1,720,964 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
Optical properties of laterally overgrown GaN pyramids grown on (111) silicon substrate
No full textOptical properties of laterally overgrown GaN hexagonal pyramids on (1 1 1) Si substrates are studied by cathodoluminescence (CL) spectroscopy and mapping techniques. The results are compared with structural properties obtained by scanning and transmission electron microscopic techniques. To clarify the origin of the bandedge and yellow-band emissions from the GaN pyramids, wavelength-resolved CL properties of normal and cleaved GaN pyramids are investigated in the top and/or cross-sectional view configurations. The cross-sectional view CL images for cleaved GaN pyramid samples show significant differences between the overgrown areas on top of the mask and the coherently grown regions over the windows. A precise reverse (identical) contrast between bandedge (yellow-band) emission intensity and threading dislocation density is observed by comparing the cross-sectional view CL and transmission electron microscopic images. It is demonstrated that a strong correlation exists between structural defects and optical properties in laterally overgrown GaN hexagonal pyramids. (C) 2002 Elsevier Science B.V. All rights reserved.
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
Optical studies of ZnO thin films grown on O- and H-plasma treated Al2O3 substrates by plasma-assisted molecular beam epitaxy
No full textComparative analysis of the structural and optical properties of ZnO thin films, grown on oxygen (O)- and hydrogen (H)-plasma treated sapphire substrates (denoted by samples O and H, respectively), by plasma-assisted molecular beam epitaxy is reported. We found that sample O has better crystal structure quality as Compared to sample H by means of high-resolution X-ray diffraction, atomic force microscopy, and Hall measurements. We observed higher intensity ratio of excitonic emission to deep-level emission, longer radiative recombination lifetime, and lower Stimulated emission threshold for sample O compared to sample H. From the results, we conclude that the O-plasma treatment on sapphire substrates may result in a decrease in the number of oxygen vacancies and better lattice matching conditions, thereby leading to an enhancement of the crystal quality and the optical properties of ZnO thin films grown on O-plasma treated sapphire substrates. (C) 2008 Elsevier Ltd. All rights reserved.
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
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