1,721,440 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
Manipulation of the fate of long chain polyunsaturated fatty acids in cultured cells
No full textWe have studied the biosynthesis of long chain polyunsaturated fatty acids (LC-PUFA) from their precursors in cultured cells undergoing physiological modifications, or under the influence of lipid-lowering drugs or ethanol. The formation of arachidonic acid (AA, 20:4 n-6) from the percursor linoleic acid (LA, 18:2 n-6) in the neuroblastoma cells SK-N-BE is enhanced at early stages of differentiation, and declines when differentiation is complete, in concomitance with maximal accumulation of AA in cell lipids. In the monocytic cells THP-1, the biosynthesis of LC-PUFA is also enhanced by treatment with the HMGCoA reductase inhibitor simvastatin (S), an effect which is reverted by mevalonate and other intermediates of cholesterol synthesis. Maximal activation of LC-PUFA synthesis by S occurs at concentrations lower than those required for maximal inhibition of cholesterol synthesis. In the hepatoma cells HepG2, ethanol decreases the biosynthesis of LC-PUFA while potentiating the incorporation of acetate into cholesterol. LC-PUFA synthesis appears thus to be modulated in the course of cell differentiation and complex interactions between LC-PUFA and cholesterol synthesis occur, as judged from data obtained through pharmacological manipulations
The intake of long chain omega-3 fatty acids through fish versus capsules results in greater increments of their plasma levels in healthy subjects
No full textDietary intake of fish vs. formulations leads to higher plasma concentrations of n-3 fatty acids
No full textThe n-3 fatty acids from fish appear to be more efficacious, in terms of cardioprotection, than equivalent amounts provided as capsules. Volunteers were given, for 6 wk, either 100 g/d of salmon, providing 383 mg of EPA and 544 mg of DHA, esterified in glycerol lipids, or 1 or 3 capsules of fish oil/d, providing 150 mg of EPA and 106 mg of DHA or 450 mg of EPA and 318 mg of DHA, as ethyl esters. Further, we reevaluated data from a previous study carried out with the same design, i.e., with 3 and 6 capsules/d of fish oil, providing 1290 and 2580 mg/d EPA and 960 and 1920 mg/d DHA. Marked increments in plasma EPA and DHA concentrations (mug/mg total lipid) and percentages of total fatty acids were recorded at the end of treatment with either n-3 capsules or salmon. Net increments of EPA and DHA in plasma lipids were linearly and significantly correlated with the dose after capsule administration. Further, increments in plasma EPA and DHA concentration after salmon intake were significantly higher than after administration of capsules. The same increments would be obtained with at least two- and ninefold higher doses of EPA and DHA, respectively, if administered with capsules rather than salmon. We provide experimental evidence that n-3 fatty acids from fish are more effectively incorporated into plasma lipids than when administered as capsules and that increments in plasma concentrations of EPA and DHA given as capsules are linearly correlated with their intakes
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
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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