1,721,129 research outputs found
Galaxy activity and interaction: the optical view
No full textThe relevance of interaction to the presence of Seyfert or starburst activity in the nuclei of galaxies is examined. We focus the attention on the close environments of spectroscopically selected samples of Seyfert-1, Seyfert-2 and starburst galaxies. In particular the results of a statistical procedure aimed at finding physical pairs are tested with redshift measurements of the identified pairs. Seyfert and starburst galaxies show an excess of physical companions compared to normal galaxies. This excess tends to increase as one moves from Seyfert to starburst galaxies
ON THE EXCESS OF PHYSICAL COMPANIONS AMONG SEYFERT GALAXIES
No full textThe results of a search for close companions in two magnitude limited samples (mB less than or equal to 15.5) of 99 Seyfert 1 and 98 Seyfert 2 galaxies are presented. It is found that there is an excess of physical companions in both samples of galaxies, compared with two control samples of normal field spiral galaxies. The calculated lower limit percentages of physical companions are (12 +/- 3)% and (12 +/- 4)% for Seyfert 1 and Seyfert 2, respectively, while the upper limits on the percentage of galaxies with physical companions are in the range (0%-5%) in both control samples. The excess is confirmed by analysis of the redshifts for all pairs found in the complete, magnitude limited (B(O) less than or equal to 14.5) CfA sample of Seyfert galaxies
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
Subarcsec structures in the double nucleus of NGC 6240 disclosed with HST at 370, 430 and 500 nm
No full textWe present an analysis of three medium band width (FWHM ~ 400 - 450 Angstroms) images of the nuclear region of NGC6240 taken with the pre-COSTAR Faint Object Camera (FOC) on board of the Hubble Space Telescope. The first filter band comprises the [OII]lambda 3727 doublet, the second measures the blue continuum around 4400 { Angstroms} and the third includes Hβ + [OIII]lambda lambda 4959,5007. The images show that the apparent two galactic nuclei B (north) and A (south) identified from the ground consist of compact substructures on the tenth-arcsec scale plus faint extended emission on the arcsec scale. Within a diameter of 0\farcs26 ( ~ 120 pc), most compact features exhibit a summed line luminosity L([OIII]+Hβ ) in the range 10(39) --10(40) erg s(-1) which is comparable to that of giant HII regions. Although the data are not complete enough for a direct decomposition into line and continuum flux, probable solutions yield a LINER like [OII]/[OIII]/Hβ line ratio for the northern compact subcomponent B1. In the southern nucleus A the faint subcomponents A2 and A3 can be classified as LINER like if they are more strongly reddened than B1 or as HII-region like if not. The brightest southern compact component A1, however, exhibits line ratios that are typical of (i) a Seyfert galaxy or (ii) a high-excitation HII region. This leads to the interesting alternative that there is either (i) a hidden AGN (which is in accord with recent ASCA observations) or (ii) a hidden cluster of young massive stars. The second possibility would imply localized ongoing star formation within an environment whose visible light is dominated by radiation from older stellar populations. However, considering recent models for fast autoionizing shocks computed by Dopita & Sutherland (1995), A1 might also represent a shock-plus-precursor region. Based on observations with the NASA/ESA {\em Hubble Space Telescop
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
- …
