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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.
91

Typologie des arrêts cardiaques au regard des inégalités sociales et territoriales de santé en Ile-de-France : application au registre national des arrêts cardiaques (RéAC) / Typology of cardiac arrests with regard to social and territorial inequalities in health : application to cardiac arrest registry (REAC) data for Ile de France area

Castra, Laurent 02 October 2018 (has links)
Introduction : L'arrêt cardiaque (AC) est considéré comme un problème majeur de santé publique. Prévenir les arrêts cardiaques, les décès consécutifs et optimiser leur prise en charge sont les objectifs partagés à la fois par les professionnels de l’urgence et les décideurs des politiques de santé publique. A l’heure de la territorialisation prenant en compte les besoins des populations, très peu d’études ont été consacrées aux variations d’incidence induites par la localisation géographique des arrêts cardiaques et les caractéristiques socio-économiques des patients. L’objectif de cette thèse est d'identifier, à partir des données du registre national des arrêts cardiaques RéAC, dans les trois départements de la petite couronne d’Ile-de-France, des clusters de communes présentant une incidence élevée ou faible en matière d’arrêt cardiaque, puis de les caractériser à partir des facteurs socio-économiques qui peuvent leur être associés. Matériel et Méthodes : Nous avons étudié les données d’arrêt cardiaque des trois départements d’Ile-de-France composant la petite couronne francilienne. Nous avons ainsi travaillé sur un ensemble de 123 communes. Les données relatives aux arrêts cardiaques ont été extraites du registre français des arrêts cardiaques RéAC. Des données socioéconomiques ont été collectées pour chacune de ces communes auprès de l’Institut National de la Statistique et des Etudes Economiques (INSEE). En termes de méthodes, nous avons eu recours à une double approche sur le plan statistique, combinant des méthodes bayésiennes afin d’étudier les variations géographiques d'incidence des arrêts cardiaques et des statistiques de scan en vue d’identifier des clusters de communes selon le niveau d’incidence des arrêts cardiaques. Enfin, nous avons caractérisé et comparé ces clusters de communes selon des facteurs socioéconomiques. Résultats : Nous avons inclus 3.414 arrêts cardiaques sur une période de deux ans, entre août 2013 et août 2015. De fortes variations géographiques - significatives - ont été observées parmi 123 municipalités : 34 présentaient un risque d'incidence élevé et 37 présentaient un risque faible. Les statistiques de scan ont permis d’identifier 7 clusters significatifs sur le plan de l’incidence des arrêts cardiaques, dont 3 clusters à faible incidence (le risque relatif variait de 0,23 à 0,54) et 4 clusters à forte incidence (avec un risque relatif de 1,43 à 2). Les clusters de municipalités ayant une incidence élevée d'AC se caractérisent par un statut socioéconomique inférieur à celui des autres (clusters d'incidence d’arrêt cardiaque faible ou normale). L'analyse a montré des relations statistiquement significatives entre les facteurs de défaveur sociale et une incidence élevée. Discussion : L’analyse des taux d’incidence standardisés et lissés dans la zone de la petite couronne parisienne révèle l’existence d’une forte hétérogénéité en termes d’incidence des arrêts cardiaques. L’utilisation des statistiques de scan nous a permis d’identifier 7 clusters significatifs, dont 4 de sur-incidence et 3 de sous-incidence. Ces résultats, les premiers en France sur cette thématique, confirment ceux déjà existants dans la littérature internationale montrant une hétérogénéité spatiale de l'incidence de l'arrêt cardiaque et l’importance de certains facteurs socio-économiques. Enfin, le recours aux statistiques de scan, différente des méthodes généralement utilisées, permet de mettre en évidence l'existence de zones à haut risque d’arrêt cardiaque [...] / Cardiac arrest (CA) is considered a major public health problem. Preventing cardiac arrest and subsequent deaths and optimizing their management are objectives shared by both emergency professionals and public health policy makers. At a time when territorialization is taking into account the needs of populations, very few studies have been devoted to the variations in incidence induced by the geographical location of cardiac arrests and the socio-economic characteristics of patients. The objective of this thesis is to identify, based on data from the national register of cardiac arrests RéAC, in the three departments of the inner suburbs of Ile-de-France, clusters of municipalities with a high or low incidence of cardiac arrest, and then to characterize them based on the socio-economic factors that can be associated with them. Equipment and Methods: We studied cardiac arrest data from the three departments of Ile-de-France that make up the inner suburbs of the Paris region. We have worked on a total of 123 municipalities. Data on cardiac arrests were extracted from the French register of cardiac arrests RéAC. Socio-economic data were collected for each of these municipalities from the Institut National de la Statistique et des Etudes Economiques (INSEE). In terms of methods, we used a statistically twofold approach, combining Bayesian methods to study geographical variations in the incidence of cardiac arrest and CT statistics to identify clusters of communes according to the incidence level of cardiac arrest. Finally, we characterized and compared these clusters of municipalities according to socio-economic factors.
92

