1,720,953 research outputs found
Physical and Deep-Learning-Based Explorations of Microbe-Mediated Reactive Transport Processes in Porous Media Across Scales
No full textReactive transport (RT) simulators are important tools often used by researchers to gain insights into subsurface processes. These multi-physics simulations attempt to represent many hydro-biogeochemical phenomena, but they often fall short in terms of computational speed and physical accuracy. This dissertation provides several tools and conceptual advancements that can be used to improve the speed and accuracy of RT simulations and further our understanding of their outputs. Specifically, this work investigates microbial motility in porous microfluidic devices, a comparison of particle tracking methods in porous media, and an investigation of biomass growth and chromium reduction in the hyporheic zone. Furthermore, this dissertation details the development and performance-testing of deep-learning-based tools for the extraction of motion statistics from videos of particles and the upscaling of RT simulations. Overall, new tools and insights are provided to help improve environmental management strategies, such as bioremediation of contaminated groundwater or improved understanding of nutrient cycles in water systems.This dissertation advances our understanding of microbe-mediated reactive transport processes through a multi-scale approach that combines experimental observations, computational modeling, and innovative deep learning techniques. At the micro scale, experimental investigations reveal how different bacterial motility mechanisms respond to varying flow conditions, with peritrichous flagella enabling more resilient motility under higher flow rates compared to monotrichous flagella or pili. These findings provide crucial insights for developing more accurate models of microbial transport in subsurface environments.
To improve micro-scale investigations of bacterial transport, this dissertation gives a comparison of particle tracking (PT) methods and presents a novel deep-learning-based PT method. The comparison between PT methods provides guidance for future researchers in terms of appropriate particle tracking linking algorithms to use for dispersive particles in porous media, conditions for desirable particle tracking experimental setups, and the limitations of particle tracking as it relates to analysis of bacterial transport. The novel deep learning method, DeepTrackStat (DTS), provides a framework for extracting motion statistics from particle tracking videos, addressing fundamental limitations in traditional tracking methods while significantly reducing computational demands. DTS shows especially strong performance for high-speed particles, giving it a clear spot for application within the pantheon of PT methods.
In addition to the work at the micro scale, this dissertation also provides improvements to microbe-mediated reactive transport modeling at the Darcy scale. The integration of novel physical approaches enables comprehensive investigation of coupled hydro-biogeochemical processes in the hyporheic zone, particularly focusing on the interactions between fluid flow, biomass development, and chromium reduction. Through extensive sensitivity analyses, this work reveals that while abiotic reduction dominates in high-electron-donor environments, biotic processes crucially influence the spatial distribution of reduction hotspots. Furthermore, the research demonstrates that speed-based biomass decay significantly impacts biomass growth only under specific conditions of high fluid velocity or weak biofilm cohesion, providing important constraints for environmental management strategies. Expanding on the Darcy-scale microbe-mediated reactive transport modeling, this dissertation presents STAMNet, a neural network for upscaling reactive transport simulations that enables efficient prediction of large-scale transport phenomena while preserving the essential dynamics observed at smaller scales. STAMNet has a simple MLP structure with a spatiotemporal attention mechanism (STAM) that uses cross-dimensional residual connections to improve both spatial and temporal feature extraction.
This work's multi-scale, multi-method approach provides a foundation for improving predictions of reactive transport in heterogeneous porous media while offering practical tools for environmental monitoring and remediation. The findings and methodologies presented here advance our ability to bridge scales in reactive transport modeling, from individual bacterial behavior to field-scale predictions, while the developed deep learning tools offer new possibilities for efficient analysis and upscaling of complex environmental processes. These contributions support more informed decision-making in environmental management and provide a framework for future investigations of coupled biological, chemical, and physical processes in porous media systems
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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