1,720,974 research outputs found
Innovative strategies to streamline continuous gravitational-wave candidates in the advanced LIGO-Virgo detector era
Get PDFThe goal of the LIGO-Virgo community is the gravitational-wave (GW) search and the consequent achievement of a deep knowledge of the universe.
Although great results have been already obtained by detecting coalescing compact objects (such as binary Black Holes and even a Binary Neutron star), a lot of work remains still to be done, especially for what concerns Continuous GWs (CWs). Those signals, due to their long duration, have a central role in the study of the Universe, but are fainter than the signals we have detected so far. This Ph.D. thesis is focused on finding innovative strategies to improve CW searches in the advanced LIGO-Virgo detector era.
The most accredited CW sources are non-axisymmetric rotating neutron stars. In general, there are four different approaches to study these signals: targeted, narrow band, directed and all-sky searches. The targeted search is a search where we assume to know all information on the source (sky position, spin frequency and its derivatives). The narrow band search widens the portion of frequency and its derivatives, working on an interval centered at the known information. The directed search considers stars whose sky position is known, but no information on the star spin frequency and derivatives is provided. In these cases, we can use a matched-filter technique. In fact, having at most two parameters to span, it is possible to perform a matched-filter search changing the parameters at a reasonable computational cost. In all-sky searches we are interested to look for CWs coming from unknown sources. In this case we cannot use the matched-filter technique due to the large size of the parameter space that must be spanned. Hence, we need to use hierarchical searches, such as the FrequencyHough algorithm, which is the core of this Ph.D. work. In the FrequencyHough search, the number of candidates obtained from the procedure is too high to be followed up, so it is necessary to rank them and deeply follow up only the most significant ones. However, it is not trivial to apply the procedure over a big portion of the frequencies we need to study as the computational cost grows linearly with frequency.
Our goal is to identify CWs in the LIGO-Virgo data and estimate their parameters (sky position, frequency and first time derivative). For this purpose, we have analyzed candidates returned by the FrequencyHough pipeline to find a method to filter out the bulk of them. We have found out that any (injected) signal creates, besides a candidate with the parameters closest to those of the injected CW signal, a set of byproducts for which a small error in one of the parameters is compensated by small errors on the others according to some rules. Those byproducts have a detection statistic which tends to be higher than that for the background-noise candidates. Hence, the rules of error compensation create a correlation in the parameter space that links the sky position to the frequency and its time derivative.Once we identified those rules, and the patterns that they create, we have developed a veto procedure that uses those patterns to identify the presence of a CW signal.
If we don’t have a pattern of candidates in the parameter space, it is unlikely that we will have a signal strong enough to be successfully detected in the follow up step. The innovative procedure we developed consists of computing two additional Hough transforms on the set of initial candidates, checking whether any correlation is present in the search parameter space and, alternatively, removing the candidates. The overall procedure removes about 50% of the false candidates (without excluding those related to the injected signals).
Another aspect covered by the current Ph.D. thesis consists in trying to find alternative polarizations with respect to those that are foreseen by the General Relativity (GR).
We have studied how deep potential nonGR components of GWs can be detected by the current 5vector targeted pipeline, and proposed an ad hoc solution for their detection with this pipeline
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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