1,720,953 research outputs found
Experiment with Machine Learning on Hierarchical Multi-Modal Astronomical Data
Get PDFTato bakalářská práce představuje komplexní studii predikce rychlosti tvorby hvězd (SFR) v galaxiích pomocí multimodálních data získaných z přehlídky oblohy Sloan Digital Sky Survey (SDSS, DR7). Nejprve filtrujeme počáteční katalog SFR, abychom vytvořili vysoce kvalitní, vyčištěnou podmnožinu 11,179 galaxií, které mají platná jednorozměrná spektra a fotometrii (fotografie) v pěti pásmech. Tato práce využívá obrazy s různým rozlišením (64×64 až 8×8 px) a spektra s různým vzorkováním (4620 až 577 binů), včetně jejich měřicích nejistot, přímo z již existujícího HiSS-Cube datasetu. V této práci jsou použity tři skupiny regresních modelů: rozhodovací strom, konvoluční neuronová síť VGGNet12 a gradientní boosting LightGBM, pro tři různé modality: pouze fotometrie, pouze spektroskopie a multimodální fúze, včetně časné a pozdní fúze. Hledání hyperparametrů je prováděno pomocí metody grid search s pětinásobnou křížovou validací a hodnocení výkonu modelu je provedeno pomocí různých metrik, jako jsou R2 , MAE, RMSE a NMAD. Nejlepšího výkonu dosahuje model LightGBM s časnou fúzí s hodnotami R2 = 0,308, MAE=0,19, RMSE=0,32, což ilustruje sílu stromových algoritmů při slučování vizuálních a spektrálních znaků. VGGNet12 trénovaná pouze na fotometrických obrazech také dosahuje dobrých výsledků (R2 = 0,262), což ukazuje sílu hlubokých CNN pro učení morfologických rysů. Zajímavé je, že nižší spektrální rozlišení generalizuje lépe díky implicitnímu vyhlazování šumu. Naše výsledky potvrzují, že multimodální strojové učení dokáže přesně zachytit komplementární astrofyzikální příznaky pro odhad SFR. Metodologický základ položený v této práci umožňuje v budoucnu zkoumat sofistikovanější metody fúze a využívat další datové modality zahrnující informaci o okolním prostředí či kinematice dané galaxie.This thesis presents a comprehensive study of the prediction of star formation rates (SFR) in galaxies using multimodal data acquired from the Sloan Digital Sky Survey (SDSS, DR7). We first filter the initial SFR catalogue to produce a high-quality, cleaned subset of 11,179 galaxies that have valid one-dimensional spectra and five-band photometry. This thesis uses the multiresolution images (64×64 to 8×8 px) and spectral samplings (4620 to 577 bins), along with their measurement uncertainties, directly from the pre-existing HiSS-Cube dataset. Three groups of regression models were considered in this thesis: Decision Tree (DT), the VGGNet12 convolutional neural network, and LightGBM gradient boosting, for three different modalities: photometry-only, spectroscopy-only, and multimodal fusion, including both early and late fusion. The hyperparameter search is conducted via grid search with five-fold cross-validation, and model performance assessment is done via a range of metrics, such as R2 , MAE, RMSE a NMAD. The top performance is obtained by the early-fusion LightGBM model with R2 = 0.308, MAE=0.19, RMSE=0.32, illustrating the power of tree-based learners for fusing visual and spectral features. VGGNet12 trained on photometric images alone also performs well (R2 = 0.262), illustrating the power of deep CNNs for morphological feature learning. Interestingly, the lowest spectral resolution generalizes better because of implicit noise smoothing. Our results validate that multimodal machine learning can record complementary astrophysical features for SFR estimation accurately. Methodological groundwork laid here allows for the exploration of more sophisticated fusion methods and utilization of other data modalities incorporating the information about the circumgalactic environment or galaxy kinematics in the future
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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