1,720,953 research outputs found
Four-dimensional Variational Data Assimilation: Analysis in spaces of low regularity and application to the COVID-19 pandemic.
Full text linkEste trabajo aborda aspectos teóricos y prácticos de los problemas de asimilación de datos variacionales. En la primera parte se estudia el problema 4D-VAR en espacios de baja regularidad, con una función de costo que incorpora observaciones espaciales puntuales, lo cual requiere variables de estado continuas en el espacio. Para abordarlo, empleamos la regularidad máxima parabólica del operador y resultados de inyecciones en espacios de interpolación reales y complejos, que son esenciales para probar existencia y unicidad del problema con restricción lineal y su ecuación adjunta, que incluye medidas de regulares de Borel en el lado derecho. En el caso con restricciones semilineales, además de probar la existencia y unicidad, se analiza la diferenciabilidad del operador control-estado. La no linealidad dificulta la obtención de las condiciones de optimalidad de primer orden, en particular, al probar la existencia y unicidad de la ecuación adjunta, ya que en este caso, el operador asociado es no autónomo y es necesario un análisis directo de dicha ecuación. En la segunda parte, se explora la aplicación práctica de estos métodos para estimar la evolución de la pandemia de COVID-19 en Ecuador. Estimamos los parámetros epidemiológicos y las condiciones iniciales de un modelo SEIR compartimental, considerando incertidumbre en los datos. Usamos, dos fuentes oficiales: el conteo de casos positivos del Ministerio de Salud y una estimación de muertes en exceso con datos del Registro Civil. Se implementa además un enfoque de pronóstico multimodelo que considera la fiabilidad de los datos.This work addresses both theoretical and practical aspects of variational data assimilation problems. In the first part, we study the four-dimensional variational data assimilation (4D-VAR) problem in low-regularity spaces with a cost function that includes pointwise spatial observations, requiring continuous-in-space state variables. To tackle this, we employ maximal parabolic regularity tools along with embedding results from real and complex interpolation spaces. These are essential to establish well-posedness of the linear state and its adjoint, particularly because the adjoint’s right-hand side has regular Borel measures. In the semilinear constraint case, beyond proving the well-posedness of the state equation, we analyze the differentiability of the control-to-state mapping. Nonlinearities complicate the derivation of the first-order optimality conditions, particularly when analyzing the well-posedness of the adjoint equation, since the associated operator is non-autonomous and results on (autonomous) maximal parabolic regularity can not be applied. Therefore, a direct analysis of the adjoint equation is necessary. In the second part, we explore the practical application of variational data assimilation methods to estimate the evolution of the COVID-19 pandemic in Ecuador. We estimate key epidemiological parameters and initial conditions of a compartmental SARS-CoV-2 model under high uncertainty. Two data sources are used: official counts of positive tests from the Ecuadorian Public Health Ministry and COVID-19-related death estimates from the Civil Registry. A multimodel ensemble forecasting approach is implemented, accounting for data reliability to better capture the pandemic's dynamic
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
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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