Bilateral arm power imbalance in swim bench exercise to exhaustion     

Potts AD  Charlton JE  Smith HM 《Journal of sports sciences》2002,20(12):975-979

We examined the supposition that swimmers may exhibit an imbalance in bilateral arm power output during simulated swimming exercise. Ten competitive front crawl swimmers (5 males, 5 females; age 20.5+/-2.3 years; height 1.74+/-0.09 m; body mass 72.0+/-16.7 kg; 400 m freestyle swim time 278+/-20.5 s; mean +/- s) performed four incremental (10 W x min(-1)) swim ramp tests on a computer-interfaced biokinetic swim bench ergometer. External power output from each arm was measured continuously to exhaustion. The results showed that, throughout the course of the simulated swim, external power output clearly favoured the left arm (F1,9 = 12.5, P= 0.006). This was especially evident in the final 30 s to exhaustion, when 54.0+/-3.87% of external power output was derived from the left arm versus 46.0+/-3.87% from the right arm. The disparity in external power output was further highlighted when the participants were grouped into unilateral and bilateral breathers. Unilateral breathers (n = 5) produced 57.1+/-2.62% of external power output from the left armversus 42.9+/-2.62% from the right arm (P= 0.001). Bilateral breathers (n = 5) exhibited a more balanced external power output of 51.0+/-1.82% from the left arm and 49.0+/-1.82% from the right arm (P = 0.177). Evidence of power imbalance in the simulated swimming stroke may have important implications for optimizing swim performance. The observed power imbalance may be reduced when a bilateral breathing technique is adopted.  相似文献   

Vietnamese in America: Literary Representations     

Philip K. Jason 《Journal of American culture (Malden, Mass. : 2003)》1997,20(3):43-50

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Braided composite materials for the production of lightweight, high rigidity golf shafts   总被引：1，自引：1，他引：0  

Douglas Steven S. Swanek  Jason Carey 《Sports Engineering》2007,10(4):195-208

Braiding is not currently used in the production of golf shafts. The objective of this work was to develop, through a modelling process consisting of altering lamina sequence, a golf shaft, using braided laminas, which would have mass, stiffness and torque comparable to commercially available composite and steel shafts. A 2D conical braided composite model was previously developed and validated to predict elastic constants of braided closed meshed structures. Energy methods were used to calculate the stiffness and torque of shafts using prescribed industry approaches. Shaft mass was calculated based on geometry and density of constitutent materials. Modelled shafts had both braided and unidirectional layers and compared favourably with or were better than commercially available composite and steel shafts in terms of deflection force and twist angle; they had the same weight as composite shafts but were much lighter than steel shafts. If these findings are verified, braided composites would be a viable and effective approach to the design of future golf shafts.  相似文献   

In Physics Education,Perception Matters          下载免费PDF全文

Jason R. Sattizahn  Daniel J. Lyons  Carly Kontra  Susan M. Fischer  Sian L. Beilock 《Mind, Brain, and Education》2015,9(3):164-169

Student difficulties in science learning are frequently attributed to misconceptions about scientific concepts. We argue that domain‐general perceptual processes may also influence students' ability to learn and demonstrate mastery of difficult science concepts. Using the concept of center of gravity (CoG), we show how student difficulty in applying CoG to an object such as a baseball bat can be accounted for, at least in part, by general principles of perception (i.e., not exclusively physics‐based) that make perceiving the CoG of some objects more difficult than others. In particular, it is perceptually difficult to locate the CoG of objects with asymmetric‐extended properties. The basic perceptual features of objects must be taken into account when assessing students' classroom performance and developing effective science, technology, engineering, and mathematics (STEM) teaching methods.  相似文献   

Partisan Patriotism in the American Presidency: American Exceptionalism,Issue Ownership,and the Age of Trump     

Jason Gilmore  Charles M. Rowling 《Mass Communication and Society》2019,22(3):389-416

This study employs issue ownership theory to examine the partisan dynamics surrounding the idea of American exceptionalism in presidential discourse. We conducted a content analysis of invocations of American exceptionalism in all major U.S. presidential addresses—domestic and foreign—from the end of World War II through Trump’s 1st year in office. We find that even though Republicans have traditionally claimed ownership of American exceptionalism, patterns in presidential discourse tell a very different story. Specifically, our results show (a) in domestic contexts, Republican and Democratic presidents were very similar in their invocations of American exceptionalism during the Cold War but that Democrats have held a substantial advantage over Republicans throughout the post–Cold War era, including on issue areas that Republicans are perceived to “own” (e.g. national security); (b) in foreign contexts, Democrats have been much more outspoken in their embrace of American exceptionalism throughout both the Cold War and post–Cold War; and (c) President Trump has diverged significantly, both in substance and frequency, from his Democratic and Republican predecessors in his invocation of American exceptionalism. We reflect on the implications of these findings on our broader understanding of issue—and trait—ownership, presidential discourse, and American exceptionalism in American politics.  相似文献   