"Métodos de estimação na teoria de resposta ao item" / Estimation methods in item response theory

Azevedo, Caio Lucidius Naberezny 27 February 2003 (has links)
Neste trabalho apresentamos os mais importantes processos de estimação em algumas classes de modelos de resposta ao item (Dicotômicos e Policotômicos). Discutimos algumas propriedades desses métodos. Com o objetivo de comparar o desempenho dos métodos conduzimos simulações apropriadas. / In this work we show the most important estimation methods for some item response models (both dichotomous and polichotomous). We discuss some proprieties of these methods. To compare the characteristic of these methods we conducted appropriate simulations.
93

Fatores associados à gravidez adolescente no estado de Minas Gerais, Brasil: análise espaço-temporal / Factors associated with adolescence pregnancy in the state of Minas Gerais, Brazil: analysis space-time

Roza, Daiane Leite da 07 October 2015 (has links)
O objetivo deste trabalho foi descrever as associações entre os percentuais de gravidez na adolescência e indicadores socioeconômicos e de responsabilidade social dos municípios do estado de Minas Gerais, sudeste do Brasil, no ano de 2000 a 2010. Trata-se de um estudo ecológico, utilizando dados do Sistema de Informações sobre Nascidos Vivos (SINASC). O percentual de nascidos vivos de mães adolescentes para cada município foi calculado segundo o quociente entre o número de nascidos vivos de mães com idade entre 10 e 19 anos e o número total de nascidos vivos registrados no ano de 2000 a 2010. Modelos bayesianos e modelos aditivos generalizados foram utilizados para a obtenção de percentuais de gravidez adolescente ajustados por efeitos espaciais e para avaliar as possíveis associações com os indicadores socioeconômicos e de responsabilidade social. Os percentuais brutos de gravidez adolescente em relação ao total de nascidos vivos nos municípios de Minas Gerais no ano de 2010 variaram de 0 a 46,4%, com uma mediana de 19,6%. O primeiro e o terceiro quartis são, respectivemente, 15,6% e 23,1%. O estudo evidenciou uma estreita relação entre a gravidez na adolescência e indicadores econômicos e sociais. Os percentuais de gravidez adolescente se mostraram maiores nos municípios com menor tamanho populacional, menores valores do Índice de Desenvolvimento Humano e menores valores de outros indicadores de desenvolvimento. A forte relação entre os percentuais de gravidez adolescente e os indicadores sociais e econômicos sugerem que a gravidez adolescente é muito mais um problema social que biológico. Os programas e as ações devem ir muito além de educação sexual e informações sobre métodos preventivos de saúde. / The objective of this study was to describe associations between pregnancy rates in adolescence and socio-economic and social responsibility indicators in the municipalities of the State of Minas Gerais, Southeast of Brazil, in the year of 2010- 2010. This is an ecological study using data from the Brazilian Live Birth Information System (SINASC). The percentage of live births to adolescent mothers for each municipality was calculated based on the quotient between number of born alive infants of mothers aged 10-19 years old and total number of live births in the year of 2000-2010. Bayesian models and generalized additive model were used to obtain the percentages of adolescence pregnancy adjusted for spatial effects and to assess possible associations with socio-economic and social responsibility indicators. The crude percentage of adolescence pregnancy for the total number of live births in the municipalities of Minas Gerais in 2010 ranged from 0 to 46.4%, with median percentage being 19.6% and the first and third quartiles being 15.6% and 23.1%, respectively. This study has demonstrated a close relationship between adolescent pregnancy and socio-economic indicators. Live births to adolescent mothers percentages were found to be higher in municipalities with low population density, low human development index, and other low development indicators. The strong relationship between adolescence pregnancy percentages and socio-economic indicators suggests that adolescent pregnancy is more a social than a biological problem. Therefore, programs and actions should go beyond sexual education and information on preventive health methods.
94

