yellow), evasion (avoiding approaching vehicle), and pedestrian (person running in front of vehicle). The CNT domains included verbal and visual memory; CNT-RT (simple-, complex-, Stroop-RT individually); simple and complex attention; motor, psychomotor, and processing speed; executive function; and cognitive flexibility. Independent t tests and Hedge d effect sizes assessed driving-RT differences between groups, Pearson correlations (r) examined driving RT and CNT domain relationships among cohorts separately, and p values were controlled for false discovery rate via Benjamini-Hochberg procedures (α = 0.05).ResultsConcussed participants demonstrated slower driving-RT composite scores than controls (mean difference = 292.86 ms; 95% confidence interval (95%CI): 70.18–515.54; p = 0.023; d = 0.992). Evasion-RT (p = 0.054; d = 0.806), pedestrian-RT (p = 0.258; d = 0.312), and stoplight-RT (p = 0.292; d = 0.585) outcomes were not statistically significant after false-discovery rate corrections but demonstrated medium to large effect sizes for concussed deficits. Among concussed individuals, driving-RT outcomes did not significantly correlate with CNT domains (r-range: –0.51 to 0.55; p > 0.05). No correlations existed between driving-RT outcomes and CNT domains among control participants either (r-range: –0.52 to 0.72; p > 0.05).ConclusionSlowed driving-RT composite scores and large effect sizes among concussed individuals when asymptomatic signify lingering impairment and raise driving-safety concerns. Driving-RT and CNT-RT measures correlated moderately but not statistically, which indicates that CNT-RT is not an optimal surrogate for driving RT.     

Multidimensional joint coupling: a case study visualisation approach to movement coordination and variability

Abstract

A case study visualisation approach to examining the coordination and variability of multiple interacting segments is presented using a whole-body gymnastic skill as the task example. One elite male gymnast performed 10 trials of 10 longswings whilst three-dimensional locations of joint centres were tracked using a motion analysis system. Segment angles were used to define coupling between the arms and trunk, trunk and thighs and thighs and shanks. Rectified continuous relative phase profiles for each interacting couple for 80 longswings were produced. Graphical representations of coordination couplings are presented that include the traditional single coupling, followed by the relational dynamics of two couplings and finally three couplings simultaneously plotted. This method highlights the power of visualisation of movement dynamics and identifies properties of the global interacting segmental couplings that a more formal analysis may not reveal. Visualisation precedes and informs the appropriate qualitative and quantitative analysis of the dynamics.     

Influence of Adiposity and Maturation on the Motor Performance of Girls Aged 8 to 16 Years

ABSTRACT

Excess adipose tissue may impact the motor performance of youth. Therefore, the current study examined (a) if adiposityinfluenced performance in the jump and reach and 30-yard dash and (b) if maturation predicted motor performance. Participants (N = 267) included girls aged 8 to 16 years. Latent growth curves were used to assess changes in motor performance. Sum of skinfolds predicted jump and reach performance from age 8.5 to 10.5 years, 11.5–12.0 years, 13.0 years, and from age 14 to 14.5 years (b = ?0.013 to 0.051, p < 0.05). Sum of skinfolds predicted 30-yard dash performance from age 8.5 to 14.0 years and at age 15.5 years (b = 0.003 to 0.005, p < 0.05). Maturation did not predict performance. Future research should examine determinants that explain the link between adiposity and motor performance.     

