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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Early Parasympathetic Activity Predicts Later Childhood Social Functioning as Mediated by Emotion Regulation

Fok, Megan January 2021 (has links)
Theories of emotion regulation and social engagement indicate that resting and reactive respiratory sinus arrhythmia (RSA), which reflect vagal activity, in early childhood can inform the development of social and emotional behaviors later in life. Low RSA at baseline and during a stressful task have been associated with symptoms of ED and disorders characterized by social impairments. The current study examined the mediating role of ED at 24-months-old (mo) on the prospective association between early infant resting and reactive RSA at 5 mo on social functioning outcomes at 48 mo, and the mediating role of social functioning at 24 mo on infant RSA at 5 mo and ED at 48 mo in 237 healthy children. It was hypothesized that ED would mediate the relationship between infant RSA and later childhood social function. Results largely indicated no support of the hypotheses and that there is no mediating effect of childhood ED on early RSA on later childhood social behavior; however, there was a significant relationship between infant resting and reactive RSA and later ED. Limitations and future directions for improving the methodology are addressed. / M.S. / Early childhood heart rate has been thought to influence the development of later child emotional and social development. The Polyvagal Theory suggests that low variability in heart rate, as measured by respiratory sinus arrhythmia (RSA), is related to greater difficulties in emotional and social behavior. Finding an underlying biological reason for emotional and social development can be important for understanding childhood psychological disorders. This research study examined healthy children at three different time points during development: 5 months old (mo), 24 mo, 48 mo. RSA was measured at 5 mo, and frustration levels and social abilities at 24 and 48 mo. It was hypothesized that low RSA at 5 mo predicts low social abilities at 48 mo because of high frustration levels at 24 mo. To rule out an alternate hypothesis, this study also tested if low RSA at 5 mo predicts high frustration levels at 48 mo because of low social abilities at 24 mo. The results of this study did not support the predictions and there was no evidence of emotional abilities affecting how RSA predicts later social abilities. Possible explanations for the lack of findings and ideas for future research were discussed.
152

