Contribution of limbs’ actions to the four competitive swimming strokes: a nonlinear approach

The aim of our study was to assess the effect of the limbs’ actions on the nonlinear properties of the four competitive swimming strokes. Forty-nine swimmers performed all-out sprints at front-crawl, backstroke, breaststroke and butterfly, each one at full stroke (FS), only the arms’ stroke (AS), and only leg kicking (LK), in a total of 12 bouts, 6 per day. A speedo-meter cable was attached to the swimmer’s hip, to collect the speed-time raw data (f = 50Hz). Velocity, speed fluctuation, sample entropy and fractal dimension were derived from the speed-time series. Significant and moderate-strong effects were noted for both stroke and condition in all variables in the study (p ≤ 0.001; 0,560<η² < 0,952). The four competitive strokes and their three conditions exhibited nonlinear properties. The swimming pattern was less complex and more predictable for LK in comparison to AS and FS. Breaststroke and butterfly have more complex but more predictable patterns than backstroke and front-crawl.     

我国沿海地区水产技术推广效率时空演变研究——基于面板三阶段DEA模型的分析

本文基于2006-2016年我国沿海地区水产技术推广的面板数据,运用三阶段DEA模型对沿海11省市剔除环境因素和随机误差项前后的水产技术推广效率进行测度与分析。分析结果表明,沿海地区水产技术推广效率受环境因素影响较大,水产技术推广网站数量、渔民手机数量、渔民人均纯收入和养殖受灾面积对水产技术推广机构、推广人员、推广经费和推广资料影响显著;在剔除环境因素和随机误差项后,大部分地区水产技术推广综合技术效率和规模效率呈现下降,各地普遍处于规模报酬递增状态,规模扩张是技术推广效率提升的关键;2006-2016年,沿海各地区水产技术推广效率变化显著,沿海“渔业大省”水产技术推广效率水平明显优于其他省市。各地区应结合渔业发展现实,挖掘资源优势,加大技术推广投入力度,提高各地区水产技术推广效率。     

帕森斯的“结构——功能主义”之探析

帕森斯是现代结构功能主义学派的创始人,一生致力于构建一个包罗万象的、宏大社会学体系。帕森斯的研究取得了重大成果,但也遭到了许多批评。但是,即使是批评者也不得不承认,帕森斯的理论是现代社会学的主要参照点。帕森斯的＂结构—功能主义＂主要理论思想——社会系统理论、结构功能模型、社会变迁思想与＂分化＂理论、两分法理论与模式变量理论。     

言外语境与高职学生外语交际能力的培养研究

语境补缺假说和语境适应论等国内外最新理论为我国高职外语教学改革提供了理论依据,语境对比研究的最新成果支持真实自然的社会文化语境对语言交际能力的正面影响。创建多元化的外语交际教学语境,将语境信息顺应到交际互动教学环节,培养学生的语境认知和语境运用能力,提高真实场景中运用语境理论进行交际沟通的能力,是培养社会急需的高级应用性外语人才的有效途径。     

浅析荷恩等级理论的局限性

作为新格莱斯会话含义理论的重要推理契机和出发点,荷恩等级的建立有一定的科学性和规律性。然而困脱离语境,忽视认知结构和诸多社会变量的影响,荷恩等级理论在语言使用中有其局限性。本文拟对列文森所提出来的荷恩等级关系作一些理论上的探讨,指出荷恩等级理论的一些不足之处。     

Home advantage in Greek football

Abstract

Home advantage as it relates to team performance at football was examined in Superleague Greece using nine seasons of game-by-game performance data, a total of 2160 matches. After adjusting for team ability and annual fluctuations in home advantage, there were significant differences between teams. Previous findings regarding the role of territorial protection were strengthened by the fact that home advantage was above average for the team from Xanthi (P =0.015), while lower for teams from the capital city Athens (P =0.008). There were differences between home and away teams in the incidence of most of the 13 within-game match variables, but associated effect sizes were only moderate. In contrast, outcome ratios derived from these variables, and measuring shot success, had negligible effect sizes. This supported a previous finding that home and away teams differed in the incidence of on-the-ball behaviours, but not in their outcomes. By far the most important predictor of home advantage, as measured by goal difference, was the difference between home and away teams in terms of kicked shots from inside the penalty area. Other types of shots had little effect on the final score. The absence of a running track between spectators and the playing field was also a significant predictor of goal difference, worth an average of 0.102 goals per game to the home team. Travel distance did not affect home advantage.     

