261 |
Personnalisation robuste de modèles 3D électromécaniques du cœur. Application à des bases de données cliniques hétérogènes et longitudinales / Robust personalisation of 3D electromechanical cardiac models. Application to heterogeneous and longitudinal clinical databasesMolléro, Roch 19 December 2017 (has links)
La modélisation cardiaque personnalisée consiste à créer des simulations 3D virtuelles de cas cliniques réels pour aider les cliniciens à prédire le comportement du cœur ou à mieux comprendre certaines pathologies. Dans cette thèse nous illustrons d'abord la nécessité d'une approche robuste d'estimation des paramètres, dans un cas ou l'incertitude dans l'orientation des fibres myocardiques entraîne une incertitude dans les paramètres estimés qui est très large par rapport à leur variabilité physiologique. Nous présentons ensuite une approche originale multi-échelle 0D/3D pour réduire le temps de calcul, basée sur un couplage multi-échelle entre les simulations du modèle 3D et d'une version "0D" réduite de ce modèle. Ensuite, nous dérivons un algorithme rapide de personnalisation multi-échelle pour le modèle 3D. Dans un deuxième temps, nous construisons plus de 140 simulations 3D personnalisées, dans le cadre de deux études impliquant l'analyse longitudinale de la fonction cardiaque : d'une part, l'analyse de l'évolution de cardiomyopathies à long terme, d'autre part la modélisation des changements cardiovasculaires pendant la digestion. Enfin, nous présentons un algorithme pour sélectionner automatiquement des directions observables dans l'espace des paramètres à partir d'un ensemble de mesures, et calculer des probabilités "a priori" cohérentes dans ces directions à partir des valeurs de paramètres dans la population. Cela permet en particulier de contraindre l'estimation de paramètres dans les cas où des mesures sont manquantes. Au final nous présentons des estimations cohérentes de paramètres dans une base de données de 811 cas avec le modèle 0D et 137 cas du modèle 3D. / Personalised cardiac modeling consists in creating virtual 3D simulations of real clinical cases to help clinicians predict the behaviour of the heart, or better understand some pathologies from the estimated values of biophysical parameters. In this work we first motivate the need for a consistent parameter estimation framework, from a case study were uncertainty in myocardial fibre orientation leads to an uncertainty in estimated parameters which is extremely large compared to their physiological variability. To build a consistent approach to parameter estimation, we then tackle the computational complexity of 3D models. We introduce an original multiscale 0D/3D approach for cardiac models, based on a multiscale coupling to approximate outputs of a 3D model with a reduced "0D" version of the same model. Then we derive from this coupling an efficient multifidelity optimisation algorithm for the 3D model. In a second step, we build more than 140 personalised 3D simulations, in the context of two studies involving the longitudinal analysis of the cardiac function: on one hand the analysis of long-term evolution of cardiomyopathies under therapy, on the other hand the modeling of short-term cardiovascular changes during digestion. Finally we present an algorithm to automatically detect and select observable directions in the parameter space from a set of measurements, and compute consistent population-based priors probabilities in these directions, which can be used to constrain parameter estimation for cases where measurements are missing. This enables consistent parameter estimations in a large databases of 811 cases with the 0D model, and 137 cases of the 3D model.
|
262 |
Effekter av statisk och dynamisk stretching på sprintlöpning: : En experimentell studie av prestationen på 200 meter efter två olika uppvärmningsprotokoll / Effects of static and dynamic stretching on sprinting: : An experimental study of the performance on 200 meter after two different warm-up protocols.Langerak, Jefta, Poopuu, Morgan January 2021 (has links)
Stretching som uppvärmningsrutin inför idrottsaktiviteter anses ha både skadeförebyggande och prestationshöjande effekter. Studier antyder att statisk stretching kan ha negativ inverkan på prestationen, särskilt explosiva aktiviteter som hopp och sprintlöpning. Syftet med studien var att undersöka effekten av statisk stretching (SS) respektive dynamisk (DR) rörlighets-uppvärmningsprotokoll på prestationen vid sprintlöpning över 200 meter samt inverkan av muskellängd/rörelseomfång på eventuella effekter. Elva träningsvana löpare, 20-35 år, sju män och fyra kvinnor genomförde vid två tillfällen maximal 200-meterslöpning. Löpningarna föregicks vid ena tillfället av SS och det andra av DR i en randomiserad ordning. Tiden mättes med ett portabelt fotocellsystem. Deltagarna utgjorde sina egna kontroller och skillnaden i löptid mellan SS och DR analyserades parvis (Wilcoxon signed rank test). Korrelation mellan löptid och deltagarnas ROM i nedre extremiteten, mätt med goniometer analyserades (Kendall’s Tau B). Tendens till snabbare löptider visades efter DR (1,01%, p=0,077) jämfört med SS. Skillnader, dock ej signifikanta var störst första 100 meter (2,78%) och omvänt avslutande 100 meter(-0,40%). Ett samband antyddes mellan hur snabba löparna var och effekten av SS-DR (Tau B=0,382), där resultaten för männen, som generellt var snabbare visade signifikant samband (Tau B=0,905, p=0,003). Inga samband återfanns mellan ROM/muskellängd och prestation. Signifikant samband sågs dock mellan duration vid stretching och löptid (Tau B=0,48-0,56, p=0,021-0,042). Studien fann i linje med tidigare forskning tendenser till snabbare löptider vid DR jämfört med SS. Eventuella effekter av stretching kan vara små men av betydelse för snabba löpare på distanser upp till 200 meter. Fortsatt forskning på området bör inkludera homogena grupper där slumpmässiga effekter på prestationen minimeras. Utifrån resultaten föreslås att DR inkluderas i uppvärmningen framför SS.
