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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.
361

Some Problems in Multivariable Operator Theory

Sarkar, Santanu January 2014 (has links) (PDF)
In this thesis we have investigated two different types of problems in multivariable operator theory. The first one deals with the defect sequence for contractive tuples and maximal con-tractive tuples. These condone deals with the wandering subspaces of the Bergman space and the Dirichlet space over the polydisc. These are described in thefollowing two sections. (I) The Defect Sequence for ContractiveTuples LetT=(T1,...,Td)bead-tuple of bounded linear operators on some Hilbert space H. We say that T is a row contraction, or, acontractive tuplei f the row operator (Pl refer the abstract pdf file)
362

On the Conjugacy of Maximal Toral Subalgebras of Certain Infinite-Dimensional Lie Algebras

Gontcharov, Aleksandr January 2013 (has links)
We will extend the conjugacy problem of maximal toral subalgebras for Lie algebras of the form $\g{g} \otimes_k R$ by considering $R=k[t,t^{-1}]$ and $R=k[t,t^{-1},(t-1)^{-1}]$, where $k$ is an algebraically closed field of characteristic zero and $\g{g}$ is a direct limit Lie algebra. In the process, we study properties of infinite matrices with entries in a B\'zout domain and we also look at how our conjugacy results extend to universal central extensions of the suitable direct limit Lie algebras.
363

Effets de l'entrainement sur la performance en coup droit et l'hypersollicitation du membre supérieur en tennis / Effects of training on forehand performance and upper overuse in tennis

Genevois, Cyril 19 December 2013 (has links)
L'objectif de ce travail de doctorat étati d'examiner les modalités d'entrainement permettant de développer la vitesse de balle post impact en coup droit au tennis, tout en évaluant les risques potantiels d'hypersollicitation de l'épaule qui pourraient en résulter. Les résultats de nos différentes études ont montré que la puissance maximale développée lors d'un lancer de medecine-ball (MB) à 2 mains sur le côté expliquait 25% de la variation de la vitesse maximale de balle en coup droit et qu'elle était atteinte en utilisant une masse de MB de 5,7% du poids de corps du joueur. Toutefois, les relations entre les distances obtenues lors de ce type de lancer et la vitesse de balle en coup droit sont faibles. En revanche, les lancers de MB sur le côté à une main ont démontré une relation significative avec la vitesse maximale de balle en coup droit. Un entrainement de six semaines basé sur l'utilisation de ce type de lancers a augmenté la vitesse de balle de 11% mais la précision des coups tendait à diminuer. Finalement, un entraînement incorporant des frappes de balle avec une raquette lestée d'environ 12% a également amélioré la vitesse maximale de balle en coup droit (5%), tout en conservant la précision des coups. Enfi, la comparaison de la coordiantion musculaire entre lesles deux types de lancers de MB et la frappe en coup droit a montré que les muscles du tronc et du membre supérieur testés présentaient des modèles d'activité musculaire et des niveaux de sollicitations similaires. Ainsi, les craintes concernant un potentiel de blessure ne sembleraient pas justifiées. Ainsi, les résulats de ces tudes ont contribué à la périodisation de la préparation physique pour l'amélioration de la performance en coup droit chez le joueur de tennis compétiteur amateur / This work aimed at exploring the training modalities to develop maximal post impact ball velocity fo the tennis forehand drive, while assessing the potential risk of upper limb oeruse. The results of our studies showed that maximal power developed during a two-handed side medecine-ball(MB) throw explained 25% of the variation of maximal forehand ball velocitiy, and was achieved when using a MB mass of 5,7 % of player's body weight. However, the relationship between throwing distances and maximal ball velocity of forehand drive was weak. By contrast, a significant relationship was found between the performance for the one-handed side MB throw and the maximal velocity of the forehand drive. A six-week trainig program based on one-hand MB throws increased the ball velocity by 11%, but the shot accuracy tended to be reduced. In the same way, a six-week training program including forehand drives with an overweighted racketr about 12 % allowed the maximal forehand ball velocity to be improved (5%), without alteration in theshot accuracy. Finally, the comparison of muscular coordination between both MB throws and the forehand drive demonstrated that the trunk and upper limb muscles presented similar activity pattern and levels. The potentials for injury risk would thus not justify. In conclusion, the finding of this work contributed to the periodization of the strength and conditioning training in order to improve the forehand drive performance in nonprofessional competitive tennis players.
364

Technique de perfusion pulmonaire isolée de chimiothérapie chez le porc / Isolated lung perfusion with chemotherapy in a pig model

