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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
Oberflächen- und wellenleitergekoppelte Photomischer für Dauerstrich-Terahertz-Spektroskopie und -Kommunikation
No full textThe terahertz (THz) region, typically defined as the spectral range from 0.1 to 10 THz, holds great promise for a variety of industrial and academic applications due to its unique characteristics. Notably, many optically opaque dielectric materials are transparent to THz radiation, enabling non-destructive testing applications, such as high-resolution layer thickness measurements. Furthermore, numerous materials exhibit distinctive spectral “fingerprints” within the THz range, facilitating material detection through THz spectroscopy. With the rising demand for high-speed wireless data transmission, THz radiation, particularly in the 100 to 300 GHz range, has become increasingly significant for wireless communication applications, as high carrier frequencies promise enhanced channel bandwidths. Consequently, this frequency region is an active area of research for future communication standards, including 6G. Optoelectronic THz systems utilizing photomixers, which convert optical signals into the THz frequency range, have emerged as a particularly promising technology due to their exceptional bandwidth, which spans the entire THz spectrum. The integration of fiber-coupled or even photonic integrated components further allows for the development of compact, cost-effective systems for industrial applications. However, further research is essential to realize such compact, industry-ready systems that harness the full potential of THz radiation. This dissertation advances photomixers, particularly photoconductive antenna (PCA) receivers, for continuous wave (cw) THz spectroscopy and communication systems, enabling several new system performance records. Specifically, a peak dynamic range (DNR) of more than 132 dB, combined with over 5.5 THz bandwidth, is achieved in a coherent spectroscopy system, and a data rate of 84 Gbit/s is transmitted error-free in a fully photonic THz wireless link. Additionally, the first-ever PCAs compatible with photonic integration are developed opening new possibilities for fully integrated photonic THz systems. These achievements are enabled by several improvements of the photomixers. First, transition metal (TM) doping of the PCA’s indium-gallium-arsenide (InGaAs) absorber with iron (Fe) and rhodium (Rh) is investigated. The InGaAs:TM PCAs, in particular the Rh-doped ones, demonstrate superior performance compared to the state-of-the-art, achieving a record responsivity of 13.86 μA²/μW and noiseequivalent- power (NEP) below 0.1 fW/Hz. Next, the world’s first optical waveguide-integrated (win) PCAs for cw THz detection are developed, which, unlike traditional vertically illuminated PCAs, are excited through an optical waveguide. This approach opens up a new design space for the absorber geometry that allows for significantly more efficient absorption of the light, greatly enhancing the responsivity of the PCAs. The win-PCAs achieve up to a 500-fold increase in THz responsivity over surface-illuminated PCAs. This development also marks a significant milestone toward fully integrated photonic THz systems, as all system components are now available as waveguide-coupled devices compatible with photonic integration for the first time. Based on the improved PCAs, heterodyne receivers are developed for THz wireless communications, which feature broad bandwidths in both the THz and intermediate frequency (IF) domains to accommodate broadband communication channels. The best of these PCA receivers achieve a record IF bandwidth and conversion gain of 25 GHz and -22 dB, respectively. Finally, the performance of PIN photodiode THz emitters is enhanced by thinning their indium phosphide (InP) substrate and improving the fabrication process. The thinned substrate reduces the influence of the THz absorption by the InP, resulting in a significantly enhanced output power beyond 3 THz. In combination with the advancements in the fabrication process, a 4 dB improved peak output power is furthermore achieved. With the improved photomixers presented here, coherent cw THz spectrometers achieve over 20 dB higher DNR along with a 1.5 THz increase in bandwidth, while PCA-based fully photonic wireless links achieve a more than an 8-fold increase in capacity compared to the state-of-the-art prior to this thesis. These improvements represent a significant leap forward for photonic cw THz technology, which will advance its adoption in various application fields such as non-destructive testing and wireless communications.Der Terahertz- (THz) Frequenzbereich, üblicherweise definiert als der Bereich zwischen 0,1 und 10 THz, ist aufgrund seiner einzigartigen Eigenschaften für viele industrielle und akademische