1,722,491 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
Tuning of resonances in photonic crystal slabs
Get PDFDer Inhalt dieser Arbeit ist die Simulation und Fabrikation von photonischen Kristallen. Ähnlich wie in einem Festkörperkristall, der die Ausbreitungseigenschaften von Elektronen bestimmt, bestimmt ein photonischer Kristall die Ausbreitungseigenschaften von Photonen. Durch Anpassung des Designs des photonischen Kristalls können neuartige optoelektronische Bauelemente mit bisher unerreichbaren Eigenschaften geschaffen werden, wie zum Beispiel photonische Bandlücken, welche die Wellenausbreitung bei bestimmten Frequenzen vollständig zu unterdrücken.Weiters können durch Einbringen von Kristalldefekten Resonatoren mit hoher Güte und Wellenleiter mit niedrigen Verlusten gefertigt werden.Von besonderem Interesse sind photonische Kristallscheiben, da sie kompatibel sind mit den Standardverfahren zur Herstellung von Halbleiterbauelementen. Durch Einbringen eines Detektors in eine photonischen Kristallscheibe konnten die resonanten Moden im mitteleren-infraroten Spektralbereich (3µm-30µm) direkt gemessen werden.Als Detektor wurde ein Intersubband-Photodetektor eingesetzt. Da das Licht in die resonanten Moden wesentlich effizienter einkoppelt, wird das breitbandige Photostromspektrum durch den photonischen Kristall modifiziert. Dadurch können Detektoren mit schmalen Absorptionslinien gefertigt werden, welche zum Bestimmen der Zusammensetzung chemischer Substanzen genutzt werden können.Zur Berechnung der Bandstruktur von photonischen Kristallen sind verschiedene Simulationsstrategien verfügbar. Methoden wie die sogenannte "finite difference time domain" liefern zwar genaue Ergebnisse, speziell wenn die endliche Ausdehnung der Bauelemente berücksichtigt werden muss, aber die Berechnungszeiten sind lange und es wird viel Speicherplatz benötigt. Daher wurde für diese Arbeit die "revised plane wave expansion method" verwendet. Hier werden photonische Kristallmoden durch Summen von ebenen Wellen approximiert. In Kombination mit einem effektiven Brechungsindex, um die Modenführung in der Scheibe zu berücksichtigen, liefert diese Simulation Banddiagramme innerhalb weniger Minuten. Die Ergebnisse stimmen mit Messungen an photonischen Kristallscheiben gut überein.In einem dielektrischen planaren Wellenleiter sind die Moden nicht ausschließlich auf zwei Dimensionen beschränkt. Die elektromagnetische Feldverteilung erstreckt sich bis in das umgebende Medium und klingt dort exponentiell ab. Durch Verändern der Distanz der photonischen Kristallscheibe zum Substrat wird die elektromagnetische Feldverteilung in der Scheibe beeinflusst. Mittels anlegen einer Spannung zwischen Substrat und Scheibe kann ein elektrostatische Kraft erzeugt werden, welche die Scheibe näher zum Substrat bringt. Dadurch können die photonischen Kristallresonanzen gezielt beeinflusst werden. Derartige Bauelemente wurden simuliert, hergestellt und gemessen.The focus of this thesis is the simulation and fabrication of photonic crystals. Like a solid state crystal determines the propagation properties of electrons, a photonic crystal determines the propagation properties of photons. By tailoring the geometry of the photonic crystal novel optoelectronic devices can be obtained with properties that were previously unachievable. Complete optical bandgaps to inhibit wave propagation are possible, which are unknown from conventional bulk materials. By introducing crystal defects in photonic crystals, high Q cavities or low loss waveguides can be fabricated.Photonic crystal slabs are of particular interest as they are compatible with standard semiconductor processes. The resonant modes of photonic crystal slabs in the mid-infrared region (3µm-30µm) were measured by processing the photonic crystal from detector material. For mid-infrared light this can be achieved by intersubband absorption in a quantum well infrared photodetector. The broad photocurrent spectral response of the photodetector is modified by the photonic crystal as coupling to the resonant modes is much more efficient. This behavior allows to build detectors with narrow spectral absorption peaks, which can be used for chemical fingerprinting.To compute band diagrams for photonic crystal slabs several simulation strategies are available. Methods like finite differences time domain deliver accurate results, especially when considering the finite extensions of the devices. But they require a lot of computation time and memory space. For this thesis the revised plane wave expansion method, combined with an effective refractive index computation to account for mode guiding in the slab, was implemented. With this method band diagrams can be computed within several minutes and the results from this simulation are in good agreement to the measurements from fabricated photonic crystal slabs.In a dielectric slab wave guide the modes are not fully confined to the slab. The electromagnetic field distribution has evanescent tails that extend into the surrounding cladding region. Changing the distance from the photonic crystal slab to the substrate influences the electromagnetic field distribution in the slab and hereby the resonances in the photonic crystal. By applying a voltage between substrate and slab an electrostatic actuator is formed, the resulting force pulls the slab closer to the substrate and the photonic crystal resonances are tuned. Such device structures were simulated, fabricated and measured
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
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