1,720,971 research outputs found
Optimisation of starting conditions in track cycling
No full textPurpose
Several factors may influence cycling performance and effort intensity during cycling competitions. The present study aimed to investigate the conditions that may influence the initial acceleration during the first 5 m of a cycling competition, particularly riding position, starting angle of the crank and hand position on handlebars. To this aim, eight male cyclists amateur were tested in laboratory and on track.
Methods
Surface electromyography was also used to verify the influence of upper body on muscle activity. Moreover, to verify the results, 59 professional cyclists were observed on the track using the same set-up.
Results
Standing position increased by 10 % the initial speed and acceleration compared to seated position. A starting crank angle of 71° and the position of the hands on the upper bar of the handlebar also improved the acceleration. The effects of these parameters were additive and, therefore, the acceleration with standing position and initial crank angle of 71° was about 35 % greater than that with seated position with an initial crank angle of 47°.
Conclusions
These effects were especially important when analysing the results of competitive athletes, which also showed better initial acceleration under spontaneously adopted optimal initial conditions.
2014 Springer-Verlag Italia
Upper-limb power test in rock-climbing
No full textThe goal of the present study was to validate a new ecological power-test on athletes of different levels and to assess rock climbers' profiles (boulderers vs. route climbers). 34 athletes divided into novice, skilled and elite groups performed the arm-jump board test (AJ). Power, time, velocity, and efficiency index were recorded. Validity was assessed by comparing the distance with the value extracted from the accelerometer (500Hz) and the reliability of intra- and inter-session scores. Moreover, a principal component analysis (PCA) was used to assess the climbers' profiles. The AJ test was quite valid, showing a low systematic bias of -0.88cm (-1.25%) and low limits of agreement (<6%), and reliable (Intra-class correlation coefficient=0.98 and CV<5%), and was able to distinguish between the 3 samples (p<0.0001). There was a good correlation between relative upper-limb power (r=0.70; p<0.01) and the AJ score. Moreover, the PCA revealed an explosive profile for boulderers and either a weak and quick or slow profile for route climbers, revealing a biomechanical signature of the sub-discipline. The AJ test provides excellent absolute and relative reliabilities for climbing, and can effectively distinguish between climbing athletes of different competitive levels. Thus, the AJ may be suitable for field assessment of upper limb strength in climbing practitioners. ?????? Georg Thieme Verlag KG Stuttgart, New York
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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