The influence of deformation on barbell mechanics during the clean pull

For simplicity of biomechanical analyses, the weightlifting barbell is typically modelled as a rigid, nondeformable object. Most coaches and weightlifters, however, are aware of the elastic nature of the barbell, and its influence on the successful completion of lifting attempts. Variables such as velocity, work performed, and power output are indicators of the quality of performance during the snatch, clean, and related weightlifting pulling movements. The aim of this study was to establish whether differences exist in determining these biomechanical parameters when the centre of the barbell is analysed compared with each end of the barbell. Nine men performed three maximal-effort repetitions in the clean pull exercise at 85% of their self-reported single repetition maximum (1-RM) clean (90-155 kg) using a barbell instrumented for mechanical analysis. Results indicated that peak barbell speed was 5-30% (P < 0.05) lower for the centre of the barbell than the ends. Although differences (P < 0.05) in kinetic and potential energy were found between the centre and ends of the bar, differences between total work performed were small (< 6%; P < 0.05) and no differences were observed for average power (P > 0.05). Although approximately the same work and power occur for the centre and ends of the barbell, they manifest as different kinematics as a result of the elastic nature of the equipment. The elastic characteristics should be considered when selecting instrumentation and variables for research involving barbells. Coaches should be aware of the elasticity of barbells, including selecting appropriate viewing angles as well as understanding how deformation may affect the ends of the barbell relative to the centre.     

真空预压技术对软粘土物理与力学属性影响的试验研究

研制了一套新三轴试验仪,该仪器能将堆载和真空加载在土样上,在固结进行中能同时监控超孔隙水压力、轴向应变(沉降)与体积应变.并根据浙江省温州市原状软粘土进行了固结试验,软粘土的天然含水率是72.5%.试验结果发现,真空预压、堆载预压或真空堆载联合预压3类加固方式中,粘土的固结特性没有明显差异.研究表明3种加固方法改变了软土的一些物理属性并改善了它的力学属性.     

Net joint moments and muscle activation in barbell squats without and with restricted anterior leg rotation

Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P < 0.001) rotations, resulting in a smaller knee flexion range of motion (P < 0.001). At maximum squat depth, ankle plantar flexor (P < 0.001) and knee extensor (P < 0.001) NJM were higher in unrestricted squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.     

Exploring the Structure of Teachers’ Emotional Labor in the Classroom: A Multitrait–Multimethod Analysis

This study tests whether teachers’ emotional labor in classroom settings is optimally conceptualized according to the type of emotional labor strategy involved (genuinely expressing, hiding, and faking emotions), the specific type of emotion being performed in class (e.g., enjoyment vs. pride vs. anxiety), or both strategy type and emotion type. Multitrait–multimethod analyses of 1,086 Canadian teachers’ survey responses showed teachers’ responses to emotional labor items to be most reliably differentiated according to both specific types of emotional labor strategies as well as the valence of the emotion being performed. Findings were largely consistent with common “display rules” encouraging expression of positive emotions and hiding of negative emotions by teachers in classroom settings. Results further showed teachers’ emotional labor strategies for negative emotions to be particularly contingent on the specific discrete emotion involved, highlighting the complexity of expressing negative emotions as a behavior management strategy.     

Taiwanese teachers’ implementation of a new ‘constructivist mathematics curriculum’: How cognitive and affective issues are addressed

This paper aims to investigate the ways in which four Grade 5 teachers perceived and implemented a new constructivist mathematics curriculum, after all their past experience of traditional mathematics in Taiwan. The meaning and indicators of constructivist and traditional mathematics were explored and developed based on reviews of three countries’ mathematics curricula and studies on mathematics teaching. Through interviews and classroom observations, teachers’ practices were analyzed in these terms, separated into cognitive and affective aspects. The teachers were found to meet the new curriculum halfway, to address cognitive issues more effectively than affective ones, and to implement a common curriculum differently. The results support the need to analyze the teaching of mathematics in relation to affective as well as cognitive elements, and are discussed in relation to mathematics teaching internationally.     