Anwendungen von Interesse. Beispielsweise sind viele optisch undurchsichtige dielektrische Materialien transparent für THz- Strahlung. Dies eröffnet Anwendungsmöglichkeiten in der nichtzerstörenden Prüftechnik, wie der hochauflösenden Schichtdickenmessung. Zudem besitzen viele Materialien charakteristische spektrale „Fingerabdrücke“ im THz-Bereich, was die Detektion dieser Materialien mittels THz-Spektroskopie ermöglicht. Angesichts des stetig steigenden Bedarfs an schnellem drahtlosem Datenverkehr gewinnt THz- Strahlung, insbesondere zwischen 100 und 300 GHz, an Bedeutung für Funkanwendungen, da hohe Trägerfrequenzen hohe Kanalbandbreiten versprechen. Dieser Frequenzbereich ist daher Teil der Forschung für zukünftige Kommunikationsstandards wie 6G. Optoelektronische Systeme, die Photomischer zur Umwandlung optischer Signale in den THz- Frequenzbereich nutzen, haben sich als vielversprechende Technologie etabliert, da die optischen Komponenten extrem hohe Bandbreiten bieten, die den gesamten THz-Bereich abdecken. Fasergekoppelte oder photonisch integrierte Komponenten ermöglichen zudem die Entwicklung kompakter, kosteneffizienter Systeme für Industrieanwendungen. Es bedarf jedoch weiterer Forschung zur Realisierung solcher kompakten, industrietauglichen Systeme, die die Möglichkeiten des THz-Frequenzbereichs voll ausschöpfen. In dieser Arbeit werden Indium-Gallium-Arsenid (InGaAs)-basierte Photomischer, insbesondere photoleitende Antennen (photoconductive antenna, PCA), für Dauerstrich- (continuous wave, cw) THz- Spektroskopie- und Kommunikationssysteme verbessert, was verschiedene neue Rekorde in der System- Performance ermöglicht. Konkret wird in einem kohärenten Spektroskopie-System ein Dynamikbereich von über 132 dB zusammen mit einer Bandbreite von 5.5 THz erreicht, sowie die fehlerfreie Übertragung von 84 Gbit/s in einer voll-photonischen THz-Funkstrecke. Weiterhin werden die ersten photonisch integrierbaren PCAs entwickelt, was neue Möglichkeiten für voll-integrierte photonische THz-Systeme eröffnet. Diese Fortschritte werden durch verschiedene Verbesserungen an den Photomischern ermöglicht. Zunächst wird die Dotierung des InGaAs-Photoleiters mit Übergangsmetallen wie Eisen (Fe) und Rhodium (Rh) untersucht. Dabei zeigen die Übergangsmetall-dotierten PCAs, insbesondere die Rh-dotierten, bessere Leistung im Vergleich zum Stand der Technik, wodurch sie Rekorde in Responsivität und äquivalenter Rauschleistung (noise-equivalent-power, NEP) von 13.86 μA²/μW und unter 0.1 fW/Hz erreichen. Anschließend werden zu ersten Mal wellenleitergekoppelte (waveguide-integrated, win) PCAs zur Detektion von cw THz-Strahlung entwickelt, die, im Gegensatz zu herkömmlichen vertikal beleuchteten PCAs, durch einen optischen Wellenleiter angeregt werden. Dieser Ansatz eröffnet neue Freiheitsgrade für das Design der Absorber Geometrie, die eine vielfach effizientere Absorption des Lichts ermöglichen, was die Responsivität solcher PCAs signifikant erhöht. Die win-PCAs erreichen eine bis zu 500-fach höhere THz- Responsivität im Vergleich zu oberflächenbeleuchteten PCAs. Die Entwicklung der win-PCAs stellt einen wichtigen Schritt in Richtung vollständig integrierter THz-Systeme dar, da nun erstmals alle Komponenten eines photonischen THz Systems in wellenleitergekoppelter Form verfügbar und somit kompatibel mit photonischer Integration sind. Auf Basis der verbesserten PCAs werden Heterodynempfänger für den Einsatz in der drahtlosen THz- Kommunikation entwickelt, die eine hohe Bandbreite sowohl im THz- als auch im Zwischenfrequenz- (IF) Bereich aufweisen, um hohe Datenraten zu unterstützen. Die besten dieser Heterodynempfänger erreichen eine Rekord-IF-Bandbreite und Konversionseffizienz von über 25 GHz bzw. -22 dB. Zusätzlich wird die Leistung von auf PIN-Photodioden basierenden THz-Emittern durch die Reduktion der Dicke des Indiumphosphid (InP)-Substrats sowie durch einen überarbeiteten Herstellungsprozess verbessert. Durch das dünnere Substrat wird der Einfluss der THz-Absorption des InP verringert, was die Ausgangsleistung dieser Emitter bei Frequenzen über 3 THz signifikant erhöht. Zusammen mit den Verbesserungen im Herstellungsprozess der Dioden wird zudem bis zu 4 dB mehr Maximal-Ausgangsleistung erreicht. Durch die hier präsentierten verbesserten Photomischer erreichen kohärente THz-Spektrometer nun über 20 dB mehr Dynamikbereich und 1.5 THz mehr Bandbreite, sowie PCA-basierte voll-photonische THz-Funkstrecken eine um mehr als das 8-fache erhöhte Datenrate im Vergleich zum Stand der Technik vor dieser Arbeit. Diese Verbesserungen stellen eine signifikante Weiterentwicklung von cw THz-Technologie dar, die deren Verbreitung in zahlreichen Industrie-Anwendungen wie der zerstörungsfreien Prüfung und der Drahtloskommunikation voranbringen wird
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
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