1,721,761 research outputs found
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
Detection of Chemo-Kinematical Structures in Leo I
Full text linkContext: A variety of formation models for dwarf spheroidal (dSph) galaxies
have been proposed in the literature, but generally they have not been
quantitatively compared with observations. Aims: We search for chemodynamical
patterns in our observational data set and compare the results with mock
galaxies consisting of pure random motions, and simulated dwarfs formed via the
dissolving star cluster and tidal stirring models. Methods: We made use of a
new spectroscopic data set for the Milky Way dSph Leo I, combining 288 stars
observed with Magellan/IMACS and existing Keck/DEIMOS data, to provide velocity
and metallicity measurements for 953 Leo I member stars. We used a specially
developed algorithm called Beacon to detect chemo-kinematical patterns in the
observed and simulated data. Results: After analysing the Leo I data, we report
the detection of 14 candidate streams of stars that may have originated in
disrupted star clusters. The angular momentum vectors of these streams are
randomly oriented, consistent with the lack of rotation in Leo I. These results
are consistent with the predictions of the dissolving cluster model. In
contrast, we find fewer candidate stream signals in mock data sets that lack
coherent motions ~99% of the time. The chemodynamical analysis of the tidal
stirring simulation produces streams that share a common orientation of their
angular momenta, which is inconsistent with the Leo I data. Conclusions: Even
though it is very difficult to distinguish which of the detected streams are
real and which are only noise, we can be certain that there are more streams
detected in the observational data of Leo I than expected in pure random data.Comment: 12 pages, accepted by A&
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
A New Proper Motion Determination of Leo I
Full text linkWe measure the absolute proper motion of Leo I using a WFPC2/HST data set
that spans up to 10 years, to date the longest time baseline utilized for this
satellite. The measurement relies on ~ 2300 Leo I stars located near the center
of light of the galaxy; the correction to absolute proper motion is based on
174 Gaia EDR3 stars and 10 galaxies. Having generated highly-precise, relative
proper motions for all Gaia EDR3 stars in our WFPC2 field of study, our
correction to the absolute EDR3 system does not rely on these Gaia stars being
Leo I members. This new determination also benefits from a recently improved
astrometric calibration of WFPC2. The resulting proper-motion value, (mu_alpha,
mu_delta) = (-0.007 +- 0.035, -0.119 +-0.026) mas/yr is in agreement with
recent, large-area, Gaia EDR3-based determinations. We discuss all the recent
measurements of Leo I's proper motion and adopt a combined, multi-study average
of (mu_alpha_3meas, mu_delta_3meas) = (-0.036 +- 0.016, -0.130 +- 0.010)
mas/yr. This value of absolute proper motion for Leo I indicates its orbital
pole is well aligned with that of the Vast Polar Structure, defined by the
majority of the brightest dwarf-spheroidal satellites of the Milky Way.Comment: accepted for publication in The Astronomical Journa
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
Graphical representation of the quantitative amplification of <i>leo</i> and <i>neo</i>.
No full text<p>Example of a qPCR amplification run of <i>Tc-leo</i> and <i>Tc-neo</i>, showing the relative relationship between <i>Tc-leo</i> and <i>Tc-neo</i> expression in the <i>Tripedalia cystophora</i> rhopalium. It is evident that <i>Tc-leo</i> is expressed at higher levels than <i>Tc-neo</i> (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0098870#pone-0098870-t002" target="_blank">Table 2</a>). The two red shades each represent one replicate of <i>Tc-leo</i> and the two blue shades correspond to <i>Tc-neo</i> replicates. Green horizontal line depicts the threshold value, and the threshold cycle (C<sub>T</sub>) is determined by the cycle number, at which the concentration exceeds the threshold. The lowest C<sub>T</sub> value for a replicate was chosen for each opsin in each run. Eight runs were performed.</p
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