1,722,061 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
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
Stellar evolution with turbulent diffusion .2. The HR diagram of supergiant stars
No full textWe present new evolutionary models for high and intermediate mass stars in which the fully convective regions (inner cores, external envelopes and intermediate shells) are let extend into their surrounding regions of overshoot. However,in these layers instead of assuming mixing to be instantaneous and fully efficient, we treat it according to the diffusive scheme elaborated by Deng et al. (1996a). The major difference with respect to standard stellar models is that, while fully unstable regions turn out to be completely homogenized by the diffusive algorithm in use, this is not the case for the overshoot regions which undergo partial mixing and build up smooth chemical profiles. The diffusion algorithm makes use of the so-called scale length most effective for mixing expressed as l(d) = P-dif X 10(-5) l(o), where l(o) is the largest scale in the unstable region in units of the local cal pressure scale height Hp, and finally P-dif is a fine tuning parameter of the order of unity (see the text for more details). The analysis by Deng et al. (1996a) has clarified that P-dif = 0.4 leads to stellar models that are able to match a number of properties of massive and intermediate mass stars. The characterizing feature of these models is that they possess at the same time evolutionary characteristics that were separately typical of model calculated with different schemes of mixing. In other words, they share the same properties of models with standard overshoot, namely a wider main sequence band, higher luminosity, and longer lifetimes, but also perform extended loops that are the main signature of the semiconvective description of convection at the border of the core. The stellar models presented in this paper span the mass range 5 to 100 M(.) and go from the zero age main sequence to the stage of central He-exhaustion. They have been calculated assuming P-dif = 0.4 over the whole range of masses. Two sets of initial chemical compositions are considered, namely [Z=0.008 and Y=0.25] suited to the Large Magellanic Cloud (LMC) supergiant stars, and [Z=0.020 and Y=0.28] suited to the same stars in the solar vicinity. With the aid of these stellar models we analyze the HR diagram (HRD) of supergiant stars in the LMC by Fitzpatrick & Garmany (1990) and that of supergiant stars in the Milky Way by Blaha & Humphreys (1989). Particular attention is paid to the star counts across the HRD, the stars in the Hertzsprung-Russell gap and related possible widening of the main sequence band, the so-called ledge, the ratio of blue to red supergiants N-B/N-R, the location of Wolf-Rayet stars (WR), and the blue progenitor of the SN 1987A. We find that taking into account a plausible scatter in the chemical composition of the supergiant stars in the samples, the many stars in the gap and the ledge can be easily accounted for. However, problems remains as far as the number frequencies of stars among the various spectral types, the possibility that the main sequence band can extend to spectral types up to B3, and the ratio N-B/N-R. Furthermore, despite the net advantages offered by these new stellar models with diffusive mixing, the location of WR stars in the CMD encounters the same difficulties as with the classical models. We suggest that a distinct evolutionary scenario must be invoked for this type of stars (Deng et al. 1996b). Finally, the blue progenitor of SN 1987A is not matched by the models, even if clues can be found within the same evolutionary scheme for a possible way out
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Stellar evolution with turbulent diffusion .1. A new formalism of mixing
No full textIn this paper we present a new formulation of diffusive mixing in stellar interiors aimed at casting light on the kind of mixing that should take place in the so-called overshoot regions surrounding fully convective zones. Key points of the analysis are the inclusion the concept of scale length most effective for mixing, by means of which the diffusion coefficient is formulated, and the inclusion of intermittence and stirring, two properties of turbulence known from laboratory fluid dynamics. The formalism is applied to follow the evolution of a 20 M(.) star with composition Z=0.008 and Y=0.25. Depending on the value of the diffusion coefficient holding in the overshoot region, the evolutionary behaviour of the test stars goes from the case of virtually no mixing (semiconvective like structures) to that of full mixing over there (standard overshoot models). Indeed, the efficiency of mixing in this region drives the extension of the intermediate fully convective shell developing at the onset of the shell H-burning, and in turn the path in the HR Diagram (HRD). Models with low efficiency of mixing burn helium in the core at high effective temperatures, models with intermediate efficiency perform extended loops in the HRD, finally models with high efficiency spend the whole core He-burning phase at low effective temperatures. In order to cast light on this important point of stellar structure, we test whether or not in the regions of the H-burning shell a convective layer can develop. More precisely, we examine whether the Schwarzschild or the Ledoux criterion ought to be adopted in this region. Furthermore, we test the response of stellar models to the kind of mixing supposed to occur in the H-burning shell regions. Finally, comparing the time scale of thermal dissipation to the evolutionary time scale, we get the conclusion that no mixing in this region should occur. The models with intermediate efficiency of mixing and no mixing at all in the shell H-burning regions are of particular interest as they possess at the same time evolutionary characteristics that are separately typical of models calculated with different schemes of mixing. In other words, the new models share the same properties of models with standard overshoot, namely a wider main sequence band, higher luminosity, and longer lifetimes than classical models, but they also possess extended loops that are the main signature of the classical (semiconvective) description of convection at the border of the core
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