|
263 |
Investigation of Embedded Brand Placement within Esports / Undersökning av inbäddad varumärkesplacering inom EsportsLundberg, Carl Alexandros, Smith, Lola January 2021 (has links)
The video game and esports industry has grown exponentially over the past few years.“During recent years, esports have become one of the most rapidly growing forms ofnew media driven by the growing provenance of online games and onlinebroadcasting technologies” (Hamari and Sjöblom, 2017). Sponsors have identifiedmarketing opportunities in this rapidly growing advertising medium. Brand placementin esports is gaining momentum as a means to target audiences in an indirect andengaging way. In our study we have defined embedded brand placement in the contextof video games and esports as the practice of including a brand name, signage or otherforms of trademark merchandise integrated naturally within the game and in return,visibly featured in the esport broadcast. The aim of this study was to examine howembedded brand placement performed during different spectating scenarios whichpossess different distraction levels and in-game dynamics (audio and visual). Ourstudy explores the effectiveness of embedded brand placement within esports byemploying an eye tracking methodology as well as a brand recall exercise inconnection to participant's prior involvement with the video game, League of Legendsand the respective esports scene. The practical implications from the results of thisstudy hope to assist advertisers in making a better informed decision aboutcollaborating with esport events and uncover a better perception in regards to howthey might expect their advertising messages to perform. Through our study, we havesuccessfully contributed to the foundation of research surrounding embedded brandplacements within esports through our investigation of practical factors affecting towhich extent viewers are able to consume these advertising messages. These factorsbeing prior involvement, how differing spectating scenarios, distractions and in-gamedynamics affect fixations on advertising messages and finally how the above factorscontribute to overall brand recall as well as long-term versus short-term brandrecollection.
|
264 |
Challenges and opportunities for implementing Recognition of Prior Learning (RPL) Policy in higher educationSutherland, Lee January 2006 (has links)
Submitted in partial fulfillment for the requirements of the Degree of Doctor of Education in the Department of Educational Psychology in the Faculty of Education at the University of Zululand, 2006. / This thesis explores the responses of higher education to the national imperative to implement Recognition of Prior Learning. It makes use of a mixed methods mode of research to explore this phenomenon at three sites of higher education delivery in KwaZulu-Natal. The research investigates how these three institutions have responded to the imperative at an institutional level, in terms of policy development, organisational structures and philosophical approach. It also looks at academic staff perceptions of RPL policy and implementation and its successfulness in terms of the integration of RPL into the curriculum, the capacity of the curriculum to facilitate the assessment of RPL and the extent to which it has been implemented within the higher education system. It identifies the articulation of national policy on RPL as one of the factors that impacts on successful implementation. In so doing, barriers to the successful implementation of RPL are also identified and explored. These barriers include epistemological, material and systemic barriers. However, it also seeks to elicit the benefits that higher education sees in implementing RPL, both in terms of fulfilling the goals of higher education and in terms of the benefits for the national economic imperatives and the skills development initiative. Ultimately, the research attempts to establish the extent to which RPL has been institutionalised within the institutions in terms of a set of indicators as identified by the researcher. / University of Zululand
|
265 |
Approche Bayésienne de la survie dans les essais cliniques pour les cancers rares / Bayesian Approach to Survival in Clinical Trials in Rare CancersBrard, Caroline 20 November 2018 (has links)
L'approche Bayésienne permet d’enrichir l'information apportée par l'essai clinique, en intégrant des informations externes à l'essai. De plus, elle permet d’exprimer les résultats directement en termes de probabilité d’un certain effet du traitement, plus informative et interprétable qu’une p-valeur et un intervalle de confiance. Par ailleurs, la réduction fréquente d’une analyse à une interprétation binaire des résultats (significatif ou non) est particulièrement dommageable dans les maladies rares. L’objectif de mon travail était d'explorer la faisabilité, les contraintes et l'apport de l'approche Bayésienne dans les essais cliniques portant sur des cancers rares lorsque le critère principal est censuré. Tout d’abord, une revue de la littérature a confirmé la faible implémentation actuelle des méthodes Bayésiennes dans l'analyse des essais cliniques avec critère de survie.Le second axe de ce travail a porté sur le développement d’un essai Bayésien avec critère de survie, intégrant des données historiques, dans le cadre d’un essai réel portant sur une pathologie rare (ostéosarcome). Le prior intégrait des données historiques individuelles sur le bras contrôle et des données agrégées sur l’effet relatif du traitement. Une large étude de simulations a permis d’évaluer les caractéristiques opératoires du design proposé, de calibrer le modèle, tout en explorant la problématique de la commensurabilité entre les données historiques et actuelles. Enfin, la ré-analyse de trois essais cliniques publiés a permis d’illustrer l'apport de l'approche Bayésienne dans l'expression des résultats et la manière dont cette