1,721,079 research outputs found
Formation of Mn(3)O(4)(001) on MnO(001): Surface and interface structural stability
No full textX-ray absorption and photoemission spectroscopies, high-resolution electron energy loss spectroscopy, spot profile analysis low energy electron diffraction, and density functional theory calculations are employed to study the growth of (001) oriented Mn(3)O(4) surfaces on a Pd(100)-supported MnO(001) substrate, with the Hausmannite planar lattice constants aligned along the [110] direction of the underlying MnO(001) support. We show that despite the rather large lattice mismatch, abrupt interfaces may exist between rocksalt MnO and Hausmannite. We argue that this process is facilitated by the relatively low computed strain energy and we propose realistic models for the interface. An atop site registry between the Mn(O) atoms of the oxygen rich Mn(3)O(4) termination and the MnO(001) O(Mn) atoms underneath is found to be the energetically most favorable configuration. The significant planar expansion is accompanied by a large compression of the Mn(3)O(4) vertical lattice constant, yielding structural distortion of the O-Mn-O octahedral axis. Spot profile analysis low energy electron diffraction experiments show that the conversion reaction proceeds easily in both directions, thus indicating the reversible redox character of the transition
Ab initio study of the structural, electronic, and magnetic properties of MnO(100) and MnO(110)
No full textThe structural, electronic, and magnetic properties of the MnO(100) and (110) surfaces were studied within the standard approximation of Perdew, Burke, and Ernzerhof (PBE) and the PBE+U approach. For the (100) surface, the surface layers relax inwards for both sets of calculations. For the (110) surface an electronically driven missing row reconstruction is predicted which significantly lowers the surface energy. For all cases, the O surface atoms relax outwards in comparison to Mn, inducing a buckling of the surface layers. The antiferromagnetic type II ordering of the bulk phase is conserved for both surfaces, the local magnetic moments of Mn exhibit no change with respect to the bulk values. The magnetic ordering at the surfaces is studied in terms of the Heisenberg model and the calculated exchange coupling constants as derived from the ab initio data are significantly enhanced at the surface with respect to the bulk
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Density functional theory study of MnO by a hybrid functional approach
No full textThe ground state properties of MnO are investigated using the plane wave based projector augmented wave technique and the so-called "parameter-free" hybrid functional approach PBE0 for the approximation of the exchange-correlation energy and potential. The insulating, antiferromagnetically ordered and rhombohedrally distorted B1 structure is found to be the most stable phase of MnO, consistent with experiment. The band gap of 4.02 eV, spin magnetic moment of 4.52 mu(B), optimized lattice parameter a=4.40 angstrom, rhombohedral distortion angle alpha=0.88(0), density of states, and magnetic properties are all in good agreement with experiment. Results obtained from standard methods such as generalized gradient approximation (GGA), GGA+U and periodic Hartee-Fock are also reported for comparative purposes. In line with previous studies, our results suggest that the applied hybrid functional method PBE0, which combines 25% of the exact exchange with a generalized-gradient approximation, corrects the deficiency of semilocal density functionals and provides an accurate quantitative description of the structural, electronic, and magnetic properties of MnO without any adjustable parameter
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