乒乓球运动员膝关节损伤机制研究——对3种常用步法的膝关节负荷特征分析     

周星栋  肖丹丹  郭文霞  黄习梅  张晓栋 《中国体育科技》2020,(6):62-67

目的:了解不同性别乒乓球运动员完成并步、跳步、跨步3种常用步法时膝关节的负荷特征,并探析乒乓球运动员膝关节的损伤机制。方法:对乒乓球男、女各10名运动员完成3种常用步法动作时的下肢运动学、动力学数据进行采集和处理,并运用方差分析法比较不同性别、不同技术之间的差异。结果:受试者在完成3种步法过程中,膝关节屈角大致范围在20°~60°。当地面反作用力最大时,女运动员比男运动员表现出更小的外展角(P<0.05),跳步比并步和跨步表现出更小的外展角(P<0.05);在三维受力方面,膝关节受到垂直方向上的力最大,水平向后和向左的力次之,未表现出显著的性别差异和技术差异;在三维力矩方面,膝关节受到的伸膝力矩较大,也未表现出显著的性别差异和技术差异。结论:膝关节屈曲状态下,较大的地面反作用力和膝关节外展角易导致乒乓球运动员前交叉韧带损伤,女运动员的损伤风险小于男运动员,跳步的损伤风险小于并步和跨步;水平向后和向左的力易造成乒乓球运动员软骨和半月板损伤;过大的伸膝力矩易导致乒乓球运动员髌腱末端病和髌骨软化。  相似文献   

中小学体育教师工作特征与工作倦怠的关系:自我决定和工作旺盛感的链式中介     

王文增  刘晓明 《沈阳体育学院学报》2020,(1):29-38

目的:探讨中小学体育教师工作特征、自我决定、工作旺盛感和工作倦怠的关系。方法:采用工作特征问卷、自我决定问卷、工作旺盛感问卷和工作倦怠量表对305名中小学体育教师进行测量。结果:1)工作特征、自我决定、工作旺盛感、工作倦怠彼此间显著相关。2)链式中介效应分析表明,自我决定和工作旺盛感在工作要求和工作倦怠间起链式中介作用,其效应值为0.13,效应量为40.63%。自我决定和工作旺盛感在工作资源和工作倦怠间起链式中介作用,其效应值为-0.20,效应量为54.05%。结论:中小学体育教师的工作特征通过自我决定和工作旺盛感的链式中介效应间接影响其工作倦怠。  相似文献   

新中国成立70年来体育教育专业人才培养的演变与特征分析     

周红萍  吕万刚 《武汉体育学院学报》2020,54(8):65-71

研究新中国成立70年来体育教育专业人才培养特征与演变规律，是呈现体育教育专业发展历史的需要，是推动体育教育专业发展和改革的一项基础性工程。采用文献资料法、历史法、专家访谈法和逻辑分析法，对体育教育专业发展规模、专业定位、培养方案、课程设置、教学模式等方面开展研究，结果表明：新中国成立70年来，体育教育专业经历了学习与移植、探索与挫折、混乱与恢复、开放与改革、提速与跨越、实践与创新的演变过程。表现出专业规模不断扩大、培养目标由单一向多元发展、课程设置逐渐模块化和弹性化、选修课和实践课学时逐步增加、总学分缓慢降低、人才培养模式多样、教学方法不断更新等特征。这些演变是基于国际国内的政治、经济、文化和科技发展的历史缘由。当下，专业认证已全面铺开，坚持"一流专业"建设是培养卓越体育教师的根与本。  相似文献   

Promoting quality education in Chile: the politics of reforming teacher careers     

Alejandra Mizala 《教育政策杂志》2020,35(4):529-555

ABSTRACT

Reformers in developing countries increasingly seek to raise education quality. Yet we know little about the politics of improving education. One significant and instructive case of reforms designed to boost education quality comes from Chile, where in 2016 the government enacted a sweeping reform of teaching careers. This paper first uses a quantitative analysis of appearances in the news to identify key stakeholders and then turns to process tracing to analyze how and when these stakeholders influenced reform dynamics. Comparatively, the Chilean case differs from similar reforms elsewhere in Latin America due to the absence of business, the strong role of policy networks, and the final negotiated settlement with the teacher union. Theoretically, the analysis confirms general theories that emphasize the roles of distributive politics and policy networks.  相似文献   

Efficacy of using non-linear pedagogy to support attacking players’ individual learning objectives in elite-youth football: A randomised cross-over trial     

Simon J. Roberts  James R. Rudd  Matthew J. Reeves 《Journal of sports sciences》2020,38(11-12):1454-1464

ABSTRACT

The present study examined the efficacy of a coaching curriculum, based on non-linear pedagogy, on improving attacking players’ individual learning objectives (ILOs) in elite-youth football. Participants included 22 attacking players (i.e., centre-forwards, wide-players and attacking midfield players) from a professional football academy in England. The players were randomly appointed to both control (CON) and intervention (INT) periods following baseline measures. The INT (non-linear) and CON (linear) periods were both designed to support the ILOs provided to each player as part of the elite player performance plan. The study adopted a randomised cross-over design and ILOs considered important for attacking players (i.e., strong foot finishing, weak foot finishing, 1-v-1 and decision-making) were evaluated using the Loughborough Shooting Skill Test. The results showed significant differences for INT in 1-v-1 (P< 0.02) and decision-making (P< 0.01). However, there were no significant differences for strong foot finishing, weak foot finishing or time taken. These results support non-linear pedagogy in developing 1-v-1 game play and decision-making but not for technical shooting proficiency.  相似文献   

The effect of toxicity on COVID-19 news network formation in political subcommunities on Reddit: An affiliation network approach     