Pagès, Pierre-Benoît 03 July 2014 (has links)
Introduction : La perfusion pulmonaire isolée (PPI) est une technique expérimentale dont l’objectif est d’administrer de fortes doses de chimiothérapie dans le poumon sans effets secondaires systémiques. Cette thèse s’est déroulée en trois étapes : première étape, déterminer in vitro la chimiothérapie la plus efficace en 30 minutes sur les cellules de cancers colo-rectaux (CCR). Deuxième étape, mettre au point la technique de PPI chez le porc. Troisième étape, mener une étude d’escalade de dose de chimiothérapie chez le porc en PPI.Méthodes : Première étape, des tests de cytotoxicité in vitro ont été menés sur un panel de cellules d’adénocarcinome colique humain avec les drogues de chimiothérapie les plus efficaces dans les essais cliniques. Deuxième étape, des porcs étaient traités par perfusion de chimiothérapie dans le poumon gauche isolé de la circulation générale pendant 30 minutes puis maintenus en vie pendant un mois. Troisième étape, les doses de chimiothérapie injectés étaient augmentées par palier jusqu’à obtenir une toxicité aigüe ou le décès des animaux.Résultats : La gemcitabine (GEM) fut la drogue ayant la plus grande efficacité anti-tumorale pour un traitement de 30 min. La PPI de GEM permit d’obtenir des concentrations élevées de GEM dans le parenchyme pulmonaire et la survie des animaux pendant un mois. Il n’existait pas de fuites systémiques de GEM. L’augmentation des doses de GEM permis de déterminer la dose maximale toxique à 320 mg et la toxicité limitant la dose à 640 mg. Conclusions : La technique de PPI avec la GEM est une technique sûre et reproductible permettant d’obtenir de fortes concentrations de GEM dans le parenchyme pulmonaire. / Introduction: The isolated lung perfusion (ILP) is an experimental technique which main objective is to deliver high dose of cytotoxic agent to the lung tissue without systemic exposure. The thesis took place in three stages: first stage, setting in vitro the chemotherapy the most efficient against colorectal cancer (CCR) cells in 30 min. Second stage, develop the ILP technique in a pig model. Third stage, lead a dose escalation study with chemotherapy by ILP.Methods: First stage, efficacy of various cytotoxic molecules against a panel of human CCR cell lines was tested in vitro after a 30-minute exposure. Second stage, pigs were treated with chemotherapy delivered by ILP during 30 minutes and kept alive during a month. Third stage, chemotherapy doses were increase in order to obtain acute toxicity or death of animals.Results: Gemcitabine (GEM) was the most efficient drug against CCR cells in 30 minutes. ILP with GEM permit to maintain high concentration in the lung parenchyma and pigs survival during one month. No systemic leaks were detected. Dose increase of GEM conduct to determine the maximal tolerated dose of GEM by ILP to 320 mg. Conclusions: ILP with GEM is a safety and reproducible technique allowing high GEM concentrations in the lung tissue.
365

Comparação de dois metodos de mensuração da pressão inspiratoria maxima em pacientes com e sem alterações do nivel de consciencia / Comparison of two methods of measurement of maximal inspiratory pressure in patients with and without alterations of the level of conscience

