1,720,980 research outputs found
Synthesis of Fully Dense Anatase TiO2 Through High Pressure Field Assisted Rapid
No full textHigh density bulk nanostructured TiO2 was prepared through densification of anatase nanopowder by the high-pressure field-assisted rapid sintering method in the temperature range 600-1000 degrees C, under a uniaxial pressure of 620 MPa. In these sintering conditions samples characterized by a grain size between 40 and 150 nm have been obtained. Nearly full densification was observed for temperatures above 700 degrees C, while phase transition towards the rutile phase was observed in samples sintered at temperatures >= 800 degrees C. It was therefore possible, for the first time, to completely retain the anatase phase in bulk high-density samples
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
The role of local structural distortions in the stabilisation of undoped nanocrystalline tetragonal zirconia
No full textNanopowders of pure or very lightly doped zirconia were studied by means of total scattering and pair distribution function analysis, with the aim of understanding how the size of the particles (if a size limit of about 20 nm is not exceeded) tends to stabilise the tetragonal polymorph at room temperature. Total scattering and PDF analyses, together with Rietveld refinements, showed that the tetragonal model is indeed applicable to the average structure of these nanocrystalline zirconia samples, and provided comparable results. However, all the samples, with no influence from the dopant content, showed a similar local distortion for r < 10 Å. In this region, the data were fitted with two slightly different tetragonal structures, with a tetragonal distortion that decreases with the Rmax used, giving rise to a structure closer to the average tetragonal one (given by Rietveld as well as by average PDF refinements). In the first coordination shell, however, an orthorhombic distortion fits very well both in intensity and in position. This distortion may be responsible of the increased RMS strain local level, and therefore of the stabilisation of the high temperature structure at room temperature. © 2014 Elsevier 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
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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