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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
Laser stimulated self-organization in simple and complex thin-film systems
No full textDas Leitmotiv der vorliegenden Dissertation besteht in der Untersuchung laserstimulierter Selbstorganisation verschiedener Dünnschichtsysteme. Im Vergleich zu anderen Fertigungsprozessen wird die Strukturierung bei der Selbstorganisation nicht durch die direkte Kontrolle des verwendeten Werkzeuges bestimmt. Wie in der Einleitung genauer erläutert, wird vielmehr eine dynamische Materie-Umverteilung stimuliert. Bestehende Modelle dieser Selbstorganisationen beziehen sich fast usschließlich auf die initialen Systemparameter und vernachlässigen die zeitliche Veränderung und Reaktivität der Dünnschichten während der Laserstrukturierung. Aus diesem Grund wurden in dieser Arbeit Dünnschichten verschiedener physikochemischer Eigenschaften (z. B. aus Metallen oder metall-organischen Präkursoren) strukturiert. Die Komplexität des Systems wurde hierfür, ausgehend vom reinen Substrat, stetig erhöht. Dabei wurde unter anderem der Einfluss des Substrats, der Oxophilie und des Legierungsverhaltens der Dünnfilme auf die Nanostrukturierung untersucht. Bei Bestrahlung mit linear polarisiertem Licht entstehen LIPSS (engl.: laser-induced periodic surface structures), welche aus periodischen, linearen
Nanostrukturen bestehen. Die Ausrichtung und Periodizität der LIPSS werden maßgeblich durch die Art des Materials und die Bestrahlungs-Parameter bestimmt. Durch Bestrahlung von Oberflächen mit zirkular polarisiertem Licht können zweidimensionale periodische Muster erzeugt werden. Die selbstorganisierten Strukturen werden folglich in 1D-LIPSS (Streifen) und 2D-LIPSS (Wabenmuster und geordnete Nanopartikelfelder) unterteilt. Der Fokus dieser Arbeit liegt dabei auf der Untersuchung der weniger bekannten 2D-LIPSS. Als in der akademischen Forschung gut etabliertes, anwendungsrelevantes und zugleich simples Modellsystem wird Silizium gewählt. Durch die Bestrahlung der Oberfläche bei gleichzeitiger lateraler Bewegung des Laserspots können 1D-LIPSS erzeugt werden. Da durch die Verwendung von zirkular polarisiertem Laserlicht keine inhärente Vorzugsrichtung vorliegt, stellt sich die Bewegungsrichtung des Lasers als einzige richtungsgebende Komponente der LIPSS-Erzeugung heraus. Die Kristallausrichtung kann hierbei als zweiter Einflussfaktor ausgeschlossen werden. Zur Erhöhung der Komplexität wird das System um einen möglichst inerten Metalldünnfilm erweitert. Dazu werden Siliziumwafer mit einer Goldschicht im einstelligen Nanometerbereich bedampft. Die Laserstimulation dieser Dünnfilme führt zur Selbstorganisation des Goldes zu periodisch angeordneten Nanopartikeln. Die Partikel sind teilweise in das Si-Substrat eingesunken, wessen kristallographische Ausrichtung die Partikel-Morphologie bestimmt. So besitzen diese auf einer Si(100)-Oberfläche eine linsenförmige Form, während auf einer Si(111)-Oberfläche die Form abgerundeter, flacher Dreiecke entsteht. Bei analog durchgeführten Experimenten unterschiedlicher reaktiveren Metalldünnschichten aus Silber, Kupfer, Eisen, Zink und Titan entstehen neben den periodisch angeordneten Nanopartikelfeldern (hexagonal oder quadratisch) ebenfalls Metall-Wabenmuster und 1D-LIPSS. Durch graduelles Erhöhen der eingebrachten Gesamtenergie kann allgemein ein Morphologie Verlauf der Metallstrukturen ausgehend von einer Entnetzung, über eine Bildung von 1DLIPSS, Wabenmustern und letztendlich geordneter Nanopartikelfelder beobachtet werden. Der exakte Verlauf und die dabei auftretenden Strukturtypen sind systemabhängig. Als entscheidende Einflussfaktoren zeigen sich das chemische Element, die Schichtdicke und die Bestrahlungsparameter, wie beispielsweise Pulsenergie oder Pulszahl. Dabei wird der Einfluss des Metalls auf den Strukturierungsprozess vor allem durch seine Wechselwirkung mit dem Substrat und durch die