根据球墨铸铁的理化特性 减少其铸件质量缺陷

针对电机的生产过程中经常出现的铸件质量问题,经技术攻关反复试验,探索出解决方法。     

冷却塔风机电机绕组烧毁及控制系统优化

绕组烧毁是电机常见故障。绕组烧毁前的迹象不容易发现,而烧毁后一些导致烧毁的直接原因又被掩盖,给事后分析增加了难度。文章就电机密封、绕组绝缘破坏等几方面进行了分析,同时阐述闭式冷却塔系统优化对于电机及时维修和避免循环水温度带来换热器温度变化。     

运用内部注意焦点促进初学者掌握开放式运动技能学习的研究

对"内部注意焦点是否促进初学者开放式运动技能的学习"及其生物力学基础进行研究。共21名北京体育大学教育学院非专选学生参加本研究。实验结果表明:内部注意焦点更有利于初学者学习开放式运动技能。图像解析数据表明,在技能掌握阶段接受内部注意焦点指导的学生,其保持测试时动作的协调模式与指导教师的更加一致,且不同动作间的协调模式一致性更高,说明内部注意焦点更能加速初学者开放式运动技能的学习。     

龙门刨床工作台电气传动系统的改造

本文阐述了运用西门子6RA70全数字直流调速系统和三菱FX2N-80MR型PLC对龙门刨床工作台电气传动系统进行改造,对6RA70全数字直流调速系统的调试运行作详细介绍。     

Self-controlled learning benefits: exploring contributions of self-efficacy and intrinsic motivation via path analysis

Research has shown learning advantages for self-controlled practice contexts relative to yoked (i.e., experimenter-imposed) contexts; yet, explanations for this phenomenon remain relatively untested. We examined, via path analysis, whether self-efficacy and intrinsic motivation are important constructs for explaining self-controlled learning benefits. The path model was created using theory-based and empirically supported relationships to examine causal links between these psychological constructs and physical performance. We hypothesised that self-efficacy and intrinsic motivation would have greater predictive power for learning under self-controlled compared to yoked conditions. Participants learned double-mini trampoline progressions, and measures of physical performance, self-efficacy and intrinsic motivation were collected over two practice days and a delayed retention day. The self-controlled group (M = 2.04, SD = .98) completed significantly more skill progressions in retention than their yoked counterparts (M = 1.3, SD = .65). The path model displayed adequate fit, and similar significant path coefficients were found for both groups wherein each variable was predominantly predicted by its preceding time point (e.g., self-efficacy time 1 predicts self-efficacy time 2). Interestingly, the model was not moderated by group; thus, failing to support the hypothesis that self-efficacy and intrinsic motivation have greater predictive power for learning under self-controlled relative to yoked conditions.     

Prognostic relevance of motor talent predictors in early adolescence: A group- and individual-based evaluation considering different levels of achievement in youth football

ABSTRACT

In the debate about the usefulness of motor diagnostics in the talent identification process, the prognostic validity for tests conducted in early adolescence is of critical interest. Using a group- and individual-based statistical approach, this prospective cohort study evaluated a nationwide assessment of speed abilities and technical skills regarding its relevance for future achievement levels. The sample consisted of 22,843 U12-players belonging to the top 4% in German football. The U12-results in five tests served as predictors for players’ selection levels in U16-U19 (youth national team, regional association, youth academy, not selected). Group-mean differences proved the prognostic relevance for all predictors. Low individual selection probabilities demonstrated limited predictive values, while excellent test results proved their particular prognostic relevance. Players scoring percentile ranks (PRs) ≥ 99 had a 12 times higher chance to become youth national team players than players scoring PR < 99. Simulating increasing score cut-off values not only enhanced specificity (correctly identified non-talents) but also led to lower sensitivity (loss of talents). Extending the current research, these different approaches revealed the ambiguity of the diagnostics’ prognostic relevance, representing both the usefulness and several pitfalls of nationwide diagnostics. Therefore, the present diagnostics can support but not substitute for coaches’ subjective decisions for talent identification, and multidisciplinary designs are required.     

基于虚拟仪器的电机转速检测系统

基于美国NI公司的LabVIEW图形化编程语言,针对电机参数的检测进行虚拟仪器编程设计,开发出电动机转速和机电时间常数的在线测试系统.该系统分为人机界面,功能模块和外部电路三部分,改进了传统仪器在显示、储存、读取方面的限制.