Regulation of sinoatrial node and pacemaking mechanisms in health and disease

El Khoury, Nabil 12 1900 (has links)
Le noeud sinusal (NS) est le centre de l‟automatisme cardiaque. Grâce à son activité électrique spontanée, il dicte la fréquence cardiaque (FC) en réponse aux demandes physiologiques. A ce jour, le NS demeure un sujet de recherche important puisque les mécanismes moléculaires responsables de sa régulation sont encore méconnus. Par exemple, les processus menant à la bradycardie sinusale et à la maladie du sinus (MS) chez les personnes âgées sont mécompris et présentement l‟implantation d‟un stimulateur cardiaque demeure le seul traitement disponible. Ainsi, l‟objectif de cette thèse était de déterminer les changements moléculaires et cellulaires se produisant au niveau du NS en réponse à divers stimuli physiologiques et pathologiques afin d'établir leurs rôles potentiels dans la régulation de la FC et le développement de la MS. Dans les deux premiers chapitres, la grossesse est présentée comme modèle physiologique. En effet, la réponse adaptative aux demandes croissantes de la mère et du foetus engendre des changements physiologiques considérables au niveau du myocarde, dont une augmentation de la FC essentielle pour la perfusion adéquate des organes. Toutefois, cette augmentation peut aussi favoriser le développement d‟arythmies. Dans le troisième chapitre, l‟inflammation, un facteur présent lors du vieillissement et dans plusieurs pathologies où la MS se manifeste, a fait l‟objet d‟une étude dans le but de déterminer son rôle dans le développement de la MS. Les résultats obtenus dans cette thèse démontrent que la grossesse induit une hausse de la FC chez la souris gestante similaire à celle retrouvée chez la femme enceinte. Cette accélération était due à un remodelage électrique du NS. Plus spécifiquement, la fréquence des potentiels d‟action ainsi que la densité et l‟expression des courants pacemaker (If) et calcique de type L (ICaL) étaient augmentées. De plus, une accélération des transitoires calciques spontanés et de la vitesse de relâche calcique du réticulum sarcoplasmique a été observée. La régulation de l‟automaticité par un stimulus pathologique, l‟interleukine-1β, est abordée par la suite. L‟interleukine-1β, une cytokine ayant un rôle majeur comme médiateur inflammatoire, se retrouve en concentrations élevées dans plusieurs maladies associées avec la ii MS. Nos résultats démontrent que l‟interleukine-1β engendre une diminution de l‟automaticité associée à une réduction de If et ICaL dans les cardiomyocytes humains de type nodal dérivés de cellules souches induites pluripotentes (hiPSC-CM). En parallèle, le phénotype électrophysiologique et moléculaire des hiPSC-CM a été caractérisé démontrant leur homologie avec les cellules du NS humain adulte, les validant comme modèle in vitro de cellules nodales humaines. En conclusion, les études présentées dans cette thèse démontrent que le NS est plus qu‟un simple tissu régulé par l‟innervation autonome. En effet, son automaticité est dynamique et peut être influencée par des facteurs physiologiques ou pathologiques. Nos résultats contribuent ainsi à une meilleure compréhension des mécanismes sous-jacents à l‟automaticité. Ces avancées sont importantes non seulement pour la santé des femmes, mais aussi pour les individus souffrant de la MS. À terme, nous espérons que ces résultats contribueront au développement de stratégies thérapeutiques pour traiter des complications liées aux troubles d‟automaticité cardiaque. / The sinoatrial node (SAN) is the dominant cardiac pacemaker. With its spontaneous automaticity, it dictates rhythm and controls heart rate in response to varying physiological demands. Despite its modest size, the SAN is a very heterogeneous and complex structure that remains the topic of research efforts due, in part, to uncertainties in the mechanisms that regulate pacemaking in various conditions. For instance, the processes that lead to severe sinus bradycardia and SAN dysfunction (SND) in the elderly are unknown and to date, the implantation of electronic pacemaker remains the only SND treatment. Accordingly, the overall objective of this thesis was to explore and highlight the molecular and cellular changes that occur within the SAN in both physiological and pathological states, while determining how they contribute to regulation of heart rate and potentially SND. In the first two chapters, we present pregnancy as a physiological model considering it is a period during which substantial adaptive changes to the myocardium and increases in heart rate occur. Paradoxically, the rapid rate, which is essential for adequate organ perfusion of both mother and foetus, may also increase vulnerability to certain arrhythmias. In the third chapter, inflammation, a central process in pathology and common factor to several diseases and even ageing, was evaluated as potential underlying circumstance contributing to the development of sinus bradycardia and SND. Combinations of in vivo, ex vivo, biochemical, molecular and cellular approaches were used in order to generate an integrated understanding of the models we examined. Our data shows that in pregnant mice, an increase in heart rate similar to that of pregnant women occurs and was due to an electrical remodelling of the SAN. Specifically, an increase in action potential frequency of isolated individual SAN cells was observed. This was attributed to increased expression and density of pacemaker (If) and L-type Ca2+ currents (ICaL) along with a rapid spontaneous Ca2+ transient rate and faster intracellular sarcoplasmic reticulum Ca2+ release. We then demonstrate that the pro-inflammatory cytokine interleukin-1β which is a major inflammatory mediator that is upregulated in several diseases associated with SND, iv dramatically slows automaticity by reducing If and ICaL density in nodal-like cardiomyocytes derived from human-induced pluripotent stem cells (hiPSC-CM). Importantly, in that study, hiPSC-CMs were also physiologically and molecularly characterized revealing their high resemblance to adult human SAN and a potential use as a novel in vitro model to study pacemaking in humans. In conclusion, the results of this thesis demonstrate that the SAN is not a simple, neurally controlled tissue, but a rather dynamic pacemaker that undergoes extensive intrinsic remodelling during states of health and disease. The results contribute to understanding physiological mechanisms of pacemaking and how they are altered by disease and may be relevant for both women‟s health and the individuals affected by SND. Ultimately, we hope these findings will be helpful in the development of therapeutic strategies to treat pacemaking-related complications.
153

