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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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Web sites are increasingly used by academic libraries to promote key services and collections to teaching faculty. This study analyzes the content, location, language, and technological features of fifty-four academic library Web pages designed especially for faculty to expose patterns in the development of these pages.  相似文献   
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Within the school of thought known as Critical Thinking, identifying or finding missing assumptions is viewed as one of the principal thinking skills. Within the new subject in schools and colleges, usually called Critical Thinking, the skill of finding missing assumptions is similarly prominent, as it is in that subject's public examinations. In this article we examine how school‐ and college‐focused texts explain and teach ‘this very important skill’. The same texts also deal with the nature of assumptions, validity and the role of stated reasons in arguments, and the way these matters are tackled will also be examined in our inquiry. In addition we explore what respected contributors to the critical thinking movement have had to say about some of these issues.  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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Twenty doctoral students in the disciplines of chemistry and history were interviewed to better understand the socialization processes that influence their success and how these processes differ by year in the degree program and disciplinary culture. Five major themes emerged describing these socialization processes and how they facilitate or impede degree success, including Ambiguity, describing the programmatic guidelines and expectations that surrounded much of the students’ experience; Balance, pointing to the students’ need to balance graduate school responsibilities along with external relationships and demands; Independence, describing the students’ desire to find equilibrium as they transitioned to the role of independent scholar; Development, highlighting the significant cognitive, personal, and professional development that occurs in these students’ graduate experience; and Support, describing the faculty, peer, and financial support needed for the students’ success in their degree programs. Suggestions for policy, practice, and further research are discussed.  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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