1,720,971 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
Reprocessable vinylogous urethane cross-linked polyethylene via reactive extrusion
No full textVitrimers are an emerging class of permanently cross-linked materials, where exchange reactions of
cross-links provide malleability. The most promising application of these materials is to impart reprocessability
to thermoset polymers, such as cross-linked polyethylene (PE). Here, a facile and easy to scale-up
method for the preparation of cross-linked PE vitrimers is presented by combining reactive extrusion and
injection molding using exchange reactions of vinylogous urethanes. Very low retention times (<15 min)
inside the extruder were required and the obtained elastomeric vitrimers have increased melt strength
and a cross-link density dependent plateau modulus. Control over the amount of cross-links per chain in
the final polymer was possible by varying the co-monomer feed in the preparation of the precursor polymers,
which allowed the tuning of the final material properties such as melt viscosity and rubber plateau
modulus. For polymers with an amount of >1.9 cross-links per chain, stress-relaxation is largely controlled
by the exchange reactions of vinylogous urethanes. It was found that the activation energy depended on
the cross-link density. Reprocessability of the vitrimers is demonstrated by four cycles of molding and
tensile strength testing revealing minor degradation of the material
Polyethylene vitrimers via silyl ether exchange reaction
Full text linkFunctional polyethylene (PE) bearing pendant hydroxyl groups was dynamically crosslinked via reactive extrusion using commercially available N,N0 -Bis[3-(trimethoxysilyl)propyl] ethylenediamine (TMSPEDA). This fast and efficient way allowed to produce PE vitrimers without synthetic effort or use of solvents, which makes the process environmentally friendly and easy to upscale. The dynamic crosslinking transformed thermoplastic PE into an elastic solid with greatly improved melt strength as revealed by DMTA and rheology. Mechanical properties could be tuned by varying the amount of TMSPEDA crosslinker. All prepared vitrimers were sparingly soluble in xylene and were not affected by moisture demonstrating crosslinked character, improved solvent resistance and excellent hydrolysis resistance which is of great importance for industrial applications. Despite the crosslink nature of the material, the dynamic silyl ether exchange enabled processability and recyclability of this system using industrially relevant techniques like injection and compression molding
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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