1,720,962 research outputs found
Energy Cost of Human Locomotion on Land and in Water
No full textMaximal absolute speeds in human locomotion range from a minimum of about 7km?h-1 in swimming (100m free style) to over 70km?h-1 in cycling (200m with a flying start), whereas the maximal muscular power of elite athletes competing in these events is essentially equal. Hence these large speed differences depend on the specific characteristics of each form of locomotion. These will be described in some detail with the aim of providing a comprehensive overview of the resulting energy cost of transport under different sets of conditions, such as constant versus accelerated or decelerated speed, uphill versus downhill slopes, the effects of barometric pressure, and of the characteristics of the terrain. The resulting overall picture can be condensed in a limited number of equations allowing us to predict overall energy expenditure as well as maximal speed in the locomotion considered, provided that a few parameters concerning the subject and the environmental conditions in question are known
Energy cost and metabolic power in elite soccer: a new match analysis approach
No full textPurpose: Video match analysis is used for the assessment of physical performances of professional soccer players, particularly for the identification of "high intensities" considered as "high running speeds." However, accelerations are also essential elements setting metabolic loads, even when speed is low. We propose a more detailed assessment of soccer players' metabolic demands by video match analysis with the aim of also taking into account accelerations. Methods: A recent study showed that accelerated running oil a flat terrain is equivalent to running uphill at constant speed, the incline being dictated by the acceleration. Because the energy cost of-running uphill is known, this makes it possible to estimate the instantaneous energy cost of accelerated running, the corresponding instantaneous metabolic power, and the overall energy expenditure, provided that the speed (and acceleration) is known. Furthermore. the introduction of individual parameters makes it possible to customize performance profiles, especially as it concerns energy expenditure derived from anaerobic Sources. Data from 399 "Serie-A" players (mean +/- SD; age = 27 +/- 4 yr, mass = 75.8 +/- 5.0 kg, statute = 1.80 +/- 0.06 m) were collected during the 20072009 season. Results: Mean match distance was 10,950 +/- 1044 m, and average energy expenditure was 61.12 +/- 6.57 kJ.kg(-1). Total distance covered at high power (>20 W.kg(-1)) amounted to 26% and corresponding energy expenditure to approximately 42% of the total, "High intensities" expressed as high-power output are two to three times larger than those based only oil running speed. Conclusions: The present approach for the assessment of top-level soccer players match performance through video analysis allowed us to assess instantaneous metabolic power, thus redefining the concept of-high intensity" on the basis of actual metabolic power rather than on speed alone
Quantifying metabolic energy contributions in sprint running: a novel bioenergetic model
Get PDFPurpose: To develop a bioenergetic model representing the dynamics of metabolic power—including aerobic, anaerobic lactic, and anaerobic alactic contributions—during 100–400 m sprints. This study calculates maximum anaerobic capacities using sprint data and assesses the model’s ability to predict performance across various sprint distances. Methods: Sprint energetics were estimated applying di Prampero et al. (J Exp Biol 208:2809–2816, 2005) method using velocity and time-split data from the 2009 World Athletics Championships to model metabolic power over the men’s and women’s 100–200-400 m events. Aerobic power was modeled with an exponential function, anaerobic lactic power with a bi-exponential function, and anaerobic alactic power with a log-normal function. Maximal anaerobic lactic and alactic capacities were estimated from available performances. Simulations were made to predict the distance traveled by hypothetical male and female athletes achieving World Championship performances on the 100–200-400 m. Results: The model closely fit metabolic power trajectories (R2 = 0.94–0.98). Maximal anaerobic alactic capacities were 376 J kg−1 (male) and 259 J kg−1 (female), and maximal anaerobic lactic capacities were 1314 J kg−1 (male) and 1194 J kg−1 (female). Simulations of distance traveled revealed mean absolute errors of 0.31% and 1.63% for male and female, respectively. Higher female errors likely stem from underestimating anaerobic lactic contribution due to male-derived parameters and limited available data. Conclusion: This model aligns closely with theoretical bioenergetic principles and experimental findings, providing valuable insights that improve our understanding of sprint running energetics and performance. Further refinements, incorporating female-specific parameters and collecting data from various distances, could broaden the model’s applicability
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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