1,721,556 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
Dynamic expression of homeostatic ion channels in differentiated cortical astrocytes in vitro
Full text linkThe capacity of astrocytes to adapt their biochemical and functional features upon physiological and pathological stimuli is a
fundamental property at the basis of their ability to regulate the homeostasis of the central nervous system (CNS). It is well
known that in primary cultured astrocytes, the expression of plasma membrane ion channels and transporters involved in
homeostatic tasks does not closely reflect the pattern observed in vivo. The individuation of culture conditions that promote
the expression of the ion channel array found in vivo is crucial when aiming at investigating the mechanisms underlying their
dynamics upon various physiological and pathological stimuli. A chemically defined medium containing growth factors and
hormones (G5) was previously shown to induce the growth, differentiation, and maturation of primary cultured astrocytes.
Here we report that under these culture conditions, rat cortical astrocytes undergo robust morphological changes acquir-
ing a multi-branched phenotype, which develops gradually during the 2-week period of culturing. The shape changes were
paralleled by variations in passive membrane properties and background conductance owing to the differential temporal
development of inwardly rectifying chloride (Cl−) and potassium (K+) currents. Confocal and immunoblot analyses showed
that morphologically differentiated astrocytes displayed a large increase in the expression of the inward rectifier Cl− and K+
channels ClC-2 and Kir4.1, respectively, which are relevant ion channels in vivo. Finally, they exhibited a large diminution
of the intermediate filaments glial fibrillary acidic protein (GFAP) and vimentin which are upregulated in reactive astrocytes
in vivo. Taken together the data indicate that long-term culturing of cortical astrocytes in this chemical-defined medium
promotes a quiescent functional phenotype. This culture model could aid to address the regulation of ion channel expression
involved in CNS homeostasis in response to physiological and pathological challenge
Structural and functional modularity of voltage-gated potassium channels
No full textSequence similarity among known potassium channels indicates the voltage-gated potassium channels consist of two modules: the N-terminal portion of the channel up to and including transmembrane segment S4, called in this paper the 'sensor' module, and the C-terminal portion from transmembrane segment S5 onwards, called the 'pore' module. We investigated the functional role of these modules by constructing chimeric channels which combine the 'sensor' from one native voltage-gated channel, mKv1.1, with the 'pore' from another, Shaker H4, and vice versa. Functional studies of the wild type and chimeric channels show that these modules can operate outside their native context. Each channel has a unique conductance-voltage relation. Channels incorporating the mKv1.1 sensor module have similar rates of activation while channels having the Shaker pore module show similar rates of deactivation. This observation suggests the mKv1.1 sensor module limits activation and the Shaker pore module determines deactivation. We propose a model that explains the observed equilibrium and kinetic properties of the chimeric constructs in terms of the characteristics of the native modules and a novel type of intrasubunit cooperativity. The properties ascribed to the modules are the same whether the modules function in their native context or have been assembled into a chimera
pH modulation of an inward rectifier chloride current in cultured rat cortical astrocytes
No full textThe effects of changes in extra- and intracellular pH in the pathophysiological range (6.0-8.0) on astroglial plasma membrane ionic currents were investigated with the whole-cell patch-clamp technique. In cultured rat neocortical type-1 astrocytes differentiated by a long-term treatment with dibutyryl cyclic-AMP, exposure to an extracellular pH of 6.4 induced, as compared with the control extracellular pH at 7.3, a sustained and reversible increase in the holding current at -60mV. The rise in current was accompanied by a decrease in the apparent input resistance. Ion substitution experiments indicated that extracellular pH 6.4 upregulated the resting Cl- conductance, whereas an opposite effect could be observed at extracellular pH 8.0. Recordings of isolated Cl- currents showed that this modulation occurred on the previously identified hyperpolarization-activated, inwardly rectifying Cl- current, I(Clh). Extracellular acidification to pH 6.4 shifted the voltage dependence of I(Clh) activation by ~20mV towards more positive potentials, whereas a ~20mV opposite shift was observed upon exposure to extracellular pH 8.0. These effects were paralleled by an increase (extracellular pH 6.4) or decrease (extracellular pH 8.0) in the maximal conductance. Decreasing (6.0) or increasing (8.0) the intracellular pH shifted the steady-state activation of I(Clh) towards more negative or positive potentials, respectively, leaving unchanged the current sensitivity to extracellular pH modifications.The modulation of the inward rectifier Cl- current expressed by differentiated cultured neocortical astrocytes indicates that extra- and intracellular changes in pH occurring in a pathophysiological range may contribute to regulating Cl- accumulation in astroglial cells. Copyright (C) 2000 IBRO
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
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