The accuracy of computational fluid dynamics analysis of the passive drag of a male swimmer

The aim of this study was to build an accurate computer-based model to study the water flow and drag force characteristics around and acting upon the human body while in a submerged streamlined position. Comparisons of total drag force were performed between an actual swimmer, a virtual computational fluid dynamics (CFD) model of the swimmer, and an actual mannequin based on the virtual model. Drag forces were determined for velocities between 1.5 m/s and 2.25 m/s (representative of the velocities demonstrated in elite competition). The drag forces calculated from the virtual model using CFD were found to be within 4% of the experimentally determined values for the mannequin. The mannequin drag was found to be 18% less than the drag of the swimmer at each velocity examined. This study has determined the accuracy of using CFD for the analysis of the hydrodynamics of swimming and has allowed for the improved understanding of the relative contributions of various forms of drag to the total drag force experienced by submerged swimmers.     

体力活动与癌症生存研究的10大问题

摘要：今天的美国有1 400万的癌症存活者,其中的很多存活者中都接受了多种治疗,包括手术、放疗、化疗、靶向治疗等。这些治疗能够延长生存时间,但同时也会带来很多急慢性的副作用,危害健康,影响生活质量。体力活动（PA）与癌症生存这一领域发展迅速,主要研究PA对癌症患者的影响。基于该领域的研究进展,提出了以下10大研究问题：1）PA能够降低癌症复发风险、和/或提高存活吗？2）PA能够影响癌症治疗决策、完成率、和/或患者对治疗的反应吗？3）癌症存活者的最佳运动处方是什么？4）静坐少动行为对癌症存活者有何影响？5）癌症存活者最有效的体力活动干预方案是什么？6）哪些癌症会影响病人对PA的反应？7）癌症存活者进行体力活动时需要注意的安全问题有哪些？8）哪些具体的癌症症状可以由PA解决？9）对于癌症晚期患者,体力活动还有何作用？10）如何将体力活动研究结果转化到临床和社区肿瘤实践中来？上述问题的回答至关重要,这不仅关系到体力活动和癌症存活这一研究领域的发展,更重要的是,能够为每年数百万新诊断为癌症的病人、正在接受癌症治疗的病人、治疗结束处于恢复中的病人或是那些正在与晚期癌症抗争的病人带来福音。     

DNA microarray wet lab simulation brings genomics into the high school curriculum

We have developed a wet lab DNA microarray simulation as part of a complete DNA microarray module for high school students. The wet lab simulation has been field tested with high school students in Illinois and Maryland as well as in workshops with high school teachers from across the nation. Instead of using DNA, our simulation is based on pH indicators, which offer many ideal teaching characteristics. The simulation requires no specialized equipment, is very inexpensive, is very reliable, and takes very little preparation time. Student and teacher assessment data indicate the simulation is popular with both groups, and students show significant learning gains. We include many resources with this publication, including all prelab introductory materials (e.g., a paper microarray activity), the student handouts, teachers notes, and pre- and postassessment tools. We did not test the simulation on other student populations, but based on teacher feedback, the simulation also may fit well in community college and in introductory and nonmajors' college biology curricula.     

Postural stability,clicker reaction time and bow draw force predict performance in elite recurve archery

Recurve archery is an Olympic sport that requires extreme precision, upper body strength and endurance. The purpose of this research was to quantify how postural stability variables both pre- and post-arrow release, draw force, flight time, arrow length and clicker reaction time, collectively, impacted on the performance or scoring outcomes in elite recurve archery athletes. Thirty-nine elite-level recurve archers (23 male and 16 female; mean age?=?24.7?±?7.3 years) from four different countries volunteered to participate in this study prior to competing at a World Cup event. An AMTI force platform (1000Hz) was used to obtain centre of pressure (COP) measurements 1s prior to arrow release and 0.5s post-arrow release. High-speed footage (200Hz) allowed for calculation of arrow flight time and score. Results identified clicker reaction time, draw force and maximum sway speed as the variables that best predicted shot performance. Specifically, reduced clicker reaction time, greater bow draw force and reduced postural sway speed post-arrow release were predictors of higher scoring shots. It is suggested that future research should focus on investigating shoulder muscle tremors at full draw in relation to clicker reaction time, and the effect of upper body strength interventions (specifically targeting the musculature around the shoulder girdle) on performance in recurve archers.     

Sports History: Reflections on My Journey So Far

Abstract

In this article, I reflect on my journey into sports history and my career path so far. I also discuss my experiences as part of the British Society of Sports History.     

Fact and fantasy in chemical analysis

Chemical analysis is now so precise and sophisticated a science that it is difficult to appreciate that scarcely a century ago its deficiencies were a cause for public scandal. This article reviews some of the main causes for complaint and how they were remedied.