1,720,953 research outputs found
Analyse des temporalen Informationsgehalts hochauflösender resting state-fMRI Daten mithilfe von Blind Source Separation-Algorithmen
Full text linkDie BOLD-fMRI-Datenanalyse ist eine herausfordernde Aufgabe - mitunter bedingt durch den starken Einfluss von Störgrößen. Diese Störgrößen sind teilweise physiologischen Ursprungs (darunter fallen beispielsweise der Herzrhythmus oder aber auch die Atmung). In der sogenannten "resting state" fMRI-Forschung wird farbiges Rauschen zu einem noch größerem Problem, da BOLD-Fluktuationen dort einen kleineren Signalanteil ausmachen, als die so genannte "BOLD response" in der "task-related" fMRI-Forschung. Das Ausmaß dieses Problems ist in der Forschung noch nicht lange bekannt. Physiologisch bedingtes Rauschen wird durch Aliasing-Effekte in das Signal zeitlich niedrig auflösender Scans gespiegelt (wenn das Nyquist-Shannon-Abtasttheorem ignoriert wird). Mit dem Aufkommen von schnellen Multiband-Sequenzen ist es jedoch möglich geworden, solche Aliasing-Effekte zu vermeiden, sofern die Abtastfrequenz hoch genug eingestellt wird. Und nachdem lange Zeit angenommen wurde, dass "resting state" Netzwerke eine Bandbreite im Bereich von 0.01-0.1 Hz haben, schien es, als könnten zeitlich hochauflösende Scans durch die Anwendung einfacher Zeitfilter von physiologischem Rauschen befreit werden. Aktuelle Studien haben jedoch gezeigt, dass "resting state" Netzwerke auch in Frequenzbereichen >0.1 Hz identifiziert werden können. Die Anwendung von Zeitfiltern erwies sich daher als nachteilig, da diese relevante Signalanteile ebenso eliminiert, wie Rauschen. Ein neuer (auf einer sogenannten "Blind Source Separation"-Methode basierender) Ansatz zur Rauschentfernung wird im Rahmen dieser Arbeit vorgestellt. Zeilich hochauflösende BOLD-fMRI-Daten werden in zeitlich unabhängige Komponenten zerlegt. Diese Zeitreihen werden im Frequenzbereich analysiert und Komponenten, die physiologischem Rauschen zugeordnet werden können, werden in die Datenrekonstruktion nicht miteinbezogen. Dieser neue Algorithmus wurde auf reale fMRI Daten angewandt (und parallel dazu wurden die selben Daten mit einem Bandpass-Filter gefiltert). Die bandgepassten Daten und die mittels dem neuen Algorithmus analysierten Daten wurden einer sogenannten "seed-based correlation"-Analyse unterzogen um festzustellen, ob bezüglich der funktionellen Konnektivität signifikante Unterschiede festgestellt werden können. Die Ergebnisse haben gezeigt, dass dies sehr wohl der Fall ist. Mit Ausnahme der funktionellen Konnektivität, die speziell im Bezug auf das auditive resting state Netzwerk bestimmt wurde, scheinen diese signifikanten Unterschiede jedoch nicht in spezifischen Mustern aufzutreten. Andere explorative Ansätze (z.B. eine Clusteranalyse) könnten Teil zukünftiger Analysen zur Validierung dieses neuen Ansatzes sein und zum Vergleich des Selbigen mit ähnlichen Ansätzen dienen.BOLD-fMRI data analysis is challenging - in part due to the strong influences by non-white noise, some of which has physiological origins (e.g. cardiac activity or respiration). Noise becomes even more of a problem in resting state fMRI research, since BOLD fluctuations account for a smaller portion of signal than the BOLD response in specific task-related fMRI signals does. Researchers have not always been aware of the great extent of this problem. Physiological noise is aliased into scans of a low temporal resolution (i.e. if the Nyquist criterion is not satisfied). But with the advent of multiband sequences, which facilitate higher sampling rates, it became possible to circumvent aliasing of high frequency noise into the signal of interest, if only the sampling frequency was set high enough. Since resting state networks have commonly been assumed to have abandwidth lying in the range of 0.01-0.1 Hz, it seemed, as if scans of high temporal resolution could be freed from physiological noise by temporal ltering. Recent studies have, however, revealed that resting state networks could also be identified in frequency ranges >0.1 Hz. Hence, the application of temporal lters turned out to be disadvantageous, since it eliminates useful information just as well as noise. A novel approach to noise removal (based on blind source separation) is presented in this thesis. BOLD-fMRI data of high temporal resolution is decomposed into temporally independent components (time courses) and corresponding weights.The time courses are analysed in the frequency domain and components deemed to be related to physiological noise were excluded from subsequent data reconstruction. fMRI data have been processed with this new algorithm and have (in another processing pipeline) been band passed (as a reference). The band passed data and the data processed by means of the proposed algorithm have both been subjected to seed-based correlation analysis in order to determine whether signi ficant differences in functional connectivity could be observed. Results indicate that the different approaches did in fact lead to such signi cant differences. With the exception of the functional connectivity assessed for the auditory resting state network, the differences did however not appear to occur in specific patterns. Other exploratory approaches (e.g. cluster analysis) could be used in future analyses in order to further validate this new noise removal approach and to compare results to those of similar approaches (e.g. CORSICA, PESTICA)
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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