Energy cost of different skating techniques in cross-country skiing     

Millet GP  Boissiere D  Candau R 《Journal of sports sciences》2003,21(1):3-11

The aims of this study were to compare the aerobic energy cost of four 'on-snow' skating techniques in cross-country skiing and to examine the relationships between performance and aerobic energy cost. Twelve male skiers from recreational to national standard performed four level skating trials of 6 min duration in random order, each at the same submaximal velocity but with a different skating technique: (1) 'offset' (V1), using a double asymmetrical and asynchronous pole plant as weight is transferred to one ski; (2) 'two-skate' (V2A), where the pole plant is symmetrical; (3) 'one-skate' (V2), where there is a pole plant as weight is transferred to each ski; and (4) 'conventional', without poles. Oxygen uptake (VO2), pulmonary ventilation, the respiratory exchange ratio and heart rate were measured using a K4(b2) portable gas analyser. The aerobic energy cost (VO2/mean speed) and heart rate were higher (P < 0.05) in the one-skate than in the offset condition. This may be explained by the greater and more efficient use of the upper body and the lower variation in centre of gravity velocity in the offset condition. The aerobic energy cost was 5-9% higher (P < 0.01) in the conventional than in the other techniques, probably because of the shorter duration of propulsive forces within a cycle in the conventional skating condition. Moreover, in ski skating, the mechanical efficiency (propulsive forces/total forces) was shown to be higher in the upper than in the lower limbs. The correlation coefficient between performance and aerobic energy cost was significant in the two-skate (r = 0.68, P = 0.02), one-skate (r = 0.72, P = 0.01) and conventional (r = 0.62, P = 0.04) conditions, but not in the offset condition (r = 0.50, P = 0.10). Our results stress the importance of the upper body component in cross-country skiing and that the aerobic energy cost discriminates between skiers of different standards.  相似文献   

Dyad pedagogy in practical anatomy: A description of the implementation and student perceptions of an adaptive approach to cadaveric teaching     

Dearbhla P. Cullinane  Denis S. Barry 《Anatomical sciences education》2023,16(1):99-115

Prior to the challenges imposed by the Covid-19 pandemic, anatomy practical sessions at Trinity College Dublin involved eight to 10 students per donor station, rotating between digital learning, anatomical models/osteology, and dissection activities for three hours weekly. To maintain cadaveric participation in the anatomy laboratory while adhering to distancing guidelines, a transition to dyad pedagogy was implemented. This mode of delivery allowed two students per donor station to spend one hour per week in the anatomy laboratory with all digital learning elements transferred to the virtual learning platform Blackboard as pre- and post-practical session learning activities. Dyad pedagogy has been explored in clinical settings and simulation procedural-based training but is yet to be fully verified in anatomy education. To determine the effectiveness of hybrid practical sessions and reduced donor to student ratios, the opinions of first year medical students were examined using an online questionnaire with a 51% response rate. Although students recognized the merits of more time in the anatomy laboratory, including opportunities for self-directed study and exposure to anatomical variation, they felt that having two students per station enabled sufficient hands-on time with the donor body and fostered learning opportunities that would not be possible with larger groups. Strong preferences for quality time with the donor body supported by online resources suggests this modality should be a key consideration in course design for anatomy curricula and emphasizes the importance of gauging students' preferences to optimize satisfaction and learning output when pivoting to blended learning strategies in anatomy education.  相似文献   

On homogeneity and its application in sliding mode control     

Emmanuel Bernuau  Denis Efimov  Wilfrid Perruquetti  Andrey Polyakov 《Journal of The Franklin Institute》2014

The paper is reviewing the tools to handle high-order sliding mode design and robustness. The main ingredient is homogeneity which can be checked using an algebraic test and which helps us in obtaining one of the most desired properties in sliding mode control that is finite-time stability. This paper stresses some recently obtained results about homogeneity for differential inclusions and robustness with respect to perturbations in the context of input-to-state stability. Lastly within this framework, most of the popular high-order sliding mode control schemas are analysed.  相似文献   