Monteiro, Ludmila Soccio 11 October 2006 (has links)
Orientadores: Sebastião Araujo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-08T00:31:25Z (GMT). No. of bitstreams: 1 Monteiro_LudmilaSoccio_M.pdf: 1802463 bytes, checksum: 2ba5bfd3d0b955709113de784abbcd7c (MD5) Previous issue date: 2006 / Resumo: Antecedentes. A aferição da pressão inspiratória máxima (PImax) é um método efetivo para avaliação da força muscular inspiratória, usada também como método diagnóstico e como índice preditivo de desmame da ventilação mecânica. Porém, não existe consenso na literatura sobre o tempo de oclusão de vias aéreas necessário para se obter uma PImax verdadeira durante o desmame da ventilação mecânica. Objetivos. Comparar dois métodos de mensuração da PImax e avaliar se o nível de consciência interfere nos valores obtidos. Métodos. Vinte e oito pacientes de ambos os sexos, hemodinamicamente estáveis, sem sedação, com suporte ventilatório mecânico por tempo = 48 horas, com parâmetros mínimos de desmame da ventilação, foram divididos em dois grupos: pacientes com pontuação na escala de coma de Glasgow (ECGL) = 15 e ECGL < 15. A aferição foi dividida em duas fases e, em cada fase, foram realizadas três mensurações com um intervalo de um minuto entre elas, obtendo-se assim a média entre as três: a via aérea foi ocluída com uma válvula unidirecional por 20 segundos (PImaxT20), ou, por um tempo máximo de um minuto, se um platô de pressão inspiratória não fosse observado durante três inspirações consecutivas (PImaxTid). Após um descanso de 15 minutos, foram realizadas novamente as mensurações na ordem previamente estabelecida (aleatória). Resultados. A média das medidas da PImaxTid (55,8 ± 25,0 cmH2O), no grupo total (n = 28), foi maior que a média das medidas da PImaxT20 (43,1 ± 15,5 cmH2O), com p = 0,002, e o tempo médio para a obtenção da PImaxTid foi de 30,2 ± 11 segundos. Quando divididos em dois grupos, ECGL = 15 (n = 14) e ECGL < 15 (n = 14), esse tempo médio foi de 23,8 ± 7,7 e 36,7 ± 10,0 segundos, respectivamente (p = 0,0019). Conclusões. A PImaxTid, neste grupo heterogêneo de pacientes em desmame da ventilação mecânica, mostrou valores superiores àqueles da PImaxT20, especialmente naqueles com algum grau de comprometimento do estado de consciência (ECGL < 15), sugerindo que necessitem de um tempo maior de oclusão da válvula unidirecional para se atingir a PImax real. Assim, o método comumente utilizado de 20s parece ser insuficiente para se mensurar a verdadeira PImax em pacientes com ECGL < 15. Novos estudos são necessários, agora num grupo mais homogêneo de pacientes (exemplo: com comprometimento neurológico estrutural), para determinar se realmente há necessidade de um tempo de oclusão maior que 20 segundos, ou se os valores obtidos no presente estudo simplesmente representam uma supervalorização desta PImax / Abstract: Background. Maximum inspiratory pressure (PImax) is an effective parameter for the evaluation of inspiratory muscular force and an useful predictive index during weaning from mechanical ventilation (MV). However, there is no consensus in the literature concerning the time of airway occlusion necessary to get a true PImax during weaning from MV. Objectives. To compare two methods of PImax measurement and to evaluate the influence of patients¿ level of conscience (LOC) on their values. Methods. Twenty eight patients of both sexes, hemodynamically stable, without sedation, with MV support for a time = 48 hours and in a weaning process, were divided into two groups: patients with Glasgow coma scale score (GCS) = 15 and GCS < 15. PImax measurement was done in two phases and, in each phase, three measures, with an interval of one minute between them, had been carried through, getting thus the average between the three ones: the airway was occluded with an unidirectional valve for 20 seconds (PImaxT20), or, for a maximum time of one minute, if a plateau of inspiratory pressure was not observed during three consecutive inspirations (PImaxTid). After a rest of 15 minutes, PImax measurement had been carried through again in an order previously randomized. Results. The average of measures of the PImaxTid (55.8 ± 25.0 cmH2O), in the total group (n = 28), was greater that the average of the measures of the PImaxT20 (43.1 ± 15.5 cmH2O), with p = 0.002, and the average time for the attainment of the PImaxTid was of 30.2 ± 11 seconds. When divided in two groups, GCS = 15 (n = 14) and GCS < 15 (n = 14), the average times were of 23.8 ± 7.7 and 36.7 ± 10.0 seconds, respectively (p = 0.0019). Conclusions. PImaxTid, in this heterogeneous group of patients in MV weaning, has shown greater values than those of PImaxT20 especially in those with some degree of the state of LOC alteration (GCS < 15), suggesting that the formers need a longer time of airway occlusion with the unidirectional valve to reach the real PImax. Thus, the method commonly used of 20 seconds seems to be insufficient to measure the true PImax in patients with GCS <15. Further studies, now in a more homogeneous group of neurological patients (example: with structural neurological injury), are needed to verify if these patient are really dependent of a longer airway occlusion time to reach their real PImax, or if the values that have been found in the present study simply represent an overestimation of this variable / Mestrado / Pesquisa Experimental / Doutor em Cirurgia
366

Efeitos da suplementação de betaína, combinada ou não com a suplementação de creatina, sobre a força máxima, potência e concentrações intramusculares de fosforilcreatina, em indivíduos não treinados em força / Effects of betaine supplementation, combined or not with creatine supplementation on maximal strength, power output and muscle phosphorylcreatine content in non-resistance trained subjects

