Optimizing kick rate and amplitude for Paralympic swimmers via net force measures

Kicking is a key component of freestyle swimming yet the optimum combination of kick rate and kick amplitude remains unknown. For Paralympic swimmers, with upper and lower limb disabilities, the influence of the kick plays an important role in net force production. To determine optimum kick characteristics, 12 Paralympic swimmers aged 19.8 ± 2.9 years (mean ± s) were towed at their individual peak freestyle speed. The experimental conditions were (i) a prone streamline glide for passive trials and (ii) maximal freestyle kicking in a prone streamline for active trials at different speeds and kick amplitudes. Kick rate was quantified using inertial sensor technology. Towing speed was assessed using a novel and validated dynamometer, and net force was assessed using a Kistler force-platform system. When peak speed was increased by 5%, the active force increased 24.2 ± 5.3% (90% confidence limits), while kick rate remained at approximately 150 kicks per minute. Larger amplitude kicking increased the net active force by 25.1 ± 10.6%, although kick rate decreased substantially by 13.6 ± 5.1%. Based on the current kick rate and amplitude profile adopted by Paralympic swimmers, these characteristics are appropriate for optimizing net force.     

Szenario-basierter Systemtest von Software-Produktfamilien

Zusammenfassung In der Produktfamilienentwicklung werden durch zwei Entwicklungsprozesse, Domain und Application Engineering, zun"achst wiederverwendbare Entwicklungsartefakte produziert, um diese anschlie?end zur Konstruktion von kundenspezifischen Applikationen einzusetzen. Die Wiederverwendbarkeit wird durch die explizite Definition der Variabilit"at der geplanten Applikationen einer Produktfamilie erzielt. Diese proaktive Wiederverwendung ist bisher in den konstruktiven Entwicklungsphasen realisiert, jedoch noch nicht im Test. Mit ScenTED (Scen_ario based TE_st Case D_erivation) wird in diesem Beitrag eine wiederverwendungsorientierte Technik zur Testfallerstellung f"ur den Systemtest, dem Test eines ausf"uhrbaren Systems gegen spezifizierte Use-Cases, von Produktfamilien vorgestellt. ScenTED basiert auf zwei Kernideen: der Erhaltung der Variabilit"at in Testf"allen und der Szenario-basierten Verfeinerung der Testf"alle. Durch die Erhaltung der Variabilit"at wird die Wiederverwendbarkeit von Testf"allen gesichert; die Szenario-basierte Verfeinerung erm"oglicht Nachvollziehbarkeit durch die durchg"angige Nutzung von Szenarien. In diesem Beitrag wird die ScenTED-Technik an einem Beispiel erl"autert und Erfahrungen aus dem industriellen Einsatz diskutiert.

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Product family engineering consists of two development processes: Domain engineering and application engineering. Reuseable artefacts are created in the domain engineering process. These artefacts are used for the creation of customer specific applications during the application engineering process. Reusability is achieved with the explicit definition of variability that specifies the potential applications of the product family. The proactive reuse has been realized in the construnction phases of the development process, but not within the test phases. We propose ScenTED (Scen_ario based TE_st Case D_erivation) for the creation of reusable test cases for a use case based system testing in product family engineering. ScenTED has two key ideas: The first is the preservation of variability in test cases and the second idea is the scenario-based refinement of test cases. The preservation of variability ensures the reusability of test cases. The scenario-based refinement enables the traceability from requirements to test cases. We present the ScenTED technique in this article with an example and discuss an industrial case study.