approche permet d’enrichir l’analyse fréquentiste d’un essai. / Bayesian approach augments the information provided by the trial itself by incorporating external information into the trial analysis. In addition, this approach allows the results to be expressed in terms of probability of some treatment effect, which is more informative and interpretable than a p-value and a confidence interval. In addition, the frequent reduction of an analysis to a binary interpretation of the results (significant versus non-significant) is particularly harmful in rare diseases.In this context, the objective of my work was to explore the feasibility, constraints and contribution of the Bayesian approach in clinical trials in rare cancers with a primary censored endpoint. A review of the literature confirmed that the implementation of Bayesian methods is still limited in the analysis of clinical trials with a censored endpoint.In the second part of our work, we developed a Bayesian design, integrating historical data in the setting of a real clinical trial with a survival endpoint in a rare disease (osteosarcoma). The prior incorporated individual historical data on the control arm and aggregate historical data on the relative treatment effect. Through a large simulation study, we evaluated the operating characteristics of the proposed design and calibrated the model while exploring the issue of commensurability between historical and current data. Finally, the re-analysis of three clinical trials allowed us to illustrate the contribution of Bayesian approach to the expression of the results, and how this approach enriches the frequentist analysis of a trial.
|
266 |
Some Aspects of Bayesian Multiple TestingHerath, Gonagala Mudiyanselage Nilupika January 2021 (has links)
No description available.
|
267 |
Advanced Characterization of Defect and Grain Structures in Net-Shape Hot Isostatically Pressed IN-718Georgin, Benjamin M. January 2020 (has links)
No description available.
|
268 |
Microstructural Evaluation in Friction Stir Welded High Strength Low Alloy SteelsAbbasi Gharacheh, Majid 04 November 2011 (has links) (PDF)
Understanding microstructural evolution in Friction Stir Welding (FSW) of steels is essential in order to understand and optimize the process. Ferritic steels undergo an allotropic phase transformation. This makes microstructural evolution study very challenging. An approach based on Electron Backscattered Diffraction (EBSD) and phase transformation orientation relationships is introduced to reconstruct pre-transformed grain structure and texture. Reconstructed pre-transformed and post-transformed grain structures and textures were investigated in order to understand microstructural evolution. Texture results show that there is evidence of shear deformation as well as recrystallization in the reconstructed prior austenite. Room temperature ferrite exhibits well-defined shear deformation texture components. Shear deformation texture in the room temperature microstructure implies that FSW imposes deformation during and after the phase transformation. Prior austenite grain boundary analysis shows that variant selection is governed by interfacial energy. Variants that have near ideal BCC/FCC misorientation relative to their neighboring austenite and near zero misorientation relative to neighboring ferrite are selected. Selection of coinciding variants in transformed prior austenite Σ3 boundaries supports the interfacial-energy-controlled variant selection mechanism.
|
269 |
Application Of Statistical Methods In Risk And ReliabilityHeard, Astrid 01 January 2005 (has links)
The dissertation considers construction of confidence intervals for a cumulative distribution function F(z) and its inverse at some fixed points z and u on the basis of an i.i.d. sample where the sample size is relatively small. The sample is modeled as having the flexible Generalized Gamma distribution with all three parameters being unknown. This approach can be viewed as an alternative to nonparametric techniques which do not specify distribution of X and lead to less efficient procedures. The confidence intervals are constructed by objective Bayesian methods and use the Jeffreys noninformative prior. Performance of the resulting confidence intervals is studied via Monte Carlo simulations and compared to the performance of nonparametric confidence intervals based on binomial proportion. In addition, techniques for change point detection are analyzed and further evaluated via Monte Carlo simulations. The effect of a change point on the interval estimators is studied both analytically and via Monte Carlo simulations.
|
270 |
More Obstacles for the Graduate Student Author: Open Access ETDs Trigger Plagiarism DetectorsDawson, DeDe, Langrell, Kate 14 December 2023 (has links) (PDF)
Supporting graduate students as authors is one of the many services we provide at the University Library, University of Saskatchewan (USask). Graduate students often submit articles to journals based on content from their electronic theses or dissertations (ETDs). Recently, we have noticed an increase in the number of such article submissions being flagged for possible rejection on “plagiarism” or “prior publication” grounds. We suspect this may be because plagiarism detection software is increasingly being integrated into publishers’ article submission systems. This software is triggered by the existence of the student’s open access (OA) ETD in our institutional repository. This happens despite OA ETD inclusion in repositories being a common practice and despite journal policies often allowing submission of articles based on ETDs. We review common practices and guidelines around publishing of ETD content, two recent cases of journals initially rejecting such submissions by graduate student authors of our institution, and our reflections on this issue and how to address it.
|
Page generated in 0.0457 seconds