1,720,982 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Adsorption model and phase transitions of diblock perfluoroalkylated surfactants at the water—alkane interface
Get PDFWe present a theory of the adsorption behaviour and phase transitions in monolayers of perfluoroalkylated alcohols,
, at the water∣oil interface, and validate it for a range of temperatures and surfactant structures. The reason for the observed cohesive behaviour is identified as dispersion attraction between the fluorocarbon blocks. The London constant is determined from the increment of the lateral attraction parameter with the size of the fluorocarbon chain. The monolayers exhibit phase transition from liquid expanded state to van der Waals crystal. However, they are supercritical with respect to the gas–liquid transition. For the description of the liquid phase, we use the sticky disc model – fluid monolayer made of hard discs interacting with a short-ranged sticky potential. For the crystalline phase, a two-dimensional cell model is developed using the same interaction potential. This new model coincides with the empirical equation of state of Jura and Harkins, and ascribes physical meaning to its parameters. We extend the theory of Ivanov et al. for the adsorption constant
to diblock molecules; it predicts accurately the dependence of
and the adsorption heat on the surfactant structure. An invariant phase diagram of the monolayers is constructed
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Effective osmotic cohesion due to the solvent molecules in a delocalized adsorbed monolayer.
Get PDFA molecular thermodynamic model is derived for an uncharged delocalized surfactant monolayer adsorbed at a liquid interface, taking explicit account for the solvent molecules present in the monolayer. The model is based on the scaled particle theory of hard-disc mixtures, and is also extended to sticky discs (i.e. attraction between the adsorbed molecules). Upon compression of the adsorbed layer, the solvent is expelled from it. The respective osmotic effect on the equation of state is shown to be equivalent to an effective lateral depletion attraction between the surfactant molecules. This effective osmotic cohesion causes an increase of the value of the attraction parameter β of the monolayer. The smaller the size of the surfactant polar head group is, the larger the effective attraction the model predicts. This trend is verified with data for the adsorption at water|air surface of alcohols, undissociated acids, and hexaethylenglycol monoalkyl ethers. The proposed theory allows the amount of solvent in the monolayer to be estimated, which is shown to be important for the neutron reflectivity of the surface
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Theory of adsorption of ethoxylates at the water | oil and water | air interfaces. 1. Monolayers of single-component and Poisson distributed alkylphenol ethoxylates.
Get PDFCurrently, the bulk thermodynamic properties of an arbitrary liquid mixture of oligomers are accessible with reasonable accuracy through popular 3D statistical models (SAFT, Flory-Huggins) under a wide range of conditions. These models are implemented in widely available software suites used for process design. The hypothesis investigated here is that the same is, in principle, achievable with monolayers of mixed surfactants on liquid surfaces. A molecular thermodynamic theory of the adsorption of alkylphenoxypolyethoxyethanols, CnH2n+1C6H4(OC2H4)mOH, on fluid interfaces is presented. It covers homologues of m = 0-10; water|alkane and water|gas interfaces; single surfactants and surfactant mixtures. The adsorption behaviour has been predicted as a function of the structure of the ethoxylated surfactants and the model has been validated against tensiometric data for forty systems. All values of the adsorption parameters have been either predicted, independently determined, or at least compared to a theoretical estimate. The single surfactant parameters have been used to predict the properties of 'normal' Poisson distributed mixtures of ethoxylates, in good agreement with literature data. Partitioning between water and oil, micellization, solubility and surface phase transitions are also discussed
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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