Cross‐Country Skiing     

Johnny Nilsson  Per Tveit  Olav Eikrehagen 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(1):85-108

The purpose was to study the adaptation to speed in the temporal patterns of the movement cycle and determine any differences in velocity, cycle rate and cycle length at the maximum speed level in the different classical style and freestyle cross‐country skiing techniques. Eight skilled male cross‐country skiers were filmed with a digital video camera in the sagittal plane while skiing on a flat cross‐country ski track. The skiers performed three classical style techniques the diagonal stride, kick double poling and the double poling technique and four freestyle techniques paddle dance (gear 2), double dance (gear 3), single dance (gear 4) and combiskate (gear 5) at four different self‐selected speed levels slow, medium, fast and their maximum. Cycle duration, cycle rate, cycle length, and relative and absolute cycle phase duration of the different techniques at the different speed levels were analysed by means of a video analysis system. The cycle rate in all tested classical and freestyle techniques was found to increase significantly (p < .01) with speed from slow to maximum. Simultaneously, there was a significant decrease in the absolute phase durations of all the investigated skiing techniques. A minor, not significant, change in cycle length, and the significant increase in cycle rate with speed showed that the classical and freestyle cross‐country skiing styles are dependent, to a large extent, on an increase in cycle rate for speed adaptation. A striking finding was the constant relative phase duration with speed, which indicates a simplified neural control of the speed adaptation in both cross‐country skiing styles. For the practitioner, the knowledge about the importance of increasing cycle frequency rather than cycle length in the speed adaptation can be used to optimise a rapid increase in speed. The knowledge about the decrease in absolute phase duration, especially the thrust phase duration, points to the need for strength and technique training to enable force production at a high cycle rate and skiing speed. The knowledge that the relative phase duration stays constant with speed may be used to simplify the learning of the different cross‐country skiing techniques.  相似文献   

From romance to rocket science: speed dating in higher education     

Olav Muurlink 《高等教育研究与发展》2011,30(6):751-764

This article is the first comprehensive review of speed dating in the tertiary sector. While speed dating has its origins as a networking technique to connect singles, it has only more recently made its way into the academy. Since 2005 universities world-wide have begun to adopt speed dating protocols as a tool for building research culture. An extensive review of the brief history of speed dating in university settings indicates that the motivation for organising events tends to fall into six clusters. Each motivation is discussed here, as well as two potential as-yet-unexplored outcomes for research students in academe: increasing wellbeing through improving social relations and aiding the conceptualising of theses. Finally the authors raise the need for further research in this area to establish its real impact and to identify best practices.  相似文献   

Technology Education: Diversity or Chaos?     

Svein Sj⊘berg 《Studies in Science Education》2013,49(1):289-297

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Pole length and ground reaction forces during maximal double poling in skiing   总被引：1，自引：0，他引：1  

Nilsson J  Jakobsen V  Tveit P  Eikrehagen O 《Sports biomechanics / International Society of Biomechanics in Sports》2003,2(2):227-236

The purpose of the investigation was to study the relationship between thrust phase duration, ground reaction force, velocity increase after pole thrust and pole angles versus pole length during double poling in roller skiing. Seven male regional elite cross-country skiers volunteered as subjects for the study. The subjects performed a maximal double pole thrust on roller skis with each of the three different pole lengths: 'short', self-selected (normal) and 'long'. The short and long poles were 7.5 cm shorter and 7.5 cm longer than the self-selected pole length. The subjects made seven maximal pole thrusts with each pole length, which were randomly selected during 21 trials. For each trial the subjects accelerated from a 1.2 m high downhill slope attaining a speed of 3.92 m.s-1 before making a maximal double pole thrust on a force plate placed at the bottom of the slope. The vertical (F2), anterior-posterior (Fy) and mediolateral (Fx) reaction forces of the left pole were measured by the force plate. The positions of the pole were recorded in 3-D by an opto-electronic system. Thrust phase duration, impulse, mean force, velocity increase after pole thrust and pole angles were calculated from the recorded data. Double poling with long poles produced a significantly larger propulsive anterior-posterior reaction force impulse and velocity increase than normal (p < .05) and short poles (p < .05). This was in spite of a larger mean anterior-posterior reaction force being produced with short poles. Thus, thrust phase duration was a primary factor in determining propulsive anterior-posterior impulse. For the practitioner, the results can be useful in the selection of pole length when the aim is to increase thrust phase duration, anterior-posterior force impulse and velocity.  相似文献   

Decentralisation of Higher Education and Research in Norway     

Svein Kyvik 《比较教育学》1983,19(1):21-29

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模糊对象和模糊性的逻辑     

奥拉夫·阿歇姆 《中山大学学报论丛》2008,1(2)

