1,720,955 research outputs found
Investigation of the photocycle of bacterial phytochromes Agp1 and Agp2 using FTIR spectroscopy
No full textDie Phytochromfamilie umfasst lichtempfindliche Proteine, die wichtige Regulationsprozesse in Pflanzen, Bakterien und Pilzen steuern. Im pflanzenpathogenen Bakterium Agrobacterium fabrum absorbieren die Phytochrome Agp1 und Agp2 mithilfe eines kovalent gebundenen Biliverdin-Chromophors Licht im roten bis nahinfraroten Bereich. Aufgrund dieser Eigenschaften sind sie für optogenetische Anwendungen von großem Interesse. In dieser Arbeit wurden Agp1 und Agp2 mittels FTIR- und UV-Vis-Spektroskopie untersucht. Ein neu entwickelter Messaufbau mit Helium-Kryostat ermöglichte Messungen bis 4 K. Dabei konnte das Meta-F-Intermediat von Agp2 analysiert werden, das einen Verzweigungspunkt zwischen produktivem und unproduktivem Reaktionsweg darstellt. Die Experimente zeigten, dass hohe Lichtintensität und Temperatur die Bildung des aktiven Zustands fördern, was auf eine zusätzliche Funktion als Temperatursensor hindeutet. Für Agp1 wurden erstmals Intermediate bei Tiefentemperatur FTIR-spektroskopisch erfasst. Eine pH-abhängige Untersuchung legt eine Keto/Enol-Tautomerie der C19=O-Gruppe des Ring D nahe. Als Protonendonor wird Histidin 280 vermutet. Kryo-Messungen zeigten in beiden Phytochromen Schwingungsänderungen im Carbonylbereich, was auf frühe photochemische Reaktionen hinweist. Für Agp2 wurden zwei frühe Lumi-F-Photoprodukte (ELF1, ELF2) postuliert. Die Ergebnisse wurden durch Raman-Spektroskopie und QM/MM-Berechnungen ergänzt und in einer gemeinsamen Publikation veröffentlicht. Eine weitere ist in Vorbereitung.The phytochrome family comprises light-sensitive proteins that regulate key processes in plants, bacteria, and fungi. In the plant pathogen Agrobacterium fabrum, the phytochromes Agp1 and Agp2 use a covalently bound biliverdin chromophore to absorb light in the red to near-infrared range, making them highly relevant for optogenetic applications. In this study, Agp1 and Agp2 were investigated using FTIR and UV-Vis spectroscopy. A newly developed setup including a helium cryostat enabled measurements down to 4 K. This allowed detailed analysis of the Meta-F intermediate of Agp2, which represents a branching point between productive and unproductive photoconversion pathways. The results show that higher light intensity and temperature promote formation of the active state, suggesting an additional role as a temperature sensor. For Agp1, low-temperature FTIR spectroscopy enabled the first observation of early intermediates. pH-dependent measurements indicate a keto/enol tautomerization of the C19=O group on ring D. Histidine 280 is proposed as the proton donor involved in this process. Cryogenic spectra revealed vibrational changes in the carbonyl region for both phytochromes, indicating early photochemical events. For Agp2, two early Lumi-F photoproducts (ELF1 and ELF2) are proposed. The findings were complemented by Raman spectroscopy and QM/MM calculations and published as part of a collaborative study. A second publication is currently in preparation
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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