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Structure and Glass Transition Behavior of As-Rich As-Se Glasses: Modeling and Experiment
No full textChalcogenide glasses have been widely used in various technologies due to their wide IR transparency and good glass forming ability. Arsenic selenide glasses (AsxSe100-x), in particular, have been readily adopted for IR applications and widely studied to provide insights into fundamental structure-property relationships. Arsenic rich AsxSe100-x glasses (? > 40), however, are marked by the presence of unusual structural phenomena which influence the properties of these glasses and are not yet fully understood, including features such as molecular units (As4Se3) and a second calorimetric signal during the glass transition. Therefore, the structure of these glasses has been reexamined in As-rich compositions using Raman spectroscopy and atomic simulations in an effort to clarify the structure and elucidate the origin of the second calorimetric signal. High-resolution Raman spectra of the As-Se glass binary reveal a complex evolution of the structure with increasing As content. The evolution of the structure in Se-rich compositions is consistent with the chain-crossing model, as previously established in the literature. However, analysis of the As-rich spectra with multivariant curve resolution (MCR) techniques reveals mixed As-(Se3-x, Asx) units and As-(As3) units as well as molecular As4Se3 and As4 butterfly units. A model of the spectrum made by fitting Gaussian functions to the MCR components was then used for structural analysis. The population of As4Se3 units was derived, which shows a maximum at x = 60% and a decoupling from the population of As-rich units, consistent with a local minimum in . Ab initio molecular dynamics modelling of the structure of As60Se40 glass was also performed. Comparison of the structure derived from characterization of the model to reported
experimental measurements of the glass show generally good agreement. Analysis of the structural units found in the model support the existence of As4Se3 molecules in the glass while casting further doubt on the presence of As4Se4. Furthermore, the individual molecular As4 units previously attributed to the 203 cm-1 peak in the Raman spectrum are found to be absent, with As4 butterfly units incorporated into the glass network present instead. First-principles Raman spectrum calculations performed on the As4 butterfly units find that the Raman spectrum of these units vary significantly depending on the configuration. Using various chain configurations and modifying the relaxation of these chains through tension suggests a convergence of the asymmetric stretching mode of these units toward the spectral feature near 203 cm-1 found in the glass, supporting the assignment of this feature to As4 butterfly units. Finally, the dynamics of the glass transition for As-rich As-Se glasses were characterized through modulated differential scanning calorimetry (MDSC) and reveal a bimodal glass transition exhibiting different relaxation behaviors for the two observed components. The prominence of this bimodal signal is maximized at the As60Se40 composition, coinciding with the local minimum in and the maximum population of As4Se3 molecules. In situ Raman spectroscopy of the As60Se40
composition heated through the show that the first peak in MDSC measurements correlates with the relaxation of the amorphous backbone while the second peak is associated with the decomposition of As4 butterfly units. Features associated with As4Se3 molecules appear to alter at the onset of , indicative of decoupling of these units from the glass network in accordance with reported behavior of molecular glasses
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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