1,720,989 research outputs found
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
Selektive MR Bildgebung mit paralleler Sendetechnik (pTx)
No full textDer Schwerpunkt dieser Dissertation liegt in der Entwicklung von
Hochfrequenz (HF)-Pulsenfür dedizierte Anwendungen in der
Magnetresonanztomographie (MRT) unter Verwendungder parallelen Sendetechnik
(pTx). Die wissenschaftlichen Beiträge dieser Arbeit umfassendabei den
Entwurf und die Implementierung neuer Algorithmen, welche mit Hilfe von
Simu-lationen und in-vivo Human-Experimenten auf einer kommerziell
verfügbaren 3T pTx MRTScanner-Platform validert wurden.In der MRT sind
HF-Pulse essentiell für die Signalgenerierung als auch für die
Unterdrückungvon unerwünschten Signalquellen. Bei ihrer Anwendung werden
Atomkerne im untersuchtenProbanden angeregt, welche daraufhin ein messbares
Signal abgeben. Das hochfrequenteMesssignal wird von Empfangsspulen erfasst
und schließlich in Bilder rekonstruiert. Auf-grund von limitierenden
physikalischen Effekten wie Magnetfeld-Inhomogenitäten,
Kernspin-Relaxationsprozessen und der auftretenden Erwärmung von
Patientengewebe, müssen dieHF-Pulse idealerweise so genau, so kurz und so
energieeffizient wie möglich sein. Die pTx-Technologie versucht diesen
Anforderungen durch die Bereitstellung von neuen räumlichenFreiheitsgraden
entgegenzutreten. Viele Studien wurden auf Basis von
einzel-angefertigtenpTx-Platformen durchgeführt und haben die vielen
Vorteile und Möglichkeiten, aber auchpotentielle Gefahren der vermehrten
Freiheitsgrade aufgezeigt. Das robuste Design und dieÜberführung von pTx
HF-Pulsen in das klinische Umfeld sind stets Gegenstand der
aktuellenForschung und Ziel dieser Arbeit.Die entstandenen
wissenschaftlichen Beiträge können zu drei verschiedenen
Applikations-feldern zugeordnet werden. Zuerst wird die Performanz von 2-D
räumlich-selektiven HF-Pulsen(2DHFs) für die Inner-Volume-Bildgebung
verbessert. Hier wird die HF-Anregung auf einenbestimmten Bildbereich (ROI)
eingeschränkt, um Bilder mit verringerten geometrischenVerzerrungen und
höherer Auflösung zu ermöglichen. Neue k-Raum Trajektoriendesignswerden für
2DHF-Pulse vorgeschlagen, welche um 43% genauer und gleichzeitig um
79%energieeffizienter sind oder deutlich verkürzte Pulszeiten um Faktor
größer zwei aufzeigen. Diedarauf basierenden diffusions-gewichteten Bilder
zeigen einen bis zu 40% Signal-zu-Rausch(SNR)-Gewinn gegenüber zu
konventionellen Designs.In zweiten Anwendungsfeld wird der zusätzliche
HF-Anregungskanal zur Kompensation vonSignalverlusten in Gradienten-Echo
(GRE)-Bildern verwendet. Die Signalverluste werdendabei durch
patienten-spezifische Magnetfeld-Verzeichnungen ausgelöst. Ein schnelles,
ro-bustes und voll automatisiertes Verfahren wird vorgeschlagen, um diesen
Signalverlustenschicht-spezifisch entgegenzuwirken. Maßgeschneiderte
HF-Pulse werden unter Einbezug dergemessenen
Hauptmagnetfeld-Inhomogenitäten und HF-Sendespulen-Sensitivitätsprofilen
berechnet. Im Durschnitt können 47% der Signalausfälle in
Multi-Schicht-Aufnahmen wieder-hergestellt werden.Schließlich wird ein 2-D
Spiral-Trajektoriendesign für die Verwirklichung von anatomischgeformten
Sättigungspulsen ausgearbeitet, welches eine inhärente Energieeffizienz
bietet. DiePulse streben eine möglichst genaue Unterdrückung von
unerwünschten Signalquellen, wiez.B. sich bewegenden inneren Organen an, um
damit Bewegungsartefakte in den resultieren-den Bildern auszuschließen. Das
vorgeschlagene 2DHF-Spiral-Design zeigt in verschiedenenanatomischen
Regionen eine optimale Ausgewogenheit zwischen HF-Energieeffizienz
undräumlicher Abbildungsgüte und übertrifft andere bekannte Ansätze. Das
Verfahren wurdehinsichtlich mehrerer Anregungs-Frequenzen erweitert. Damit
können die räumlich geformtenPulse auch andere Gewebetypen wie Fett
selektiv unterdrücken.The focus of this thesis is on the development of radio-frequency (RF)
pulses for dedicatedapplications in magnetic resonance imaging (MRI)
utilizing the parallel transmission (pTx)technology. The contributions
include their algorithmic design and implementation as well assimulations
and human in-vivo experiments on a commercially available clinical pTx
MRIscanner platform at 3T.The role of RF pulses in MRI is essential for
both the signal generation and suppression ofundesired signal sources.
Basically, an RF pulse excites nuclear spins within a subject thatare
measured by resonant coils and subsequently reconstructed into images.
Besides the needfor accuracy, the RF pulses require to be as short and as
energy efficient as possible due tomain field inhomogeneity, spin
relaxation and patient tissue heating limitations. Recently,
theintroduction of the pTx technology facilitated new spatial degrees of
freedom to satisfy theserequirements. Many studies based on custom-built
pTx platforms have proven great benefits,but also showed potential pitfalls
coming along with the increased degrees of freedom. Therobust design and
transfer of pTx RF pulses to a clinical setup and applications is
stillon-going research and topic of this thesis.The contributed work can be
divided into three application fields. First, the performanceof 2-D
spatially selective RF pulses (2DRFs) is improved for inner-volume imaging.
Here,RF excitation is limited to a region of interest (ROI) to allow for
less distorted images withhigher resolution. New k-space trajectory designs
are proposed for 2DRF pulses, which showup to 43% better accuracy with 79%
improved RF power efficiency or substantially shortenedpulse durations by
more than a factor of two. Resulting diffusion weighted images show
ansignal-to-noise ratio (SNR) increase up to 40% compared to conventional
designs.Then, the additional RF transmit channel is used to pre-compensate
signal losses inducedby patient-specific main field perturbations in
gradient recalled echo (GRE) images. A fast,robust and fully automatized
method is proposed to reduce these signal voids on a slice-to-slice basis.
Tailored RF pulses are designed using the measured main field inhomogeneity
andRF transmit coil sensitivity profiles. Signal dropouts in multi-slice
images can be recoveredon average by 47%.Finally, an inherent RF power
efficient 2-D spiral trajectory design is employed to realizeanatomically
shaped saturation pulses. The pulses aim to accurately suppress
undesiredsignal sources, like moving inner organs, to avoid motion
artifacts. The proposed 2DRFspiral design proves to show the optimal
balance of RF power efficiency and spatial fidelityin various anatomical
locations and clearly outperforms other common design strategies.The
approach is further extended to multiple frequencies, so that the shaped
pulses can alsoselectively saturate other tissue types such as fat
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