1,720,956 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
Cell volume in the regulation of cell proliferation and apoptotic cell death
No full textCell proliferation must - at some time point - lead to increase of cell volume and one of the hallmarks of apoptosis is cell shrinkage. At constant extracellular osmolarity those alterations of cell volume must reflect respective changes of cellular osmolarity which are hardly possible without the participation of cell volume regulatory mechanisms. Indeed, as shown for ras oncogene expressing 3T3 fibroblasts, cell proliferation is paralleled by activation of Na(+)/H(+) exchange and Na(+),K(+),2Cl(-) cotransport, the major transport systems accomplishing regulatory cell volume increase. Conversely, as evident from CD95-induced apoptotic cell death, apoptosis is paralleled by inhibition of Na(+)/H(+) exchanger and by activation of Cl(-) channels and release of the organic osmolyte taurine, major components of regulatory cell volume decrease. However, ras oncogene activation leads to activation and CD95 receptor triggering to inhibition of K(+) channels. The effects counteract the respective cell volume changes. Presumably, they serve to regulate cell membrane potential, which is decisive for Ca(++) entry through I(CRAC) and the generation of cytosolic Ca(++) oscillations in proliferating cells. As a matter of fact I(CRAC) is activated in ras oncogene expressing cells and inhibited in CD95-triggered cells. Activation of K(+) channels and Na(+)/H(+) exchanger as well as Ca(++) oscillations have been observed in a wide variety of cells upon exposure to diverse mitogenic factors. Conversely, diverse apoptotic factors have been shown to activate Cl(-) channels and organic osmolyte release. Inhibition of K(+) channels is apparently, however, not a constant phenomenon paralleling apoptosis which in some cells may even require the operation of K(+) channels. Moreover, cell proliferation may at some point require activation of Cl(-) channels. In any case, the alterations of cell volume are obviously important for the outcome, as cell shrinkage impedes cell proliferation and apoptosis can be elicited by increase of extracellular osmolarity. At this stage little is known about the interplay of cell volume regulatory mechanisms and the cellular machinery leading to mitosis or death of the cell. Thus, considerable further experimental effort is required in this exciting area of cell physiology
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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