1,720,957 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
Properties of Rhodanese from the Liver of Tilapia Oreochromis Niloticus, in Asejire Lake, Nigeria
Get PDFStaff PublicationThe study investigates the purification and characterisation of rhodanese from the liver of the tilapia fish (Oreochromis niloticus) collected from Asejire Lake in Nigeria. This was with a view to understanding the biochemical basis of the survival of the fish in cyanide polluted water. Rhodanese was isolated and purified from liver tissue homogenate of tilapia using CM-Sephadex ion exchange chromatography and Sephadex G-75 gel filtration. The specific activity of the enzyme was 56.86 U/mg. The Km values for KCN and Na2S2O3 as substrates were 0.1240 ± 0.0021 mM and 0.0516 ± 0.0097 mM, respectively. The apparent molecular weight was estimated by gel filtration on a Sephacyl S-400 column to be 35,460 Da. The optimal activity was found at pH 6.5 and the temperature optimum was 40°C. The rhodanese enzyme showed that the activity of the enzyme was not affected by MgCl2, KCl, NH4Cl, MnCl2 and CaCl2 while AlCl3, inhibited the enzyme
Characterization of a cellulase from the haemolymph of the giant African snail (Archachatina marginata)
Get PDFThe giant African snails (Archachatina marginata) are herbivorous tropical gastropods. They are commonly located in areas littered with decaying vegetable matters which they feed on. When the haemolyph of this organism was passed through Sephadex G-200, the resin was digested. The ability of snails to digest vegetable matters and the digestion of Sephadex G-200 resin by the haemolyph led to the suspicion of the presence of cellulase in snail haemolyph. Cellulase from haemolyph of the giant African snail was purified to homogeneity by a combination of gel filtration on BioGel P-300 and ion-exchange chromatography on DEAE-Sephadex. The homogeneity of the pure enzyme was adjudged by polyacrylamide gel electrophoresis in the absence and presence of sodium dodecyl sulphate. The subunit molecular weight was 16,875±1,556 daltons and the apparent molecular weight as determined by gel filtration was 52,000 daltons. Thus, the enzyme is at least a dimer. The enzyme had a specific activity of 1359.09 units/mg of protein. The Michaelis-Menten constant (Kmax) for carboxymethyl (CM)-cellulose was 5.17± 0.74 mg/ml and the maximum velocity (Vmax) was 1067±195 units/ml. The enzyme did not degrade salicin, cellobiose and o-nitrophenyl-β-D-glucopyranoside. In addition, its activities towards filter paper and cotton wool were insignificant compared with its activity towards CM-Cellulose. Linamarin was found to inhibit the action of the enzyme to about 18%. The high specificity for CM-cellulose and the rapid decrease in the viscosity of CM-cellulose suggests that the enzyme is likely an endoglucanase.Key words: Snail, cellulase, endoglucanase, heamolymph, gastropod
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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