1,720,975 research outputs found
Development and preclinical application of robotic tools to assist in performing endoscopic retrograde cholangiopancreatography : MAGIE Project : Model of Assistance for Gesture in Interventional Endoscopy
No full textLa cholangiopancréatographie rétrograde par voie endoscopique (CPRE) est une procédure endoscopique interventionnelle mini-invasive dont l'objectif est de réaliser un traitement au sein des voies biliaires. Les deux principales pathologies traitées sont la maladie lithiasique et les tumeurs bilio-pancréatiques. L'interprétation de l'anatomie biliaire dans le contexte de sténoses situées au niveau de la convergence biliaire supérieure (région péri-hilaire) et la manipulation du fil guide dans cette anatomie biliaire complexe sont les limites qui poussent à développer de nouveaux outils d'aide au guidage des instruments dans les voies biliaires. Nous nous sommes donc penchés durant ce travail de thèse sur la modélisation des voies biliaires par segmentation-reconstruction 3D, sur l'aide à la localisation des instruments de CPRE par recalage 2D-3D et tracking et, enfin, le design et la validation d'instruments actifs.Nous avons effectué des segmentations manuelles d'arbres biliaires à partir d'images de bili-IRM pour des cas de sténoses malignes péri-hilaires. Sur la base de ces segmentations, une étude rétrospective analysant la prise en charge de ces patients a pu montrer les limites de la CPRE 2D actuelle avec un nombre élevé d'injections de contraste inutiles, des prothèses inutiles ou mal placées, ainsi que des CPRE à répétition évitables. Une reconstruction 3D pourrait améliorer la technique de drainage endoscopique. Un travail en collaboration avec une équipe spécialisée a été initié pour mettre au point une segmentation-reconstruction automatisée. Les premiers résultats sont très encourageants même si inférieurs à la vérité terrain. Le travail se poursuit au niveau de la constitution d'une base de données qui permettra de renforcer l'apprentissage profond.Le second objectif de ce travail était le tracking et la localisation 3D automatique peropératoires des ancillaires au sein des voies biliaires complexes. Nous voulions ici développer un système d'aide temps-réel indiquant explicitement à l'opérateur le secteur intra-hépatique où se trouve son fil guide. Une première étape, fondée sur l'intelligence artificielle, a consisté à mettre au point une segmentation automatique du fil guide dans l'image de fluoroscopie 2D. Les modèles CNN mis au point par une équipe spécialisée permettent à ce stade de segmenter assez systématiquement une part significative des instruments. Sur cette base, la seconde étape a consisté à imaginer et tester un algorithme de localisation peropératoire des ancillaires. En s'appuyant sur la fusion entre reconstruction anatomique 3D et segmentation du fil-guide à l'image, un programme a été développé, lequel retourne une probabilité de localisation. La sensibilité de l'algorithme est de 91%. Dans le cas d'arbres biliaires complexes, les performances sont moins bonnes mais restent élevées avec une sensibilité de 86%. De futurs développements sont en cours afin de fiabiliser l'algorithme.Le troisième objectif de ce travail était de contribuer à l'émergence d'un fil guide de nouvelle génération pouvant s'orienter de façon active dans l'espace afin de naviguer plus aisément au sein de l'arbre biliaire, pathologique ou non. Pour ce faire, nous nous sommes appuyés sur la technologie des alliages à mémoire de forme (AMF). Des modèles 3D d'arbre biliaire ont été imprimés en utilisant les segmentations réalisées en interne. Un modèle dupliquant l'environnement complet de la CPRE, appelé ‘modèle-CPRE', a été conçu puis fabriqué afin de pouvoir tester les fils guides intelligents. Une première série de tests a comparé un fil guide intelligent (Gecko 35Ⓡ, BCV) à deux fils guides utilisés en pratique courante. Au total, les premières manipulations montrent une faisabilité avec un cathétérisme de la majorité des secteurs intra-hépatiques. Après impression de nouveaux modèles et amélioration du modèle-CPRE, une seconde série de tests avec d'autres experts sera réalisée.Endoscopic retrograde cholangiopancreatography (ERCP) is a minimally invasive interventional endoscopic procedure whose objective is to provide treatment within the bile ducts. The two main pathologies treated are stone disease and biliopancreatic tumors.The interpretation of the biliary anatomy in the setting of strictures located at the level of the upper biliary convergence (peri-hilar region) and the manipulation of the guide wire in this complex biliary anatomy greatly limit the procedures success, which pushed us to develop new tools to better navigate within the bile ducts. We focused during this thesis work on the modelization of the bile ducts by 3D segmentation-reconstruction, on assisted localization of ERCP instruments by 2D-3D registration and tracking and, finally, the design and validation of active instruments.We performed manual segmentations of biliary trees from biliary MRI images for cases of malignant perihilar strictures. Based on these segmentations, a retrospective study analyzing the management of these patients showed the limits of current 2D ERCP with a high number of unnecessary contrast injections, unnecessary or poorly placed biliary stents, as well as unwarranted repeat ERCPs. 3D reconstruction could improve the endoscopic technique. Collaborative work with a specialized team was initiated to develop automated segmentation-reconstruction. The first results are encouraging although not as performant as the manual ground truth. The database is being increased with more cases that will strengthen the deep learning.The second objective of this work was the automatic intraoperative 3D tracking and localization of instruments within complex bile ducts. Here we wanted to develop a real-time assistance system explicitly indicating the intra-hepatic sector where the guide wire is located. A first step, based on artificial intelligence, consisted of developing an automatic segmentation of the guide wire in the 2D fluoroscopy image. The CNN models developed by a specialized team allows the segmentation of a significant portion of the instruments at this stage.The second step consisted on the development and testing of an algorithm for intraoperative localization of the guide wire. Based on the fusion between 3D anatomical reconstruction and segmentation of the guidewire in the 2D image, a program was developed which gives a localization probability. The sensitivity of the algorithm is 91%. In the case of complex biliary trees, lower performances are seen, but remain high with a sensitivity of 86%. Future developments are underway to render the algorithm more reliable.The third objective of this work was to contribute to the emergence of a new generation of guide wires which can be actively oriented in space in order to navigate more easily within the biliary tree, pathological or not. We relied here on shape memory alloy technology. 3D models of the biliary tree were printed using the manual segmentations. A model duplicating the complete CPRE environment, called ‘CPRE-model', was designed and then manufactured in order to be able to test the intelligent guidewires. A first series of tests compared an intelligent guidewire (Gecko 35Ⓡ, BCV) to two guidewires used in current practice. Overall, the first manipulations show feasibility with catheterization of the majority of intrahepatic sectors. After printing new models and improving the CPRE model, a second series of tests with other experts will be carried out
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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