1,720,958 research outputs found
Design, development and evaluation of centrifugal ventricular assist devices
No full textHeart disease is the developed world's biggest killer, and the shortage of donor hearts has accelerated the development of mechanical alternatives. \ud
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Scientists, engineers and clinicians have attempted to replicate the human heart with a mechanical device for over 50 years. Although a number of pulsating devices have been developed, and in some cases worked briefly, they have invariably failed to match the success of heart transplantation.\ud
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In an attempt to produce a suitable alternative, current research is focused on devices that do not replace the heart; but rather work along side it to assist its function. Many of these devices help the failing left ventricle; however some patients require the additional implantation of a second device to assist a failing right ventricle. This increases implantation time and associated risk, and because of the size of the current devices, reduces the access of smaller patients to this vital technology.\ud
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The overall thesis objective focuses on the progressive design, development and preliminary evaluation of two novel centrifugal type ventricular assist devices, a bi-left ventricular device (Bi-LVAD) and a single bi-ventricular assist device (Bi-VAD). The devices have the respective capability to assist either the left ventricle, or both ventricles of a failing heart. The current concept for each VAD employs both magnetic and hydrodynamic suspension techniques to float a rotating double impeller, a technique that aims to reduce blood damage and component wear, two of the major problems encountered with current generation devices. \ud
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Each VAD design was developed by conducting experimentation and drawing conclusions from a variety of engineering research fields, such as flow visualization, rotary pump design and testing, fluid dynamics, hemodynamics and heart failure, and magnetic motor bearing design.\ud
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In order to evaluate pump prototype designs, it was necessary to design and develop a novel pulsatile systemic and pulmonary mock circulation loop capable of reproducing the hemodynamics of heart failure in the systemic and pulmonary circuits. The investigation then specifically examined the static hydraulic forces on the impeller of a centrifugal blood pump during operation in this mock circulation loop. The recorded magnitude and direction of radial and axial thrust then influenced the selection of magnetic and hydrodynamic bearing configurations to minimise impeller touchdown in the intended hemodynamic environment. This research required the development of correctly designed impeller (semi-open/closed) and volute (single, double, circular) components for each ventricular assist application and a unique test facility to isolate impeller hydraulic forces in addition to the mock circulation loop.\ud
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The proposed Bi-LVAD incorporates symmetrical blade designs on each side of the double sided impeller. The device assists the function of the left ventricle only with symmetrical axial pressure distribution and elimination of stagnant regions beneath the impeller. These features improve axial touchdown capacity and reduce thrombus formation respectively. The proposed Bi-VAD incorporates different blade designs on each side of the double impeller to augment the function of both the left and right cardiac chambers. The design has the additional potential to act as a total artificial heart (TAH). To date there is no Bi-VAD/TAH system available that incorporates an LVAD and RVAD in one rotary pump.\ud
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Successful development of each innovative VAD will provide an alternative to heart transplantation, potentially saving lives of many terminal heart patients each year. No longer would heart transplant candidates need to wait for the untimely death of a donor to provide a suitable heart. Instead, this new generation device would be available immediately, and be almost universally compatible with all patients. It has the potential to dramatically increase a patient’s expected lifetime, and to deliver them a higher quality of life
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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