Fatores associados à gravidez adolescente no estado de Minas Gerais, Brasil: análise espaço-temporal / Factors associated with adolescence pregnancy in the state of Minas Gerais, Brazil: analysis space-time

Daiane Leite da Roza 07 October 2015 (has links)
O objetivo deste trabalho foi descrever as associações entre os percentuais de gravidez na adolescência e indicadores socioeconômicos e de responsabilidade social dos municípios do estado de Minas Gerais, sudeste do Brasil, no ano de 2000 a 2010. Trata-se de um estudo ecológico, utilizando dados do Sistema de Informações sobre Nascidos Vivos (SINASC). O percentual de nascidos vivos de mães adolescentes para cada município foi calculado segundo o quociente entre o número de nascidos vivos de mães com idade entre 10 e 19 anos e o número total de nascidos vivos registrados no ano de 2000 a 2010. Modelos bayesianos e modelos aditivos generalizados foram utilizados para a obtenção de percentuais de gravidez adolescente ajustados por efeitos espaciais e para avaliar as possíveis associações com os indicadores socioeconômicos e de responsabilidade social. Os percentuais brutos de gravidez adolescente em relação ao total de nascidos vivos nos municípios de Minas Gerais no ano de 2010 variaram de 0 a 46,4%, com uma mediana de 19,6%. O primeiro e o terceiro quartis são, respectivemente, 15,6% e 23,1%. O estudo evidenciou uma estreita relação entre a gravidez na adolescência e indicadores econômicos e sociais. Os percentuais de gravidez adolescente se mostraram maiores nos municípios com menor tamanho populacional, menores valores do Índice de Desenvolvimento Humano e menores valores de outros indicadores de desenvolvimento. A forte relação entre os percentuais de gravidez adolescente e os indicadores sociais e econômicos sugerem que a gravidez adolescente é muito mais um problema social que biológico. Os programas e as ações devem ir muito além de educação sexual e informações sobre métodos preventivos de saúde. / The objective of this study was to describe associations between pregnancy rates in adolescence and socio-economic and social responsibility indicators in the municipalities of the State of Minas Gerais, Southeast of Brazil, in the year of 2010- 2010. This is an ecological study using data from the Brazilian Live Birth Information System (SINASC). The percentage of live births to adolescent mothers for each municipality was calculated based on the quotient between number of born alive infants of mothers aged 10-19 years old and total number of live births in the year of 2000-2010. Bayesian models and generalized additive model were used to obtain the percentages of adolescence pregnancy adjusted for spatial effects and to assess possible associations with socio-economic and social responsibility indicators. The crude percentage of adolescence pregnancy for the total number of live births in the municipalities of Minas Gerais in 2010 ranged from 0 to 46.4%, with median percentage being 19.6% and the first and third quartiles being 15.6% and 23.1%, respectively. This study has demonstrated a close relationship between adolescent pregnancy and socio-economic indicators. Live births to adolescent mothers percentages were found to be higher in municipalities with low population density, low human development index, and other low development indicators. The strong relationship between adolescence pregnancy percentages and socio-economic indicators suggests that adolescent pregnancy is more a social than a biological problem. Therefore, programs and actions should go beyond sexual education and information on preventive health methods.
95

