1,721,175 research outputs found
A patch-clamp study of bovine chromaffin cells and of their sensitivity to acetylcholine.
No full textBovine chromaffin cells were enzymatically isolated and kept in short term tissue culture. Their electrical properties were studied using recent advances of the patch-clamp technique (Hamill, Marty, Neher, Sakmann & Sigworth, 1981). 2. When a patch pipette was sealed tightly to a chromaffin cell ('cell-attached configuration') current wave forms due to intracellular action potentials could be observed. The frequency of the wave forms was altered by changing the pipette potential. When acetylcholine was present in the pipette solution, acetylcholine-induced single channel currents were evident in the patch recording. Action potential wave forms were then often seen to follow acetycholine-induced single channel currents. 3. In the cell-attached configuration, large single channel current events did not resemble square pulses but showed exponential relaxations with time constants of the order of 50 ms. 4. After rupture of the patch of membrane, the pipette--cell seal remained stable ('whole-cell recording', Hamill et al. 1981). Chromaffin cells were found to have a resting potential of -50 to -80 mV, and an input resistance around 5 G omega. The high cell resistance accounts for the relaxing currents evident in the cell-attached configuration. 5. In the best cases, the effective time constant of the voltage clamp in the whole-cell recording mode was 15 microseconds. Exchange of small ions such as Na+ ions between pipette and cell interior solutions was then complete within 15 s. 6. Acetylcholine-induced currents were obtained at various acetylcholine concentrations. Single acetylcholine-induced channels had a slope conductance of 44 pS between -100 and -55 mV, and a mean duration of 27 ms at -80 mV (at room temperature)
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
A guide to cost-effectiveness acceptability curves
Full text linkUse of cost-effectiveness acceptability curves, as a method for summarising information on uncertainty in cost-effectiveness, has become widespread within applied studies. This includes several studies in the mental health field. This editorial uses examples from recent papers to illustrate how cost-effectiveness acceptability curves are constructed, what they represent and how they should be interpreted
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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