The Sum Is Greater Than the Parts: Deconstructing Homemade PowerPoint Games     

Jason P. Siko  Michael K. Barbour 《学校用计算机》2015,32(3-4):167-182

Homemade PowerPoint games are a low-tech alternative for using game design in classrooms. To date, much of the research examining the games has not shown an improvement in performance. This has led some to question whether the games are properly aligned with the instructional strategies researchers have used as justifications to support using them. This study examined how increasing the structure of the game design project affected student performance when compared to control groups, as well as those who created games in previous iterations of the study. In addition, we examined the effects of student performance when two of the instructional strategies (microtheme writing and question writing) were tested in isolation. Most of the comparisons showed no statistical difference in performance; however, results from the final iteration yielded significant gains when compared to the control group.  相似文献   

Academic workload: the silent barrier to the implementation of technology-enhanced learning strategies in higher education     

Mary Sarah-Jane Gregory  Jason Michael Lodge 《Distance Education》2015,36(2):210-230

The effect of technology-enhanced learning (TEL) strategies in higher education has arguably been transformative despite the not-insignificant barriers existing in this context. Throughout the discourse very little attention has been paid to those primarily responsible for this implementation—academic teaching staff. This paper aims to highlight the impact of academic workload allocations, an often silent barrier to the uptake of TEL strategies in higher education. We will discuss the effects of academic identity and culture, preferential time allocation to associative activities, academic technological capacity, university policies and workload and funding models on the uptake, and implementation on TEL in higher education. Our aim is to highlight the risks to staff, students and institutions should these concerns not be addressed and to propose a model for utilisation by all staff responsible for implementing flexible workload models supportive of further implementation of TEL strategies across the sector.  相似文献   

An improvement on the transient response of tracking for the sampled-data system based on an improved PD-type iterative learning control     

Fu-Ming Chen  Jason Sheng-Hong Tsai  Ying-Ting Liao  Shu-Mei Guo  Ming-Chung Ho  Fu-Zen Shaw  Leang-San Shieh 《Journal of The Franklin Institute》2014

An improvement on the transient response of tracking for the sampled-data system based on an improved PD-type iterative learning control (ILC) is proposed in this paper. The developed analog ILC method and the high-gain property tracker design methodology are first combined to significantly reduce learning epochs and overcome the initial condition shift problem and discontinuous reference input in the traditional ILC. Besides, the proposed ILC improves the transient response and decreases the rate of weighting matrices Q$Q$ to R$R$ under the traditional linear quadratic tracker design. First, the off-line observer/Kalman filter identification (OKID) is used to determine the appropriate (low-) order system parameters and state estimator for the physical system with unknown system equation, so that the model-based PD-type ILC can be implemented for practical applications. Then, to improve the transient response and decrease the control effort, the proportional difference type (PD-type) ILC algorithm is combined with the high-gain property linear quadratic tracker (LQT) design to construct the high performance tracker for the model-based sampled-data systems. Furthermore, the discrete-time version high performance tracker design for the unknown stochastic sampled-data system via the iterative learning control method is proposed in this paper based on the Euler method and the digital redesign approach. Finally, some examples are given for illustrating the effectiveness of the proposed method.  相似文献   

Where Did All the Data Go? Internet Security for Web‐Based Assessments     

Mark D. Shermis  Jason Averitt 《Educational Measurement》2002,21(2):20-25

The purpose of this article is to enumerate a series of security steps that might be taken by those researchers or organizations that are contemplating web-based tests and performance assessments. From a security viewpoint, much of what goes on with web-based transactions is similar to other general computer activity, but the recommendations here focus on what can be done to avoid the loss, compromising, or modification of data collected by or stored through the Internet.  相似文献   

Bridging knowledge: A collective undergraduate thesis development approach     

Jason K. Holdsworth  Özgür Arun 《Educational gerontology》2017,43(11):561-567

While there are various approaches to gerontological and geriatrics (and social sciences) education globally, a component commonly included in undergraduate education is a final thesis project. In Turkey, the Department of Gerontology at Akdeniz University has undertaken a unique approach to thesis development that values and draws on accessing the greater expertise and knowledge of faculty and students through joint collaborations. We offer an overview of the eleven stages of a collective thesis development approach as an alternative to the conventional way of conducting oversight of undergraduate thesis projects. With four years of experience, observed benefits of a collective thesis development approach for students include the opportunity to draw on the comradery, insights, and experience of a plurality of educators and aspiring students while developing, executing, and documenting a thesis project. Benefits to advisors/educators include profiting from the strengths in other advisors and wider exposure to current research, findings, and methodological approaches. So while there may be multifold variations in curriculum content and educational approaches, it is of great importance that educators create “spaces” that give value to and foster the pursuit of collective wisdom through joint collaborations. (188 words)  相似文献