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Abundances in the planetary nebula NGC 6153
No full textSpectra in the visual, infrared and ultraviolet, of the planetary nebula NGC 6153 are presented. They are analysed to obtain the abundance and physical conditions in the nebula. It is found that NGC 6153 is a very unusual nebula, its abundance of many elements being higher than any other nebul
Abundances in the planetary nebula NGC 6153
No full textSpectra in the visual, infrared and ultraviolet, of the planetary nebula NGC 6153 are presented. They are analysed to obtain the abundance and physical conditions in the nebula. It is found that NGC 6153 is a very unusual nebula, its abundance of many elements being higher than any other nebul
Abundances in the planetary nebula NGC 6153
No full textSpectra in the visual, infrared and ultraviolet, of the planetary nebula NGC 6153 are presented. They are analysed to obtain the abundance and physical conditions in the nebula. It is found that NGC 6153 is a very unusual nebula, its abundance of many elements being higher than any other nebul
Abundances in the planetary nebula NGC 6153
No full textSpectra in the visual, infrared and ultraviolet, of the planetary nebula NGC 6153 are presented. They are analysed to obtain the abundance and physical conditions in the nebula. It is found that NGC 6153 is a very unusual nebula, its abundance of many elements being higher than any other nebul
Block Card 6153 Foth Drive
No full textThis image was produced by the Auditor's Office in Lucas County, Ohio for tax assessment purposes. Associated dates are approximate. Descriptive terms related to this photograph include: Ranch Style | 6153 Foth Drive (Toledo, Ohio) | Dwelling | Douglas Meadows Addition (Toledo, Ohio) | Trilby Area (Toledo, Ohio)
NGC 6153: Reality is complicated
Get PDFWe study the kinematics of emission lines that arise from many physical
processes in NGC 6153 based upon deep, spatially-resolved, high resolution
spectra acquired with the UVES spectrograph at the ESO VLT. Our most basic
finding is that the plasma in NGC 6153 is complex, especially its temperature
structure. The kinematics of most emission lines defines a classic expansion
law, with the outer part expanding fastest (normal nebular plasma). However,
the permitted lines of \ion{O}{1}, \ion{C}{2}, \ion{N}{2}, \ion{O}{2}, and
\ion{Ne}{2} present a constant expansion velocity that defines a second
kinematic component (additional plasma component). The physical conditions
imply two plasma components, with the additional plasma component having lower
temperature and higher density. The [\ion{O}{2}] density and the [\ion{N}{2}]
temperature are anomalous, but may be understood considering the contribution
of recombination to these forbidden lines. The two plasma components have very
different temperatures. The normal nebular plasma appears to be have
temperature fluctuations in part of its volume (main shell), but only small
fluctuations elsewhere. The additional plasma component contains about half of
the mass of the N and O ions, but only \% of the mass of
H ions, so the two plasma components have very different chemical
abundances. We estimate abundances of \,dex and . Although they are all
complications, multiple plasma components, temperature fluctuations, and the
contributions of multiple physical processes to a given emission line are all
part of the reality in NGC 6153, and should generally be taken into account.Comment: 55 pages, 51 figures, 9 tables, accepted for publication in The
Astronomical Journa
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
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