1,720,963 research outputs found

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

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    “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

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    We 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

    Pregnancy induced hypertension: a role for peroxidation in microvillus plasma membranes.

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    Abstract It has been recently hypothesized that in PIH a placental oxidant- antioxidant imbalance might cause the release of lipoperoxidation products into the circulation, with subsequent damage of endothelial cell membranes. In this hypothesis the endothelial cell and further increase in circulating lipoperoxide levels, which are by themselves able to induce smooth muscle constriction and increased pressor responsiveness to angiotensin II. In order to investigate this issue, we studied the basal content of lipid peroxides in terms of malondialdehyde (MDA) in the syncytiotrophoblast plasma membranes (SPM) from PIH women. Moreover, we investigated the susceptibility to peroxidation of SPM using an in vitro oxidative stress as a tool to verify the predisposition to the in vivo development of peroxidation products. The fatty acid composition of the membranes was also analyzed. Microvillus membrane lipoperoxide concentrations were significantly increased in PIH women (62.8 ± 7.6 ng MDA/mg prot) compared with healthy pregnant subjects (37.6 ± 4.8 ng MDA/mg prot; p < 0.01). The formation of TBARS under the action of phenylhydrazine was significantly greater in PIH women (90.3 ± 7.4 mmol MDA/mol cholesterol) than in normal pregnant subjects (68.6 ± 6.4 mmol MDA/mol cholesterol; p < 0.01). In PIH microvillus membrane we also observed a significant increase of the content of polyunsaturated arachidonic acid. The increased susceptibility to oxidative stress of SPMs from PIH women might be due either to reduced antioxidant systems or to an abnormality of the lipid composition of the membrane. The present work also demonstrated in PIH a reduction in the SPM content of saturated fatty acids with an increase in polyunsaturated fatty acids, which are the major substrate for peroxidation. On the other hand, the higher lipoperoxidation may be due to the observed increased susceptibility to peroxidative stress, to a primary reduction in placental perfusion with tissue hypoxia or to both factors, which can potentiate each other
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