1,721,089 research outputs found
Functional genomic investigation of the metabolism of Campylobacter jejuni during in vitro growth
No full textCampylobacter jejuni is an important food-borne pathogen, and a major cause of bacterial gastroenteritis in both developing and developed nations. Despite this, relatively little is known regarding the way in which C. jejuni colonises hosts, causes disease or survives in the environment during transmission between hosts. The publication of the first C. jejuni genome sequence in 2000 highlighted that many of the paradigms from other, better characterised, bacteria such as Escherichia coli and Salmonella enterica do not necessarily hold for Campylobacter spp (Parkhill et al, 2000). This thesis describes the detailed analysis of C. jejuni, during in vitro growth in batch culture. This work was carried out in order to better understand the physiology of this species in this widely used experimental system, to provide a useful data source for the large number of researchers using batch grown C. jejuni, and as a screening process to identify novel and potentially important aspects of C. jejuni physiology. DNA microarray analysis was performed to measure changes in transcript abundance during different phases of the growth cycle, and expression changes were identified by significance and fold-change filtering, and by time course clustering analysis. A subset of the gene expression changes identified by microarray analysis was confirmed by quantitative RT-PCR. A number of phenotypic characteristics of C. jejuni were examined during batch growth, and correlation with gene expression changes was assessed. Microscopy was used in conjunction with bacterial tracking software and fluorescent dyes to monitor motility, respiratory activity and viability throughout the growth cycle. These measures strongly suggested the presence of a two-stage stationary phase, with high levels of motility and respiratory activity until mid-stationary phase, followed by rapid decline of these cellular functions. The utilisation of amino acids, which constitute major carbon sources for C. jejuni, was monitored by analysis of culture supernatants and preferential substrates for growth were identified. Proton nuclear magnetic resonance analysis of culture supernatants was performed and confirmed the depletion of certain amino acids, and identified a pattern of acetate production and assimilation throughout the growth cycle. This trend is characteristic of an „acetate switch‟ mechanism of bacterial metabolism characterised by acetate production during phases of nutrient abundance, followed by assimilation and utilisation of this substrate during nutrient limitation. This switch from production to assimilation occurs in mid-stationary phase. Mutants of the genes putatively involved in the acetate switch were examined. Mutants of the pta and ackA genes, encoding probable phosphate acetyltransferase and acetate kinase enzymes, showed reduced acetate production during growth, and did not exhibit an „acetate switch‟. These mutants appeared to survive less well than the wild-type strain during stationary phase and thereafter. Several genes of unknown function, with potential roles in peptide utilisation were identified using data from the microarray analysis. Two loci, consisting of the Cj0917c gene, and the Cj1580c – Cj1584c putative operon were mutated in C. jejuni by allelic replacement. Growth assays in complex and defined media were performed, in an attempt to identify a putative function. Mutants of Cj0917c showed similar growth characteristics to the wild-type strain, but Cj1580c – Cj1584c deletion mutants exhibited a growth defect in defined media. Assay variability precludes any firm conclusions on the role of this locus, but a putative function in the utilisation of amino acids and di- and tri-peptides is discussed
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
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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