1,720,956 research outputs found
Planetas y discos en estrellas binarias
Get PDFTesis (Lic. en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2020.Fil: Cerioni, Matías Pablo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.Desde la detección del primer exoplaneta (Mayor & Quéloz, 1995), análisis observacionales sobre las diferencias entre sistemas planetarios en estrellas individuales o múltiples siempre ha estado truncado por la escasez en la muestra de planetas en binarias. Luego de 25 años de acumular observaciones, hoy tenemos el lujo de contar con ∼200 planetas orbitando estrellas binarias (∼4000 en estrellas individuales), y por lo tanto en este trabajo ofrecemos un primer acercamiento al panorama observacional de planetas en estrellas binarias, analizando las distribuciones de parámetros de sus componentes, e indagando en la frecuencia de discos de escombros en tales sistemas, componente que puede ser útil para determinar la frecuencia de planetas con dos soles.Since the detection of the first exoplanet (Mayor & Quéloz, 1995), observational analyses of the differences between planetary systems in single or multiple stars have always been truncated by the scarcity of detected planets orbiting binaries. After 25 years of accumulating observations, we finally have the luxury of knowing about ∼200 planets orbiting binary stars (∼4000 in single stars), and therefore in this work we offer a first approach to the observational overview of planets in binary stars, analyzing the parameter distributions of their components, and inquiring into the frequency of debris disks in such systems, a component that may be useful to determine the frequency of planets with two suns.Fil: Cerioni, Matías Pablo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina
Conditions for Convergent Migration of N-Planet Systems
No full textGiven an N-planet system with coplanar, low eccentricity orbits, and under the effects of an external non-conservative force, we derive necessary conditions for the orbital migration to undergo global convergent migration and allow the formation of a mean-motion resonance chain. Since the conditions are expressed in terms of the time-derivatives of the semimajor axes, the method is applicable to any non-conservative force, including disk–planet interactions and tides. Although the number of possible conditions increase exponentially with the number of bodies, the calculations may be enormously simplified adopting a tree diagram for the decision process. We deduce explicit expressions for N= 3 and N= 4 together with applications to Kepler-60 and Kepler-223 assuming a simple prescription for Type-I migration and no inner disk edge. This disk model is chosen for simplicity and to highlight the applicability of the method. We also present all the necessary steps for the implementation of an algebraic tree algorithm for the general N-planet case, and discuss possible implications for the migration history of the TOI-178 and TRAPPIST-1 systems.Fil: Beauge, Cristian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; ArgentinaFil: Cerioni, Matías. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomía Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomía Teórica y Experimental; Argentin
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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