1,720,963 research outputs found
The effects of relativistic corrections on cosmological parameter estimations from Sunyaev-Zeldovich effect cluster surveys
No full textSunyaev-Zeldovich effect (SZE) cluster surveys are anticipated to yield tight constraints on cosmological parameters, such as the equation of state of dark energy. In this paper, we study the effect of relativistic corrections of the thermal SZE on the cluster number counts expected from a cosmological model and thus, assuming that other cosmological parameters are known to high accuracies, on the determination of the w-parameter and sigma(8) from an SZE cluster survey, where w = p/rho (with p the pressure and rho the density of dark energy) and sigma(8) is the rms of the extrapolated linear density fluctuation smoothed over 8 Mpc h(-1). For the purpose of illustrating the effects of relativistic corrections, our analyses mainly focus on nu = 353 GHz and S-lim = 30 mJy, where nu and S-lim are the observing frequency and the flux limit of a survey, respectively. These observing parameters are relevant to the Planck survey. It is found that from two measurable quantities, the total number of SZE clusters and the number of clusters with redshift z greater than or equal to 0: 5, sigma(8) and w can be determined to a level of +/-1% and +/-8%, respectively, with 1 sigma uncertainties from a survey of 10,000 deg(2). Relativistic effects are important in determining the central values of sigma(8) and w. If we choose the two quantities calculated relativistically from the flat cosmological model with sigma(8) = 0.8284 and w = -0.75 as input, the derived sigma(8) and w would be 0.819 and -0.81, respectively, if relativistic effects are wrongly neglected. The location of the resulting sigma(8) and w in the sigma(8)-w plane is outside the 3 sigma region around the real central sigma(8) and w.Astronomy & AstrophysicsSCI(E)0ARTICLE2713-71959
Measuring the deviation from the linear and deterministic bias through cosmic gravitational lensing effects
No full textSince gravitational lensing effects directly probe inhomogeneities of dark matter, lensing-galaxy cross-correlations can provide us important information on the relation between dark matter and galaxy distributions, i.e., the bias. In this paper, we propose a method to measure the stochasticity/nonlinearity of the galaxy bias through correlation studies of the cosmic shear and galaxy number fluctuations. Specifically, we employ the aperture mass statistics M-ap to describe the cosmic shear. We divide the foreground-galaxy redshift z(f) < z(s) into several bins, where z(s) is the redshift of the source galaxies, and calculate the quantity (MapNg(z(f)))(2)/(hN(g)(2)(z(f))) for each redshift bin. Then, the ratio of the summation of (MapNg(z(f)))(2)/(N-g(2)(z(f))) over the bins to (M-ap(2)) gives a measure of the nonlinear/stochastic bias. Here, N-g(z(f)) is the projected surface number density fluctuation of foreground galaxies at redshift z(f), and M-ap is the aperture mass from the cosmic-shear analysis. We estimate that for a moderately deep weak-lensing survey with z(s) = 1, source galaxy surface number density n(b) = 30 galaxies arcmin(-2), and a survey area of 25 deg(2), the effective r-parameter that represents the deviation from the linear and deterministic bias is detectable in the angular range of 1'-10' if \r - 1\ greater than or similar to 10%. For shallow, wide surveys such as the Sloan Digital Sky Survey with z(s) = 0: 5, n(b) = 5 galaxies arcmin(-2), and a survey area of 10(4) deg(2), a 10% detection of r is possible over the angular range 1'-100'.Astronomy & AstrophysicsSCI(E)7ARTICLE133-4159
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
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
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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