1,720,976 research outputs found
THE EFFECT OF BINARITY AND METALLICITY IN THE SPECTRA OF WC AND W0 STARS
No full textstatistical analysis of the main emission lines common to the WC and WO stars is made based on an extensive set of spectral data. To define the trends in equivalent width ( Wλ), line ratios, and line widths, median values are derived for single-spectrum stars of different spectral class. We find that in Galactic WO and WC4 stars, Wλ (C IV 581 nm) is smaller compared to in extragalactic objects. In both Galactic and extragalactic stars, Wλ (O V 559 nm) smoothly increases towards early WC and WO stars. It is argued that differences in stellar wind structure, in combination with the ambient metallicity, may be the cause of the anomalies. Variation of the profile of the 465 nm blend indicates a substantial contribution of He II 468 nm for the WCE and WO stars. In addition, we comment on the carbon abundances in relation to the evolutionary status of these objects. We also give an estimate of the OB/WR continuum flux ratio in composite-spectrum systems
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
The Low Resolution Spectrum of Selected B[e] Stars with Warm Dust
No full textWe analyze the low resolution optical spectrum of several B[e] stars collected at the Loiano and Asiago Observatories within the observing campaign for hot star candidates with warm dust envelopes: IRAS 00470+6429, IRAS 01441+6026 (V 832 Cas) IRAS 06071+2925, IRAS 06070--0938 (AS 119), IRAS 07080+0605 (HBHA 717--01), IRAS 03421+2935 (MWC 728), IRAS 06259--1301 (HD 45677), and the suspected B[e] star V439 Cyg. We also observed the IRAS objects (not described here): 17449+2320, 17200-1355, 18316--0028, 19156-0935, 19587-2257, 20017+3227, and 20134+2712
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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