1,720,953 research outputs found
Environmental Genomics as a source for the isolation of new operons and gene clusters from microbial consortia
No full textZentraler Aspekt dieser Arbeit war die Isolierung von neuartigen Biotinbiosyntheseoperons aus mikrobiellen Konsortien mit Hilfe kombinierter Anreicherung und direktem Klonieren. Hierzu wurden Cosmid-Genbanken aus Anreicherungskulturen mit einer Fragment-Größe von ca. 30 kb angelegt. Anschließend wurden die Genbanken auf Klone durchmustert, die möglicherweise Biotinbiosyntheseoperons (bio-Operons) tragen. Dabei wurden mit Hilfe funktionaler Komplementation sechs Cosmid-Klone identifiziert, die signifikante Mengen an Biotin produzierten. DNA-Sequenzanalysen der Cosmidklone zeigten, dass in allen Fällen vollständige bio-Operons vorhanden waren und die Sequenzanalysen identifizierten eine Reihe weiterer neuer Gene. Die Biotinproduktion der positiven Klone lag in einem Bereich von einigen pg/ml bis zu 3 800 pg/ml in definierten Medium. Aufgrund der sehr hohen Syntheseleistung wurde der Cosmid-Klon pCosHE2 für die Konstruktion von Biotin-überproduzierenden Mikroorganismen ausgewählt und das drauf enthaltende bio-Operon in verschiedene Vektoren kloniert. Diese bio-Konstrukte wurden in Bakterien aus neun verschiedenen Gattungen mobilisiert und anschleißend deren Biotinproduktionsfähigkeiten auf Mineralmedium getestet. Als Wirte für die Expression von Umwelt-isolierten bio-Genen wurden dabei Corynebacterium glutamicum, Sinorhizobium meliloti, Rhizobium NGR234, Rhizobium etli, Ralstonia eutropha, Agrobacterium tumeafciens, Klebsiella planticola, Escherichia coli und Xanthomonas campestris gewählt. Interessanterweise, nur E. coli-Stämme die das bio-Operon aus dem pCosHE2 überexprimierten, zeigten eine sehr hohe Biotinkonzentration (> 0,2 mg/l) im Kulturüberstan, wobei bis zu 3,5 mg/l Biotin gemessen wurden. Weitere Arbeiten konzentrierten sich auf die Analyse regulatorischer Phänomene bei Biotinsynthese und Aufnahme. Mit Hilfe von 2D-Gelelektrophorese wurden einige Proteine identifiziert, die in Zusammenhang mit dem Biotin-regulatorischen Netzwerk in gram-negativen Bakterien stehen.The main goal of the present work was the isolation of biotin biosynthesis genes and operons from microbial consortia employing a combined enrichment and direct cloning strategy. Cosmid libraries with large inserts of DNA (>30 kb) were constructed from enrichment cultures, which had been inoculated with different environmental samples. The cosmid libraries were screened for clones containing complete biotin biosynthesis operons (bio-operons) by functional complementation in E. coli. Altogether, six cosmid clones were identified that produced significant amounts of biotin. Sequence analysis of the complete cosmid clones identified six bio-operons and many other novel genes. Biotin synthesis rates of the tested clones were highly variable and ranged from just a few pg/ml to 3,800 pg/ml in defined medium. Because the clone designated pCosHE2 showed the highest biotin biosynthesis rates the corresponding bio-operon was subcloned into different vectors and the constructs were transferred into bacteria from nine different genera to test the potency for commercial biotin production. Hosts for the expression of the environmentally derived bio-genes included Corynebacterium glutamicum, Sinorhizobium meliloti, Rhizobium sp. NGR234, Rhizobium etli, Ralstonia eutropha, Agrobacterium tumeafciens, Klebsiella planticola, Escherichia coli and Xanthomonas campestris. Surprisingly, significant amounts of biotin (> 0.2 mg/l) were synthesized only in E. coli carrying extra copies of the pCosHE2 derived bio-operon. Up to 3.5 mg/l biotin were found in culture supernatant of recombinant E. coli strains grown on defined media in batch cultures. Additional studies focused on regulatory aspects linked to biotin biosynthesis and biotin uptake in gram-negative bacteria. For this purpose 2-dimensional gel electrophoresis was employed and this work has led to the identification of several proteins involved in the biotin-regulatory network
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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