Avaliação do seio maxilar e estruturas adjacentes em indivíduos edêntulos total ou parcial na região posterior da maxila / Evaluation of the maxillary sinus and adjacent structures in total or partial edentulous individuals in the posterior maxila

Terrero Perez, Angel 03 April 2018 (has links)
Os seios maxilares são os maiores seios paranasais e seu desenvolvimento apresenta uma variabilidade entre os indivíduos, já que sofre um processo de expansão progressiva durante a vida toda, principalmente nos casos de perdas dentárias, provocando pneumatização do seio em direção ao rebordo alveolar, reduzindo sua altura. Quando essa altura óssea alveolar residual é insuficiente, uma cirurgia de levantamento de seio pode ser realizada para ganhar altura óssea e posterior instalação de implantes dentários. Em alguns casos, podem apresentar variações anatômicas, levando ao insucesso da técnica cirúrgica, por desconhecimento ou falta de planejamento através de exames complementares. Para evitar esse tipo de acidentes e complicações em implantodontia é preciso a ajuda de exames complementares para um melhor planejamento cirúrgico e protético, como é o caso da tomografia computadorizada de feixe cônico, que fornece imagens em três dimensões, possibilitando uma melhor avaliação do seio maxilar. Portanto, o objetivo deste estudo foi descrever as diferentes variações anatômicas apresentadas no seio maxilar em pacientes edêntulos total e parcial da região posterior da maxila, realizar mensurações do osso alveolar residual, paredes do seio e determinar a relação da artéria alveolar superior posterior com o seio maxilar, através da avaliação de tomografia computadorizada de feixe cônico disponíveis nos arquivos de imagens digitais do departamento de Cirurgia, Estomatologia, Patologia e Radiologia da Faculdade de Odontologia de Bauru da Universidade de São Paulo FOB/USP. / The maxillary sinus is the largest of the paranasal sinuses and its development presents a variability among the individuals, since it undergoes a process of progressive expansion during the whole life, mainly in the cases of dental losses, provoking pneumatization of the sinus toward the alveolar ridge, reducing your Height. When this residual alveolar bone height is insufficient, a sinus lift surgery can be performed to gain bone height and subsequent installation of dental implants. In some cases, they may present anatomic variations, leading to the failure of the surgical technique, due to lack of knowledge or lack of planning through complementary tests. To avoid such accidents and complications in implantology, it is necessary the help of complementary examinations for a better surgical and prosthetic planning, as is the case of conical beam CT, which provides images in three dimensions, allowing a better evaluation of the maxillary sinus. Therefore, the objective of this study was to describe the different anatomical variations presented in the maxillary sinus in total and partial edentulous patients of the posterior maxillary region, to perform measurements of the residual alveolar bone, sinus walls and to determine the relation of the posterior superior alveolar artery with the sinus maxillary, through the evaluation of conical beam computed tomography available in the digital images archives of the Department of Surgery, Stomatology, Pathology and Radiology of the Faculty of Dentistry of Bauru of the University of São Paulo FOB / USP.
154

Développement d’un modèle expérimental porcin d’autorétroperfusion myocardique à coeur battant : évaluation des réponses hémodynamiques et cardiaques avant et après occlusion de l’artère interventriculaire antérieure : potentialités d’applications cliniques / Development of a porcine beating-heart model of self-myocardial retroperfusion : evaluation of hemodynamic and cardiac responses to ischemia and clinical applications

