1,720,962 research outputs found
Rheological manifestation of the second self-similar structure in gelation process of PAN/DMSO/H2O system
No full textThe gelation process in Polyacrylonitrile (PAN)/Dimethyl Sulfoxide (DMSO)/Water (H2O) systems was studied by rheology. Chambon-Winter criterion was used to detect the critical gelation temperature variation. Interestingly, we found that the loss tangent coincided at two different temperatures in different frequency periods with the temperature decreased. By using the physical and mathematical analysis, we were able to tell that the first one was the critical sol-gel transition temperature, which appeared at higher temperatures under lower frequencies; and the second point was an indication of another self-similar structure, which appeared at lower temperatures under higher frequencies. We analyzed the coarsening mechanism in the gelation process of ternary blends, and considered that the volume growth of the physical linkage can interpret this unusual phenomenon. A 'Joint Point to Joint Section' model, similar to nucleation process, was proposed to interpret the mechanism of the growth of the physical linkages. Based on the above data, phase boundaries of critical gel and the second self-similar structure can be drawn. As the PAN or water content increased, both transition temperatures increased, which indicated the non-solvent water favored the aggregation of PAN molecules and promoted the forming of the second self-similar structure. (C) 2015 Elsevier Ltd. All rights reserved
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
The interplay between gelation and phase separation in PAN/DMSO/H2O blends and the resulted critical gels
No full textIsothermal aging experiments are carried out in Polyacrylonitrile/Dimethylsulfoxide/H2O (PAN/DMSO/H2O) blends, and rheological and optical methods are used to investigate the interplay between phase separation and gelation. Two types of gel structures are found. In most samples, gelation is induced by phase separation in PAN concentrated regions, yet it will subsequently slow the kinetics of phase separation down by altering the concentration balance and fluctuation. As a result, the drop of light transmittance becomes slower and a phenomenon called "RT reversal" is observed. At last, the phase separated morphology is replaced by gel structure, which inherits the inhomogeneity in PAN content distribution. Another type of gel grows from homogeneous solution and its structure disperses uniformly in space. Moreover, the temperature dependence of critical gel properties, like its size limits and thermodynamics, is discussed. It is found that the self-similar structure in homogeneous critical gel covers wider length scales and possesses stronger gel stiffness than those of inhomogeneous ones. The activation energy for gelation is also calculated, which reveals no obvious dependence on original PAN concentration or temperature
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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