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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
Die Suche nach neuen bioaktiven Sekundärmetaboliten aus Actinomyceten
No full textIm Rahmen dieser Arbeit wurde an Sekundärmetaboliten aus verschiedenen Actinomyceten geforscht.Der Stamm Actinokineospora bangkokensis 44EHWT gehört zur Gattung der Actinokineospora. Da von dieser Gattung bislang nur sechszehn verschiedene Stämme isoliert wurden, zählen sie zu den seltenen Actinomyceten. Die Untersuchung seltener Gattungen ist beim Screening nach neuen Naturstoffen eine vielversprechende Quelle. Aus A. bangkokensis konnten die neuen Polyen-Antimykotika Thailandin A und B isoliert und deren Struktur aufgeklärt werden. Das Thailandin-Biosynthesegencluster wurde identifiziert und mittels Geninaktivierung bestätigt.Durch kombinatorische Biosynthese lassen sich neue Naturstoffe mit verbesserten Eigenschaften generieren. In den Stämmen Streptomyces diastatochromogenes Tü6028 und Streptomyces viridochromogenes Tü57 konnten die Gene für die Methylsalicylsäure-Biosynthese von Polyketomycin und Avilamycin erfolgreich deletiert werden. Die Gendefekte konnten jedoch in beiden Stämmen weder mit den pokMs- noch mit den aviNM-Genen komplementiert werden, sodass trotz Neukombination von Genen keine neuen Derivate gebildet wurden. Weiter konnte S. viridochromogenes Tü57 durch die Supplementierung von CaCl2 im Medium effizient durch Konjugation manipuliert werden.In Folge der pokOIV-Deletion der Polyketomycin-Biosynthese wird das fast stille Foxicin-Biosynthesegencluster in S. diastatochromogenes Tü6028 nun stärker exprimiert (Peintner, 2008), sodass weitere Untersuchungen an Foxicin möglich waren. Nach Aufreinigung und verschiedenen spektroskopischen Versuchen konnten die Strukturen und Konfigurationen von Foxicin A und B geklärt werden. Das Foxicin-Biosynthesegencluster wurde erfolgreich identifiziert und mittels Geninaktivierung bestätigt. Nach in silico Analyse des Genclusters wurde ein Biosynthesemodell aufgestellt. Die Adenylierungs-Domäne FoxBI wurde heterolog in E. coli produziert, aufgereinigt und die Spezifität in einem in vitro Assay untersucht. Foxicin A fungiert durch Eisenkomplexierung als Siderophor, kann wie andere Quinone Elektronen aufnehmen und zeigt zusätzlich antibiotische Aktivität gegenüber anderen Bakterienstämmen. Weitere Aktivitätsassays wurden durchgeführt. Das Foxicin-Biosynthesegencluster konnte mittels Genome Mining in weiteren Streptomyceten identifiziert werden. In diesen Stämmen scheint das Cluster jedoch still zu sein. Ein phylogenetischer Baum wurde infolge von Sequenzvergleichen des PKS/NRPS-Hybridgens foxBII aufgestellt. Weiterhin wurden die Informationen der Naturstoffe Aranciamycin, Avilamycin, Landomycin, Mensacarcin, Polyketomycin, Rishirilid, Simocyclinon und Urdamycin in die MIBiG-Datenbank (Medema et al., 2015) eingegeben.Im Rahmen dieser Arbeit wurden die Genome der fünf Actinomyceten S. diastatochromogenes Tü6028, S. diastatochromogenes 1628, S. calvus, S. glomeroaurantiacus und A. bangkokensis 44EHWT sequenzieren lassen. Die Draft-Genome von A. bangkokensis 44EHWT und S. diastatochromogenes Tü6028 wurde dabei genauer analysiert.In this work studies on secondary metabolites of different actinomycetes were performed. The strain Actinokineospora bangkokensis 44EHWT belongs to the genus of Actinokineospora. Until now, only sixteen Actinokineospora strains were isolated, thus the genus is one of the rare actino-mycetes. The studies on rare actinomycetes are very promising in order to identify novel secondary metabolites. The new polyene antimycotika thailandin A and B were isolated from A. bangkokensis and their structures were elucidated. The strain was genetically modified. Thereby, the biosynthetic gene cluster of thailandin was identified and verified by targeted gene inactivation. Novel natural products with better features can be generated through combinatorial biosynthesis. In the strains Streptomyces diastatochromogenes Tü6028 and Streptomyces viridochromogenes Tü57, the genes for methylsalicylic acid biosynthesis of polyketomycin and avilamycin were successfully deleted, respectively. The following complementation with neither pokMs- nor aviNM-genes did not lead to novel compounds in both strains despite of the new combination of genes. In addition, the strain S. viridochromogenes Tü57 was efficiently manipulated by conjugation through supplement-ation of CaCl2 into the media. After deletion of the pokOIV gene of polyketomycin biosynthesis, the almost silent foxicin biosynthetic gene cluster is highly expressed in the strain S. diastatochromogenes Tü6028 (Peintner, 2008), allowing further studies on foxicin. The structure and absolute configuration of foxicin A and B were elucidated as result of purification and various spectroscopic experiments. The foxicin biosynthetic gene cluster was successfully identified and verified by gene inactivation experiments. In silico analysis of the gene cluster led to a biosynthetic model. The adenylation domain FoxBI was heterologously produced in E. coli, purified and its specificity was analyzed in an in vitro assay. Foxicin A acts as a siderophor through chelating ferric iron, is able to accept electrons and shows antibiotic properties against other bacterial strains. Further activity assays were conducted. The foxicin biosynthetic gene cluster was also identified in various other Streptomyces strains by genome mining. However, the gene clusters seem to be silent. A phylogenetic tree was constructed by comparison of the PKS/NRPS hybrid FoxBII sequences. Furthermore, information about aranciamycin, avilamycin, landomycin, mensacarcin, polyketomycin, rishirilide, simocyclinone and urdamycin natural products were added to MIBiG database (Medema et al., 2015). Additionally, the genomes of the five actinomycetes S. diastatochromogenes Tü6028, S. diastato-chromogenes 1628, S. calvus, S. glomeroaurantiacus and A. bangkokensis 44EHWT were sequenced. The draft genomes sequences of A. bangkokensis 44EHWT and S. diastatochromogenes Tü6028 were further analyzed
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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