Flutuações cambiais e política monetária no Brasil : evidências econométricas e de simulação

Furlani, Luiz Gustavo Cassilatti January 2008 (has links)
A literatura sobre economia monetária vem despertando interesse crescente dentro da macroeconomia. Devido aos avanços computacionais, os modelos têm se tornado cada vez mais complexos e precisos, permitindo estudar detalhadamente as relações entre as variáveis reais da economia e as variáveis nominais. Dessa forma, através de um modelo de equilíbriogeral estocástico e dinâmico (DSGE) baseado em Gali e Monacelli (2005), é proposto e estimado um modelo para a economia brasileira através de métodos bayesianos, com o intuito de avaliar se o Banco Central do Brasil (BCB) considera variações cambiais na condução da política monetária. O resultado mais importante do presente trabalho é que não há evidências de que o BCB altere diretamente a trajetória dos juros devido a variações na taxa de câmbio. Um exercício de simulação também é realizado. Conclui-se que a economia acomoda rapidamente choques induzidos separadamente na taxa de câmbio, nos termos de troca, na taxa de juros e na inflação mundial. / The literature on monetary economy has aroused growing interest in macroeconomics. Due to computational advancements, models have been increasingly more complex and accurate, allowing for the in-depth analysis of the relationships between real economic variables and nominal variables. Therefore, using a dynamic stochastic general equilibrium (DSGE) model, based on Gali and Monacelli (2005), we propose and estimate a model for the Brazilian economy by employing Bayesian methods so as to assess whether the Central Bank of Brazil takes exchange rate fluctuations into account in the conduct of monetary policy. The most striking result of the present study is that the Central Bank of Brazil does not directly change the interest rate path due to exchange rate movements. A simulation exercise is also used. Our conclusion is that the economy quickly accommodates shocks induced separately on the exchange rate, on the terms of trade, on the interest rate, and on global inflation.
96

Random finite sets in Multi-object filtering

Vo, Ba Tuong January 2008 (has links)
[Truncated abstract] The multi-object filtering problem is a logical and fundamental generalization of the ubiquitous single-object vector filtering problem. Multi-object filtering essentially concerns the joint detection and estimation of the unknown and time-varying number of objects present, and the dynamic state of each of these objects, given a sequence of observation sets. This problem is intrinsically challenging because, given an observation set, there is no knowledge of which object generated which measurement, if any, and the detected measurements are indistinguishable from false alarms. Multi-object filtering poses significant technical challenges, and is indeed an established area of research, with many applications in both military and commercial realms. The new and emerging approach to multi-object filtering is based on the formal theory of random finite sets, and is a natural, elegant and rigorous framework for the theory of multiobject filtering, originally proposed by Mahler. In contrast to traditional approaches, the random finite set framework is completely free of explicit data associations. The random finite set framework is adopted in this dissertation as the basis for a principled and comprehensive study of multi-object filtering. The premise of this framework is that the collection of object states and measurements at any time are treated namely as random finite sets. A random finite set is simply a finite-set-valued random variable, i.e. a random variable which is random in both the number of elements and the values of the elements themselves. Consequently, formulating the multiobject filtering problem using random finite set models precisely encapsulates the essence of the multi-object filtering problem, and enables the development of principled solutions therein. '...' The performance of the proposed algorithm is demonstrated in simulated scenarios, and shown at least in simulation to dramatically outperform traditional single-object filtering in clutter approaches. The second key contribution is a mathematically principled derivation and practical implementation of a novel algorithm for multi-object Bayesian filtering, based on moment approximations to the posterior density of the random finite set state. The performance of the proposed algorithm is also demonstrated in practical scenarios, and shown to considerably outperform traditional multi-object filtering approaches. The third key contribution is a mathematically principled derivation and practical implementation of a novel algorithm for multi-object Bayesian filtering, based on functional approximations to the posterior density of the random finite set state. The performance of the proposed algorithm is compared with the previous, and shown to appreciably outperform the previous in certain classes of situations. The final key contribution is the definition of a consistent and efficiently computable metric for multi-object performance evaluation. It is shown that the finite set theoretic state space formulation permits a mathematically rigorous and physically intuitive construct for measuring the estimation error of a multi-object filter, in the form of a metric. This metric is used to evaluate and compare the multi-object filtering algorithms developed in this dissertation.
97

