1,720,982 research outputs found
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
Computerbasierte Modelle der Kontrast- und Orientierungsverarbeitung im primären visuellen Kortex
No full textDer primäre visuelle Kortex (V1) ist das erste kortikale Areal, das in der Verarbeitung visueller Informationen involviert ist. Die Zellen dieses Areals reagieren auf grundlegende Stimuluseigenschaften wie Kontrast oder Orientierung. Auch wenn es sich um den meistuntersuchten Teil des visuellen Systems – und um einen der meistuntersuchten Teile des Gehirns insgesamt – handelt, sind viele Fragen über die beteiligten neuronalen Mechanismen bis heute offen. Anatomische Studien zeigen, dass der größte Teil der Eingaben, den Neuronen in V1 erhalten, nicht von den früheren visuellen Strukturen sondern aus dem Kortex selbst stammen. Die Antwort von Neuronen ist in einem großen Maße von der Aktivität der umgebenden Neuronen im lokalen kortikalen Netzwerk bestimmt. In dieser Arbeit verwenden wir Computermodelle dieser Netzwerke, um deren Beitrag zur visuellen Verarbeitung zu klären und vergleichen die Simulationsergebnisse mit elektrophysiologischen Ableitungen aus dem V1 der Katze. Wir untersuchen zunächst die Rolle des lokalen Schaltkreis in der Erzeugung von Orientierungsselektivität. Die Orientierungspräferenzen von Neuronen im V1 höherer Säugetiere sind nicht zufällig verteilt sondern variieren kontinuierlich und resultieren in einer Orientierungskartenstruktur. Durch systematische Untersuchungen zweier Klassen von Netzwerkmodellen zeigen wir, dass sich die experimentell beobachteten Abhängigkeit der Selektivität von der Kartenposition am besten in einem Netzwerk, das in einem stark rekurrenten Regime arbeitet, erklären lässt. In diesem Netzwerk sind die rekurrenten exzitatorischen und inhibitorischen Ströme annähernd ausbalanciert und dominieren die afferenten Ströme. Diese Resultate werden in einer zweiten Studie bestätigt, in der wir zeigen das ein solches Netzwerk auch experimentell beobachtete Unterschiede in der Variabilität der zeitlichen Antwort erklären kann. Wir untersuchen dann einen weiteren Aspekt der Verarbeitung in V1, die nichtlineare Normalisierung von Zellantworten: Anstatt die Antwort kontinuierlich mit dem Kontrast eines Stimulus zu steigern, saturieren die Antworten kortikaler Zellen deutlich unter den maximal möglichen Aktivitäten. Außerdem werden die Antworten auf zwei Stimuli, die gleichzeitig an der gleichen Position präsentiert werden, nicht linear addiert sondern sind typischerweise kleiner als die Summe der Antworten, wenn die Stimuli einzeln präsentiert werden. Wir zeigen, wie diese Normalisierung aus der Kombination von Eigenschaften der afferenten Eingabe mit der Modulation durch das lokale kortikale Netzwerk hervorgehen kann. Aufgrund des starken Einfluss des Netzwerks kann die Stärke dieser Modulation eine starke Abhängigkeit von der Position in der Orientierungskarte zeigen. Schließlich betrachten wir den Einfluss des lokalen Netzwerks auf die Modulation der Antworten, die durch Stimuli außerhalb des klassischen rezeptiven Feldes hervorgerufen werden, d. h. von Stimuli, die keinerlei Antwort hervorrufen, wenn sie alleine präsentiert werden. Diese Modulationen haben ihren Ursprung außerhalb des lokalen Netzwerks und werden über langreichweitige Verbindungen oder Rückprojektionen von höheren Arealen weitergeleitet. Obwohl wir in dem Modell keinerlei direkte Abhängigkeit dieser Modulation von der Kartenposition einfügen, geschieht die endgültige Verarbeitung dieser Modulation im lokalen Netzwerk und führt damit zu Unterschieden in der resultierenden Modulation für Zellen an verschiedenen Kartenpositionen. Diese Verarbeitung durch das lokale Netzwerk erklärt dann auch experimentell beobachtete Unterschiede in der Orientierungsspezifizität der Modulation.The primary visual cortex (V1) is the first cortical area involved in the processing of visual information, responding to basic features of a visual stimulus like contrast or orientation. Although it is the best studied part of the visual system — and one of the best studied areas in the brain in general — many questions about the involved neural mechanisms remain unclear to date. Anatomical studies show that most of the input received by neurons in V1 does not arise from the earlier visual structures but from within the visual cortex. To a large extent, the response of a neuron is determined by the activity of the surrounding neurons in the local cortical network. In this thesis, we employ computational models of these networks in V1 to shed some light on its contribution to visual processing, comparing the simulation results to electrophysiological recordings from cat V1. We first investigate the role of the local circuitry in the generation of orientation selectivity. Orientation preferences of neurons in V1 of higher mammals are not distributed randomly but vary continuously resulting in an orientation map structure. By systematically exploring two classes of network models we show that the experimentally observed dependence of tuning properties on position in this map is best explained in a network that operates in a strongly recurrent regime, where recurrent excitatory and inhibitory inputs are approximately balanced and dominate the afferent input. These results are confirmed in a second study, where we show that such a network can also explain observed differences in the variability of temporal responses. We then focus on another aspect of input transformation in V1, the non-linear normalization of cell responses: Instead of consistently increasing the response with the contrast of a stimulus, responses of cortical cells saturate well below the maximal levels that would be possible physiologically. In addition, the response to two stimuli at the same position in the visual field is not linearly added but typically smaller than the sum of the responses to the two stimuli presented alone. We demonstrate how such normalization can arise from the combination of afferent input properties with the modulation provided by the local cortical network. Due to the strong influence of the network, the amount of this normalization can show a strong dependence on the position in the local orientation map. Finally, we study the influence of the local network on the response modulation caused by stimuli presented outside of the classical receptive field of a neuron, i. e. by stimuli that do not elicit a response when presented alone. These modulations have their origin outside of the local network and are propagated via long-range connections or via feedback from higher areas. While we explicitly do not include any direct dependence of this modulatory input on the map position, the final processing of the surround influences happens in the local recurrent circuit, leading to differences in the net modulation between cells at different map positions. This processing by the local network then also explains experimentally observed differences in the orientation specificity of the surround influence
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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