1,720,978 research outputs found
DEBUSSY 2.0: The new release of a Debye user system for nanocrystalline and/or disordered materials
No full textThe new release of DEBUSSY is introduced, a free open-source package devoted to the application of the Debye function analysis of powder diffraction data from nanocrystalline, defective and/or nonperiodic materials. The general strategy of the suite remains unchanged, following a two-step approach managed by the CLAUDE and DEBUSSY programs, respectively. The first step essentially consists in generating a database where structural, size and shape information on a nanocrystal population is stored; the second step consists in the calculation, through the Debye scattering equation, of the total diffraction pattern using the previously generated database and a set of model parameters provided by the user and then optimized by the program. The novelties lie in the computational, modelling and graphical levels, and several new programs and features have been added. Among these are a new general comprehensive input file format (.ddb) for the database generation, the automatic management of the space-group symmetry and.cif file, new nanocrystal shapes, size-dependent site occupancy factors and thermal parameters for each atomic species, new lattice expansion functions, and a newly developed algorithm for calculating the standard errors of the optimized parameters. The CLAUDE suite also includes a program for calculation of the pair distribution function. Last but not least, a graphical user interface, which makes it easier to edit input files, execute the programs of the suite in a chain-like way, and plot the results in an automatic or custom manner, is provided
Crystals: Structure and Microstructure of Nanocrystals Using the Debye Function Analysis
No full textX-Ray Powder Diffraction Characterization of Nanomaterials
No full textWe discuss here what important knowledge can be gained by X-ray diffraction (of course, more specifically, we talk of X-ray powder diffraction) experiments on nanoparticles and nanomaterials in general. Historically, the uses of X-ray diffraction have been to investigate (a) the crystal structure of materials at the atomic scale and (b) their microstructure, a broad term meaning deviations from perfect crystalline order on a scale that is larger than the atomic one but still microscopic. In fact, macroscopic properties of materials tend to depend on both of those. For nanomaterials, the focus is to understand how the small crystal domain extension and related phenomena influence properties that differ – often in a very useful way – from the parent crystalline material. This means that the focus is on the microstructure, due to the fact that reduced domain extension is a (strong) deviation from crystal order – this is by definition something that extends to infinity. Of course there exist crystalline phases that are stable only at the nanoscale – and in such case, the crystal structure determination still is very important. In this contribution, we shall review all modern experimental methods and especially – as this is the core of the method – the data analysis techniques currently used, from the oldest, based on the Bragg formalism to interpret crystal diffraction, to the newest, relying on atomic-scale modeling
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
Structure and oxygen mobility in nanocrystalline ceramics for micro-solid oxide fuel cells
No full textDispelling 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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