1,720,963 research outputs found
Emulating the first billion years of the Universe
Full text linkThe first detection of the 21-cm signal is now within reach with the upcoming Square Kilometre Array (SKA). The SKA is expected
to deliver tomographic maps of the 21-cm signal across more than half of the observable Universe, providing transformative
constraints on the astrophysical and cosmological processes that shaped its evolution. At present, however, such measurements
remain out of reach, primarily due to challenges in data analysis and interpretation. Instead, we only have upper limits on the 21-
cm power spectrum, reported by several SKA precursors. In this thesis, I employ machine learning to facilitate and enhance the
interpretation of both current and upcoming cosmic dawn and epoch of reionisation observations within a Bayesian inference
framework. Current upper limits on the 21-cm power spectrum become informative only when combined with complementary
observations. To enable such synergistic analyses, I developed a machine-learning emulator of six summary statistics, which
accelerates inference by more than four orders of magnitude compared to direct simulation. Despite the increasing realism of
simulations, current Bayesian inferences of the 21-cm power spectrum remain limited by the small simulation volumes required
for computational feasibility. Small box sizes restrict the number of large-scale modes that can be probed, setting a fundamental
lower bound on the precision of forward-modelled power spectra at large scales — a limitation known as sample variance. To
address this limitation, I developed a simulator-independent framework that mitigates sample variance with a score-based
diffusion model and thereby significantly improves the constraining power of the inference. Put together, the work presented in
this thesis is aimed at squeezing the most juice out of current upper limits and upcoming first detections of the 21-cm power
spectrum, thereby extracting the maximum possible amount of information out of them
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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