Serena Menegassi Del Favero 04 December 2012 (has links)
A betaína é um trimetil derivado do aminoácido glicina. Os seus principais efeitos fisiológicos são atuar como um osmólito e como doador de radicais metil. Especulase que a betaína possa contribuir para a síntese de creatina no músculo esquelético pelo fornecimento de grupos metil, resultante da conversão de betaína em dimetilglicina, para a remetilação de homocisteína em metionina. Os efeitos da suplementação de creatina sobre o desempenho são conhecidos e relacionam-se principalmente ao aumento na ressíntese de fosforilcreatina (PCR). Autores de estudos recentes têm atribuído seus resultados positivos em relação ao aumento de força muscular a um possível efeito da betaína sobre as concentrações de PCR. Essa variável, entretanto, não foi avaliada, de maneira que os mecanismos responsáveis pelo aumento de força advindo da suplementação de betaína ainda são inexplorados em humanos. Diante disso, este estudo teve como objetivo investigar os efeitos da suplementação de betaína, combinada ou não com a suplementação de creatina, sobre as concentrações intramusculares de PCR, e a produção de força e potência muscular em indivíduos não treinados em força. Além disso, as respostas fisiológicas e ergogênicas da suplementação de betaína e creatina foram comparadas e avaliados os possíveis efeitos aditivos desses suplementos. Foi conduzido um estudo duplo-cego, randomizado, controlado por placebo. Trinta e quatro sujeitos foram divididos em quatro grupos: Betaína (BET; 2 g/dia), Creatina (CR; 20 g/dia), Betaína + Creatina (BET + CR; 2 + 20 g/dia) e Placebo (PL). No período basal (PRÉ) e após 10 dias de suplementação (PÓS), os indivíduos submeteram-se a avaliações do consumo alimentar e da composição corporal, a testes de força e potência muscular e à quantificação intramuscular de PCR. Após a intervenção, as concentrações intramusculares de PCR foram maiores nos grupos CR e BET + CR, quando comparados ao grupo PL (p = 0,004 e p = 0,006, respectivamente). Não houve diferenças significativas entre os grupos BET e PL (p = 0,78) e CR e BET + CR (p = 0,99). Os grupos CR e BET + CR apresentaram maior produção de potência muscular no exercício de agachamento, quando comparados ao grupo PL (p = 0,003 e p = 0,041, respectivamente). Resultados similares foram encontrados para o exercício de supino. Os grupos CR e BET + CR também demonstraram aumento significativo de força muscular (teste de 1-RM) do teste PRÉ para o teste PÓS nos exercícios de supino e agachamento (CR: p = 0,027 e p 0,0001; BET + CR: p = 0,03 e p 0,0001 para membros superiores e inferiores, respectivamente). Não houve diferenças significativas para os testes de força e de potência muscular entre os grupos BET e PL e os grupos CR e BET + CR. Também não houve diferença significativa entre os grupos para a composição corporal. O consumo alimentar permaneceu inalterado ao longo do estudo. Os resultados permitem concluir que a suplementação de betaína, combinada ou não com a suplementação de creatina, não aumenta o conteúdo intramuscular de PCR e não afeta o desempenho de força e de potência muscular / Betaine is a trimethyl derivative of the amino acid glycine. The main physiological functions of betaine are to act as an organic osmolyte and as a donor of methyl radicals. It is speculated that betaine may contribute to the synthesis of creatine in skeletal muscle through the donation of a methyl group, resulting from the conversion of betaine to dimethylglycine, to homocysteine to form methionine. The effects of creatine supplementation on performance are well known and are related primarily to an increase in fosforilcreatina resynthesis (PCR). Authors of recent studies have attributed its positive results regarding the increase of muscle strength to a possible effect of betaine on the concentrations of PCR. However, this variable was not assessed, so that the mechanisms responsible for the increase in muscle strength coming from betaine supplementation in humans are still unexplored. In light of this, the aim of this study was to investigate the effect of betaine supplementation combined or not with creatine supplementation on muscle PCR content, muscle strength and power output in non-resistance trained subjects. Additionally, we compared the ergogenic and physiological responses to betaine versus creatine supplementation. Finally, we also tested the possible additive effects of creatine and betaine supplementation. A randomized, double-blind, placebo-controlled study was conducted. Thirty and four subjects were assigned into four groups: Betaine (BET; 2 g/day), Creatine (CR; 20 g/day), Betaine + Creatine (BET + CR; 2 + 20 g/day) or Placebo (PL). At baseline (PRE) and after 10 days of supplementation (POST) body composition, food intake, muscle strength and power and muscle PCR were assessed. The CR and BET + CR groups presented greater increase in muscle PCR content than PL (p = 0.004 and p = 0.006, respectively). PCR content was comparable between BET versus PL (p = 0.78) and CR versus BET + CR (p = 0.99). CR and BET + CR presented greater muscle power output than PL in the squat exercise following supplementation (p = 0.003 and p = 0.041, respectively). Similarly, bench press average power was significantly greater for the CR-supplemented groups. CR and BET + CR groups also showed significant pre- to post-test increase in 1-RM squat and bench press (CR: p = 0.027 and p 0.0001; BET + CR: p = 0.03 and p 0.0001 for upper- and lower-body assessments, respectively). No significant differences for 1-RM strength and power were observed between BET versus PL and CR versus BET + CR. Body composition did not differ between the groups. Dietary intake was unchanged throughout the study. Thus, we concluded that betaine supplementation does not augment muscle PCR content and betaine supplementation combined or not with creatine supplementation does not affect strength and power performance in non-resistance trained subjects
367

