Comparison of support leg kinetics between side-step and cross-step cutting techniques

The purpose of this study was to investigate differences in the support leg joint moment and moment power between side-step (SS) and cross-step (CS) cutting techniques with a prescribed 90° cutting angle. Ground reaction forces (1,000 Hz) and three-dimensional kinematics (250 Hz) of SS and CS cutting techniques were collected from 20 male college athletes. Normalised peak knee extension moment was larger in the SS technique than in the CS technique (0.40 ± 0.10 in SS; 0.26 ± 0.08 in CS). In the SS technique, the knee extensors ( ? 0.10 ± 0.06 in SS; ? 0.02 ± 0.04 in CS) and ankle plantarflexors ( ? 0.12 ± 0.05 in SS; ? 0.07 ± 0.03 in CS) did significantly more negative work (normalised). The direction change angle (40.5 ± 8.7° in SS; 33.0 ± 6.8° in CS) and the decrease in horizontal velocity of the centre of mass ( ? 0.63 ± 0.23 m/s in SS; ? 0.31 ± 0.23 m/s in CS) were significantly larger in the SS technique. These results suggest that the SS technique is an effective means of changing running direction at the expense of velocity of the centre of mass and that the CS technique is better for minimising the reduction in horizontal velocity of the centre of mass.     

Anticipatory postural adjustments during cutting manoeuvres in football and their consequences for knee injury risk

Abstract

Anticipatory postural adjustments (APAs), i.e. preparatory positioning of the head, the trunk and the foot, are essential to initiate cutting manoeuvres during football games. The aim of the present study was to determine how APA strategies during cutting manoeuvres are influenced by a reduction of the time available to prepare the movement.

Thirteen football players performed different cutting tasks, with directions of cutting either known prior to the task or indicated by a light signal occurring 850, 600 or 500 ms before ground contact.

With less time available to prepare the cutting manoeuvre, the head was less orientated towards the cutting direction (P = 0.033) and the trunk was even more rotated in the opposite direction (P = 0.002), while the foot placement was not significantly influenced. Moreover, the induced higher lateral trunk flexion correlated with the increased knee abduction moment (r = 0.41; P = 0.009).

Increasing lateral trunk flexion is the main strategy used to successfully perform a cutting manoeuvre when less time is available to prepare the movement. However, higher lateral trunk flexion was associated with an increased knee abduction moment and therefore an increased knee injury risk. Reducing lateral trunk flexion during cutting manoeuvres should be part of training programs seeking the optimisation of APAs.     

高职思想政治理论课程课堂实践教学对策研究

从高职院校思想政治理论课程课堂实践教学的内涵、存在的问题出发,着重阐述高职院校思想政治理论课程课堂实践教学的研究对策。     

浅析现代足球运动中抢断球技术的运用

以我国甲A球队上海申花队和17届世界杯中的部分比赛为研究对象，采用录象观察法和理论分析法，对当今民办足球比赛中抢断球技术的运用进行分析研究，结果表明：抢断的成功率，主要取决于场上的队员能否把握住抢断的时机。     

奥林匹克运动实践中的危机倾向

现代奥林匹克运动在取得巨大成就的同时，也面临许多难以解决的问题，潜伏着严重的危机，主要是：政治干扰，民族问题，由于职业选手参赛而引发的信仰危机和参赛条件的不平等，商业化与奥林匹克理想的矛盾，商业化加大地区间体育发展的差距及其对奥运会正常赛事的干预。     

基于边信息抗仿射变换的数字图像水印算法

设计抗几何攻击的图像水印算法是数字水印技术研究中的难点。仿射变换是典型的几何攻击，能够使目前大多数数字水印算法失效。基于带边信息的水印模型，本文提出了一种利用Zernike矩的抗仿射变换多比特图像水印算法。该算法将归一化图像的Zernike矩作为边信息，利用量化技术对的水印信息进行编码和嵌入。实验证明，本文提出的算法不仅具有很好的抗仿射变换和抗JPEG压缩的鲁棒性，而且具有较小的嵌入失真和较大的水印容量。     

矩形管柱和H形钢梁端板连接分析

高频焊接矩形管生产效率高,抗扭性能好,平面外刚度大,根据需要内部可充填混凝土以提高抵抗局部屈曲的能力,比焊接H型钢的轻钢厂房有更好的经济性。为提高梁柱连接节点的承载力、减小节点变形,需在节点区外包槽钢。本文分析了节点区不同厚度、不同形式外包槽钢和不同的柱内加劲肋设置等对节点强度和刚度的影响,得出了满足刚性连接要求的节点区外包槽钢厚度计算公式。研究了柱加劲肋、螺栓排列、螺栓数目、槽钢宽度和槽钢下伸长度等的影响。建议了箱形柱柱顶与梁上翼缘齐平,槽钢与梁端板等厚,槽钢向上伸出长度以满足安装一排高强螺栓的要求,并设置三角形加劲肋与柱顶盖板和槽钢焊接,箱形柱顶和槽钢内面满焊的节点形式。分析表明这种节点有很高的刚度和强度,能满足刚性连接的要求。     

巴斯卡分布NB(r,p)中参数r的估计

巴斯卡分布NB（r,p)是重要的离散型分布之一，当r已知时，巴斯卡分布NB（r,p)中未知参数p(p∈（0，1））的估计是众所周知的。本文分别在p已知和未知的条件下，研究了参数r(r∈（1，2，…}）的估计，并得到了它们的渐近性质。     

政治哲学视角下中国特色社会主义体育自信的理论研究

运用文献资料、逻辑分析等方法在政治哲学视角下对中国特色社会主义体育自信的概念、我国体育存在的不自信现象进行分析,并提出中国特色社会主义体育自信的意义,旨在建设我国特色社会主义体育自信并为我国政治服务,促进我国体育的良性发展。研究认为：我国体育改革取得了巨大的成绩,但是却存在着严重的体育不自信现象,这个问题制约着我国体育的发展,应该引起我们的重视。并提出建立我国特色社会主义体育自信的意义：有利于坚定体育改革的信心;有利于凝聚力量建设体育事业;有利于弘扬体育精神和构建体育文化;有利于矫正崇洋心理等。     

加强大学生政治参与的思考

培养大学生理性政治参与意识,端正大学生政治参与动机,提高大学生政治参与能力,破解大学生政治参与难题,实现大学生的有序、理性的政治参与对于增强大学生的政治责任感、归属感,加快我国政治发展、推动社会全面进步具有重要的意义。