1,721,054 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
Thermotoga maritima AglA, an extremely thermostable NAD(+)-, Mn2+-, and thiol-dependent alpha-glucosidase
No full textThe gene for the alpha-glucosidase AglA of the hyperthermophilic bacterium Thermotoga maritima MSB8, which was identified by phenotypic screening of a T. maritima gene library, is located within a cluster of genes involved in the hydrolysis of starch and maltodextrins and the uptake of maltooligosaccharides. According to its primary structure as deduced from the nucleotide sequence of the gene, AglA belongs to family 4 of glycosyl hydrolases. The enzyme was recombinantly expressed in Escherichia coli, purified, and characterized. The T. maritima alpha-glucosidase has the unusual property of requiring NAD(+) and Mn2+ for activity. Co2+ and Ni2+ also activated AglA, albeit less efficiently than Mn2+ T. maritima AgLA represents the first example of a maltodextrin-degrading alpha-glucosidase with NAD(+) and Mn2+ requirement. In addition, AgLA activity depended on reducing conditions. This third requirement was met by the addition of dithiothreitol (DTT) or beta-mercaptoethanol to the assay. Using gel permeation chromatography, T. maritima AgLA behaved as a dimer (two identical 55-kDa subunits), irrespective of metal depletion or metal addition, and irrespective of the presence or absence of NAD(+) or DTT. The enzyme hydrolyzes maltose and other small maltooligosaccharides but is inactive against the polymeric substrate starch. AglA is not specific with respect to the configuration at the C-4 position of its substrates because glycosidic derivatives of D-galactose are also hydrolyzed. In the presence of all cofactors, maximum activity was recorded at pH 7.5 and 90 degrees C (4-min assay). AglA is the most thermoactive and the most thermostable member of glycosyl hydrolase family 4. When incubated at 50 degrees C and 70 degrees C, the recombinant enzyme suffered partial inactivation during the first hours of incubation, but thereafter the residual activity did not drop below about 50% and 20% of the initial value, respectively, within a period of 48 h
Biochemical properties and structural features of the thermostable maltodextrin transglycosidases from Thermotoga maritima
No full textMaltosyltransferase (MTase) is an extremely thermostable enzyme which, based on its primary structure, is classified into glycoside hydrolase family 13. The enzyme is a non-hydrolytic transglycosidase (maltodextrin glycosyltransferase, MGTase) which catalyses the transfer of maltosyl units from alpha-1,4-linked glucans or malto-oligosaccharides to other alpha-1,4-linked glucans, maltooligosaccharides or glucose. MTase represents the first exo-MGTase known. To date, the only organism known to produce a starch-converting enzyme with this unique reaction chemistry is the hyperthermophilic bacterium Thermotoga maritima, a strictly anaerobic heterotroph with a maximum growth temperature of 90degreesC. In addition to MTase, T. maritima possesses a second MGTase, 4-alpha-glucanotransferase (GTase), also a member of the glycoside hydrolase family,13. In contrast to MTase, GTase displays a broad transfer specificity. Recently, crystals of recombinant MTase and GTase have been obtained by the hanging-drop vapor-diffusion method, and the crystal structures of MTase and its complex with maltose have been determined at, 2.4 and 2.1 Angstrom resolution, respectively. In this communication, the enzymatic characteristics of MTase and GTase are reviewed, and structural features, possibly of importance for the unique transfer specificity and thermostability of MTase, are discussed
Biochemical properties and structural features of the thermostable maltodextrin transglycosidases from Thermotoga maritima
No full textMaltosyltransferase (MTase) is an extremely thermostable enzyme which, based on its primary structure, is classified into glycoside hydrolase family 13. The enzyme is a non-hydrolytic transglycosidase (maltodextrin glycosyltransferase, MGTase) which catalyses the transfer of maltosyl units from alpha-1,4-linked glucans or malto-oligosaccharides to other alpha-1,4-linked glucans, maltooligosaccharides or glucose. MTase represents the first exo-MGTase known. To date, the only organism known to produce a starch-converting enzyme with this unique reaction chemistry is the hyperthermophilic bacterium Thermotoga maritima, a strictly anaerobic heterotroph with a maximum growth temperature of 90degreesC. In addition to MTase, T. maritima possesses a second MGTase, 4-alpha-glucanotransferase (GTase), also a member of the glycoside hydrolase family,13. In contrast to MTase, GTase displays a broad transfer specificity. Recently, crystals of recombinant MTase and GTase have been obtained by the hanging-drop vapor-diffusion method, and the crystal structures of MTase and its complex with maltose have been determined at, 2.4 and 2.1 Angstrom resolution, respectively. In this communication, the enzymatic characteristics of MTase and GTase are reviewed, and structural features, possibly of importance for the unique transfer specificity and thermostability of MTase, are discussed
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
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