Forward acceleration of the centre of mass during ski skating calculated from force and motion capture data

The purpose of this paper was to present and evaluate a methodology to determine the contribution of bilateral leg and pole thrusts to forward acceleration of the centre of mass (COM) of cross-country skiers from multi-dimensional ground reaction forces and motion capture data. Nine highly skilled cross-country (XC) skiers performed leg skating and V2-alternate skating (V2A) under constant environmental conditions on snow, while ground reaction forces measured from ski bindings and poles and 3D motion with high-speed cameras were captured. COM acceleration determined from 3D motion analyses served as a reference and was compared to the results of the proposed methodology. The obtained values did not differ during the leg skating push-off, and force–time curves showed high similarity, with similarity coefficients (SC) >0.90 in the push-off and gliding phases. In V2A, leg and pole thrusts were shown to contribute 35.1 and 65.9% to the acceleration of the body, respectively. COM acceleration derived from ground reaction forces alone without considering the COM position overestimated the acceleration compared to data from motion analyses, with a mean difference of 17% (P < 0.05) during leg push-off, although the shapes of force–time curves were similar (SC = 0.93). The proposed methodology was shown to be appropriate for determining the acceleration of XC skiers during leg skating push-off from multi-dimensional ground reaction forces and the COM position. It was demonstrated that both the COM position and ground reaction forces are needed to find the source of acceleration.     

Exposing Privilege and Racism in The Great White North: Tackling Whiteness and Identity Issues in Canadian Education

As social justice–oriented teachers and teacher educators, it can seem as if we are fighting a losing battle against neoliberal education policies designed to disrupt and dismantle our field. In this article we draw upon traditions of critical race theory, counterstorying, and critical hope to examine the complex realities of contemporary teacher education and envision an alternate reality in which our profession develops and thrives. To do so, we first present a series of autoethnographic critical case studies that highlight dilemmas of practice. We then invite readers to examine each case through multiple lenses, as they grapple with the complexities of a visionary path forward. In so doing, we offer tools for critical professional development that articulate, deconstruct, and reimagine social justice–oriented teacher education and activism in this changing landscape. We close with recommendations to increase our collective capacity as social justice teacher educators, placing a central emphasis on the need for community, critical professional development, and hope.     

The influence of physical exercise on the relation between the phase of cardiac cycle and shooting accuracy in biathlon

This study examined the influence of physical exercise on the relation between shooting accuracy and the phase of the cardiac cycle in which the shot is fired. Thirteen experienced biathletes (8 females, mean age 17 years) fired from the standing position at rest and right after a submaximal exercise on a bicycle ergometer. Shooting accuracy and the timing of each shot relative to the R-waves of the electrocardiogram (ECG) were recorded. Best shots (with greatest accuracy) and worst shots (with lowest accuracy) were fired prevalently in different phases of the cardiac cycle. In the rest condition, best shots were fired less frequently from 200 to 300?ms and more frequently from 500 to 600?ms after the R-wave, compared to worst shots. In the exercise condition, best shots were fired less frequently from 100 to 200?ms after the R-wave and from 20% to 30% of the R-R interval, compared to worst shots. These findings support the hypothesis that shooting accuracy is influenced by the cardiac cycle phase due to the ballistocardiac recoil generated at each heartbeat. To achieve best results athletes could be trained (e.g. through biofeedback) to fire within a specific phase of the cardiac cycle.     

Sharing of retracted COVID-19 articles: an altmetric study

Objective:This study examines the extent to which retracted articles pertaining to COVID-19 have been shared via social and mass media based on altmetric scores.Methods:Seventy-one retracted articles related to COVID-19 were identified from relevant databases, of which thirty-nine had an Altmetric Attention Score obtained using the Altmetrics Bookmarklet. Data extracted from the articles include overall attention score and demographics of sharers (e.g., geographic location, professional affiliation).Results:Retracted articles related to COVID-19 were shared tens of thousands of times to an audience of potentially hundreds of millions of readers and followers. Twitter was the largest medium for sharing these articles, and the United States was the country with the most sharers. While general members of the public were the largest proportion of sharers, researchers and professionals were not immune to sharing these articles on social media and on websites, blogs, or news media.Conclusions:These findings have potential implications for better understanding the spread of misleading or false information perpetuated in retracted scholarly publications. They emphasize the importance of quality peer review and research ethics among journals and responsibility among individuals who wish to share research findings.     

Ein Vorgehensmodell für die Multimedia-Entwicklung mit Autorensystemen

Multimedia-Anwendungen sind interaktive Softwaresysteme und verlangen als solche, mit softwaretechnischen Methoden erstellt zu werden. Sie werden heutzutage in der Regel mit Hilfe von Autorensystemen entwickelt, die eine Ad-hoc-Entwicklung auf Implementierungsniveau unterstützen. Hierdurch und wegen des Fehlens etablierter Vorgehensmodelle für die Multimedia-Softwareentwicklung reduziert sich der Multimedia-Entwicklungsproze? auf die Implementierungsphase. Dies führt zu den in der Softwaretechnik bekannten Problemen wie mangelnder Konzeption und fehlender Dokumentation. Wir stellen in diesem Beitrag ein Vorgehensmodell für die Entwicklung von Multimedia-Anwendungen vor, in dessen Mittelpunkt eine Analyse- und Entwurfsphase im Hinblick auf eine Implementierung der Multimedia-Anwendung mit einem Autorensystem stehen. Ausgehend von einem frameworkbasierten Analysemodell der Anwendung und einem Modell der Realisierungsm?glichkeiten mit einem konkreten Autorensystem wird systematisch ein Implementierungsmodell auf Instanzebene abgeleitet, das als Eingabe für das Autorensystem verwendet wird. Das postulierte Vorgehensmodell wird exemplarisch für das Autorensystem Director am Beispiel der Dom?ne multimedialer Lehr-/Lernanwendungen erl?utert.     

Dynamics and control of the shape and size of a sitting drop-like meniscus, occurring in single-crystal growth

This paper concerns the following topics: dependence of shape and size of a static meniscus sitting like a drop on the controllable part of pressure difference across the free surface; stability of static menisci; procedure for creation of a stable static meniscus, appropriate for the growth of a rod with constant radius; temperature gradients and crystallization front displacement; equation for crystal dimension change rate; evolution of crystal radius and of the level of crystallization front; and control of cross-section during growth. This kind of problems appears in semiconductor single-crystal rod growth from a melt by edge-defined film-fed growth (EFG) technique. The novel case where the upper radius of the meniscus is larger than the shaper radius and the meniscus is sitting like a drop is analyzed. For some of the topics numerical illustrations are given. The obtained results can be useful in experiment planning and technology design of single-crystal rod growth by the EFG method. With this aim this study was undertaken.     

INI-GraphicsNet

Ohne Zusammenfassung     

中国电视节目的出口: 一种消费者理论的透视

迄今为止,外国尤其是西方国家进口中国电视节目的情况仍较少.在对这一问题的探索中,应当将研究重点放在复杂的增值价值链中的最后一个要素--消费者身上.这是使“中国制造“的电视节目得以从本国市场进入国外市场的基本条件,同时也是是一门特殊的学问.如何使中国在全球电视节目市场中的策略变得更加有影响力可以从消费者理论的角度进行推究.文化差异将导致障碍,然而这些障碍必然要被不同形式的投资所突破,相关内容将在下文中被讨论.……