1,720,963 research outputs found
Improving the Planck sky maps through Bayesian component separation
No full textThe Planck satellite has provided a multitude of data images of the full microwave sky, or sky maps, since it saw first light in 2009. Its observations of the Cosmic Microwave Background (CMB) data has been paramount in the estimation of cosmological parameters vital in many branches of physics and astronomy. Although the processing of this information is coming to an end, the data still exhibit significant systematic effects coupled with foreground contamination, which impairs our ability to determine these parameters accurately. In this thesis, we provide an overview of the Planck data analysis process with emphasis on Bayesian component separation methods for foreground removal. Furthermore, we seek to improve upon a new set of sky maps provided by Reijo Keskitalo at Lawrence Berkeley Laboratories. We do this by applying component separation in order to reveal systematic effects, which are subsequently corrected during map-making. This process is then repeated until systematic errors and foregrounds are suppressed to a satisfactory extent. Lastly, we present the results of our analysis with the application of the latest generation sky maps. These maps were produced as a result of the efforts described in this thesis. We conclude that the new sky maps exhibit a significant reduction in instrumental errors, in comparison to the current state-of-the-art
Closing the Loop: Joint Analysis of CMB Systematics and Foregrounds
No full textThe Cosmic Microwave Background (CMB) radiation is the oldest signal in the universe. It teaches us about the first moments after the universe came into existence, and thus informs us about its subsequent evolution.
The CMB serves as the faint backdrop of the night sky, obscured by all the other astrophysical objects (primarily clouds of gas), which we call foregrounds. For precise measurements of the CMB, we require detailed characterization of these, and also of the observing instruments' systematics. Furthermore, the problems of foreground separation and instrument systematics are tightly interwoven.
This thesis presents my work on disentangling this relationship. This is done by leveraging observations from several different experiments and simultaneous consideration of systematics and foregrounds in a “loop”-like manner. Through the application of these methods, my colleagues and I have created some of the cleanest maps of the sky in the microwave range, in the world. These maps in turn inform us about important properties of the universe
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
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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