Effects of starting score-line,game location,and quality of opposition in basketball quarter score

Abstract

In several team sports, the game starting score-line may be understood as a measure of performance accomplishment and hence might have an effect on players' subsequent efforts. The aim of this study was to identify the effect of the starting score-line, game location, and quality of opposition on basketball game quarter final score. The sample comprised 504 game quarters from the Spanish Basketball Professional League and these were classified as balanced (difference in scores equal of 8 points or less, n=194) and unbalanced (difference in scores of more than 8 points, n=310) using k-means cluster procedures. The effects of the predictor variables on game quarter outcome (difference between points scored and points received) in the whole game and in the second, third, and fourth game quarters were analysed using linear regression analysis. The starting game quarter score-line was only significant in unbalanced situations with very similar effects among different game quarters. The greater the difference in accumulated score at the beginning of each quarter, the more points recovered by the teams who were losing. A small effect from the quality of the opponent was found in the second and third quarters, whereas game location only had an effect when analysing the whole game and second quarter using balanced and unbalanced game quarters combined.     

Differential Effects of Three Teachers Over a Unit of Instruction

The purpose of this study was to describe the effects of three teachers on psychomotor, affective, and cognitive outcomes over a 15-lesson volleyball unit. Three intact middle school physical education classes were used. Pre- and posttests were administered for the overhead set, forearm pass, and serve psychomotor skills. A semantic differential test with four affective dimensions and a written test on the rules, strategies, and mechanics of volleyball were also administered pre- and posttest. Data on instructional characteristics were obtained using academic learning time (ALT-PE); observation system for content development (OSCD-PE), and a content analysis of lessons.

The following were key aspects of the results: (a) Teachers differed in their approaches to the content of the unit more than in the characteristics of their instruction as determined through observational data; (b) teachers differed in respect to the psychomotor skills for which they were able to produce statistically significant student gain; (c) the skill level of students played a major role in psychomotor outcomes; (d) affective measures started high and remained high from pre- to posttest with significant change occurring positively with the low-skilled in one measure; (d) cognitive learning was significant from pre- to posttest in rules and mechanics but not in strategies. Instructional characteristics, as described in this study, did not change from skill to skill, but student learning did. This led the authors to conclude that the instrumentation for instructional variables was not sensitive to differences in the way individual skills were handled by individual teachers.     

Improved sentence retrieval using local context and sentence length

In this paper we propose improved variants of the sentence retrieval method TF–ISF (a TF–IDF or Term Frequency–Inverse Document Frequency variant for sentence retrieval). The improvement is achieved by using context consisting of neighboring sentences and at the same time promoting the retrieval of longer sentences. We thoroughly compare new modified TF–ISF methods to the TF–ISF baseline, to an earlier attempt to include context into TF–ISF named tfmix and to a language modeling based method that uses context and promoting retrieval of long sentences named 3MMPDS. Experimental results show that the TF–ISF method can be improved using local context. Results also show that the TF–ISF method can be improved by promoting the retrieval of longer sentences. Finally we show that the best results are achieved when combining both modifications. All new methods (TF–ISF variants) also show statistically significant better results than the other tested methods.     

A review on the basketball jump shot

The ability to shoot an effective jump shot in the sport of basketball is critical to a player's success. In an attempt to better understand the aspects related to expert performance, researchers have investigated successful free throws and jump shots of various basketball players and identified movement variables that contribute to their success. The purpose of this study was to complete a systematic review of the scientific literature on the basketball free throw and jump shot for the purpose of revealing the critical components of shooting that coaches, teachers, and players should focus on when teaching, learning, practising, and performing a jump shot. The results of this review are presented in three sections: (a) variables that affect ball trajectory, (b) phases of the jump shot, and (c) additional variables that influence shooting.