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The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to "pull" on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum.  相似文献   
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While previous research has consistently cited education as a high risk profession for negative workplace relationships, there has been little consideration of the impact of workplace bullying for those involved. This paper seeks to address this lacuna through the analysis of 24, in-depth interviews with self-identified victims of workplace bullying who work, or have worked, in primary schools. The study reveals the profound physical, psychological, social, and economic effects of these toxic behaviors upon the interviewees, along with the resistance strategies they employed to help them cope with their experiences. Through a lens of Foucauldian conceptualisation of power, this study explores the broader implications for school organizational culture, as well as for individual teachers and the pupils they teach.  相似文献   
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Universalist claims are often made about sport which is, as a consequence, increasingly written into national and international policy as an entitlement of citizenship or even human right. Further, in most countries physical education (PE) is a compulsory component of children's education, and sport is seen as central to this. Consequently, in the interests of justice sport must aspire to be egalitarian, that is, relevant to and meaningful for boys and men, and girls and women. In this context three fundamental questions are asked in relation to sport: (1) Do all citizens want to participate? (2) Who counts as a citizen? and (3) What are justice and equality? Feminist political and citizenship theory particularly the work of Pateman, Lister and Fraser is used to explore these questions and interrogate the ‘who’ of citizenship and the ‘what’ of justice in relation to framing sport policy in Europe and the UK. It is argued that notwithstanding the extensive use of the Council of Europe definition of sport,11. ‘“Sport” means all forms of physical activity which, through casual or organised participation, aim at expressing or improving physical fitness and mental well-being, forming social relationships or obtaining results in competition at all levels' (CE, 1992 CE. (1992/2001). European sports charter. Retrieved from https://wcd.coe.int/ViewDoc.jsp?Ref=Rec(92)13&;Sector=secCM&;Language=lanEnglish&;Ver=rev&;BackColorInternet=9999CC&;BackColorIntranet=FFBB55&;BackColorLogged=FFAC75 [Google Scholar]2001 CE. (1992/2001). European sports charter. Retrieved from https://wcd.coe.int/ViewDoc.jsp?Ref=Rec(92)13&;Sector=secCM&;Language=lanEnglish&;Ver=rev&;BackColorInternet=9999CC&;BackColorIntranet=FFBB55&;BackColorLogged=FFAC75 [Google Scholar]). and despite or even because of the widespread adoption of the language of gender equality and gender mainstreaming, although formal sport citizenship rights might be accorded to all individuals and regarded as gender neutral, this masks a discourse of androcentric sport citizenship. This has captured European and UK sport policy and provision and is hindering further progress towards gender justice in sport and therefore PE. Given the universal and compulsory aspirations of sport particularly within PE, gender justice should be conceptualised not only as cultural recognition, political representation and economic redistribution within the normalised frame of competitive performance sport or ‘sport for sports sake’; but also as a critical meta-political remapping and reframing of sport as sport and physical recreation or ‘sport for all’.  相似文献   
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The cadence that maximises power output developed at the crank by an individual cyclist is conventionally determined using a laboratory test. The purpose of this study was two-fold: (i) to show that such a cadence, which we call the optimal cadence, can be determined using power output, heart-rate, and cadence measured in the field and (ii) to describe methodology to do so. For an individual cyclist's sessions, power output is related to cadence and the elicited heart-rate using a non-linear regression model. Optimal cadences are found for two riders (83 and 70 revolutions per minute, respectively); these cadences are similar to the riders’ preferred cadences (82–92?rpm and 65–75?rpm). Power output reduces by approximately 6% for cadences 20?rpm above or below optimum. Our methodology can be used by a rider to determine an optimal cadence without laboratory testing intervention: the rider will need to collect power output, heart-rate, and cadence measurements from training and racing sessions over an extended period (>6 months); ride at a range of cadences within those sessions; and calculate his/her optimal cadence using the methodology described or a software tool that implements it.  相似文献   
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Purpose

Metalloproteinases are a key component of the pathogenesis of abdominal hernias. Obesity is considered a risk factor in herniogenesis and hernia recurrence. The aim of this study was to evaluate the serum concentrations of metalloproteinase-2 (MMP-2), MMP-9, MMP-13, and adiponectin in morbidly obese and nonoverweight controls.

Materials and methods

The participants were recruited from among patients undergoing bariatric and non-bariatric surgery and divided into two groups: I (body mass index (BMI)≥35 kg/m2, n=40) and II (BMI<25 kg/m2, n=30). Serum concentrations of MMP-2, MMP-9, MMP-13, and adiponectin were measured using enzyme-linked immunosorbent assay (ELISA).

Results

A statistically significant difference between groups was observed for MMP-2 concentration. The median MMP-9 concentration was higher in the obese group, but the difference was not statistically significant. Median MMP-13 concentrations did not differ between groups. Serum adiponectin concentration was insignificantly higher in the non-obese group.

Conclusions

The elevated serum MMP-2 and MMP-9 concentrations in obese individuals may be related to the higher incidence of incisional hernias in this population.
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This study evaluates the use of an open‐ended question to determine students' knowledge structure on the topic of galvanic cells. The open‐ended question was developed and administered to 163 Grade 10 students who had earlier completed a course on electrochemistry. Students' responses were marked as well as coded on the basis of the fields identified from their responses. This was then evaluated statistically to determine the collective knowledge structure of the sample of students. The knowledge structure thus mapped contains both canonical concepts and alternative conceptions (ACs). An important finding emerging from this study is that instructors need to focus student's attention on the dynamic processes involving electrons and ions during the operation of galvanic cells. In order for students to fully understand how a galvanic cell operates, they need to see the whole picture. There are three critical components that lead to students' understanding of how an oxidation–reduction reaction can generate energy and how a circuit is complete: transfer of electrons during oxidation–reduction half‐reactions, flow of electrons within metals, and migration of ions in solution. Also, we found that it is possible for students to use correct chemistry concepts in an incorrect way by establishing linkages among these in an inappropriate manner. We reiterate that apart from evaluating students' ACs, it is also important to evaluate the links between the concepts and conceptions present in students' knowledge structure so that teaching can be made more effective.  相似文献   
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