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Phytotxic effects of dissolved organic matter (DOM) with Paraquat, 2,4-D and Naphthalene
No full textIn Hydrokultur wurde an Herbstrübe (Brassica rapa ssp. rapa) die Kombinationswirkung von löslicher organischer Substanz (DOM) aus Grünlandoberboden (0-10 cm) und aus Weizenstroh mit zwei Herbiziden, dem kationischen, zweiwertigen Paraquat und der Säure 2,4-D sowie einem zweiringigen polyzyklischen aromatischen Kohlenwasserstoff (PAK), Naphthalin, mittels Wachstumstests von 5 Tagen im Klimaschrank, bei 22 °C für 16 Stunden hell und bei 16 °C für 8 Stunden dunkel, getestet. In DOM wurde der Anteil von hochmolekularen, hydrophoben Bestandteilen (Fulvo- und Huminsäuren) durch XAD-8 Fraktionierung bestimmt. Eine Interaktion zwischen Xenobiotikum und DOM wurde mittels Fluoreszenzquenching untersucht. Mithilfe einer zweifaktoriellen Varianzanalyse wurden die Einflüsse von Xenobiotikum-Konzentration und von Herkunft und Konzentration von DOM auf die Kombinationswirkung ermittelt. Es ließen sich folgende Schlüsse ziehen: Eine qualitative interaktionsrelevante Variabilität von DOM ließ sich durch den Anteil der Huminstoff-Fraktion, die bei pH 2 an das XAD-8 Harz gebunden wird, nicht feststellen. Es lassen sich aus demselben Material und mit denselben Methoden zu verschiedenen Terminen nicht identische DOM herstellen. Der Zeitpunkt der Grünlandbodengewinnung ist entscheidend für die Wirkung des aus ihm gewonnenen DOM auf das Pflanzenwachstum. Paraquat und 2,4-D wurden von beiden DOM-Quellen komplexiert, von Grünlandboden-DOM dagegen gar nicht. Ein signifikanter Einfluß von Xenobiotikum-Konzentration und DOM auf die Kombinationswikrung konnte für 2,4-D und Naphthalin nachgewiesen werden. Neben den genannten Einflußfaktoren Xenobiotikum-Konzentration und DOM für die Kombinationseffekte konnte ein Einflußfaktor von durchschnittlich 33 % bisher nicht erklärt werden. Die Auswertung der Kombinationswirkung sieht bei allen Xenobiotika etwa gleich aus. Durchschnittlich fielen die Kombinationswirkungen überwiegend antagonistisch aus (42 %), direkt gefolgt von synergistisch negativ (38 %), 12 % fielen synergistisch positiv und 10 % additiv aus. Durch die Verschiedenartigkeit der Zusammensetzung der identisch extrahierten DOM, läßt sich eine Kombinationswirkung durch vorherige quantitative Analyse der Huminstoffe allein jedoch nicht prognostizieren. Zusätzlich wurde eine Studie an DOM aus konventionell bewirtschaftetem Ackerboden durchgeführt. Die Ergebnisse zeigen, dass Xenobiotika über den erwarteten Wirkungszeitraum hinaus im Boden eingeschlossen oder gebunden sein können und nach einer Serie erosiver Regenfällen durch DOM wieder mobilisiert werden können und zwar als aktiv ökotoxische Substanzen.The combined effect of dissolved organic matter (DOM) from grassland top soil (0-10 cm) and wheat straw with two herbicides, the cationic, bivalent Paraquat and the acid 2,4-D, as well as the two-ring polycyclic aromatic hydrocarbon (PAH), Naphthalene, was studied on turnip (Brassica rapa ssp. rapa) with 5 day growth tests in hydroculture in a phytotron for 16 hours at 22°C and daylight and for 8 hours at 16°C in the dark. The humic hydrophobic fraction (fulvic and humic acids) was determined using XAD-8 resin. An interaction between the xenobiotics and DOM was detected by fluorescence quenching. Using two-factor analysis of variance, the influence of xenobiotic-concentration, source and concentration of DOM on the combined effect was determined. The following findings can be stated: A qualitative variability, responsible for the potential of interaction with xenobiotics could not be detected by defining the quality of humic substances bound to XAD-8 resin at pH 2. No identical DOM solutions could be prepared using the same materials and procedure at different times. The time of acquirement of grassland soil for DOM preparation is evident for its effect on plant growth. Paraquat and 2,4-D have been complexed by both DOM sources, but 2,4-D to a much lower extend. Naphthalene was not always complexed by straw-DOM, but was never complexed by grassland soil-DOM. A significant effect of the xenobiotic concentration and DOM in the combined effect could only be proved for 2,4-D and Naphthalene. Beside the factors xenobiotic concentration and DOM for the explanation of the combined effect another factor of ón average 33% couldn't be explained yet. The combined effects of all xenobiotics were fairly similar. It dominated the antagonistic effect with on average 42%, followed by the synergistic negative effect (38%), the synergistic positive effect (12%) and the additive effect (19%). Due to the high individual variability of identically extracted DOM, the effect of DOM on the phytotoxicity of an organic xenobiotic cannot be predicted from its quantitative humic content. In a surplus study DOM from a soil of conventional field was examined for its phytotoxicity. Results show, that xenobiotics might be captured within the soil layer for a period longer than its expected effective time and then be mobilized by DOM after a series of erosive rainfalls, remaining ecotoxicologically active
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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