The impact of SSCI and SCI on Taiwan’s academy: an outcry for fair play

The increasing importance of the competition in global university ranking has resulted in a paradigm shift in academic governance in East Asia. Many governments have introduced different strategies for benchmarking their leading universities to facilitate global competitiveness and international visibility. A major trend in the changing university governance is the emergence of a regulatory evaluation scheme for faculty research productivity, reflected by the striking features of the recent changing academic profile of publication norms and forms that go beyond the territories of nation-states in the East and West. With the expansion of the Taiwanese higher education system in the last two decades, the maintenance of quality to meet the requirements for international competitiveness has become a key concern for policy makers. Since 2005, the Ministry of Education has introduced a series of university governance policies to enhance academic excellence in universities and established a formal university evaluation policy to improve the competitiveness and international visibility of Taiwanese universities. In so doing, the government has legalized a clear link between evaluation results and public funding allocation. Research performance is assessed in terms of the number of articles published in journals indexed by the Science Citation Index (SCI), the Social Science Citation Index (SSCI), and the Arts and Humanities Citation Index and in terms of citation rates and associated factors. Therefore, evaluation has taken on a highly quantitative dimension. Despite the efforts of concerned parties to encourage academic excellence, the abovementioned quantitative evaluation indicators have resulted in bitter complaints from the humanities and social sciences, whose research accomplishments are devalued and ignored by the current quantitative indicators. In this paper, the authors describe the recent petition for collective action initiated by university faculty to protest the privileging of SSCI and SCI publications as critical indicators for academic performance regardless of faculty discipline and specialization. The article concludes its argument with a group petition calling for more diverse and reliable indicators in recognizing the research of different natures and disciplines while creating culturally responsive evaluation criteria for social sciences and humanities in the Taiwanese academe. The article not only sheds light on academic evaluation literature, especially on the uncertain paradox of globalization and market economy, but also proposes alternatives to the evaluation system for humanities and social sciences in higher education.     

Exploring individuals’ subjective well-being and loyalty towards social network sites from the perspective of network externalities: The Facebook case

This study aims to investigate users’ subjective well-being and loyalty towards social network sites (SNSs). Despite the growing role of network externalities in SNS continuance decisions, the SNS usage literature has paid scant attention to the relationship between network externalities, SNS identification, and users’ subjective well-being. In this study, we identify four components of network externalities: perceived network size, external prestige, compatibility, and complementarity. In the research model, both network size and external prestige are hypothesized positively to affect SNS identification. Perceived compatibility and perceived complementarity are hypothesized positively to affect user satisfaction. Satisfaction and SNS identification are hypothesized positively to affect user subjective well-being and loyalty towards the SNS. Users’ subjective well-being is hypothesized positively to affect their loyalty towards the SNS. Data collected from 615 valid users of Facebook provide strong support for most of these hypotheses. The findings indicate that perceived network size negatively affects users’ SNS identifications. Other components of network externalities have positive effects on SNS identification and satisfaction, which in turn have positive effects on users’ subjective well-being and loyalty towards SNS. Implications for theory and practice and suggestions for future research are also discussed.     

顶尖级乒乓球运动员的特质分析

每一位乒乓球世界冠军都有自己的成功秘诀.本文对这些顶尖级乒乓球运动员成功的一些共同特点进行了研究,以供他人在训练和自我培养的过程中参考,从而加速迈向成功的道路.研究对象与方法本文研究对象为2 0名获得过世界冠军的乒乓球运动员,研究方法为归纳法.研究结果本文归纳出世界乒乓球顶级运动员具有6个方面的特质(1)坚决果断--有着不达目的决不罢休的决心;(2)毅力--能够坚持长期、不间断的训练;(3)技能学习--善于学习国内、外优秀选手的技术优点,博采众长;(4)扎实的功底--有自己坚实的技术基础;(5)独特的技术风格--具鲜明的、独一无二的技术风格;(6)良好的心态--精力集中,有正确的胜负观.