1,720,981 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
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
Polimerización radical viviente de mirceno a través del proceso RAFT
No full text"Monomers from renewable sources, such as terpenes, have become a focus of interest for polymer chemistry. Myrcene, a single monoterpene was quite polymerized in this work through the technology of reversible addition-fragmentation chain-transfer polymerization (RAFT) in bulk, using for the first time the chain transfer agents (CTA). The polymerization systems were carried out at temperatures of 65°C and 90°C varying the initiator / CTA ratios for each of the dithiobenzoates. The polymerizations made to measure a kinetic of pseudo first order with a linear growth of the molar masses with respect to the conversion, with a range of
polydispersity (PDI) between 1.29 to 4.41 with the polymerizations at 90°C which are major PDI for both CTAs. The conversion values were low in comparation with its analogous polymerizations by free radicals, but with the large difference of polymyrcene by RAFT it acquired a characteristic color of the CTA and the absence of some type of cross-linking. The study of NMR microstructure of the polymer showed 91% of the 1,4 addition with the coexistence of its cis and trans isomers. The extension of the polymer chain with styrene by RAFT polymerization was carried out as a macro chain transfer agent to the polymyrcene synthetized previously by RAFT resulting in a block copolymer wich maintained a low polydispersity. The formation of copolymer confirmed the ends of the dithiobenzoate chain of the polymyrcene used.
Liberación de doxorrubicina en células MCF-7 utilizando nanopartículas de sílice modificadas con poli (B-amino éster)
No full textEl cáncer es una de las principales enfermedades causantes de un alto índice de muertes a nivel mundial, debido a esto, se han desarrollado diversas terapias para eliminar a las células cancerosas. Una de las estrategias es la quimioterapia, que implica el uso de fármacos antineoplásicos para eliminar las células cancerosas o inhibir su crecimiento. Sin embargo, estos fármacos suelen tener efectos secundarios adversos al actuar indiscriminadamente sobre las células en división de todo el organismo. De esta forma, se han desarrollado sistemas de liberación focalizada, cuyo objetivo es liberar el fármaco en el sitio de interés sin dañar a las células sanas. De esta manera se han sintetizado nanopartículas recubiertas con polímeros hidrolizables ante estímulos, como el pH ácido debido al pH del microambiente que presentan los tumores (6.5-5.5). Sin embargo, aún existe un limitado número de investigaciones sobre la evaluación de la liberación in vitro y la acción específica de estos sistemas sobre las células cancerosas. Por tal motivo, en esta investigación se propuso evaluar la toxicidad de un nuevo sistema de liberación compuesto de nanopartículas mesoporosas de sílice recubiertas con Poli (β-amino éster) y cargado con el fármaco doxorrubicina, sobre las líneas celulares de cáncer de mama MCF-7 y sana de fibroblastos humanos hFB. Para lograrlo, el trabajo se dividió en tres etapas. En la primera etapa se sintetizaron las nanopartículas mesoporosas de sílice (NMS) y a su vez el polímero que las recubrió, el cuál fue Poli (β-amino éster) (PbAE), posteriormente, dichos materiales fueron caracterizados mediante las técnicas SEM, TEM, SARXD, FTIR, RMN y TGA. En la segunda etapa, la doxorrubicina (DOX) se encapsuló en el complejo NMS-PbAE, previamente sintetizado y, por último, el complejo NMS-PbAE-DOX fue probado en las líneas celulares MCF-7 y hFB. Después de la confirmación de la síntesis del complejo de liberación, se demostró citotoxicidad con el complejo NMS-PbAE-DOX sobre ambas líneas celulares. Sin embargo, en células MCF-7, el complejo demostró una mayor toxicidad que la DOX libre. Lo que puede sugerir que en este tipo de células hubo una mayor internalización mediada por las nanopartículas. Sin embargo, con los ensayos realizados no fue posible establecer una acción diferencial del complejo entre ambas líneas celulares. Esto porque se demostró que el pH desciende durante el cultivo in vitro de manera similar, a un pH ácido en el rango de liberación del complejo. Por tal motivo, estudios con otros modelos como cultivos en 3D o in vivo deben ser realizados para demostrar la acción específica de este sistema de liberación sobre células de cáncer
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
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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