1,720,988 research outputs found
New Atomic Data For Iron-Peak Elements For Use In Astrophysical Modeling
Full text linkSupernovae (SN) and supernova remnant (SNR) plasmas represent some of the most
extreme and unusual objects in the universe. X-ray spectra of supernova remnant plasmas
are key to understanding the mechanism and dynamics of supernova explosions. In recent
years, there have been observations of Cr and Mn X-ray emission lines from a wide range
of supernova remnant plasmas. Diagnostics that use these emission features are currently
hampered by a lack of atomic data for these Fe-peak elements. The purpose of this research
is to generate the high quality atomic data needed by the astrophysics community. We focus
on the atomic data for He-like Fe-peak elements Cr22+, Mn23+, Fe24+, Co25+, and Ni26+. As
an example of the use of this new data, our spectral analysis is carried out for the Galactic
supernova remnant W49B.
The new electron-impact excitation data are calculated using a Dirac R-matrix suite
of codes and include the infinite energy limit points on the collision strengths. The data
are compared with available literature values, including recent Dirac R-matrix calculations,
quantifying the influence of radiation damping and relativistic effects on the new collision
data. This dataset includes calculated dipole and non-dipole radiative rates. For each ion,
level-resolved electron-impact excitation cross sections and Maxwellian rate coefficients are
generated for the 1s nl configurations for 1s < nl < 5g. He-like K photon emissivities are
calculated for each ion, and the importance of including the two photon transition is shown.
The photon emissivity coefficients (PECs) are used, along with previously calculated
data for the H-like ion stages, to investigate the evidence of overionization in the SNR
plasma W49B. The He-like data are then used to determine relative abundances of Cr and
Mn to Fe in W49B. The role of recombination as a populating mechanism for the He-like
line emission is investigated. We discuss the implications of this work, both for the general diagnostics using these He-like lines, and in answering some of the current uncertainties over
the nature and makeup of W49B
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
Towards Exascale Computations Supporting Experiments and Astrophysics
No full textOur prime computational effort is to support current and future measurements of atomic photoionization cross-sections at various synchrotron radiation facilities, and ion-atom collision experiments, together with plasma, fusion and astrophysical applications. In our work we solve the Schrödinger or Dirac equation using the R-matrix or R-matrix with pseudo-states approach from first principles. Finally, we present cross-sections and rates for radiative charge transfer, radiative association, and photodissociation collision processes between atoms and ions of interest for several astrophysical applications
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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