1,720,963 research outputs found
Effect-directed identification and fate analysis of potent antiandrogenic coumarin derivatives in a central European river
No full textSurface waters are adversely affected by the discharge of wastewater that is containing numerous anthropogenic micropollutants. In consequence, endocrine disrupting effects like androgenicity and antiandrogenicity are frequently observed in the aquatic environment. Even if a large list of androgen axis disruptors is available, linking of adverse effects to responsible chemicals is hampered by a great share of this compound group, which is remaining unknown. Structure elucidation of these “unknowns” in environmental mixtures of typically thousands of compounds is extremely challenging even despite powerful tools like effect-directed analysis (EDA) are available. In this thesis, a novel, multidimensional fractionation approach was developed to support EDA of surface waters with endocrine disrupting activity. In chapter 2, four reversed phases were selected with a focus on the separation of androgens and antiandrogens. To this end, a representative mixture of 39 endocrine disrupting compounds (EDCs) was separated on a set of 17 columns with widely differing bond chemistries. After exclusion of columns with poor peak shapes and chromatographic resolution those stationary phases displaying the highest degree of orthogonal separation selectivity for EDCs were depicted using principal component analysis and Spearman rank correlation: aminopropyl-, octadecyl-, and pyrenyl ethyl silica phase. Additionally, a pentafluorophenyl silica phase was chosen due to promising results reported in the literature. A surface water sample with antiandrogenic activity was fractionated in parallel on the four selected columns. The resulting coverage of the virtual two-dimensional separation space with non-target peaks confirmed the high degree of orthogonality of the selected stationary phases. Besides, the separation of co-eluting isobaric compounds led to a 4.8fold increase of the number of detected peaks. Consequently, the fractionation system is facilitating the chemical identification of organic micropollutants by chemical target, suspect and non-target screening using high resolution mass spectrometry. In chapter 3, the established fractionation approach was applied to minimize the complexity of a surface water sample collected close to the effluent of a waste water treatment plant in the river Holtemme in Germany. In concert with a miniaturized luciferase reporter gene cell-based anti-AR-CALUX assay and LC-HRMS/MS non-target screening the highly potent antiandrogen 4-methyl-7-diethylaminocoumarin (C47), as well as the two less active derivatives 4-methyl-7-ethylaminocoumarin (C47T1) and 4-methyl-7-aminocoumarin (C47T2) were identified. The measured in vitro effect was quantitatively confirming C47 as the major cause of antiandrogenicity. Furthermore the antiandrogenic activity of C47 was also observed in vivo in spiggin-gfp Medaka already at the concentration equal to the concentration in the non-concentrated water extract. The longitudinal and temporal distribution of C47 and its derivatives along the whole river stretch was investigated in chapter 4. A constant exposure of the aquatic ecosystem by the three antiandrogens was observed at all sites downstream of the wastewater treatment plant of Silstedt, which was identified as the continuous source that is releasing C47, C47T1 and C47T2 in the gram per day range. Moreover, all compounds were detected in sediment and biota represented by the ubiquitous species Gammarus pulex. In this context, an experimental evaluation did not confirm typically proposed hydrophobic interaction to organic carbon as the driving force of partitioning into sediment but suggested cation binding of these aromatic amines to sediment. Finally, the coumarin derivatives were assessed as persistent as C47 is solely partially degraded to the less antiandrogenic potent C47T1 and C47T2 in the WWTP while a further attenuation of the compounds within the river was solely attributed to dilution by groundwater inflow
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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