Grandmougin, Daniel 01 June 2018 (has links)
Partie I : Objectifs. Ce travail propose une étude anatomique du coeur de porc afin d’élaborer des recommandations pour la réalisation d’une chirurgie cardiaque expérimentale. Matériels et méthodes. 16 porcs ont été étudiés. Le réseau coronaire artériel a été étudié chirurgicalement (n=13) et angiographiquement (n=10). Le réseau veineux coronaire a été analysé par dissections anatomiques (n=13) et injections rétrogrades de bleu de méthylène via le sinus coronaire (n=8). Résultats. Le positionnement intrapéricardique spécifique du coeur de porc, limite l’accès à l’aorte ascendante et à l’oreillette droite et nécessite des précautions particulières pour la réalisation d’une sternotomie et d’une canulation de l’aorte ascendante avec cardioplégie antérograde par la racine de l’aorte. Le réseau coronaire artériel est comparable au réseau humain (réseau droit dominant: 70%). Le sinus coronaire reçoit 4 afférences contre 3 chez l’homme. L’étude de la distribution de surface du réseau veineux nécessite la ligature préalable de la veine azygos gauche et confirme une asymétrie de perfusion au détriment du VD. La paroi antérieure du VD étant drainée par des petites veines cardiaques indépendantes du sinus coronaire. Conclusions. La connaissance des spécificités anatomiques cardiaques du porc a permis d’établir des recommandations pour la réalisation du modèle d’autorétroperfusion myocardique et plus largement de procédures chirurgicales cardiaques expérimentales sécurisées. Partie II : Objectifs. La perfusion rétrograde dans le sinus coronaire est utilisée pour la diffusion d’une solution de cardioplégie. Nous avons développé un modèle porcin d’autorétroperfusion myocardique à coeur battant (SMR) utilisant le réseau veineux coronaire pour assurer l’oxygénation du myocarde ventriculaire gauche. Ce modèle nous a permis d’évaluer les réponses hémodynamiques et cardiaques induites par SMR avant et après occlusion de l’artère IVA. Matériels et Méthodes. Une dérivation entre l’aorte ascendante et le sinus coronaire a été mise en place pour assurer une perfusion rétrograde sélective de la grande veine coronaire en sang oxygéné (SMR). Un groupe Contrôle (n=6) a permis de collecter des données physiologiques de référence et un groupe SMR (n=6) a été spécifiquement dédié à l’évaluation du concept d’autorétroperfusion myocardique après occlusion de l’artère IVA pendant au moins 240 minutes. Le débit cardiaque (CO), la pression maximale intra-VG (Pmax in-LV), le volume éjecté (SV), la fraction d’éjection ventriculaire gauche (FEVG), la durée diastolique (DD), la fréquence cardiaque (HR) et la pression artérielle systémique ont été monitorés en continu durant la période d’autorétroperfusion au moyen d’un cathéter de conductance type Millar® avant et après occlusion de l’IVA. La qualité de la perfusion systémique périphérique a été évaluée par l’analyse de la microcirculation sublinguale. En fin de procédure, les coeurs étaient prélevés pour une analyse histologique. Résultats. L’évaluation échographique de la FEVG était biaisée par la sternotomie alors que celle réalisée par le cathéter de conductance ne l’était pas. Le débit cardiaque après sternotomie a chuté en moyenne de 7.51% (P < 0.05). L’autorétroperfusion avec artère IVA perméable a généré des effets inotropes positifs, caractérisés par une augmentation du CO, du SV, de la Pmax in-LV et de la FEVG (P <0.0001). Après occlusion de l’IVA, l’autorétroperfusion a assuré, durant 240 minutes, une oxygénation myocardique et une compensation hémodynamique garantissant la préservation de la perfusion périphérique. L’analyse histologique a confirmé l’absence d’infarctus myocardique. Conclusions. L’autorétroperfusion myocardique a confirmé des propriétés inotropes positives et protectrices contre l’ischémie ouvrant des perspectives d’applications intéressantes / Part I: Objectives. This work reports an anatomic study of swine heart in order to produce technical recommendations and achieve successful experimental cardiac surgical procedures. Methods. 