1,720,956 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
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
Stammentwicklung zur heterologen Expression von Sekundärstoffclustern in Aktinobakterien
No full textIn this study we could show the biosynthetic potential of the genus Streptomyces by sequencing the genome of Streptomyces fulvissimus, which revealed 32 putative biosynthetic gene clusters. We were able to elucidate the biosynthesis of the macrodiolide antibiotic pamamycin by knocking out responsible genes in the pamamycin biosynthetic cluster and analyzing the resulting intermediates. We could show that succinyl-CoA is utilized as a starter unit and either malonyl-CoA, methylmalonyl-CoA or ethylmalonyl-CoA are used as extender units in pamamycin biosynthesis. The knowledge of the pamamycin biosynthesis was used to engineer our heterologous host, the model organism Streptomyces albus J1074, in a specific direction. We focused our efforts to reduce or abolish the cellular concentration of methylmalonyl-CoA and ethylmalonyl-CoA in S. albus J1074 to reduce the compound spectrum of produced pamamycins. We could greatly influence the compound spectrum and we could identify the bottleneck of pamamycin production as succinyl-CoA. We could also prove that the metabolism of valine is the sole provider for the biosynthesis of pamamycin. Furthermore we could show the dependency of antibiotic production on gene dosage and we could increase the production of several secondary metabolites by increasing the number of clusters present on the genome.Wir konnten das genetische Potential des Genus Streptomyces anhand der kompletten Genom-Sequenz von Streptomyces fulvissimus, der 32 putative Biosynthese-Gencluster besitzt, zeigen. Außerdem konnten wir die Biosynthese des Makrodiolid-Antibiotikums Pamamycin aufklären, indem die für die Biosynthese verantwortlichen Gene ausgeknockt und die daraus entstandenen Intermediate nachgewiesen wurden. In der Pamamycin-Biosynthese wird Succinyl-CoA als Startereinheit verwendet, auf welche entweder Malonyl-CoA, Methylmalonyl-CoA oder Ethylmalonyl-CoA als weitere Bausteine folgen können. Dieses Wissen nutzten wir, um unseren heterologen Stamm Streptomyces albus J1074 gezielt zu verändern. Unser Ziel war es, die intrazellulären Konzentrationen von Methylmalonyl-CoA und Ethylmalonyl-CoA in S. albus zu verringern um das Substanzspektrum der produzierten Pamamycine einzuschränken. Wir konnten das Substanzspektrum der produzierten Pamamycine stark beeinflussen, dadurch Succinyl-CoA als den limitierenden Faktor der Biosynthese identifizieren, und nachweisen, dass sich die Pamamycin-Biosynthese ausschließlich aus dem Metabolismus von Valin speist. Durch das Einbringen mehrerer Biosynthesegencluster in denselben genetischen Hintergrund konnten wir die Produktion verschiedener Antibiotika steigern und dadurch zeigen, dass die Sekundärstoffproduktion von der Anzahl der Gencluster abhängig ist
Strain development for heterologous expression of secondary metabolite clusters in actinobacteria
Full text linkIn this study we could show the biosynthetic potential of the genus Streptomyces by sequencing the genome of Streptomyces fulvissimus, which revealed 32 putative biosynthetic gene clusters. We were able to elucidate the biosynthesis of the macrodiolide antibiotic pamamycin by knocking out responsible genes in the pamamycin biosynthetic cluster and analyzing the resulting intermediates. We could show that succinyl-CoA is utilized as a starter unit and either malonyl-CoA, methylmalonyl-CoA or ethylmalonyl-CoA are used as extender units in pamamycin biosynthesis. The knowledge of the pamamycin biosynthesis was used to engineer our heterologous host, the model organism Streptomyces albus J1074, in a specific direction. We focused our efforts to reduce or abolish the cellular concentration of methylmalonyl-CoA and ethylmalonyl-CoA in S. albus J1074 to reduce the compound spectrum of produced pamamycins. We could greatly influence the compound spectrum and we could identify the bottleneck of pamamycin production as succinyl-CoA. We could also prove that the metabolism of valine is the sole provider for the biosynthesis of pamamycin. Furthermore we could show the dependency of antibiotic production on gene dosage and we could increase the production of several secondary metabolites by increasing the number of clusters present on the genome.Wir konnten das genetische Potential des Genus Streptomyces anhand der kompletten Genom-Sequenz von Streptomyces fulvissimus, der 32 putative Biosynthese-Gencluster besitzt, zeigen. Außerdem konnten wir die Biosynthese des Makrodiolid-Antibiotikums Pamamycin aufklären, indem die für die Biosynthese verantwortlichen Gene ausgeknockt und die daraus entstandenen Intermediate nachgewiesen wurden. In der Pamamycin-Biosynthese wird Succinyl-CoA als Startereinheit verwendet, auf welche entweder Malonyl-CoA, Methylmalonyl-CoA oder Ethylmalonyl-CoA als weitere Bausteine folgen können. Dieses Wissen nutzten wir, um unseren heterologen Stamm Streptomyces albus J1074 gezielt zu verändern. Unser Ziel war es, die intrazellulären Konzentrationen von Methylmalonyl-CoA und Ethylmalonyl-CoA in S. albus zu verringern um das Substanzspektrum der produzierten Pamamycine einzuschränken. Wir konnten das Substanzspektrum der produzierten Pamamycine stark beeinflussen, dadurch Succinyl-CoA als den limitierenden Faktor der Biosynthese identifizieren, und nachweisen, dass sich die Pamamycin-Biosynthese ausschließlich aus dem Metabolismus von Valin speist. Durch das Einbringen mehrerer Biosynthesegencluster in denselben genetischen Hintergrund konnten wir die Produktion verschiedener Antibiotika steigern und dadurch zeigen, dass die Sekundärstoffproduktion von der Anzahl der Gencluster abhängig ist
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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