1,720,956 research outputs found
INFLUENCE OF MN DOPING ON THE SUPERCONDUCTING PROPERTIES OF THE YBA2CU3-XMNXOY SYSTEM
No full textMn is substituted at Cu site in YBa2Cu3O7 (YBCO) compound and its effect on superconductivity of YBa2Cu3-xMnxOy (x = 0.0, 0.03, 0.09, 0.15, 0.21, 0.30) system has been studied. It is discussed that the resistivity upturn at low temperature in heavily doped samples may be due to the presence of Mn derived impurity phase. Mn appeared to reduce hole density without affecting the 1/T behavior of the Hall coefficient (R(H)). An attempt has been made to correlate the results of susceptibility with resistivity, hole density and structural changes with the Mn content
Study of Normal State Behaviour and Microstructure in YBa2Cu3-xCoxOy System
No full textThe effect of Co in the system has been studied. It is found that the normalstate resistive and magnetic properties change with the microstructure of the samples. The scanning electron microscopy (SEM) observations show that the morphology of the grains changes with Co concentration. Resistivity, a.c. susceptibility and X-ray diffraction (XRD) results are discussed together with SEM observations
XAS and XPS Study of Electronic Structure of the Tivalent Cuprate the La2Li0.5Cu0.5O4-d.
No full textWell-characterized stoichiometric La2Li0.5Cu0.5O4-delta (delta almost-equal-to 0.04) has been studied using high resolution CuL3- and OK-edges absorption (XAS) and Cu 2p3/2 X-ray photoelectron spectroscopy (XPS) techniques. The system is found not to have any Cu 3d8 configuration in its ground state but instead reveals a high density of the holes created by doping of monovalent lithium for the divalent copper in the oxygen 2p levels resulting in a 3d9L copper configuration by charge transfer. The formal valence of copper in it is found to be as high as almost-equal-to 2.84 in agreement with chemical analysis. The empirical correlation between the shift of the main XPS line (3d10L) and intensity ratio of the satellite (3d9) to the main line is examined and, also, a new correlation between the energy spread of the XPS satellite and the energy separation of the CuL3 absorption lines due to transitions from (3d9) and (3d9L) states is suggested
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
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
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