1,720,981 research outputs found
COORDINATED UV-OPTICAL OBSERVATIONS OF QUASARS - THE EVOLUTION OF THE LYMAN ABSORPTION
No full textThe average flux decrement shortward the Ly(alpha) emission, due to the well-known ''forest'' of absorptions, has been measured in the spectra of 8 quasars. Quasi-simultaneous optical and IUE observations of the two low redshift quasars PKS 0637-75 (z=0.654) and MC 1104+16 (z=0.632) have been carried out, obtaining relatively high S/N, spectrophotometrically calibrated data on their energy distribution from the rest frame H(beta) to the Lyman continuum. Six more quasars in the redshift range 2.5-3.4 have been observed in the optical domain. For all the quasars the ''intrinsic'' continuum slope and normalization have been estimated longward the Ly(alpha) emission and extrapolated towards the Lyman continuum to measure the average depressions, which have been compared with the model statistics of the Ly(alpha) clouds. When all the known classes of absorbers are taken into account with plausible values for their equivalent width distribution and evolution, a good agreement is obtained with the observations. The results for the observed continuum decrement at z approximately 0.65 are identical to those predicted by the evolution with redshift of the number of Ly(alpha) forest systems including the HST data and within 2sigma of the predicted value using the ''standard'' Ly(alpha) evolution (as determined only at high z)
NGC 4262: a Virgo galaxy with an extended ultraviolet ring
No full textContext. The Galaxy Ultraviolet Explorer (GALEX) satellite has recently shown the presence of an extended, outer ring studded with UV-bright knots surrounding the lenticular galaxy NGC 4262. Such a structure-not detected in the optical-is coupled with a ring of atomic (HI) gas.
Aims: We want to show that both star-forming and HI rings surrounding this SB0 galaxy share the same radial distance from the galaxy center and spatial orientation. We also model the kinematics of the ring(s) and of the galaxy body.
Methods: We make use of archive FUV and NUV GALEX data plus HI observations from the literature.
Results: We confirm that the UV-bright and atomic gas rings of NGC 4262 have the same extent and projected spatial orientation. Their kinematics is not coupled with that of the galaxy stars.
Conclusions: It is possible that NGC 4262 has undergone a major gas stripping event in the past that was the origin of the present “necklace” of UV-bright knots
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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