1,720,961 research outputs found
Modeling and Optimization of Individualized Liver Contrast-enhanced CT Imaging
No full textMore than half of clinical CT imaging in the United States involves the use of iodinated contrast materials. The use of such contrast agents in CT imaging enhances tissue contrast, particularly in soft tissue organs such as the liver, pancreas, spleen, and kidneys, and thus improves the depiction of a variety of disorders. Despite the critical role of contrast media administration in clinical practice, there is a lack of standardization in contrast administration techniques across institutions. As a result, many studies have indicated inconsistencies in contrast enhancement across different patients, posing clinical diagnostic risk in over- and under-enhanced patient cases. In addition, contrast agents have been known to potentially increase the risk of contrast-induced acute kidney injury (CI-AKI) and cause allergic reaction, such as urticaria or anaphylactic shock in small number of patients. Therefore, given the diagnostic benefit, risks, and the prevalence usage of iodinated contrast agent in CT imaging, there is a need to devise a mechanism to increase the consistency and adequacy of organ contrast enhancement through the personalization of contrast administration and scanning parameters for each patient according to their known pre-scan attributes.This dissertation primarily focuses on liver imaging as clinically, liver is one of the most vulnerable and susceptible organs to diffuse diseases (fatty liver, hepatitis, cirrhosis), benign tumors, cancers (especially hepatocellular carcinoma), and metastasis development from non-liver primary cancers. While there are other modalities which can be used to image liver, contrast-enhanced CT imaging is the most commonly used technique to screen for these abnormalities in both healthy and ill individuals as improvement of the disease outcome relies on the accuracy of early diagnosis from the screening.
The purpose of this dissertation was to demonstrate the feasibility and clinical utility of building a patient-informed hepatic parenchyma contrast enhancement prediction model using retrospective clinical images. This project was conducted in two parts: 1) constructing the patient-informed contrast enhancement prediction model using retrospective patient cases and prior knowledge, 2) implementing a prospective preliminary clinical test using the prediction model on limited number of patients.
The first part of the dissertation (chapters 2 and 3) covers both the preparatory works in building the contrast enhancement prediction model and the process of building the model itself. In chapter 2, we used a small library of patients to explore the feasibility of potentially building a liver parenchyma contrast enhancement model. Some of these works included determining any correlations between the available patient attributes (height, weight and wight-derivative factors, sex, age) and the contrast enhancement HU level of the patient at the time of scan (portal venous phase). The correlation we observed enabled us to build a machine learning model using patient attributes to predict the contrast enhancement level of the liver at the time of scan. In chapter 3, we expanded our patient library and introduced a method of building a more robust contrast enhancement model using Gaussian function and neural network.
In the second part of the dissertation (chapter 4), we turned our focus to applying the patient-informed prediction model prospectively in the clinic. Chapter 4 involved the development of a graphical user interface which contains the prediction model of the previous chapter to provide prospective, real-time prediction of a patient’s hepatic parenchyma contrast enhancement level given patient attributes and the starting CT number value of the parenchyma. To make the tool useful in the clinical setting, the prediction model was paired with an optimization algorithm to determine alternative injection and scanning protocol in real time, targeting changes needed to the scanning parameters of patients with predicted under- or over-enhancement of the hepatic parenchyma at the time of scan. A pilot study of 24 patients undergoing contrast-enhanced CT imaging with Renal Cell Carcinoma (RCC) scanning protocol was conducted to assess the feasibility of using the aforementioned patient-informed tool to inform scanning and contrast injection parameters of each patient. For 19 of the 24 patients, we also compared the outcome of this study (contrast enhancement level) with their previous conventional RCC- protocol or abdominal contrast-enhanced CT imaging. We concluded the dissertation with summative conclusions, clinical implications, and potential future directions of this project.
In conclusion, this dissertation developed a patient-informed liver parenchyma prediction model using retrospective clinical cases and explored the potential benefit of implementing such model in the clinic through a feasibility clinical study.
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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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