错误动作矫正对网球教学的正向刺激研究

根据网球教学中大学生错误动作高发的现象,研究认为,教师可以根据日常教学总结与归纳错误动作,在进行基本的分类基础上,融入教法、转化为教学内容,对教学自身和大学生的学习兴趣激发具有积极作用。     

论陀螺运动的历史演变及其发展现状

陀螺运动最初只是一项古老的中国民间体育娱乐活动,人们参加此项运动的目的主要是锻练身体,将其作为生活、娱乐的一种消遣方式。随着时代的发展,陀螺的制造工艺和运动技术得到了改善和发展,陀螺运动也经历了一次次的历史演变。因其功能和价值的增加,该项运动已得到国家和地方政府的重视,并已进行大力推广。在此采用文献资料法、实地考察法、访谈法和综合分析法等研究方法对陀螺运动的历史演变、发展现状做一回顾和阐述。     

莆田湄洲里社妈祖宫庙调查

对湄洲岛14座里社妈祖宫庙进行了较全面的田野调查,记录相关资料和数据,并从中归纳出宫庙和妈祖信仰呈现出的特色,最后提出一些相关建议。     

The Effects of Grade Level,Type of Motion,Cueing Strategy,Pictorial Complexity,and Color on Children's Interpretation of Implied Motion in Pictures

The ability of kindergarten and 3rd-grade children to accurately interpret implied motion in pictures was examined. Sixty-four children responded to pictures from experimental conditions that varied type of motion, cueing strategy, pictorial complexity, and color. The 3rd-grade children were more adept at identifying implied motion than the kindergarten children, the postural motion condition was more effective than the flow-line condition in conveying motion, and cues and relevant pictorial background information increased accuracy of interpretation.     

Does film criticism affect box office earnings? Evidence from movies released in the U.S. in 2003

In a market characterized by a very large number of consumers, irregularly and infrequently choosing from a constantly changing menu of possibilities, widely available impartial information and advice would be expected to make a significant impact on demand. In the U.S. in 2003, however, there was zero correlation between critical ratings for films and gross box office earnings. For movies released on more than 1,000 screens, critical ratings were indeed positively related to gross earnings, and, together with production budgets and the number of opening screens, explained more than half the variance. But films with only limited opening release received higher average ratings. This is especially the case for foreign movies and documentaries but also true for American films, whose ratings, though positively related to the box office, seldom have enough influence to propel a movie into later wide exhibition or high earnings.

Muscle coordination,activation and kinematics of world-class and elite breaststroke swimmers during submaximal and maximal efforts

The aims of this study were to describe muscular activation patterns and kinematic variables during the complete stroke cycle (SC) and the different phases of breaststroke swimming at submaximal and maximal efforts. Surface electromyography (sEMG) was collected from eight muscles in nine elite swimmers; five females (age 20.3 ± 5.4 years; Fédération Internationale de Natation [FINA] points 815 ± 160) and four males (27.7 ± 7.1 years; FINA points 879 ± 151). Underwater cameras were used for 3D kinematic analysis with automatic motion tracking. The participants swam 25 m of breaststroke at 60%, 80% and 100% effort and each SC was divided into three phases: knee extension, knee extended and knee flexion. With increasing effort, the swimmers decreased their SC distance and increased their velocity and stroke rate. A decrease during the different phases was found for duration during knee extended and knee flexion, distance during knee extended and knee angle at the beginning of knee extension with increasing effort. Velocity increased for all phases. The mean activation pattern remained similar across the different effort levels, but the muscles showed longer activation periods relative to the SC and increased integrated sEMG (except trapezius) with increasing effort. The muscle activation patterns, muscular participation and kinematics assessed in this study with elite breaststroke swimmers contribute to a better understanding of the stroke and what occurs at different effort levels. This could be used as a reference for optimising breaststroke training to improve performance.     

The relevance of body positioning and its training effect on badminton smash

One of the dominant skills in badminton is the forehand overhead smash, which consists of 1/5 attacks during games. Empirical evidences show that one has to adjust the body position in relation to the coming shuttlecock to produce a powerful and accurate smash. Therefore, positioning is a fundamental aspect influencing smash quality. Unfortunately, a search of literature has shown that there is a dearth/lack of study on this fundamental aspect. The goals of this study were to determine the influence of positioning and training experience on smash quality in order to discover information that could help learn/acquire the skill. Using 3D motion capture and full-body biomechanical modelling, 14 skilled and 15 novice players were analysed. Results have revealed that the body positioning has direct influence on shuttlecock release angle and clearance height of the offensive player. The results also suggest that, for training the positioning of beginners, one could conduct a self-selected comfort position towards a statically hanged shuttlecock and then step one foot back – a practical reference marker for learning. As one gains experience through repetitive training, improved limbs’ coordination would increase smash quality further. We hope our findings will benefit practitioners for developing effective training programmes for beginners.     

静电除尘器中纳米颗粒运动与荷电特性

通过建立静电除尘器(electrostatic precipitator,ESP)内纳米颗粒沉积及荷电的数值模型,耦合流场、电场、颗粒荷电及颗粒运动等子模型,研究ESP内纳米颗粒的运动与荷电特性.研究发现纳米颗粒在ESP中的受力方向和大小会随着其运动而不断改变,其沉积效率曲线相较于微米级颗粒,呈现出U型的特征,经证明这...     

Joint power generation differentiates young and adult sprinters during the transition from block start into acceleration: a cross-sectional study

The aim of this study was to investigate differences in joint power generation between well-trained adult athletes and young sprinters from block clearance to initial contact of second stance. Eleven under 16 (U16) and 18 under 18 (U18) promising sprinters executed an explosive start action. Fourteen well-trained adult sprinters completed the exact same protocol. All athletes were equipped with 74 spherical reflective markers, while an opto-electronic motion analysis system consisting of 12 infrared cameras (250 Hz, MX3, Vicon, Oxford Metrics, UK) and 2 Kistler force plates (1,000 Hz) was used to collect the three-dimensional marker trajectories and ground reaction forces (Nexus, Vicon). Three-dimensional kinematics, kinetics, and power were calculated (Opensim) and time normalised from the first action after gunshot until initial contact of second stance after block clearance. This study showed that adult athletes rely on higher knee power generation during the first stance to induce longer step length and therefore higher velocity. In younger athletes, power generation of hip was more dominant.     

Biomechanical differences between left- and right-handed baseball pitchers

Left-handed baseball pitchers are thought to have a number of theoretical advantages compared to right-handed pitchers; however, there is limited scientific research detailing differences in the pitching mechanics of right- and left-handed pitchers. Therefore, this study sought to understand whether any kinematic and kinetic differences existed between right- and left-handed baseball pitchers. A total of 52 collegiate pitchers were included in this study; 26 left-handed pitchers were compared to 26 age-, height-, weight- and ball velocity-matched right-handed pitchers. Demographic information, passive shoulder range of motion and kinematic and kinetic data were obtained for each pitcher participating in the study. Results indicated that left-handed pitchers did not have a glenohumeral internal rotation deficit as compared to right-handed pitchers. Kinematic analysis indicated that elbow flexion, horizontal glenohumeral abduction and wrist coronal plane motion were significantly different between the two study cohorts. It was also noted that left-handed pitchers had increased elbow varus moments. The findings of this study suggest that pitching coaches should be aware that there are biomechanical differences between left- and right-handed pitchers.