1,720,959 research outputs found
Fast scintillating ZnO ceramics for relativistic heavy-ion beam diagnostics
Full text linkThis thesis focuses on the study of inorganic scintillating ceramics based on zinc oxide prepared by uni-axial hot pressing in vacuum and doped with different elements such as indium and gallium. The optical and luminescent properties of these samples were tested under heavy-ion irradiation. The investigations are motivated by the need to eventually replace plastic scintillators, which are currently standard for beam diagnostics in fast-counting scintillation detectors but suffer severely from radiation damage. ZnO-based ceramic scintillation detectors are expected to be radiation hard and as such particularly suitable for beam diagnostics at heavy-ion accelerator facilities for absolute beam intensity measurements and calibration of beam current measuring devices such as ionization chambers and secondary electron transmission monitors.
The ion irradiation experiments were performed at the universal linear accelerator UNILAC and at the heavy-ion synchrotron SIS18 of the GSI Helmholtz Center for Heavy Ion Research (Darmstadt, Germany). The ceramic samples were irradiated under various beam conditions, including ions between 40Ar and 238U ions, beam energies from 4.8 to 500 MeV/u, and fluences up to 10^13 ions/cm^2. The light output and emission spectra of ion-induced luminescence were recorded in-situ during sample irradiation.
Under all beam conditions, the intensity of the luminescent light decreases with increasing ion fluence. The evolution of the light intensity as a function of fluence is described with the model suggested by Birks and Black, yielding the critical fluence of 50% intensity loss for the stopping powers of the respective ions. The ZnO-based ceramics show more than 100 times higher radiation hardness compared to standard plastic scintillators used in heavy-ion beam diagnostics. Non-irradiated In-doped and Ga-doped ZnO ceramics exhibit intense exciton-related near-band-edge emission combined with very low defect-related deep-level emission.
When exposed to heavy ions, the intensity of the near-band-edge emission decreases, but no new emission bands associated with radiation-induced defects are observed. In-situ optical light transmission measurements were performed in the wavelength range of 300 to 1000 nm. With increasing ion fluence, the spectra show a more and more pronounced reduction in transmission in the 390-600 nm range, while no change is observed at higher wavelengths. Important to note is that the ionoluminescence intensity decreases faster than the optical transmission. The kinetics of luminescent light emission was characterized using fast photomultiplier tube signals. Before ion exposure, both In-doped and Ga-doped ZnO ceramics exhibit ultrafast scintillation decay times of less than a nanosecond. No change in scintillation decay time is observed as a result of ion irradiation.
The second part of the thesis concentrated on the design and construction of a prototype ZnO(In) based scintillation detector. The performance of this prototype was tested with various 300 MeV/u ions (40Ar-238U) including a variation of the beam spot position across the active area of the prototype detector. Compared to the plastic reference detector, the ZnO ceramic prototype showed 100% counting efficiency. Considering the radiation hardness results, the ceramic detector is expected to have an operational lifetime at least 100 times longer than the plastic scintillation detectors currently used for beam diagnostics at GSI. The new detector prototype represents a tool with significantly improved properties for heavy-ion beam diagnostics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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