Slow-Twitch Fiber Proportion in Skeletal Muscle Correlates With Insulin Responsiveness

Stuart, Charles A., McCurry, Melanie P., Marino, Anna, South, Mark A., Howell, Mary E. A., Layne, Andrew S., Ramsey, Michael W., Stone, Michael H. 01 May 2013 (has links)
Context: The metabolic syndrome, characterized by central obesity with dyslipidemia, hypertension, and hyperglycemia, identifies people at high risk for type 2 diabetes. Objective: Our objective was to determine how the insulin resistance of the metabolic syndrome is related to muscle fiber composition. Design:Thirty-nine sedentary men and women (including 22 with the metabolic syndrome) had insulin responsiveness quantified using euglycemic clamps and underwent biopsies of the vastus lateralis muscle. Expression of insulin receptors, insulin receptor substrate-1, glucose transporter 4, and ATP synthase were quantified with immunoblots and immunohistochemistry. Participants and Setting: Participants were nondiabetic,metabolic syndrome volunteers and sedentary control subjects studied at an outpatient clinic. Main Outcome Measures: Insulin responsiveness during an insulin clamp and the fiber composition of a muscle biopsy specimen were evaluated. Results: There were fewer type I fibers and more mixed (type IIa) fibers in metabolic syndrome subjects.Insulin responsiveness and maximal oxygen uptake correlated with the proportion of type I fibers.Insulin receptor,insulin receptor substrate-1, and glucose transporter 4 expression were not different in whole muscle but all were significantly less in the type I fibers of metabolic syndrome subjects when adjusted for fiber proportion and fiber size.Fat oxidation and muscle mitochondrial expression were not different in the metabolic syndrome subjects. Conclusion:Lower proportion of type I fibers in metabolic syndrome muscle correlated with the severity of insulin resistance. Even though whole muscle content was normal, key elements of insulin action were consistently less in type I muscle fibers, suggesting their distribution was important in mediating insulin effects
368

Maximal voluntary occlusal bite force in young adult men -a pilot study

Alkhaiat, Reem, Jaber, Zahra January 2020 (has links)
Background: Maximal voluntary occlusal bite force (MVOBF) is the maximal force applied by the jaw muscles in dental occlusion. MVOBF is one parameter for functional capacity of the jaw system.  Aim: To evaluate MVOBF in different positions in the bite and to evaluate possible intra-individual differences between sessions.  Methods: MVOBF was measured with an electronic bite force device, with transducers sensitive to force, in 20 healthy men (mean 24.5 years). Eligibility of participants was full dental occlusion, Angle Class I relation, no diagnosis according to Diagnostic criteria for temporomandibular disorders. The test included three repeated measurements on each site: first molar right, first molar left and central incisor, in random order, with test-retest study design. Unpaired T-test was used to test the MVOBF in different positions in the bite and paired T-test for possible intra-individual differences between sessions. A post hoc test for repeated measure one-way ANOVA was added.  Results: MVOBF in different positions in the bite was lower in the incisor area compared with the molar region (P&lt;0.0001), but similar between right and left molar side (P=0.48 and P= 0.96, respectively). No intra-individual differences between sessions (molar right P= 0.40; molar left P= 0.81; incisor area P= 0.66). The intra-individual variability for repeated measurements showed variability for incisor area (P= 0.007), but not for molar right and left region (P=0.95 and P=0.49, respectively).  Conclusion: The results may provide reference values for MVOBF in young adult men, to be compared with men with pain or dysfunction in the jaw system.
369