Legierungseigenschaften bestimmt. Darauf aufbauend können zwei geschichtete Metall-Dünnfilme in einem einzigen Schritt strukturiert und legiert werden. Um das Spektrum der für die Laserstrukturierung verwendbaren Materialklassen zu erweitern, werden in einer Pionierarbeit mit Hilfe eines Spincoaters Dünnfilme eines metall-organischen MoS2-Präkursors [Mo2S4(S2CNnBu2)2] auf Siliziumwafer mit unterschiedlichen Siliziumdioxid-Schichtdicken aufgetragen. Anders als bei den Metalldünnfilmen verläuft die laserinduzierte Selbstorganisation des Präkursors bei niedrigen Pulszahlen über eine rein thermische Umverteilung, d. h. ohne Materialverlust und unter Erhalt der chemischen Integrität. Durch eine deutliche Erhöhung der Pulsenergie kann der Präkursor während des Strukturierungsprozesses gleichzeitig zu MoS2-Nanokristallen umgewandelt werden. Dieser Umwandlungsprozess verläuft allerdings unter deutlichem Verlust der LIPSS-Qualität. Sowohl die Strukturierung der geschichteten Metallsysteme als auch die des metall-organischen Präkursors verdeutlichen dabei die Anwendbarkeit des Strukturierungsverfahrens auf komplexe Schichtsysteme, bestehend aus verschiedenartigen Materialklassen. Die präsentierten Verfahren eignen sich folglich zur Herstellung verschiedener opto-elektronischer Geräte auf Halbleiterbasis. Als exemplarisches Anwendungsbeispiel laser-strukturierter Oberflächen werden im abschließenden Teil der Arbeit laser-generierte Goldkatalysatoren auf Silizium einem carbothermischen Wachstumsprozess von Zinkoxid- (ZnO) Nanostrukturen unterzogen. Durch die Laserbestrahlung entstehen sowohl passivierte als auch freiliegende Goldpartikel, deren Größe und Dichte einen wesentlichen Einfluss auf das Strukturwachstum haben, welches durch die Lasereinwirkung gezielt kontrolliert werden kann. Die Bestrahlung ermöglicht somit die ortsaufgelöste Steuerung der Morphologie, Dichte, Höhe und Breite der ZnO-Strukturen.This dissertation is guided by the theme of laser-induced self-organization of various thin film systems. Contrarily to similar manufacturing techniques, during self-organization the surface is not just directly modified by the tool itself. As further explained in the introduction section, the surface is rather modified by a stimulated material-reorganization. State-of-the-art pattern formation theories are often solely based on the initial system properties. These idealized models lack the consideration of laser mediated reactions and changes of material properties, as well as substrate interactions. To tackle aforementioned shortcomings, various thin films, e.g. inert and reactive metallic thin films, as well as organo-metallic precursor films, were irradiated. The influence of the thin film’s physicochemical properties on the pattern evolution and the final nanostructure expression were evaluated. Starting with the bare substrate, the system was first extended by an inert metal and subsequently by more reactive metallic thin films. Finally, the pattern formation of metal-organic precursor thin films was studied, providing a clear contrast to the metallic thin films in terms of material properties. When generated by linearly polarized laser light, these so-called laser-induced periodic surface structures (LIPSS) consist of periodically arranged nanowires or ridges. The periodicity and orientation are functions of the structured materials itself, as well as of the irradiation parameters. Upon laser irradiation with circularly polarized light, two dimensional periodic nano-structures were obtained. As a consequence, LIPSS generated in this work are classified into 1D-LIPSS (nanowires) and 2D-LIPSS (honeycomb-like arrangements and nanoparticle-arrays). This work was done with great emphasis on the less common 2D-LIPSS. Silicon (Si) is one of the most researched, yet application-oriented and simple materials, being the ideal candidate for a model-system. Arial illumination of a silicon surface leads to the formation