16 swines were studied. Coronary artery vessels were surgically (n=13) and angiographically (n=10) assessed. Coronary venous vessels were studied by anatomic dissections (n=13) and retrograde injection of methylene blue through the coronary sinus (n=8). Results. Specific pericardial positioning of swine heart dramatically differs from human heart resulting in a limited access to ascending aorta and right atrium, requiring surgical precautions to perform a safe sternotomy and canulation of ascending aorta with an antegrade cardioplegia. Arterial coronary pattern is similar to that of humans (right dominant supply: 70%). Pig coronary sinus receives 4 main branches vs 3 in human sinus. Preliminary ligation of the left azygos vein is required to visualize the surface distribution of methylene blue within the venous vessels, thereby confirming an optimized perfusion of the left ventricle whereas the right ventricle remains poorly perfused. This asymmetry of perfusion results from a specific venous drainage of the right ventricle through small cardiac veins disconnected from coronary sinus. Conclusions. Anatomic knowledge of swine heart validated surgical guidelines for designing the model of self-myocardial retroperfusion and safely performing experimental cardiac surgical procedures. Part II: Background. Retrograde perfusion into the coronary sinus is used to deliver cardioplegia. We developed an in-vivo porcine beating-heart model of self-myocardial retroperfusion (SMR) using the venous route to supply myocardial oxygenation and sought to assess hemodynamic and cardiac responses triggered by SMR before and after a prolonged occlusion of the LAD.Methods. A bypass-line between the ascending aorta and the coronary sinus was made to perform a selective retrograde perfusion of the great cardiac vein with oxygenated blood (SMR). A Control group (n=6) was assigned to collect baseline data, and an SMR group (n=6) was dedicated to undergo SMR with occlusion of LAD for 240 minutes. Cardiac output (CO), maximal pressure in the LV (Pmax in-LV), stroke volume (SV), left ventricular ejection fraction (LVEF), diastolic durations, heart rate, and arterial systemic pressure were evaluated with conductance catheters for the following periods: basal (before SMR), SMR with patent LAD, and SMR with occluded LAD. In order to assess peripheral perfusion, patterns of sublingual microcirculation were analyzed. At the end of the procedures, the hearts were harvested for histology. Results. Echographic LVEF evaluation was affected by sternotomy, but conductance catheter evaluation was not. Following pericardiotomy, CO decreased by 7.51% (P < 0.05). SMR with patent LAD showed inotropic properties with improvements in CO, SV, Pmax in-LV and LVEF (P < 0.0001). Following LAD occlusion, SMR supplied myocardial oxygenation with hemodynamic compensation and preserved the peripheral perfusion. Histology confirmed no signs of infarct. Conclusions. SMR showed capacities to produce inotropic effects and protect against ischemia, opening interesting potential applications
155

