1,722,039 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
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
Chemical abundances in clusters of galaxies
No full textWe study the origin of iron and α-elements (O, Mg, Si) in clusters of galaxies. In particular, we discuss the [O/Fe] ratio and the iron mass-to-luminosity ratio in the intracluster medium (ICM) and their link to the chemical and dynamical evolution of elliptical and lenticular galaxies. We adopt a detailed model of galactic evolution incorporating the development of supernovae-driven galactic winds which pollute the ICM with enriched ejecta. We demonstrate quantitatively, after David et al. (1991), the crucial dependence upon the assumed stellar initial mass function in determining the evolution of the mass and abundances ratios of heavy elements in typical model ICMs. We show that completely opposite behaviours of [α/Fe] ratios (i.e. positive versus negative ratios) can be obtained by varying the initial mass function without altering the classic assumptions regarding type Ia supernovae progenitors or their nucleosynthesis. Our results indicate that models incorporating somewhat flatter-than-Salpeter initial mass functions (i.e. x=~1, as opposed to x=1.35) are preferred, provided the intracluster medium iron mass-to-luminosity ratio, preliminary [α/Fe]>0 ASCA results, and present-day type Ia supernovae rates, are to be matched. A simple Virgo cluster simulation which adheres to these constraints shows that ~70% of the measured ICM iron mass has its origin in type II supernovae, with the remainder being synthesized in type Ia systems
On Dwarf Galaxies as the Source of Intracluster Gas
No full textRecent observational evidence for steep dwarf galaxy luminosity functions in several rich clusters has led to speculation that their precursors may be the source of the majority of gas and metals inferred from intracluster medium (ICM) X-ray observations. Their deposition into the ICM is presumed to occur through early supernovae-driven winds, the resultant systems reflecting the photometric and chemical properties of the low-luminosity dwarf spheroidals and ellipticals we observe locally. We consider this scenario, utilizing a self-consistent model for spheroidal photochemical evolution and gas ejection via galactic superwinds. Insisting that post-wind dwarfs obey the observed color-luminosity-metallicity relations, we conclude that the bulk of the ICM gas and metals does not originate within their precursors
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
Summary of Recent Progress in Understanding HVCs
Full text linkAbstract: The study of high-velocity clouds has progressed much since the appearance of the review article by Wakker & van Woerden (1997), less than two years ago. Much of this progress is described in these workshop proceedings. Here we update the review article, summarizing the topics discussed at the workshop as well as covering the recent literature. We follow the outline of the review, describing HI properties in Sect. 2 and 3, interactions between HVCs and other gas in Sect. 4, observations at wavelengths other than 21-cm in Sects. 5 and 6, absorption-line studies of metallicities and distances in Sects. 7 and 8, extra-galactic HVCs in Sect. 9, the Magellanic Stream in Sect. 10, and a discussion of HVC origins in Sect. 11. Key contributions of the past two years include (a) the first determination of a distance bracket for an HVC: d=4-10 kpc for Complex A (van Woerden et al. 1999); (b) the first determinations of a true metallicity: 1/4 solar for HVC 287+22+240 (Lu et al. 1998), and 1/10 solar Complex~C (Wakker et al. 1999); (c) the recognition of a leading counterpart to the Magellanic Stream (Gardiner & Noguchi 1996; Lu et al. 1998; Putman et al. 1998), indicative of a tidal origin; (d) the quickly growing number of optical emission line observations (primarily H-alpha) of HVCs, led by Tufte et al. (1998) and Bland-Hawthorn et al. (1998); and (e) the proposal by Blitz et al. (1999) that HVCs are intergalactic remnants of the formation of the Local Group.
Summary of Recent Progress in Understanding HVCs
Full text linkAbstract: The study of high-velocity clouds has progressed much since the appearance of the review article by Wakker & van Woerden (1997), less than two years ago. Much of this progress is described in these workshop proceedings. Here we update the review article, summarizing the topics discussed at the workshop as well as covering the recent literature. We follow the outline of the review, describing HI properties in Sect. 2 and 3, interactions between HVCs and other gas in Sect. 4, observations at wavelengths other than 21-cm in Sects. 5 and 6, absorption-line studies of metallicities and distances in Sects. 7 and 8, extra-galactic HVCs in Sect. 9, the Magellanic Stream in Sect. 10, and a discussion of HVC origins in Sect. 11. Key contributions of the past two years include (a) the first determination of a distance bracket for an HVC: d=4-10 kpc for Complex A (van Woerden et al. 1999); (b) the first determinations of a true metallicity: 1/4 solar for HVC 287+22+240 (Lu et al. 1998), and 1/10 solar Complex~C (Wakker et al. 1999); (c) the recognition of a leading counterpart to the Magellanic Stream (Gardiner & Noguchi 1996; Lu et al. 1998; Putman et al. 1998), indicative of a tidal origin; (d) the quickly growing number of optical emission line observations (primarily H-alpha) of HVCs, led by Tufte et al. (1998) and Bland-Hawthorn et al. (1998); and (e) the proposal by Blitz et al. (1999) that HVCs are intergalactic remnants of the formation of the Local Group
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