Consistency of performances in the Tkatchev release and re-grasp on high bar

The Tkatchev on the high bar is a release and re-grasp skill in which the gymnast rotates in a direction during flight opposite to that of the preceding swing. Since the release window is defined as the time during which the gymnast has appropriate linear and angular momentum to ensure the bar can be re-grasped, it was speculated that the release windows for this skill would be smaller than for dismounts that are less constrained. One senior male gymnast competing at national standard performed 60 Tkatchev trials. A four-segment planar simulation model of the gymnast and high bar was used to determine the release windows in 10 successful and 10 unsuccessful performances of the Tkatchev recorded using a Vicon motion analysis system. Model parameters were optimized to obtain a close match between simulations and recorded performances in terms of rotation angle (1 degree), bar displacements (0.01 m), and release velocities (1%). Each matched simulation was used to determine the time window around the actual point of release for which the model had appropriate release parameters to complete the Tkatchev successfully. The release windows for the successful trials were small compared with those of dismounts. The unsuccessful trials were associated with later release and later timing of the actions at the shoulders and hips.     

Book reviews

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Book reviews

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Institut national d'Etude du travail et d'Orientation professionnelle

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UNESCO     

“Good” organisational reasons for “ineffectual” research: Evaluating summative evaluation of museums and galleries

New displays, galleries and exhibitions in museums and galleries are increasingly subject to summative evaluations, wide-ranging investigations that examine how visitors respond to and engage with particular initiatives. These evaluations provide insights into the behaviour and attitudes of visitors and the ways in which particular exhibitions, exhibits and information resources facilitate engagement, participation and learning. Unfortunately, however, summative evaluation has relatively little impact either on the particular initiative or more generally in contributing to our knowledge of visitor behaviour and understanding of best practice. In this paper, we suggest that the relative lack of impact of summative evaluation is not primarily due to any methodological shortcomings or the idiosyncrasies of some of the approaches that are used. Rather, the organisational and institutional context in which summative evaluation is commissioned, undertaken and received can impose contradictory demands and undermine the opportunity of learning from and applying the findings of evaluation.     

Internationalisation and distance education: a Hong Kong case study

The accelerating globalisation of world economic relations has been paralleled by a progressive internationalisation of higher education, including the use of distance education. But the modification of distance education materials and the provision of local tutorial support are only rarely undertaken, despite the fact that in social science and the humanities such materials are culturally saturated. This Hong Kong case study in teacher education examines the issues, describes the opportunities and difficulties involved, and argues that cultural adaptation merits a higher priority than at present.     

Microliter-bioreactor array with buoyancy-driven stirring for human hematopoietic stem cell culture

This work presents the development of an array of bioreactors where finely controlled stirring is provided at the microliter scale (100–300 μl). The microliter-bioreactor array is useful for performing protocol optimization in up to 96 parallel experiments of hematopoietic stem cell (HSC) cultures. Exploring a wide range of experimental conditions at the microliter scale minimizes cost and labor. Once the cell culture protocol is optimized, it can be applied to large-scale bioreactors for stem cell production at the clinical level. The controlled stirring inside the wells of a standard 96-well plate is provided by buoyancy-driven thermoconvection. The temperature and velocity fields within the culture volume are determined with numerical simulations. The numerical results are verified with experimental velocity measurements using microparticle image velocimetry (μPIV) and are used to define feasible experimental conditions for stem cell cultures. To test the bioreactor array’s functionality, human umbilical cord blood-derived CD34⁺ cells were cultured for 7 days at five different stirring conditions (0.24–0.58 μm∕s) in six repeated experiments. Cells were characterized in terms of proliferation, and flow cytometry measurements of viability and CD34 expression. The microliter-bioreactor array demonstrates its ability to support HSC cultures under stirred conditions without adversely affecting the cell behavior. Because of the highly controlled operative conditions, it can be used to explore culture conditions where the mass transport of endogenous and exogenous growth factors is selectively enhanced, and cell suspension provided. While the bioreactor array was developed for culturing HSCs, its application can be extended to other cell types.     

Assessment and Productive Research

This paper discusses the ways in which institutions and academics might creatively determine their plans for research, in the light of the assessment exercises.
It is difficult to know how to be systematic and optimistic about generating and completing research; most of the best efforts come from individuals' own initiatives rather than from the proddings of an assessment machine or a quality industry. That does not mean, however, that we should not try to think about research in a systematic fashion but the system does little to help us do so.
The second problem is that the policies underlying the assessment exercises are largely wrong, and designed to be purgative rather than developmental, reductionist rather than a contribution to creating a larger and more useful scientific base in this country.
The paper spends some time on these uncertainties, because they inevitably affect what academic groups just coming to terms with the research mission can and should do. It then discusses ways in which academics can build up their own academic mandates.     

Sources of bias in performance evaluation: Two experiments

Attribution and stereotyping theories predicted that poor-performing black workers would receive lower evaluations than corresponding Whites, while good performance would have the reverse effect. “Dress and lifestyle” was also predicted to influence performance evaluation. Male business students, evaluating bogus employees differing in race, dress, and behaviorally described performance, provided weak support for the second hypothesis. A second experiment investigated the possibility that perceived social class, rather than race, was the relevant variable in the operation of a stereotype confirmation—contrast process. Individual differences in stereotyping were also measured. No support for the specific hypothesized process was found, but results supported the potential relevance of attribution theory to a configural performance-evaluation model. Results were also discussed in terms of worker-perceived discrimination.     

Pluralisme linguistique au Liban

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