Quantification of the manifestations of fatigue during treadmill running

Abstract

During whole-body exercise, fatigue is difficult to quantify; however, changes to mechanical, physiological and psychological systems during exercise are associated with the development of fatigue. To quantify fatigue, one must therefore assess changes occurring in these variables. The purpose of this study was to demonstrate a method to assign weightings to selected variables and to combine them into a single value quantifying changes occurring during exercise. Twelve female recreational runners performed one hour of treadmill running, during which heart rate, respiration rate, stride frequency and six selected psychological variables were collected at defined intervals throughout the run. Data were normalised and a principle component analysis was performed. The resulting first eigenvector was termed the “contribution vector” and indicated the weighting of each variable towards the global exercise-induced changes in the body. The projection of data onto the contribution vector resulted in a value described as the “fatigue index”. An assessment of the generalisation of the method to new data was performed using a leave-one-out cross-validation procedure and indicated that the index is accurate to within 3.01% of the maximum index value measured. The method developed here has the advantage over current methods due to its multifactorial, causal and customisable nature.     

基于PCA的安徽省上市公司经营业绩分析

现有文献对上市公司的经营业绩评价主要强调财务指标,而较少涉及反映企业成长特征的非财务指标。本文在重视财务指标的基础上,强调影响企业长期经营业绩的非财务指标的作用,利用2010年安徽省60家上市公司的经营数据进行了实证分析,得出的结论为:安徽省上市公司的盈利能力整体不高,还有较大的上升空间;从企业生长周期来看,安徽省的上市公司仍处于成长阶段,但资产管理能力较好。     

美国、澳大利亚、瑞典中小学校长资格制度比较研究

美国、澳大利亚和瑞典三个国家的中小学校长资格制度在资格标准、资格认定、资格证书方面既存在共同因素,又各具特色。总结其经验和特点,主要表现在:校长资格标准、资格认定和资格证书制度构成校长资格制度的基本框架;中小学校长"教学领导者"角色得以凸显;校长专业素质养成和评价得以重视;校长专业组织的作用得以充分发挥。对三个国家中小学校长资格制度的比较和分析将为完善我国中小学校长资格制度提供有益借鉴。     

合作原则在中西文化中的映射

格赖斯提出的合作原则作为一种会话准则 ,在一定程度上具有普遍性。然而 ,人们对此原则的阐释和运用在很大程度上依赖不同的文化背景 ,即不同的社会和文化可能具有其独特的会话交往规则。这篇文章试图从东西方文化在运用合作原则时存在的差异这一角度出发 ,探讨东西方文化的不同点 ,从而尽量避免在跨文化交际中出现的交际失误     

2007年度旅游上市公司投资价值分析

选取我国21家旅游上市公司作为样本,运用SPSS工具对这21家公司2007年度的34个财务指标进行主成分分析,得出六个主成分,分别命名为获利能力因子、投资回报能力因子、经营获现能力因子、营运能力因子、资本结构因子及规模扩张因子,这些因子的综合运用可以较全面地反映旅游上市公司的投资价值．同时运用主成分综合评价函数对旅游上市公司的投资价值进行排序．     

25年生马尾松种源遗传变异及选择研究

对福建省大田桃源林场引种的25年生的马尾松种源试验林进行了调查分析,结果表明：各种源间生长分化明显。8年、10年生的种源排名结果与25年后有很大变化;秩次相关不显著;两广种源在中幼期生长较快,而闽西种源在后期生长良好,25年生时已经赶超两广种源。根据主成分分析和聚类分析,将参试种源分成优、良、中、差4大类,生长最好的福建武平种源25年生时,平均胸径为29.25cm（年均1.17cm）,平均树高为19.44m,平均材积0.5631m^3,为别是对照（福建大田）的1.56、1.08和2.41倍,是最差种源湖南慈利的2.22、1.60和6.72倍。列在第一名的福建武平种源材积是第二名的广东信宜种源的1.14倍,增产的效果明显。     

地方政府经济行为变异问题研究

改革开放三十多年来,中国地方政府对于地方经济发展、制度创新与变革、实现宏观调控目标等做出了重要贡献,但由于中央对地方相对"软化"的制度约束环境以及自身独立的经济主体等多种因素,地方政府经济行为存在偏差,出现了违背追求全社会公共福利的行为变异。运用委托代理理论可从地方政府面临多任务委托合同、绩效评价标准缺乏参照、固定任期制导致短期行为严重以及地方政府间"准联邦式"竞争关系四方面分析行为变异的原因。     

基于主成分分析的人耳识别系统研究

针对人耳识别技术的研究现状,采用主成分分析提取人耳图像特征,在此基础上建立一个人耳识别系统。实验结果验证了利用主成分分析提取人耳图像特征的可行性与高效性,为解决该类问题提供了一个有效的新途径。     

The association between principal leadership and student achievement: A multivariate meta-meta-analysis

A multivariate random-effects meta-meta-analysis was conducted to synthesize the association between principal leadership and student achievement. A total of 12 prior meta-analyses with 18 effect sizes were included in this meta-meta-analysis. The quantitative analysis showed that principal leadership has a statistically significant positive relationship with student achievement (Cohen's d = 0.34). The qualitative analyses revealed that: (a) with the accumulation of knowledge, there appears to have been a trend toward more consistent and precise estimates of principal leadership's effect on student achievement; (b) there was still not enough evidence to argue a specific leadership model or practice is more effective in improving student achievement than others; and (c) the educational contexts seem to moderate the effect of principal leadership. The significance and limitations of the current study, as well as the recommendations for future research, are discussed.