1,721,011 research outputs found
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
Low resolution transmission spectroscopy of exoplanet atmospheres using ground-based and space telescopes
Get PDFThe research on exoplanet atmospheres has expanded rapidly over the last two decades since the first detection of an exoplanet atmosphere. Hot Jupiters– gas giants orbiting their host star on very close-in orbits–have always been at the forefront of exoplanet research as they are the easiest to detect due to their size and short orbits. However, their origins are not fully understood and by studying their atmospheres we aim to gain insight into their formation and evolution.
In this thesis I present spectroscopic observations of three transiting hot Jupiters. For the first two exoplanets I am utilising data from the ground-based telescope NTT (La Silla Observatory), while for the last one data from the space telescope JWST is used. My study of the atmosphere of WASP-94Ab in the optical wavelength range revealed a sodium absorption as well as a scattering slope indicative of Rayleigh scattering. The optical transmission spectrum of HATS-46b I retrieved using ground- based data showed a fairly feature less spectrum and the atmospheric retrieval anal- ysis provided evidence for clouds in the atmosphere. The last observations presented in this thesis used JWST/NIRCam data of hotJupiter WASP-39b in the infrared wavelength range, and were part of the JWST Early Release Science(ERS) program from the Transiting Exoplanet Community.
The retrieved spectrum showed strong watervapour absorption and indicated a low carbon-to-oxygen(C/O)ratio. I show that the two telescopes provide access to different wavelength ranges and thus different possible scientific findings. Combining data from different tele- scopes/instruments from both ground-based and space telescopes is becoming more important than ever for our field to help understand degeneracies in both models and data, in order to further our knowledge of exoplanet atmospheres and in turn learn about the origins of hot Jupiter
LRG-BEASTS: sodium absorption and Rayleigh slope in the atmosphere of WASP-94A b using NTT/EFOSC2
No full textWe present the first spectroscopic study of an exoplanet atmosphere using the EFOSC2 instrument on the New Technology Telescope (NTT). The obtained transmission spectrum of the hot Jupiter WASP-94Ab in the optical wavelength range (3800 - 7140 A) suggests a sodium absorption in the atmosphere of WASP-94Ab, implying a fairly clear atmosphere. In addition, we observe a slope in the blue end of the transmission spectrum, indicating the presence of Rayleigh scattering.
The WASP-94 system is a binary system, with both bright (Vmag ~ 10) F type stars hosting one confirmed hot Jupiter, where one of them, WASP-94Ab, is transiting. WASP-94Ab orbits its host star in a 4 day misaligned, retrograde orbit at a distance of 0.055 AU. It is an optimal target for transmission spectroscopy as it is reported to have an inflated radius of 1.7 Jupiter radii, a mass of 0.5 Jupiter masses and an equilibrium temperature of 1500 K. However, no atmospheric studies have been published to date.
These results demonstrate that the NTT/EFOSC2 is able to characterise exoplanet atmospheres, achieving the necessary precisions with errors of less than one atmospheric scale height
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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