United States: Federal policies for education for the disadvantaged : Organisation for Economic Co-operation and Development (OECD). Paris: OECD, 1981. pp. 126. $8.50 (paper)     

Denis P. Doyle 《Economics of Education Review》1984,3(2):160-161

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Teaching reading: the psycholinguistic invasion     

Denis H. Stott 《Literacy》1981,15(3):19-25

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'Theory and Practice' in the sociology of Paulo Freire     

Denis Gleeson 《Higher Education Quarterly》1974,28(3):362-371

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A Case Study of Changing the Learning Environment in Law: Introducing Computer-Supported Collaborative Activities     

Laura R. Winer  Denis Berthiaume  Nicolina Arcuri 《Educational Research and Evaluation》2013,19(4-6):441-472

This article reports on a 3-year case study of the introduction of computer-supported collaborative activities in a previously traditional lecture-based law course at a large North American research university. The evolving design of the activities is described, as well as the students' and professor's reactions to the new learning environment. Results show that students perceived that the new emphasis on skills was valuable, and that the collaborative learning activities contributed to their learning of content and technical skills as well as teamwork. Implications for design of such activities as well as factors to consider are presented, for instance, any changes must be considered systemically, with evaluation and workload being key components.  相似文献   

Depression and Anxiety in the Postnatal Period: An Examination of Infants’ Home Language Environment,Vocalizations, and Expressive Language Abilities     

Ruth Brookman  Marina Kalashnikova  Janet Conti  Nan Xu Rattanasone  Kerry-Ann Grant  Katherine Demuth  Denis Burnham 《Child development》2020,91(6):e1211-e1230

This longitudinal study investigated the effects of maternal emotional health concerns, on infants’ home language environment, vocalization quantity, and expressive language skills. Mothers and their infants (at 6 and 12 months; 21 mothers with depression and or anxiety and 21 controls) provided day-long home-language recordings. Compared with controls, risk group recordings contained fewer mother–infant conversational turns and infant vocalizations, but daily number of adult word counts showed no group difference. Furthermore, conversational turns and infant vocalizations were stronger predictors of infants’ 18-month vocabulary size than depression and anxiety measures. However, anxiety levels moderated the effect of conversational turns on vocabulary size. These results suggest that variability in mothers’ emotional health influences infants’ language environment and later language ability.  相似文献   

A Longitudinal Study on Stability and Transitions Among Bullying Roles     

Izabela Zych  Maria M. Ttofi  Vicente J. Llorent  David P. Farrington  Denis Ribeaud  Manuel P. Eisner 《Child development》2020,91(2):527-545

Trajectories of stability and change in bullying roles were examined through a longitudinal prospective study of 916 school students followed up biannually from age 11 to 17. Perpetrators and victims had relatively stable trajectories with most of the children remaining in the same role over time or becoming uninvolved. Bully/victim was the most unstable role with frequent transitions to perpetrators or victims. Developmental change in bullying roles was found with a decrease in physical forms over time in bullies and victims but with persistently high perpetration and victimization in bully/victims. These findings open new horizons in research and practice related to bullying and can be useful for its early detection or design of targeted interventions.  相似文献   

探析ICT环境下的信息素养     

许明  Denis Legros 《现代远程教育研究》2008,(5):57-59

信息与通信技术（ICT）的迅猛发展和广泛运用改变了传统的知识媒介和人类的读写基础。新的读写环境要求社会个体具备新的信息素养。信息素养是一个统一连贯的有机整体,至少应包括信息搜索能力、信息读取能力、信息评估能力、信息组织能力和信息再使用能力等五种基本能力。信息素养对社会个体提出了新的认知要求,改变了社会个体的学习模式和知识积累过程,开辟了教育教学的新思路和新的科研领域。本文从观察信息与通信技术的表现形式及其影响入手,深入探对了信息素养的构成要素、认知要求及影响。  相似文献