1,720,966 research outputs found
An ab-initio study of a, b, and ? crystal phases of TiCl3: geometry, electronic structure, and magnetism
No full textSurface Temperature Effects on Dissociative Chemisorption of H2 on Cu(100)
No full textAt present, much remains unknown about the effect surface phonons and surface temperature may have on the reactivity of molecules at surfaces. Here, this problem is addressed for the dissociation of H2 on copper, which is a benchmark system for activated dissociative chemisorption on a metal surface. Ab Initio Molecular Dynamics (AIMD) calculations, quantum dynamics calculations using a static surface model, and experiments are reported and compared on the effects of surface temperature (Ts) on the initial state-selected reaction of (v = 0, j = 8) and (v = 1, j = 4) H2 scattering from Cu(100) and the orientational dependence of this process, at Ts = 1030 K. In the theory, the specific reaction parameter approach to density functional theory (SRP-DFT) was used. The rotational quadrupole alignment parameters computed for H2 reacting on the hot Cu(100) surface (1030 K) are smaller than the values computed with a static surface model. The initial state-selected reaction probabilities computed with AIMD for the hot surface are shifted to lower energies, by 40–60 meV, and broadened with respect to static surface quantum dynamics results. The rotational quadrupole alignment parameters computed with AIMD are in good agreement with experiment if the experimental results are shifted to lower energies by 100–150 meV. The AIMD average desorption energies underestimate the experimental results by 150–180 meV. Our study shows that the H2 + Cu(100) system presents a useful benchmark for the simultaneously accurate description of dissociative chemisorption and surface thermal effects on reaction because surface temperature effects on the (100) surface are much more pronounced than on the Cu(111) surface, while the (100) face does not yet show surface reconstruction at temperatures of interest to associative desorption experiment
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
Bottom-up approach to innovative memory devices: I. Intrinsic and environmental effects on the molecular component
No full textThe 50 nm-thick polystyrene (PS) film, involved in some innovative memory devices, contains 8-hydroxyquinoline
(8HQ) molecules and gold nanoparticles. A model where molecular localized properties directly
reflect on macroscopic behavior of a complex system has been tested in the present work, which is focused
on the structural and electronic properties of the 8HQ-PS mixture modeled in a continuum scheme: one 8HQ
molecule with a polarizable continuum model (PCM) whose reliability has been checked by comparison with
periodic DFT calculations of 8HQ-PS crystalline structures. A comprehensive study of the keto-enolic
tautomerization of 8HQ has been performed, at the DFT level using B3LYP, LC-PBE, and M052X functionals
and a polarized double- basis set. The energetics of the obtained structures (minima and transition states)
have been refined by single point calculations at the CCSD(T) level with the aug-cc-pVDZ basis set. Our
calculations predict the enolic tautomer to be the most stable for the isolated and PS-solvated 8HQ in its
neutral form, with a tautomerization barrier much larger than the thermal energy at the working conditions.
The opposite trend has been found for the charged (both positive and negative) 8HQ, with ketonic tautomers
being the most stable. In a first approximation of weak interaction with the aluminum electrodes, the electricfield
effects have also been taken into account for the calculations of electron affinities and ionization potentials
of 8HQ molecules. The electron and hole injection barriers issuing from these results are in good agreement
with the experimental observations
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
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