1,723,673 research outputs found
NGC 7814
No full text
object name: NGC 7814
telescope: Mittelman Observatories 0.5m at New Mexico Skies
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[Delaware, Lackawanna & Western, Engine Drawing Card, Sketch No. 7814]
No full textThis engine drawing card was created for Delaware, Lackawanna & Western Railroad, Class 14-3-46 1/4 E. Section 14 1/4 E. Sketch 7814, Copy Spec. [field left blank]
A tale of two galaxies: Light and mass in NGC 891 and NGC 7814
Full text linkThe two edge-on galaxies NGC 891 and NGC 7814 are representative of two extreme morphologies: the former is disk-dominated while the latter is almost entirely bulge-dominated. It has been argued that since the two galaxies, which are optically so different, have similar rotation curves their total mass distributions cannot be related in any way to the light distributions. This would lead to the conclusion that dark matter is the dominating component of the mass. We have derived new rotation curves from recent, high-sensitivity HI observations and have found that the shapes of the rotation curves are significantly different for the two galaxies. They indicate that in NGC 7814 the mass is more concentrated to the centre as compared to NGC 891. This reflects the distribution of light which is more centrally concentrated in NGC 7814 than in NGC 891. Mass and light do seem to be closely related. This is confirmed by the analysis of the rotation curves in mass components: solutions close to the maximum light (bulge + disk) do provide excellent fits. In NGC 891 bulge and disk can explain the rotation curve without any need for dark matter out to similar to 15 kpc. In NGC 7814 the bulge dominates in the inner parts; further out the rotation curve is well reproduced by a maximum disk but its M/L ratio is excessively high. A substantial dark matter contribution, closely coupled to the luminous component, seems, therefore, necessary
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
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