Implication des biofilms dans la rhinosinusite chronique et l’évaluation des traitements avec un modèle in vitro

Bendouah, Zohra 08 1900 (has links)
Introduction : La chronicité de la rhinosinusite, sa résistance aux antibiotiques, et ses exacerbations aiguës laissent croire que les biofilms sont impliqués dans la rhinosinusite chronique. Objectifs : Nous avons évalué la capacité des bactéries Pseudomonas aeruginosa, staphylocoques à coagulase négative et Staphylococcus aureus à former des biofilms par un essai in vitro, et si cette capacité de formation a un lien avec l’évolution de la maladie. Nous avons évalué in vitro l’effet de la moxifloxacine, un antibiotique utilisé dans le traitement de la rhinosinusite chronique sur des biofilms matures de Staphylococcus aureus. Méthodes : Trent et une souches bactériennes ont été isolées de 19 patients atteints de rhinosinusite chronique et qui ont subit au moins une chirurgie endoscopique des sinus. L’évolution de la maladie a été notée comme "bonne" ou "mauvaise" selon l’évaluation du clinicien. La production de biofilm a été évaluée grâce à la coloration au crystal violet. Nous avons évalué la viabilité du biofilm après traitement avec la moxifloxacine. Ces résultats ont été confirmés en microscopie confocale à balayage laser et par la coloration au LIVE/DEAD BacLight. Résultat et Conclusion : Vingt deux des 31 souches ont produit un biofilm. La production d’un biofilm plus importante chez Pseudomonas aeruginosa et Staphylococcus aureus était associée à une mauvaise évolution. Ceci suggère un rôle du biofilm dans la pathogenèse de la rhinosinusite chronique. Le traitement avec la moxifloxacine, à une concentration de 1000X la concentration minimale inhibitrice réduit le nombre des bactéries viables de 2 à 2.5 log. Ces concentrations (100 µg/ml - 200 µg/ml) sont faciles à atteindre dans des solutions topiques. Les résultats de notre étude suggèrent que l’utilisation de concentrations supérieure à la concentration minimale inhibitrice sous forme topique peut ouvrir des voies de recherche sur de nouveaux traitements qui peuvent être bénéfiques pour les patients atteints de forme sévère de rhinosinusite chronique surtout après une chirurgie endoscopique des sinus. / Introduction: The role of biofilms in chronic diseases is increasingly recognized. Chronic rhinosinusitis, with its chronic indolent course, resistance to antibiotics, and acute exacerbations, has an evolution that parallels that of other biofilm-related diseases. Objectives: 1-To develop an in vitro method to assess the biofilm formation capacity. 2- To determine whether biofilm-forming capacity of bacteria demonstrated in chronic rhinosinusitis has an impact on persistence of the disease following endoscopic sinus surgery. 3- To determine the in vitro activity of moxifloxacin against Staphyylococcus aureus in biofilm form. Method: Thirty-one bacterial strains recovered from 19 patients with chronic rhinosinusitis at least one year post-endoscopic sinus surgery. Evolution of disease was assessed by questionnaire and endoscopy as favorable or unfavorable. The bacteria were cultured on a 96-well culture plaque and a semi-quantitative method using crystal violet to quantify biofilm production was used. Confirmation of the effect of the antimicrobial agents on viability was performed with confocal laser microscopy, using a LIVE/DEAD BacLight staining. Results: Twenty-two of 31 samples produced a biofilm thicker or equal to the positive control. Biofilm formation was associated with a poor evolution for Pseudomonas aeruginosa and Staphylococcus aureus, but not for coagulase-negative staphylococci. Biofilm treated with moxifloxacin at 1000X (0.1mg/ml – 0.2 mg/ml) gave a 2 to 2.5 log reduction in number of viable bacteria. Conclusion: We have shown that Crystal violet method is able to detect biofilm formation. There is a correlation between in vitro biofilm production by Pseudomonas aeruginosa and Staphylococcus aureus and unfavorable evolution after endoscopic sinus surgery, suggesting a role for biofilm in chronic rhinosinusitis. Increased concentrations of moxifloxacin, easily attainable in topical solutions have a potential role in the management of biofilm infections.
156

Perspektivenorientierte Erkennung chirurgischer Aktivitäten im Operationssaal

Meißner, Christian 29 April 2015 (has links) (PDF)
Die Dissertation beschäftigt sich mit der automatischen Erkennung chirurgischer Aktivitäten im Operationssaal, welche einen wichtigen Bestandteil im automatischen chirurgischen Assistenzprozess darstellt. Die automatische Assistenz ist eine der wichtigen Entwicklungen bei der fortschreitenden Technisierung in der Chirurgie. Es werden Anforderungen an ein Erkennungssystem definiert sowie ein entsprechendes Erkennungsmodell entworfen und untersucht. Die Evaluation bedient sich simulierter chirurgischer Eingriffe mit hoher Realitätsnähe. Die Ergebnisse zeigen eine grundlegende Eignung des Modells für die automatische Aktivitätserkennung multipler Eingriffstypen. Mögliche Weiterentwicklungen könnten die vorgestellte Lösung weiter vorantreiben.
157

How to precisely measure the volume velocity transfer function of physical vocal tract models by external excitation

Fleischer, Mario, Mainka, Alexander, Kürbis, Steffen, Birkholz, Peter 30 July 2018 (has links) (PDF)
Recently, 3D printing has been increasingly used to create physical models of the vocal tract with geometries obtained from magnetic resonance imaging. These printed models allow measuring the vocal tract transfer function, which is not reliably possible in vivo for the vocal tract of living humans. The transfer functions enable the detailed examination of the acoustic effects of specific articulatory strategies in speaking and singing, and the validation of acoustic plane-wave models for realistic vocal tract geometries in articulatory speech synthesis. To measure the acoustic transfer function of 3D-printed models, two techniques have been described: (1) excitation of the models with a broadband sound source at the glottis and measurement of the sound pressure radiated from the lips, and (2) excitation of the models with an external source in front of the lips and measurement of the sound pressure inside the models at the glottal end. The former method is more frequently used and more intuitive due to its similarity to speech production. However, the latter method avoids the intricate problem of constructing a suitable broadband glottal source and is therefore more effective. It has been shown to yield a transfer function similar, but not exactly equal to the volume velocity transfer function between the glottis and the lips, which is usually used to characterize vocal tract acoustics. Here, we revisit this method and show both, theoretically and experimentally, how it can be extended to yield the precise volume velocity transfer function of the vocal tract.
158

