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Cu-O-Cu in-plane angle distribution in layered superconductors probed by EXAFS
No full textAccurate Cu K-edge EXAFS spectra of doped and undoped lanthanum cuprates, collected in the temperature range 10-300 K, are analyzed taking proper account of the strong multiple-scattering (MS) signal found in these layered compounds (GNXAS method). A double-electron excitation [1s3p] channel has been evidenced and considered in the data treatment. Cu-O and Cu-(La,Sr/Ba) distance distributions have been measured, as well as the distribution of the Cu-O-Cu in-plane quasi-linear three-body configurations. In the latter case, the strong MS signal allowed an accurate study of the bond-angle distribution, associated with the buckling of the CuO2 planes. A detailed analysis of the statistical errors on the structural parameters has been performed, showing the reliability of the short-range structural refinement. The results are found to be consistent with previous diffraction and infrared data. Different features of the Cu-O-Cu distribution in superconducting and non-superconducting materials are discussed
Short-range structural properties of NdCuO andNdCeCuO studied bymultiple-scattering EXAFS data-analysis
No full textLocal structure EXAFS study of Nd2CuO4 and Nd1.85Ce0.15CuO4 using multiple-scattering data-analysis
No full textHigh-quality Cu X-edge EXAFS spectra of Nd2CuO4 and Nd1.85Ce0.15CuO4 are analysed as a function of temperature in the range T=5-70 K using the ''GNXAS'' method based on the multiple-scattering theory. The Cu-Nd and Cu-O-Cu in-plane quasi-linear distributions are studied as a function of temperature. Structural differences between doped and undoped compound are discussed
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
Single energy x-ray absorption detection: a combined electronic and structural local probe for phase transitions in condensed matter
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