1,720,955 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
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
Mechanistic insights into Lewis and Brønsted acid catalyzed conversion of sugars to platform furan derivatives in aqueous media
No full textBiomass, the only renewable source of organic carbon, can play a key role in mitigating the rising concerns over greenhouse gas emissions and diminishing petroleum reserves. A promising approach in this regard entails biomass conversion to furanic compounds that have potential to substitute petroleum precursors in producing chemicals, polymers, and fuels. This thesis is focused on gaining thermodynamic, catalytic, and mechanistic insights into the production of versatile platform furan derivatives 5-(hydroxymethyl)furfural (HMF) and furfural from biomass derived simple sugars, glucose and xylose, respectively, in aqueous media. ☐ The role of solvent in the thermochemistry of sugar dehydration reactions has been investigated. The reaction free energies were calculated using ab initio (G4) calculations combined with the COSMO-SAC solvation model. It is shown that aldose (glucose, xylose)-to-ketose (fructose, xylulose) isomerization is an equilibrium-limited reaction, whereas the ketose dehydration to the respective furan derivative is practically an irreversible reaction. Further, the choice of solvent can affect product distribution in biomass conversion; as an example, a small fraction of water in organic media suppresses anhydroglucose formation from glucose and can improve HMF selectivity. ☐ In kinetic experiments, we found that the Brønsted acid catalyzed sugar dehydration strongly depends on its molecular structure. The ketose dehydration to the respective furan derivative is much faster than the aldose dehydration. High yields of furfural (~75%) and HMF (~60%) from xylose and glucose, respectively, were obtained by combining the aldose-ketose isomerization with the ketose dehydration in a cascade of reactions in aqueous media at much lower temperature (413 K) than reported earlier. This is achieved using a Lewis acid (CrCl3 or Sn-beta) as the isomerization catalyst with a Brønsted acid (HCl or Amberlyst-15) as the dehydration catalyst in a single reactor. ☐ In order to gain mechanistic insights, the role of various metal ions in the aldose-ketose isomerization using a metal salt such as CrCl3 and AlCl3, has been investigated. Speciation of the metal salts in aqueous media was modeled, and used in conjunction with kinetics experiments; we revealed for the first time that the partially hydrolyzed ions, [Cr(H2O)5OH]2+ or [Al(H2O)5OH]2+, respectively, are the most active species for the aldose-ketose isomerization. Additionally, complex interactions between the Lewis and Brønsted acid catalysts have been explained in the sugar conversion: Brønsted acid decelerates the aldose-ketose isomerization by suppressing the equilibrium concentration of the partially hydrolyzed ions, whereas the Lewis acid promotes side reactions during fructose dehydration and HMF rehydration reactions. Thus, the catalyst loading and reactions conditions in sugar conversion need to be optimized. ☐ A strong interaction between the Cr cation and the glucose molecule in the first coordination sphere of the metal ion is indicated using extended X-ray absorption fine structure spectroscopy analysis and Car-Parrinello molecular dynamics simulation. More interestingly, mechanistic similarities are revealed among the homogeneous (CrCl3, AlCl3) and heterogeneous (Sn-beta) catalysts for the aldose-ketose isomerization using isotopic-labeling experiments. An intra-hydride transfer (C2 to C1) is the dominant reaction channel for the isomerization and a Lewis acid-Brønsted base bifunctional site is the most active site for all three catalysts. A reaction mechanism has been proposed for the Lewis acid-catalyzed isomerization and the energetics of the reaction pathway was calculated using ab initio for the Sn-beta catalyzed isomerization. Mechanistic insights are qualitatively consistent with the experimental data. ☐ The reaction mechanism of the Brønsted acid catalyzed fructose dehydration to HMF was investigated using isotopic-labeling experiments with nuclear magnetic resonance spectroscopy (NMR). The hydrogen transfer from C1 is the rate limiting step in the dehydration mechanism in both water and dimethyl sulfoxide (DMSO). Additionally, resonances corresponding to alkene and carbonyl groups were observed that compare well with an intermediate identified in the fructose dehydration reaction in DMSO. These observations suggest that the fructose dehydration in water and DMSO follows a similar reaction mechanism.University of Delaware, Department of Chemical EngineeringPh.
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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