Indirect estimation of cable tension during gymnastic movements on rings

Knowledge of external forces acting on an athlete is often required to study performance and injury mechanisms, but direct measurements are difficult to obtain. While transducers in the rings cables typically measure external forces experienced by gymnasts performing static balances and swinging movements on rings, this solution is not always acceptable and an accurate technique that does not hinder the gymnasts’ performances is desirable. This study evaluates a video-based technique for estimating cable tension on the rings apparatus. Static loading of a rings frame coupled with a planar video analysis of the mandatory damped elastic devices (DEDs) provided a tension-deflection calibration curve. Three-dimensional video and cable tension data were obtained for two male gymnasts performing static balances and dynamic swinging movements. Cable tension was measured using a force link while a planar video analysis determined time histories of the DED deflections. Combined cable tension time histories were estimated fromrelative DED deflections coupled with the tension-deflection calibration curve and the orientation of the rings cables, and were compared to measured values to evaluate the proposed technique. For static balances the RMS difference between measured and estimated combined cable tension was 83 N. For dynamic swinging movements the maximum RMS difference was 189 N, equivalent to a 4% difference when expressed as a percentage of the peak value. The indirect video-based technique developed in this study accurately estimates combined cable tension throughout movements on rings and may be considered for studies where a remote measurement is required. There is potential for the technique to be extended to other sporting situations, where indirect accurate estimates of external forces acting on an athlete are needed.     

Comparison of numerical and analytical solutions for fly casting dynamics

This paper presents an approximate analytical model of the dynamics of a tapered fly line during a standard overhead cast. During casting, the line forms a nonlinear propagating wave that is frequently referred to as a ‘loop’ by fly casters. The geometry of the loop is described by three distinct parts: a straight bottom segment (attached to a stationary fly rod), a semi-circular segment that is propagating (i.e. the loop), and a straight top segment that is also propagating, (i.e. the traveling line). A fly (particle) is attached at the end of the traveling line. A work-energy balance yields the velocity of the fly as a function of the length of the traveling line. For a uniform fly line (level line), a closed-form solution is found, while for a tapered fly line, the solution is obtained by quadrature. A critical loop diameter arises in the analysis, and it determines whether the final velocity of the fly is greater or lesser than the initial velocity of the traveling line. The analytical solutions are critically compared against numerical solutions of a general model for fly line dynamics that relaxes many of the assumptions employed in the analytical model. The agreement between the two solutions remains close during the loop propagation phase, provided a significant amount of fly line remains in the traveling line. However, as the traveling line vanishes and the loop ‘turns over’, the two solutions diverge abruptly due to the many simplifying assumptions employed in the analytical model.     

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The Perspectives of Women and Their Health-Care Providers Regarding Using an ECA to Support Mode of Birth Decisions

This study used focus groups to assess the feasibility and acceptability of adapting an Embodied Conversational Agent (ECA) to support decision-making about mode of birth after previous cesarean. Twelve women with previous cesareans, and eight prenatal providers at an academic, tertiary-care medical center, viewed a prototype ECA and were asked to share feedback on the potential role in helping women prepare for decision-making. Both groups felt that although it was somewhat “robot-like,” the ECA could provide easy access to information for patients and could augment the visit with providers. Future work is needed to improve ECA visual appeal and clarify the role and timing for utilization of decision aids using ECA technology to enhance the shared decision-making process.     

运动训练对老年小鼠骨骼肌线粒体形态变化的电镜定量研究

通过计算机图象分析系统对小鼠骨骼肌线粒体结构进行形态计量分析,发现老年小鼠骨骼肌线粒体数目与年轻鼠无异,但肌膜下线粒体减少,线粒体总体积减小。长期运动训练可明显延缓线粒体形态结构的增龄性改变,使其功能有所改善。     

浙江省优秀划船运动员赛前血清某些激素浓度的变化

通过比较划船运动员赛前和平时( 对照)血清中某些激素的水平,发现有明显差异,女性睾酮从1 .59 下降至1 .18nmol/L,男性睾酮则从18 .93 上升21.69nmol/L;女性皮质醇从543 .4 下降至206.0nmol/L,男性皮质醇从543.7 下降至226 .0nmol/L,男性雌二醇从0.158 上升至0 .310pg/L;T3 及T4 均有显著性下降。结果表明优秀划船运动员赛前晨起血清激素水平较好,有利于运动员发挥最佳水平,同时有调动免疫系统,起到保护机体的作用。     

The Significance of Scientific Capital in UK Medical Education

For decades, debates over medical curriculum reform have centred on the role of science in medical education, but the meaning of ‘science’ in this domain is vague and the persistence of the debate has not been explained. Following Bourdieu, this paper examines struggles over legitimate knowledge and the forms of capital associated with science in contemporary UK medical education. Data are presented from a study of two UK medical schools, one with a traditional, science-oriented curriculum, another with an integrated curriculum. Constructions of legitimate knowledge were explored at both schools through six months participant observation, interviews with faculty members (n=15) and students (n=37) and documentary analysis. Findings show that medical schools compete for both scientific and clinical capital, but ultimately science has greater legitimacy. ‘Science’ is defined in accordance with the structure of the traditional curriculum and has become a symbolic resource – a mark of distinction for both medical schools and medical students – which is equated with clinical competence. The significance of science is circumscribed by the medical education field, yet the struggles for scientific capital there have ramifications beyond medical education itself. It is argued that Bourdieu’s concepts are particularly useful tools for studying the meanings that science takes on outside of the scientific field.