Avaliação do seio maxilar e estruturas adjacentes em indivíduos edêntulos total ou parcial na região posterior da maxila / Evaluation of the maxillary sinus and adjacent structures in total or partial edentulous individuals in the posterior maxila

Angel Terrero Perez 03 April 2018 (has links)
Os seios maxilares são os maiores seios paranasais e seu desenvolvimento apresenta uma variabilidade entre os indivíduos, já que sofre um processo de expansão progressiva durante a vida toda, principalmente nos casos de perdas dentárias, provocando pneumatização do seio em direção ao rebordo alveolar, reduzindo sua altura. Quando essa altura óssea alveolar residual é insuficiente, uma cirurgia de levantamento de seio pode ser realizada para ganhar altura óssea e posterior instalação de implantes dentários. Em alguns casos, podem apresentar variações anatômicas, levando ao insucesso da técnica cirúrgica, por desconhecimento ou falta de planejamento através de exames complementares. Para evitar esse tipo de acidentes e complicações em implantodontia é preciso a ajuda de exames complementares para um melhor planejamento cirúrgico e protético, como é o caso da tomografia computadorizada de feixe cônico, que fornece imagens em três dimensões, possibilitando uma melhor avaliação do seio maxilar. Portanto, o objetivo deste estudo foi descrever as diferentes variações anatômicas apresentadas no seio maxilar em pacientes edêntulos total e parcial da região posterior da maxila, realizar mensurações do osso alveolar residual, paredes do seio e determinar a relação da artéria alveolar superior posterior com o seio maxilar, através da avaliação de tomografia computadorizada de feixe cônico disponíveis nos arquivos de imagens digitais do departamento de Cirurgia, Estomatologia, Patologia e Radiologia da Faculdade de Odontologia de Bauru da Universidade de São Paulo FOB/USP. / The maxillary sinus is the largest of the paranasal sinuses and its development presents a variability among the individuals, since it undergoes a process of progressive expansion during the whole life, mainly in the cases of dental losses, provoking pneumatization of the sinus toward the alveolar ridge, reducing your Height. When this residual alveolar bone height is insufficient, a sinus lift surgery can be performed to gain bone height and subsequent installation of dental implants. In some cases, they may present anatomic variations, leading to the failure of the surgical technique, due to lack of knowledge or lack of planning through complementary tests. To avoid such accidents and complications in implantology, it is necessary the help of complementary examinations for a better surgical and prosthetic planning, as is the case of conical beam CT, which provides images in three dimensions, allowing a better evaluation of the maxillary sinus. Therefore, the objective of this study was to describe the different anatomical variations presented in the maxillary sinus in total and partial edentulous patients of the posterior maxillary region, to perform measurements of the residual alveolar bone, sinus walls and to determine the relation of the posterior superior alveolar artery with the sinus maxillary, through the evaluation of conical beam computed tomography available in the digital images archives of the Department of Surgery, Stomatology, Pathology and Radiology of the Faculty of Dentistry of Bauru of the University of São Paulo FOB / USP.
159

Contribution l'étude des convertisseurs multiniveaux destinés aux applications moteurs rapides / Contribution to the study of multilevel inverters for high speed motors applications

