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Doppelt-Pionische Fusion zu 4He - Kinematisch vollstaendige Messungen ueber den Energiebereich des ABC Effekts
Get PDFThe double-pionic fusion to light nuclei slightly above the threshold is governed by the so-called ABC effect, a huge enhancement in the invariant mass spectrum of the pion pair at low masses. Now 50 years have passed since its discovery, but still this phenomenon is lacking a satisfying explanation.
One reason is that all the early experiments were inclusive, measuring only the heavy ejectile. Thus not all kinematic variables could be obtained. For this reason exclusive, kinematically complete measurements of the double-pion production were performed with the WASA detector.
This work is about the fusion to 4He. At nine beam energies over the whole energy region of the ABC effect the dd->4He pi0 pi0 reaction was measured. For the first time the energy dependence of the ABC effect was investigated in exclusive measurements. For these experiments new detector components for the WASA detector system were developed, which was also part of this thesis.
The results open a completely new view on the ABC effect. Apparently the additional information gained by the measurement of all kinematic variables is essential for the understanding of the phenomenon. Previous models developed at hand of inclusive measurements cannot reproduce the new results.
The data identify the enhancement at low pion-pion invariant masses as a very strong and narrow peak accompanied with a strong energy dependence of the total cross section. A comparison with the recent results in the basic reaction of the ABC effect, pn->d pi pi, confirms the assumption that both reactions, the fusion to deuteron and the fusion to 4He, are goverend by the same underlying process.
The results indicate that the ABC effect is driven by a resonance in the pn and Delta-Delta systems, which is strong enough to survive in a nuclear medium. And in fact the recently developed ABC resonance model describes both reactions with amazing accuracy.Die doppelt-pionische Fusion leichter Kerne wird kurz oberhalb der Energieschwelle vom sogenannten ABC-Effekt dominiert, einer riesigen Überhöhung an der Massenschwelle im Spektrum der invarianten Masse des Pionpaars. Bis heute, 50 Jahre nach seiner Entdeckung, gibt es keine zufriedenstellende Erklärung für dieses Phänomen.
Ein Grund dafür ist, dass in den früheren Messungen nur das schwere Ejektil gemessen und nicht alle kinematischen Variablen ermittelt werden konnten. Deshalb wurden mit dem WASA Detektor exklusive, kinematisch vollständige Messungen der Zwei-Pion-Produktion unternommmen.
Diese Arbeit widmet sich der Fusion zu 4He. Bei neun Strahlenergien über den gesamten Bereich des ABC-Effekts wurde die Reaktion dd ->4He pi0 pi0 gemessen. Damit wird zum erstem Mal die Energieabhängigkeit des ABC-Effekts in exklusiven Messungen untersucht. Zur Durchführung der Experimente wurden neue Detektorkomponenten für den WASA Detektor benötigt, deren Entwicklung und Aufbau ebenfalls Teil dieser Arbeit sind.
Die Ergebnissse eröffnen einen völlig neuen Zugang zum ABC-Effekt. Die zusätzlichen Informationen durch die Messung aller kinematischen Variablen erweisen sich als essentiell für das Verständnis des Phänomens. So können die konventionellen Modelle, die anhand der inklusiven Daten entwickelt wurden, die neuen Ergebnisse nicht repoduzieren.
Die Daten weisen die Überhoehung bei kleinen invarianten Pion-Pion-Massen als einen sehr hohen und schmalen Peak aus, der mit einer starken Energieabhängigkeit des totalen Wirkungsquerschnitts einhergeht. Der Vergleich mit den neuesten Ergebnissen in der Basisreaktion des ABC-Effekts, pn->d pi pi, untermauert die Vermutung, dass sowohl der Fusion zu d als auch der Fusion zu 4He derselbe Prozess zugrunde liegt.
Die Resultate weisen darauf hin, dass der ABC-Effekt von einer Resonanz in pn- und Delta-Delta-Systemen getragen wird, die stark genug ist, auch im nuklearen Medium zu bestehen. Tatsächlich beschreibt das neu entwickelte ABC-Resonanz-Modell die Daten in beiden Reaktionen mit bemerkenswerter Genauigkeit
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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