of 1D-LIPSS. As the directional bias of linearly polarized light was omitted upon using circularly polarized light, the LIPSS’s orientation was solely defined by the laser scan direction. The self-organization is not disturbed by the silicon’s crystallographic orientation and leads to well-defined surface topography modulations, absent from additional surface oxidation. In order to increase the system’s complexity, silicon wafers were coated with an inert metal thin film. The laser-irradiation of gold thin films leads to the formation of self-organized gold nanoparticles arrays with hexagonal and square periodic arrangements. The nanoparticles are partly sunken in the Si surface, whose crystallographic orientation determines the nanoparticles shape. On Si(100) surfaces the nanoparticles possess a lens shape, while on Si(111) the nanoparticles are formed like bulged triangles. Analogous experiments conducted by replacing gold with other metal thin films as silver, copper, iron, zinc and titanium also resulted
in the formation of nanoparticle arrays. Additionally, honeycomb-like metal nanostructures, as well as 1D-LIPSS emerged. Generally, the nanostructures were found in the order of dewetting, 1D-LIPSS, honeycomb-like 2D-LIPSS and eventually nanoparticle arrays, upon gradually increasing the energy dose during irradiation. Depending on the thin film’s elemental composition and thickness, as well as the irradiation conditions, e.g. pulse fluence and pulse numbers, the pattern evolution does not necessarily follow through all aforementioned types of LIPSS. The metal’s influence on the self-organization could be attributed to the metal’s free energy of oxide formation, interaction with the substrate and alloying properties. Additionally, simultaneous patterning and alloying of two stacked thin films of different elements could be achieved. Further expanding the set of available material classes for LIPSS-generation, a metal-organic thin film of a MoS2 precursor [Mo2S4(S2CNnBu2)2] was spin coated on silicon. Upon irradiating the system with linearly polarized laser pulses, 1D-LIPSS were obtained. Stimulating the system with circularly polarized laser light resulted in a rearrangement of the thin film in honeycomb-like formations (2D-LIPSS). Unlike the structuration of metallic thin films, the laser induced self-organization of the metal-organic thin films was found to occur solely by matter reorganization, maintaining both the materials chemical integrity and quantity. Significantly increasing the pulse fluence initiates the conversion of the precursor material to dendritic MoS2 nanoparticles. On the downside, the chemical conversion process leads to a significant loss in LIPSS quality. The successful structuration of stacked metal thin films, as well as the metalorganic thin films on silicon-dioxide, confirms the laser-stimulated pattern formation to be applicable to complex layer systems. The presented methods thus allow for the fabrication of diverse semiconductor-based opto-electric nano-devices. In a last part of this work, the application of aforementioned nanostructures was exemplarily examined. The usage of laser-generated gold catalysts on silicon as catalysts for the carbothermal growth of zinc oxide (ZnO) nanostructures was investigated. The laser-generated catalysts are distinguished in two different nanoparticle types. The first type consists of nanoparticles passivated by a thin SiO2-layer. The second type consists of exposed gold surfaces, acting as main catalysts responsible for the ZnO-growth. Upon adjusting the irradiation parameters, the size and areal density of the exposed gold nanoparticles are directly controlled. As a consequence, this method allows the gradual and spatial-selective control of the subsequently grown ZnO-nanostructure’s morphology, density, height, and width
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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