CR Subject Classification D2.5     

文化遗产旅游吸引物的意境空间研究——为文化遗产旅游者创造适宜的旅游环境

近来,各种公众媒体的版面充斥着对世界各地著名遗产旅游景点更新改造的报道。文化遗产旅游目的地管理者也承认良好的外部环境在提升旅游者总体满意程度方面发挥着重要作用。阐明了遗产吸引物的自然环境在决定旅游者对景点的态度和未来再次购买意向方面有重要作用．同时影响着他们对亲朋好友的传播意愿。研究表明环境因素在面对顾客塑造永久性的独特品牌形象时可被作为一种差异化工具,并以此创造一种竞争优势。     

哈佛大学

"The Harvard Law School faculty has voted unanimously(全体一致地) to overhaul(检查) its first-year curriculum by focusing more on complex problem-solving,international law, and modem law-making by government bodies and administrative agencies, marking a significant departure from more than a century of traditional legal education.     

漫谈计算机化对就业的冲击

纽约Putnam县的Rober Beardand先生在一家出版公司干了20年，在其中最后的7年中，确实是人在曹营心在汉，辞职的打算始终在心头。随着软件技术的进步，Beanland办公室的电脑变得越来越聪明、能干和快捷。很快，电脑替代了他与同事们的统计分析工作：处理信息、组合数据、设计表格。利用电脑几乎可以在一小时内搞定一切工作。     

The course as token: A construction of/by networks

In actor-network theory (ANT) the movement from the instability of science-in-the-making to the relative stability of ready-made-science is followed by tracing the path of a token or focal actor (either human or non-human) as it both constructs a network and is simultaneously transformed by the developing network. Within science education, a new course can be seen to be a token. It undergoes various transformations as it simultaneously changes those who encounter it (teachers, students, and interested actors beyond the school) and is changed by those same actors. This paper describes the way a new applied physics course introduced in British Columbia as part of a program in applied academics can be seen to construct different networks in different contexts and, in the process, to take on significantly different characteristics. Data are collected from interviews and observations in two different settings characterized in part by differences in the types of partnerships developed with industry, labour, and post-secondary groups. The success of the applied physics course in challenging traditional forms of school physics is seen to rely on the size and strength of the network in which it is imbedded.     

Re/presenting a gender equity project: Contrasting visions and versions

This article provides three different accounts of a gender-equity project in a Grade 10 science class. The three stories, a realist one of victory over oppression, a realist story of inclusion, and a reflexive story of identity, illustrate different rhetorical forms for representing research and different assumptions about gender, pedagogy, equity, and the representation of data. Any version of a project can only be a partial account. As teachers and researchers, our commitments and investments influence our questions, understandings, and representations. The content and form of our stories imply particular relationships with an audience. Those responsible for policy tend to favor realist stories that reduce complexity and increase certainty. Others may be more interested in stories that portray complexity and highlight the need for judgments in particular contexts. No one form is appropriate for all occasions. © 1998 John Wiley & Sons, Inc. J Res Sci Teach 35: 859–876, 1998.     

Validity and reliability of kick count and rate in freestyle using inertial sensor technology

Abstract

In freestyle swimming the arm action is routinely quantified by stroke count and rate, yet no method is currently available for quantifying kick. In this study, we assessed the validity and reliability of inertial sensor technology (gyroscope) to assess kick count and rate. Twelve Paralympic swimmers completed a 100-m freestyle-swimming time-trial and freestyle kicking-only time-trial three times each in a season. An algorithm was developed to detect the up and down beat of individual kicks from the gyroscope trace. For comparative purposes, underwater video analysis provided the criterion measure. The standard error of the estimate (validity) for kick count, expressed as a coefficient of variation, was 5.9% (90% confidence interval 5.5 to 6.4) for swimming, and 0.6% (0.5 to 0.6) for kicking-only trials. The mean bias for kick count was ?1.7% (?2.4 to ?1.1) for swimming, and ?0.1% (?0.2 to ?0.1) for kicking-only trials. Correlations between the sensor and video for kick count were 0.96 (0.95 to 0.97) for swimming, and 1.00 (1.00 to 1.00) for kicking-only trials. The typical error of the measurement (reliability) between trials was approximately 4% for kick count and rate. The inertial sensors and associated software used generated sufficient validity and reliability estimates to quantify moderate to large changes in kick count and rate in freestyle swimming.