1,721,016 research outputs found
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
On the Autonomic Control of Heart Rate Variability: How the Mean Heart Rate Affects Spectral and Complexity Analysis and a Way to Mitigate Its Influence
Full text linkHeart Rate Variability (HRV) analysis allows for assessing autonomic control from the beat-by-beat dynamics of the time series of cardiac intervals. However, some HRV indices may strongly correlate with the mean heart rate, possibly flawed by the interpretation of HRV changes in terms of autonomic control. Therefore, this study aims to (1) investigate how HRV indices of fluctuation amplitude and multiscale complex dynamics of cardiac time series faithfully describe the autonomic control at different heart rates through a mathematical model of the generation of cardiac action potentials driven by realistically synthesized autonomic modulations; and (2) propose an alternative procedure of HRV analysis less sensitive to the mean heart rate. Results on the synthesized series confirm a strong dependency of amplitude indices of HRV on the mean heart rate due to a nonlinearity in the model, which can be removed by our procedure. Application of our procedure to real cardiac intervals recorded in different postures suggests that the dependency of these indices on the heart rate may importantly affect the physiological interpretation of HRV. By contrast, multiscale complexity indices do not substantially depend on the heart rate provided that multiscale analyses are defined on a time- rather than a beat-basis
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
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
IKr Impact on Repolarization and Its Variability Assessed by Dynamic Clamp
No full textBackground - Repolarization and its stability are exquisitely sensitive to IKr features. Information on the relative importance of specific IKr abnormalities is missing and would assist in the evaluation of arrhythmogenic risk. Methods and Results - In single Guinea-pig myocytes, endogenous IKr was replaced by modeled IKr (mIKr) by dynamic clamp (DC) at a cycle length of 1 s. mI Kr parameters were systematically modified, and the resulting changes in action potential duration (APD) and its short term variability (SD1) were measured. We observed that (1) I Kr blockade increased SD1 more than expected by its dependency on APD; (2) mI Kr completely reversed APD and SD1 changes caused by I Kr blockade; (3) repolarization was most sensitive to inactivation shifts, which affected APD and SD1 concordantly; (4) activation shifts of the same magnitude had marginal impact on APD, but only when reducing mI Kr, they significantly increased SD1; (5) changes in maximal conductance resulted in a pattern similar to that of activation shifts. Conclusions - The largest effect on repolarization and its stability are expected from changes in I Kr inactivation. APD is less sensitive to changes in other I Kr gating parameters, which are better revealed by SD1 changes. SD1 may be more sensitive than APD in detecting I Kr -dependent repolarization abnormalities
Combined action potential- and dynamic-clamp for accurate computational modelling of the cardiac IKr current
No full textIn the present work Action-Potential clamp (APC) and Dynamic clamp (DC) were used in combination in order to optimize the Luo-Rudy (LRd) mathematical formulation of the guinea-pig rapid delayed rectifier K(+) current (IKr), and to validate the optimized model. To this end, IKr model parameters were adjusted to fit the experimental E4031-sensitive current (IE4031) recorded under APC in guinea-pig myocytes. Currents generated by LRd model (ILRd) and the optimized one (IOpt) were then compared by testing their suitability to replace IE4031 under DC. Under APC, ILRd was significantly larger than IE4031 (mean current densities 0.51±0.01 vs 0.21±0.05pA/pF; p<0.001), mainly because of different rectification. IOpt mean density (0.17±0.01pA/pF) was similar to the IE4031 one (NS); moreover, IOpt accurately reproduced IE4031 distribution along the different AP phases. Models were then compared under DC by blocking native IKr (5μM E4031) and replacing it with ILRd or IOpt. Whereas injection of ILRd overshortened AP duration (APD90) (by 25% of its pre-block value), IOpt injection restored AP morphology and duration to overlap pre-block values. This study highlights the power of APC and DC for the identification of reliable formulations of ionic current models. An optimized model of IKr has been obtained which fully reversed E4031 effects on the AP. The model strongly diverged from the widely used Luo-Rudy formulation; this can be particularly relevant to the in silico analysis of AP prolongation caused by IKr blocking or alterations
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