1,721,006 research outputs found
THE STATISTICAL NATURE OF THE BRIGHTEST GROUP GALAXIES
No full textWe examine the statistical properties of the brightest group galaxies (BGGs) by using a complete spectroscopic sample of groups/clusters of galaxies selected from the Data Release 7 of the Sloan Digital Sky Survey. We test whether BGGs and other bright members of groups are consistent with an ordered population among the total population of group galaxies. We find that the luminosity distributions of BGGs do not follow the predictions from the order statistics (OS). The average luminosities of BGGs are systematically brighter than OS predictions. On the other hand, by properly taking into account the brightening effect of the BGGs, the luminosity distributions of the second brightest galaxies are in excellent agreement with the expectations of OS. The brightening of BGGs relative to the OS expectation is consistent with a scenario that the BGGs on average have overgrown about 20% masses relative to the other member galaxies. The growth (Delta M) is not stochastic but correlated with the magnitude gap (G(1,2)) between the brightest and the second brightest galaxy. The growth (Delta M) is larger for the groups having more prominent BGGs (larger G(1,2)) and averagely contributes about 30% of the final G(1,2) of the groups of galaxies
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
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Galaxies and Gas in Dark Matter Halos and the Cosmic Web
Get PDFIn the current understanding of galaxy formation, galaxies are believed to form and evolve in dark matter halos. The dark matter halos are collapsed objects that form and grow via gravitational instability of small initial density fluctuation in the cosmic field. They are not only the hosts of galaxies but are tracers of the cosmic web of the Universe. They are thus crucial components for understanding how galaxies form and evolve within the cosmic web. This dissertation is a systematic investigation of the galaxies and gas in the dark matter halos and the cosmic web, using observation data of large galaxy surveys such as the Sloan Digital Sky Survey (SDSS), and of the Cosmic Microwave Background (CMB) survey such as the Planck, together with simulations and modellings for comparison and interpretation. Specifically, we have identified dark matter halos in the low-redshift Universe, and constructed the largest to date all-sky group catalog. We also investigated correlations between many of the galaxy and halo properties, particularly finding, for the first time, an observational proxy of halo age. Then, I developed a series of novel approaches to maximize the detection of the Sunyaev-Zel'dovich effect (SZE), and from it explored the gas properties in halos to find that the gas mass fraction even in Milky Way-size halos is about the cosmic mean fraction. The analysis identified the baryons in a warm-hot medium on halo scales. We also show that the thermal SZE can be used to constrain the mean relationship between thermal energy of IGM gas and local total matter density for the first time. We support the reliability of our methods and results with tests where the methods are applied to the mock CMB maps constructed from simulations. Finally, we present comparisons with simulations of the SZE, and discuss the implications for its constraining power of galaxy formation models.AstronomyDoctor of Philosophy (Ph.D.
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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