Guennegues, Virginie 07 December 2009 (has links)
Cette thèse traite des convertisseurs multiniveaux destinés aux applications moteurs rapides, utilisés notamment dans le domaine de l'Oil \& Gas. L'objectif est l'étude d'une structure qui permette de réduire les pertes par commutation, en comparaison avec la topologie conventionnelle NPC (Neutral Point Clamped) 3 niveaux, actuellement utilisée. De plus, la structure de convertisseur doit permettre de fournir des grandeurs d'entrée au moteur ayant un faible taux de distorsion harmonique, de manière à ne pas créer des échauffements supplémentaires dans le moteur.Après avoir effectué une étude des différentes structures existantes, la structure NPP (Neutral Point Piloted) 3 niveaux est finalement retenue au vu de ses différentes qualités. En effet, grâce à la mise en série de composants semi-conducteurs, les pertes par commutation de ces derniers sont divisées par deux par rapport aux composants homologues de la topologie NPC. Après avoir comparé les topologies NPC et NPP en termes de forme d'onde et de répartition des pertes dans les composants, l'auteur s'intéresse à la validation expérimentale de cette structure. Les performances atteintes par le convertisseur NPP sont intéressantes puisqu'elles permettent de commuter à des fréquences deux fois plus élevées que la topologie NPC pour un courant donné ou de commuter un courant plus important pour une fréquence de commutation donnée.Les schémas de commutation des différents composants du bras NPP sont étudiés afin de comprendre le gain non négligeable obtenu sur cette structure.Malgré le fait que la structure NPP permette de commuter à des fréquences deux fois plus élevées que la structure NPC, on ne peut pas s'affranchir du filtre sinus en sortie de l'onduleur de manière à respecter les contraintes harmoniques au niveau du moteur. Ainsi, une topologie de filtre sinus à inductances couplées a été introduite / This PhD thesis deals with multilevel inverters dedicated to high speed motors applications, used in Oil \& Gas applications. The main objective is to study a topology which enables reducing switching losses, in comparison with the conventional 3-level NPC (Neutral Point Clamped) topology. Moreover, the inverter has to provide motor input signals with a low harmonic distortion level, not to create undesired additional heating in the motor. After a study of the existing topologies, the 3-level NPP (Neutral Point Piloted) topology is chosen regarding all its benefits. Indeed, thanks to series connection of semi-conductor components, switching losses can be divided by two compared to homologous components on the NPC topology. After having compared NPC and NPP topologies in terms of waveforms and losses distribution in components, the author interest is the experimental validation of this topology. The performances reached by the NPP inverter are interesting because it enables to switch two times faster than for a NPC topology for a given current or to switch a higher current for a given switching frequency. The switching schemes of the NPP leg are studied to understand the gain obtained on this topology. In spite of the fact that switching frequency can be doubled on the NPP topology, the sinus filter can not be avoided in order to respect harmonic specification on the motor. A sinus filter with coupled inductances is introduced so that to responds the different sizing criteria
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How to precisely measure the volume velocity transfer function of physical vocal tract models by external excitation

Fleischer, Mario, Mainka, Alexander, Kürbis, Steffen, Birkholz, Peter 30 July 2018 (has links)
Recently, 3D printing has been increasingly used to create physical models of the vocal tract with geometries obtained from magnetic resonance imaging. These printed models allow measuring the vocal tract transfer function, which is not reliably possible in vivo for the vocal tract of living humans. The transfer functions enable the detailed examination of the acoustic effects of specific articulatory strategies in speaking and singing, and the validation of acoustic plane-wave models for realistic vocal tract geometries in articulatory speech synthesis. To measure the acoustic transfer function of 3D-printed models, two techniques have been described: (1) excitation of the models with a broadband sound source at the glottis and measurement of the sound pressure radiated from the lips, and (2) excitation of the models with an external source in front of the lips and measurement of the sound pressure inside the models at the glottal end. The former method is more frequently used and more intuitive due to its similarity to speech production. However, the latter method avoids the intricate problem of constructing a suitable broadband glottal source and is therefore more effective. It has been shown to yield a transfer function similar, but not exactly equal to the volume velocity transfer function between the glottis and the lips, which is usually used to characterize vocal tract acoustics. Here, we revisit this method and show both, theoretically and experimentally, how it can be extended to yield the precise volume velocity transfer function of the vocal tract.

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