1,720,966 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
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
Counterion complexation by calixarene ligands in cesium and potassium dodecyl sulfate micelles. A small angle neutron scattering study
No full textCesium and potassium dodecyl sulfate micellar solutions have been studied in the presence of three calix[4]arene-crown ethers able to complex cesium and potassium micellar counterions in a selective way (C(8)Cal-6 and C(3)Cal-6 for Csi and C(3)Cal-5 for K(+)). The cesium or potassium dodecyl sulfate micelles are modeled as two-shell ellipsoids. The surfactant dodecyl chains and part of the calix-crown ligands are located in the micelle hydrophobic core. Intermicellar correlations are calculated according to a multicomponent primitive model in a mean spherical approximation with a nonadditive diameter (NARMMSA). We found that calix-crown derivatives addition to cesium dodecyl sulfate micellar solutions leads to a generalized increase of the micelle aggregation number, a consistent decrease of the micelle ionization, and a micellar grow toward elongated ellipsoids. However, the addition of calixarene molecules to potassium dodecyl sulfate produces only a slight decrease of the micellar charge
Counterion complexation of calixarene ligands in monolayers and micellar solutions
No full textCalix[n]arenes and their derivatives are currently the object of several studies, due to their peculiar cavity, that is suitable for very specific and efficient complexation of ions and small organic molecules, with a high degree of efficiency and selectivity, and form host-guest systems in the solid and in the liquid state. Besides some very important applications as ion carriers and cages, they can be used for studying the counterion distribution in micellar aggregates formed by anionic amphiphiles such as alkyl-sulfates. In this paper we report the studies on the complexing properties of a new calixarene derivative, namely the 1,3-dioctyloxy-calix[4]arene-crown-6-ether (CAL), that shows a high selectivity for cesium ions, at the air/water interface and in aqueous micellar solutions of cesium dodecyl sulfate. Langmuir surface pressure (pi/A) isotherms were performed in order to study the stability of CAL films and the effect of cesium and potassium ions on the monolayer properties. In addition, small-angle neutron-scattering (SANS) experiments were carried out in order to determine the structure of the micellar system, and the interactions between the ligand and the micellar interface. Our study shows that the charge screening at the micellar interface is the predominant phenomenon that rules over the ion transport across liquid membranes, that is usually performed by macrocyclic ligands
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