1,720,953 research outputs found
Computational study of retinal blood flow coupled to a global circulation model
No full textThis work focuses on the study of retinal blood flow, using computational models to simulate the interactions between ocular circulation and global systemic dynamics. The primary aim of this work is to develop a comprehensive multiscale mathematical model that can accurately represent the blood flow dynamics in the retina, considering the complex interplay between retinal circulation, intraocular pressure, and systemic factors such as cerebrospinal fluid pressure. These interactions are essential for gaining deeper insights into the regulation and behavior of retinal blood flow under normal and pathological conditions. The first chapter provides the physiological background necessary for understanding the intricacies of ocular circulation. It explains the structure and function of the visual apparatus, with particular focus on the vascular system. Detailed descriptions are provided for the retinal and choroidal circulations, both of which are responsible for supplying the retina with oxygen and nutrients, while also facilitating the removal of waste products.
The chapter further explores the relationship between ocular circulation and systemic circulation, particularly in the context of intraocular pressure (IOP), which plays a critical role in maintaining the shape of the eye and preventing damage. The dynamics of retinal vein pulsation, influenced by both IOP and intracranial pressure, are also discussed, as well as pathological conditions related to disturbances in retinal circulation.
The second chapter reviews the mathematical models that have been developed to simulate retinal blood flow. These models vary in their complexity, from simplified lumpedparameter models to more advanced 1D, 2D, and 3D models. Each model offers a different approach to representing the retinal vascular system and its hemodynamic behavior. The chapter critically examines the strengths and limitations of each. For example,
lumped-parameter models provide a global representation of blood flow, but lack spatial resolution, while 1D models offer a more detailed representation of blood flow along the length of vessels, and 3D models capture the full complexity of retinal vasculature but at the cost of higher computational demand. The chapter discusses how advancements in computational power and imaging technologies have contributed to the development of these models, enabling a more accurate understanding of retinal circulation.
The third chapter presents the global multiscale mathematical model developed by Müller and Toro, as detailed in their foundational works . This comprehensive model integrates the circulatory system with CSF dynamics, combining one-dimensional (1D) representations of major vessels with zero-dimensional (0D) models for microcirculation, heart and pulmonary circulation, and CSF compartments. This chapter provides a detailed explanation of the model’s structure, formulation, the physical laws and numerical techniques it incorporates. Chapter 4 builds upon the global circulation model described in Chapter 3, focusing on the integration of the retinal vascular network and IOP dynamics. This chapter details how the model is adapted to simulate blood flow specifically in the retina, incorporating both the IOP and the Starling Resistor (SR) model to represent retinal perfusion. The process begins with the segmentation and correction of the retinal vessels, ensuring accurate representation of the arterial and venous networks within the eye. Once the vasculature is properly defined, the IOP model is incorporated to simulate how intraocular pressure influences blood flow through the retinal vessels. Additionally, the SR model is applied to simulate retinal vein pulsation, accounting for changes in vessel diameter and pressure during the cardiac cycle, and reflecting the dynamic nature of retinal blood flow. Chapter 5 presents the results of the simulations performed using the models developed in the previous chapters. The chapter begins with an analysis of mass conservation across the different numerical methods employed in the simulations. This analysis ensures that the models accurately preserve mass throughout the system, which is critical for the validity of the simulation results. Following this, the results primarily focus on the validation of the model’s predictions against experimental and clinical data, with a particular emphasis on systemic and cerebral hemodynamics. The model’s blood flow predictions are compared with data from the literature to validate the accuracy of the simulations. For the retinal circulation, the chapter includes a comparison of the simulated curves and values with those available in the literature. This comparison helps to validate the model’s representation of retinal blood flow dynamics, particularly in terms of pressure and flow. Additionally, the chapter compares viscoelastic and elastic models to evaluate how different vessel properties affect blood flow. Finally, the sixth chapter presents a discussion of the results, offering insights into the implications for clinical applications. The limitations of the current model will be addressed, and suggestions for future research will be provided. The chapter is concluded by a discussion how this research contributes to the understanding of retinal hemodynamics
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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