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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
Interactions of trialkyllead compounds with rat liver mitochondria.
No full textThe interactions of two trialkyllead (TAL) compounds, (trimethyl)Pb-Cl and (tributyl)Pb-Cl, with mitochodria from rat liver have been studied. A stimulation of the respiratory rate induced by the trialkyllead compounds added at low doses was observed which was not dependent on the presence of chloride in the medium. In contrast with the major current view, we propose that trialkyllead compounds behave as uncouplers of the oxidative phosphorylation and not (or not only) as Cl-/OH- exchangers. In fact the present results suggest that the TAL compounds enter the mitochondria as (alkyl)3Pb+ cations and are extruded as electroneutral (alkyl)3 Pb-OH compounds, the overall result being the transport of a proton through the membrane as in the case of classical uncouplers. The uncoupling effect could explain the toxicity of the compounds as a result of the decrease in the energy level of the cell. Furthermore, such a mechanism, in which the uptake of TAL compounds is supposed to be driven by a negative potential, could explain their preferential toxicity for neuronal cells, which maintain a higher negative-inside potential than most other cell types
Protective action of a new benzofuran derivative on lipid peroxidation and sulphydryl groups oxidation.
No full textThe antioxidant properties of a novel water-soluble antioxidant of the benzofuran family (5-hydroxy-4,6,7-trimethyl-2,3-dihydrobenzofuran-2-acetic acid, BFA) were studied. In rat liver mitochondria BFA increases the lag-time and decreases the extent of lipid peroxidation induced by ascorbate/Fe2+; an IC50 value of about 12 microM was observed. In rat liver microsomes it inhibits the lipid peroxidation induced both by NADPH/Fe2+/ADP (iron-dependent) and by cumene hydroperoxide (iron-independent), showing IC50 values of 25 and 30 microM respectively. The antioxidant efficiency of BFA is slightly higher than that of the congener compound Trolox C. BFA is also able to inhibit the oxidation of protein sulphydryl groups consequent to microsomal lipid peroxidation induced by NADPH/Fe2+/ADP. The antioxidant properties of BFA are discussed considering its hydrophilic character and pharmacological features
SOME EFFECTS OF FRUCTOSE-1,6-DIPHOSPHATE ON RAT MYOCARDIAL TISSUE RELATED TO A MEMBRANE-STABILIZING ACTION
No full textThis study aims at elucidating the mechanism of action of extracellular fructose-1 ,6-diphosphate (FDP). FDP is
able to inhibit Ca++ entry into the myocardial tissue with an IC50 value of 11·5 mM and in addition, it is bound by
rat heart slices, the binding being activated by Zn and conditions of chemical hypoxia induced by KCN and
iodoacetate. The overall effect of extracellular FDP includes an increase of frequency and amplitude of
contraction of perfused heart at concentration below l mM, and, in generai, a stimulation of the oxygen
consumption of the tissue. The antihaemolytic effect of FDP suggests its action as a membrane stabilizer. The
effects of extracellular FDP on the myocardial celi can be interpreted both on the basis of a limited permeability of
the celi membrane to it and as a purely extracellular effect transduced through the celi membrane with a final
response consisting of an increase in the intracellular FD
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
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