1,720,976 research outputs found
Characterizing The Cosmic Near-infrared And X-ray Background Fluctuations
Get PDFThe cosmic infrared background (CIB) carries an abundance of information about the star formation and galaxy growth in the Universe. Due to significant and complex foregrounds from our Galaxy, the optimal way to study the unresolved background is to actually study its fluctuations, especially at large angular scales where they reflect the clustering of unresolved populations. I measured the CIB fluctuations reaching the largest angular scale to date for such a study (1 deg), using new COSMOS data from the Spitzer Large Area Survey with Hyper-Suprime-Cam. The auto-power spectra are consistent among various epochs and are significantly correlated at the two IRAC wavelengths (3.6 & 4.5 μm), implying cosmological origin of the excess power. The CIB and Cosmic X-ray Background (CXB) cross-correlation can not only provide observational constrains on the theoretical modeling of the CIB fluctuations but also stands as a unique way to study the formation of the early black holes. Using the Chandra COSMOS Legacy data, I found that the [0.5-2] keV band is correlated with 3.6 and 4.5 μm at 4 significance level. The combined infrared (3.6 + 4.5) μm data are correlated with the X-ray data in [0.5-2], [2-7] and [0.5-7] keV bands at 5.6, 4.4 and 6.6 sigma level, respectively. The coherence between the CIB and CXB fluctuations suggests significant contribution to the CIB fluctuations from accreting black holes that is much higher than among any known populations. I further analyzed the X-ray SED of the cross-power signal, by stacking with other surveys and assuming no significant variation from the infrared. I found that the SED’s shape is consistent with the emission predicted for high-mass black hole seeds (such as direct collapse black holes) and absorbed, high-z AGNs. In the absence of a higher energy resolution in the mean cross power spectra, however, a direct differentiation between high redshift black hole models is challenging with this methodology. Future projects and missions (e.g., LIBRAE) will offer more direct observational information and enable new methods to address the nature of the CIB excess fluctuations and the X-ray counterparts.Ph.D. Thesis. University of Hawaiʻi at Mānoa 2018
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
The GALEX mission and detectors
Get PDFWe describe the Galaxy Evolution Explorer (GALEX) satellite that was launched in April 2003 specifically to accomplish far ultraviolet (FUV) and near ultraviolet (NUV) imaging and spectroscopic sky-surveys. GALEX is currently providing new and significant information on how galaxies form and evolve over a period that encompasses 80% of the history of the Universe. This is being accomplished by the precise measurement of the UV brightness of galaxies which is a direct measurement of their rate of star formation. We briefly describe the design of the GALEX mission followed by an overview of the instrumentation that comprises the science payload. We then focus on a description of the development of the UV sealed tube micro-channel plate detectors and provide data that describe their on-orbit performance. Finally, we provide a short overview of some of the science highlights obtained with GALEX
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
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