1,720,965 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
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
Fabrication and characterization of spin Hall microwave nano-oscillators
No full textDie vorliegende Masterarbeit beschäftigt sich mit der Herstellung und Charakterisierung spezieller Spin-Hall Nano-Oszillatoren. Zu Beginn werden die physikalischen Grundlagen zum Verständnis der Funktion dieser Oszillatoren dargestellt. Weiterhin wird die Brillouin-Lichtstreu- Mikroskopie vorgestellt, die zur optischen Erfassung der Magnetisierungspräzession eingesetzt wurde. Im Anschluss wird das Herstellungsverfahren dieser nanoskaligen GHz-Oszillatoren gezeigt. Der experimentelle Teil der Arbeit beschäftigt sich mit der Charakterisierung von Spin- Hall Nano-Oszillatoren mit lokalen, lateralen Verengungen, die zu einer erheblichen Stromdichteerhöhung führen. Dabei liegt der Schwerpunkt auf den Abhängigkeiten der Oszillatorleistung, -frequenz und -linienbreite von der Stärke des Gleichstromes, der diesen Bauteilen kontinuierlich Energie zuführt. Durch ortsaufgelöste Messungen konnten die gefundenen Frequenzen den jeweiligen Oszillatororten, die den Bereichen mit hoher Stromdichte entsprechen, zugeordnet werden. Weiterhin wird gezeigt, dass bei hohen Leistungen der Effekt der Frequenzverdopplung auftritt. Der experimentelle Teil schließt mit der Vorstellung eines Experiments, bei dem der Versorgungsstrom eine Modulation erfährt und die Oszillationseigenschaften über einen bestimmten Frequenzbereich verschoben werden können.The focus of this master thesis lies on the fabrication and characterization of specific spin- Hall nano-oscillators. First, the theoretical framework for the understanding of dynamic magnetic phenomena and the spin Hall effect are discussed. The following chapter is devoted to the experimental methods, in particular the instrumentation for Brillouin light scattering microscopy is introduced, which allows for the optical detection of the magnetization precession, followed by a detailed description of the fabrication process of nanoscale gigahertz oscillators using state-of-the-art electron beam lithography. The main part of the thesis is the presentation of the experimental results obtained from the characterization of the magnon spectrum in constriction-based spin-Hall nano-oscillators with locally enhanced current density. Key results are the oscillation power, frequency and linewidth as a function of the applied electric current, which is effectively compensating the intrinsic damping of the magnetization and, therefore, causing auto-oscillations of the magnetization. The spatial intensity distributions of these autooscillations were mapped with Brillouin light scattering microscopy, which also revealed higher harmonic generation in sample regions of high current density and auto-oscillation amplitude. The chapter with the experimental results concludes with the characterization of the frequency range, in which these auto-oscillators can be locked to an externally applied microwave current, superimposed to the electric current driving the magnetization precession. The thesis concludes with a summary and an outlook on future experiments based on spin-Hall effect based autooscillators and their technical applications
Frequency control of auto-oscillations of the magnetization in spin Hall nano-oscillators
No full textThis thesis experimentally demonstrates four approaches of frequency control of magnetic autooscillations in spin Hall nano-oscillators (SHNOs).
The frequency can be changed in the GHZ-range by external magnetic fields as shown in this work. This approach uses large electromagnets, which is inconvenient for future applications.The nonlinear coupling between oscillator power and frequency can be used to control the latter one by changing the applied direct current to the SHNO. The frequency can be controlled over a range of several 100 MHz as demonstrated in this thesis.
The first part of the experimental chapter demonstrates the synchronization (injection-locking) between magnetic auto-oscillations and an external microwave excitation. The additionally applied microwave current generates a modulation of the effective magnetic field, which causes the interaction with the auto-oscillation. Both synchronize over a range of several 100 MHz. In this range, the auto-oscillation frequency can be controlled by the external stimulus. An increase of power and a decrease of line width is achieved in the synchronization range. This is explained by the increased coherence of the auto-oscillations. A second approach is the synchronization of auto-oscillations to an alternating magnetic field. This field is generated by a freestanding antenna, which is positioned above the SHNO.
The second part of the experimental chapter introduces a bipolar concept of SHNOs and its experimental demonstration. In contrast to conventional SHNOs, bipolar SHNOs generate autooscillations for both direct current polarities and both directions of the external magnetic field. This is achieved by combining two ferromagnetic layers in an SHNO. The combination of two different ferromagnetic materials is used to switch between two frequency ranges in dependence of the direct current polarity since it defines the layer showing auto-oscillations. This approach can be used to change the frequency in the GHz-range by switching the direct current polarity
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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