Inspiratorisk muskelträning och dess effekt på prestationsförmågan hos fotbollsspelare : En systematisk litteraturöversikt

Larsson, Albin, Löfgren, Jesper January 2021 (has links)
Bakgrund: Inspiratorisk muskelträning (IMT) har historiskt använts inom vården, men har på senare tid uppmärksammats mer inom idrottsvärlden. IMT kan förstärka andningsmuskulaturen som är förknippat med en förhöjd prestationsförmåga.Syftet med litteraturstudien är att sammanställa befintlig forskning och undersöka om IMT har en effekt på prestationsförmågan hos fotbollsspelare. Metod: Litteraturöversikten är utformad med hjälp av PRISMA Guidelines. Artikelsökningar gjordes på PubMed, SPORTDiscus och Sports Medicine &amp; Education Index i februari 2021. Totalt valdes sex artiklar utifrån framtagna inklusionskriterier. Artiklarna kvalitetsgranskades metodologiskt av båda författarna enligt PEDro skalan och Risk of Bias 2. Resultat: Analyserade studier inkluderade 62 deltagare i IMT-grupp, 27 IMT-sham och 51 i kontrollgrupp. Genomsnittliga studiekvalitéten klassificerade som ”måttlig” med en medelpoäng på 6 av 10. Samtliga studier visade på signifikant ökning av inspiratorisk muskelstyrka med en genomsnittlig ökning på 27.2% i maximal inspiratory pressure. Majoriteten av inkluderade studier kunde även visa på signifikant förbättring av i löpdistans efter IMT-intervention. Konklusion: IMT i kombination med traditionell fotbollsträning har en effekt på prestationsförmågan i form av inspiratorisk muskelstyrka och löpdistans. En ökad inspiratorisk muskelstyrka bidrar till att individen kan arbeta på en högre intensitet under en längre tid. IMT är därmed en effektiv, lätthanterlig och billig metod för att förbättra den individuella prestationsförmågan hos fotbollsspelare. Mekanismen bakom IMT antas vara en fördröjning av metaboreflexen. Framtida forskning behöver klargöra förklaringsmodellen och även ta fram optimala riktlinjer för användandet av IMT för att nå interventionens fulla utvecklingspotential.
370

Analýza vlivu uspořádání kolagenu na mechanické vlastnosti tepen / Analysis of Influence of Collagen Organization on Mechanical Properties of Arteries

Novák, Kamil January 2018 (has links)
This dissertation thesis concerns with Analysis of Influence of Collagen Organization on Mechanical Properties of Arteries and it is divided into three main parts. Motivation for this dissertation thesis was in a study reviewing effect of material model upon resulting stresses in AAA. The effect was calculated in 70 patient-specific geometries of AAA, which exceeds the number of geometries in other scientific papers by one order. Within this study, two material models were used, i.e. real one and 100× stiffer, and obtained stresses were mutually compared. It was quantified that peak stress difference can be higher than 20 % in 10% of patients and therefore the real material model should be preferred over the artificial one although operation with this model is more demanding. The second part of this thesis deals with an identification of structural parameters (orientation and dispersion of collagen fibres) of porcine aortic tissue by using adjusted Fast Fourier Transform based algorithm. The extracted structural parameters were inserted into two-layer structure-motivated constitutive model Martufi-Gasser. This model was validated and its predictive capabilities were also tested with fine results. The most important information obtained from the digital image processing of ~9000 micrographs is existence of only one family of dispersed collagen fibres which breaks the current dogma present in many scientific papers about two families of collagen fibres. The third part concerns with a proposal of an automated phase-correlation based algorithm for obtaining collagen fibre direction from polarized light microscopy images. The proposed algorithm was verified and validated and it yields histograms of collagen fibre directions with overall number of measured points larger than it would be possible to get from any manual measurement. The limitation of the original proposed algorithm is in 90° period of polarized light intensity, thus the method results in angles in the range of 0°–90. Therefore the end of the thesis is dedicated resolving this problem and obtaining real angles in a span of 0°–180°. To this end, the microscope set-up was changed and the algorithm was adjusted accordingly. The original and the adjusted algorithms are collagen-specific, fast and an operator independent. Despite all the author´s effort put into collagen fibre waviness quantification directly from the histograms, the waviness has not been quantified yet in this way and it remains at the stage of research.

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