本文最初写于2001年,旨在探究语言上的、概念上的与本体论中的模糊性问题.文章始于这样一个问题,即模糊性仅仅是一个词的特征,抑或它也是我们的概念的特征,甚或是实在的特征?其中主要的关注点在于模糊对象的问题和相关的模糊同一性的问题.本文首先论证,即便模糊概念总可以得到进一步澄清,每个概念工具也必定是模糊的.其次,本文认为,如果不仅仅是词语,而且这些词语所表达的概念也是模糊的,那么可以论证,对象也必定是模糊的.第三,那种认为模糊对象必定具有模糊的同一性的思路是一种误解.最后一点尤为重要,因为对于模糊对象的抵制部分就来自于下述观念,即这种对象是不可能的,因为它们不遵守逻辑的同一律.本文也论述了,通过放弃二值原则以使得模糊陈述具有真和假之间的某个值或根本就没有真值的办法,也无助于解决模糊性问题,而且恰恰会造成相反的情况,即妨碍我们找到问题的解决之道.本文表明,在为真和既不真又不假之间,难以清晰地划分界限,正如在模糊的情形下要在真和假之间划界一样困难.本文的方法是利用量化模态逻辑的框架和语义学来处理这些问题.基于哥德尔模式的模态逻辑系统T,本文提出了一种关于清晰性和模糊性的量化逻辑,其中利用清晰性算子来代替必然性算子.文章还进一步讨论了模糊性和概念工具的发展之间的关联.  相似文献   

Men in limbo: former students with special educational needs caught between economic independence and social security dependence     

Gerd Skjong  Jon Olav Myklebust 《欧洲特需教育杂志》2016,31(3):302-313

Individuals in their mid-thirties are expected to be employed and economically independent. However, people with disabilities and health problems – for example, former students with special educational needs (SEN) – may have problems in this domain of adult life. In Norway, individuals with SEN frequently rely on social security and support measures from the Norwegian Labour and Welfare Administration (NAV). This article is based on the narrative analysis of life course trajectories of seven young adult males over a period of 17 years – from their enrolment in upper secondary school with special needs teaching whilst in their teens to their participation in various NAV programmes whilst in their mid-thirties. The life course approach, with an emphasis on transitions and trajectories, has been used as the theoretical framework for analysing the presented data. The hope is that, taken together, these seven stories provide a deeper insight than one individual story could offer. We find that both social structures and the earlier life course affect one’s opportunities for joining the labour market.  相似文献   

Science and the diffusion of knowledge   总被引：2，自引：0，他引：2  

Olav Sorenson  Lee Fleming   《Research Policy》2004,33(10):1615-1634

Scientists, social scientists and politicians frequently credit basic science with stimulating technological innovation, and with it economic growth. Despite a substantial body of research investigating this general relationship, relatively little empirical attention has been given to understanding the mechanisms that might generate this linkage. This paper considers whether more rapid diffusion of knowledge, brought about by the norm of publication, might account for part of this effect. We identify the importance of publication by comparing the patterns of citations from future patents to three groups of focal patents: (i) those that reference scientific (peer-reviewed) publications, (ii) those that reference commercial (non-scientific) publications; and (iii) those that reference neither. Our analyses strongly implicate publication as an important mechanism for accelerating the rate of technological innovation: Patents that reference published material, whether peer-reviewed or not, receive more citations, primarily because their influence diffuses faster in time and space.  相似文献   

Complexity, networks and knowledge flow   总被引：7，自引：0，他引：7  

Olav Sorenson  Jan W. Rivkin 《Research Policy》2006,35(7):994-1017

Because knowledge plays an important role in the creation of wealth, economic actors often wish to skew the flow of knowledge in their favor. We ask, when will an actor socially close to the source of some knowledge have the greatest advantage over distant actors in receiving and building on the knowledge? Marrying a social network perspective with a view of knowledge transfer as a search process, we argue that the value of social proximity to the knowledge source depends crucially on the nature of the knowledge at hand. Simple knowledge diffuses equally to close and distant actors because distant recipients with poor connections to the source of the knowledge can compensate for their limited access by means of unaided local search. Complex knowledge resists diffusion even within the social circles in which it originated. With knowledge of moderate complexity, however, high-fidelity transmission along social networks combined with local search allows socially proximate recipients to receive and extend knowledge generated elsewhere, while interdependencies stymie more distant recipients who rely heavily on unaided search. To test this hypothesis, we examine patent data and compare citation rates across proximate and distant actors on three dimensions: (1) the inventor collaboration network; (2) firm membership; and (3) geography. We find robust support for the proposition that socially proximate actors have the greatest advantage over distant actors for knowledge of moderate complexity. We discuss the implications of our findings for the distribution of intra-industry profits, the geographic agglomeration of industries, the design of social networks within firms, and the modularization of technologies.  相似文献