1,721,315 research outputs found
Non-equilibrium vibrational and electron energy distributions functions in atmospheric nitrogen ns pulsed discharges and μs post-discharges: the role of electron molecule vibrational excitation scaling-laws
Full text linkThe formation of the electron energy distribution function in nanosecond atmospheric nitrogen discharges is investigated by means of self-consistent solution of the chemical kinetics and the Boltzmann equation for free electrons. The post-discharge phase is followed to few microseconds. The model is formulated in order to investigate the role of the cross section set, focusing on the vibrational-excitation by electron-impact through resonant channel. Four different cross section sets are considered, one based on internally consistent vibrational-excitation calculations which extend to the whole vibrational ladder, and the others obtained by applying commonly used scaling-laws
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
AB INITIO CALCULATIONS FOR MOLECULAR TRANSITION STRENGTHS
No full textAuthor Institution: Department of Physics and Astronomy, University College LondonThe presentation shall focus on two topics of interest in molecular astrophysics: (a) Molecular R-matrix calculations of electronic transitions and (b) Ro-vibrational calculations for the opacity of water molecule
Vibration–rotation transition dipoles from first principles
No full textAbstractThe use of ab initio methods to calculate line positions and associated transition intensities for the infrared spectrum of small molecules has recently become common. The first principles calculation of transition dipoles, upon which the intensity is based, relies on three distinct steps: the quantum chemical calculation of the dipole moment surface at a grid of geometries, the accurate representation of this surface using an appropriate functional form and the wave functions used to represent the initial and final states, which in turn depend on the accuracy of the potential energy surface used to generate them. Each of these stages is discussed with a view to obtaining the highest possible accuracy. The prospect of computed transition intensities displacing measured ones as the primary source of such information is considered
Accuracy and completeness of molecular line lists
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Previous issue date: 6We review recent progress in the calculation of the global,_x000d_
high-temperature and accurate room-temperature linelists of various_x000d_
molecules relevant for the analysis of both Earth and exoplanet_x000d_
atmospheres and cool stars. These global line lists can be constructed_x000d_
based on progress in calculation of energy levels up to dissociation_x000d_
and the fitting of the molecular PESs to the experimental data close_x000d_
to dissociation. Sub-percent accuracy in the intensity of calculated_x000d_
absorption lines is achieved thanks to progress in textit{ab initio}_x000d_
electronic structure calculations which is aided by the possibility of_x000d_
characterizing their accuracy by the comparison with experimental_x000d_
intensities measured with sub-percent accuracy for some molecular_x000d_
lines. The advantage of variational calculations over experiment_x000d_
though is the ability to produce billions of lines covering all the_x000d_
isotopologues, which is clearly impossible for the experimental_x000d_
observations. Atmospherically and astrophysically important molecules_x000d_
such as chem{H_2O}, chem{CO_2}, chem{CO} and chem{H_3^+} will be considered together with some_x000d_
examples of the other molecules. _x000d
DVR3DUV: A suite for high accuracy calculations of ro-vibronic spectra of triatomic molecules
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Previous issue date: 6We present a computer code (DVR3DUV) for calculations of high-accuracy ro-vibronic spectra of triatomic molecules. The current implementation is an extension to the DVR3D suite [1], which operates with the exact kinetic energy operator, a single potential energy surface and a single dipole moment surface (ro-vibrational transitions only). _x000d_
The main function of the new code is calculation of transition intensities between different electronic states in the rotational-vibrational resolution. _x000d_
As a case study, two electronic states of SO molecule are considered. Ro-vibrational wavefunctions and energy levels for the ground state of SO are calculated using Ames PES [2], while energy levels and wavefunctions of the state are calculated using textit{ab initio} PES (MRCI-F12-AVTZ). _x000d_
Transition intensities are computed using a) Franck-Condon approximation; b) textit{ab initio} dipole moment surface between the two electronic states. Results are compared to the latest theoretical and experimental works. Future applications of the DVR3DUV code will focus on highly accurate electronic spectra for atmospherically important species, such as ozone molecule. _x000d_
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renewcommand{section}[2]{}%_x000d_
%renewcommand{chapter}[2]{}% for other classes_x000d_
begin{thebibliography}{}_x000d_
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bibitem{1} J. Tennyson, M ~A. Kostin, P. Barletta, G. J. Harris, O ~L. Polyansky, J. Ramanlal, N. F. Zobov, Computer Physics Communications 163 (2004) 85–116._x000d_
bibitem{2} X. Huang, D. ~W. Schwenke, T. ~J. Lee, J Chem Phys. 2014 ;140(11):11431_x000d_
end{thebibliography}_x000d_
endgroup} _x000d
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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