1,721,061 research outputs found
The Galactic star cluster NGC 4337: estimates of its photometric and dynamical mass
No full textIn this contribution we discuss various estimates of the mass of NGC 4337, an old open cluster located in the inner Galactic disk. We derive its mass in different ways. First, we obtain a lower estimate of the cluster mass using the surface density profile of the cluster and its luminosity and mass function by means of star counts out of a photometric data set in the UBVI passbands. This data set is also used to derive fundamental cluster parameters. Second, we obtain dynamical estimates of the cluster mass as based on a large survey of cluster star radial velocities. The dynamical estimates correspond to significantly larger values than those from star count estimates. We can roughly match these two estimate sets taking into account the contribution of invisible mass in the form of both low mass stars and remnants of high mass stars in the cluster
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
The multiple stellar population in ω Centauri: spatial distribution and structural properties
Full text linkAppropriate 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
Statistical Investigation of Apparent Distributions of Different Population RGB Stars in ω Cen
No full textUnresolved Binaries and Multiples in the Intermediate Mass Range in Open Clusters: Pleiades, Alpha Per, Praesepe, and NGC 1039
Full text linkIn this study, we continue our project to search for unresolved binary and multiple systems in open clusters exploiting the photometric diagram (H-W2)-W1 versus W2-(BP-K) first introduced in Malofeeva et al. In particular, here we estimate the binary and multiple star ratios and the distribution of the component mass ratio q in the Galactic clusters Alpha Persei, Praesepe, and NGC 1039. We have modified the procedure outlined in our first study making star counts automatic and by introducing bootstrapping for error estimation. Basing on this, we reinvestigated the Pleiades star cluster in the same mass range as in our previous work and corrected an inaccuracy in the mass ratio q distribution. The binary and multiple star ratio in the four clusters is then found to lie between 0.45 ± 0.03 and 0.73 ± 0.03. On the other hand, the ratio of systems with multiplicity more than 2 is between 0.06 ± 0.01 and 0.09 ± 0.02. The distribution of the component mass ratio q is well fitted with a Gaussian having the mode between 0.22 ± 0.04 and 0.52 ± 0.01 and the dispersion between 0.10 ± 0.02 and 0.35 ± 0.07. All clusters show a large number of the very low-mass secondary components in the binary systems with primary components below 0.5 M ⊙
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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