《International Journal of Information Management》2021

Political polarization remains perhaps the “greatest barrier” to effective COVID-19 pandemic mitigation measures in the United States. Social media has been implicated in fueling this polarization. In this paper, we uncover the network of COVID-19 related news sources shared to 30 politically biased and 2 neutral subcommunities on Reddit. We find, using exponential random graph modeling, that news sources associated with highly toxic – “rude, disrespectful” – content are more likely to be shared across political subreddits. We also find homophily according to toxicity levels in the network of online news sources. Our findings suggest that news sources associated with high toxicity are rewarded with prominent positions in the resultant network. The toxicity in COVID-19 discussions may fuel political polarization by denigrating ideological opponents and politicizing responses to the COVID-19 pandemic, all to the detriment of mitigation measures. Public health practitioners should monitor toxicity in public online discussions to familiarize themselves with emerging political arguments that threaten adherence to public health crises management. We also recommend, based on our findings, that social media platforms algorithmically promote neutral and scientific news sources to reduce toxic discussion in subcommunities and encourage compliance with public health recommendations in the fight against COVID-19.  相似文献   

Genetic Polymorphism of Angiotensin II Type 1 Receptors and Their Effect on the Clinical Outcome of Captopril Treatment in Arab Iraqi Patients with Acute Coronary Syndrome (Mid Euphrates)     

Fadhaa A. Ghafil  Bassim I. Mohammad  Hussain S. Al-Janabi  Najah R. Hadi  Hayder A. Al-Aubaidy 《Indian journal of clinical biochemistry : IJCB》2021,36(1):81

Genetic variation in the angiotensin II type 1 receptor (AT1R) has an important effect on the outcome of acute coronary syndrome (ACS) initiated treatment with captopril. This study aims to investigate the impact of genetic polymorphism of AT1R (rs5186 and rs275651) on the ACS outcome in Iraqi patients treated with captopril. A total of 250 Iraqi individuals with ACS were included in this case—control study and they were divided into two study groups; Study group 1 included 125 participants who were prescribed captopril, 25 mg twice daily and study group 2 included 125 participants who received no captopril as part of their ACS treatment (control study). The AT1R gene (rs5186) CC genotype was found to be associated with ST-elevation myocardial infarction (STEMI) (Odd’s ratio (O.R) = 1.2, P = 0.7), while AC was associated with Non-ST-elevation myocardial infarction (NSTEMI) and unstable angina (UA) (O.R = 1.2, P = 0.8). AC genotype is more prone to have Percutaneous coronary intervention (PCI) after ACS attack (O.R = 1.2, P = 0.6). CC genotype had a risk to get less improvement (O.R = 1.6, P = 0.5), so might require higher doses of captopril during acute coronary insult. The AT1R gene (rs275651) AA genotype was associated with UA (O.R = 1.3, P = 0.9). AA and AT genotypes were more prone to have PCI after ACS attack (O.R = 3.9 P = 0.2, O.R = 3.5, P = 0.3 respectively) and thus requiring higher doses of captopril. We conclude that the AT1R rs5186, rs275651 genetic polymorphisms might partially affect the clinical outcome of ACS patients treated with captopril and might have captopril resistance which requires higher doses.  相似文献   

RGAN-EL: A GAN and ensemble learning-based hybrid approach for imbalanced data classification     

《Information processing & management》2023,60(2):103235

Imbalanced sample distribution is usually the main reason for the performance degradation of machine learning algorithms. Based on this, this study proposes a hybrid framework (RGAN-EL) combining generative adversarial networks and ensemble learning method to improve the classification performance of imbalanced data. Firstly, we propose a training sample selection strategy based on roulette wheel selection method to make GAN pay more attention to the class overlapping area when fitting the sample distribution. Secondly, we design two kinds of generator training loss, and propose a noise sample filtering method to improve the quality of generated samples. Then, minority class samples are oversampled using the improved RGAN to obtain a balanced training sample set. Finally, combined with the ensemble learning strategy, the final training and prediction are carried out. We conducted experiments on 41 real imbalanced data sets using two evaluation indexes: F1-score and AUC. Specifically, we compare RGAN-EL with six typical ensemble learning; RGAN is compared with three typical GAN models. The experimental results show that RGAN-EL is significantly better than the other six ensemble learning methods, and RGAN is greatly improved compared with three classical GAN models.  相似文献   

体育英语专业学术论文研究的演进、分类与特征分析          下载免费PDF全文

王玉杰  李延超 《体育科研》2018,(1):43-47,65

通过文献资料法、数据统计法对体育英语专业学术论文研究的演进、分类和特征进行分析。研究表明，体育英语专业学术论文研究可根据体育英语专业的开设、北京奥运会的举办、新一轮的《全民健身计划》3个时间节点将其分为起步阶段、初步提升阶段、飞速发展阶段；内容大致分为办学类、教学类、复合应用类等3个方面，体育英语专业学术论文在学科交叉性、人才融合性、研究深度待拓展等方面与其他学术论文存在一定的差异。  相似文献   

创新网络与企业技术创新动态能力协同演进研究——基于系统动力学的分析_*     

王昌林 《科技管理研究》2018,(21)

本研究利用系统动力学方法,从知识流动的角度描述、量化、模拟企业创新网络与企业技术创新动态能力协同演进的过程。模型分析结果表明当前企业创新绩效取决于技术创新动态能力与创新网络协同演进路径：技术创新动态能力→创新网络构建与演化→外部知识内化→创新绩效→技术创新动态能力。在协同演进的过程中随着企业技术创新的发展,在创新绩效驱动三要素中,动态能力以及创新网络知识内化对创新绩效提升具有边际递增的效应,同时创新战略、产业政策平台和管理平台对企业技术创新都存在显著影响,但这种影响作用存在较大差异。  相似文献