Assessing the Effect of Prior Distribution Assumption on the Variance Parameters in Evaluating Bioequivalence Trials

Ujamaa, Dawud A. 02 August 2006 (has links)
Bioequivalence determines if two drugs are alike. The three kinds of bioequivalence are Average, Population, and Individual Bioequivalence. These Bioequivalence criteria can be evaluated using aggregate and disaggregate methods. Considerable work assessing bioequivalence in a frequentist method exists, but the advantages of Bayesian methods for Bioequivalence have been recently explored. Variance parameters are essential to any of theses existing Bayesian Bioequivalence metrics. Usually, the prior distributions for model parameters use either informative priors or vague priors. The Bioequivalence inference may be sensitive to the prior distribution on the variances. Recently, there have been questions about the routine use of inverse gamma priors for variance parameters. In this paper we examine the effect that changing the prior distribution of the variance parameters has on Bayesian models for assessing Bioequivalence and the carry-over effect. We explore our method with some real data sets from the FDA.
98

Bayesian assessment of reliability dynamics for age-dependent systems / Bajesinis patikimumo dinamikos vertinimas nuo amžiaus priklausančioms sistemoms

Iešmantas, Tomas 31 August 2011 (has links)
Age-dependent highly reliable systems provide small amount of statistical information and for that reason classical frequentist methods cannot be applied due to their asymptotical assumptions. However, Bayesian methods, due to their ability to naturally couple all sources of information (including expert subjective opinions) and not rely on asymptotic assumptions, are attractive approach to solve small sample problems in age-dependent reliability modelling. In this thesis Bayesian paradigm and its applicability were presented and general methodology to analyse previously mentioned problem was obtained. Methodology successfully was applied for two real data samples: failures in European natural gas grid and electrical Instrumentation and Control components. It was concluded that presented approach is able to easily investigate small samples in nonlinear age-dependent models. Also, analysis showed that different model goodness-of-fit approaches can provide different inferences and that sometimes it can fail due to nonlinearities and heteroscedasticity present in data. For that reason Bayesian posterior model averaging procedure were applied and concluded that it gives more reliable and better calibrated results than would be in one model case. Also adaptive Metropolis superiority over classical Metropolis – Hastings algorithm for highly correlated parameters and nonlinearities in model was validated. / Nuo amžiaus priklausomos aukšto patikimumo sistemos suteikia labai mažai statistinių duomenų ir dėl šios priežasties klasikiniai dažninistiniai metodai negali būti taikomi, nes jie remiasi asimptotinėmis prielaidomis. Tačiau Bajesiniai metodai, dėl jų savybės natūraliai sujungti visus informacijos resursus (įskaitant ir subjektyvią ekspertinę nuomonę) ir nesiremti asimptotinėmis prielaidomis yra patraukli paradigma, tinkama spręsti mažų imčių problemas nuo amžiaus priklausomo patikimumo modeliavime. Šiame darbe pristatomas Bajesinis požiūris ir jo pritaikymas bei buvo sudaryta bendra metodologija, kaip analizuoti anksčiau minėtą problemą. Metodologija buvo sėkmingai pritaikyta dviems realioms sistemoms analizuoti: gedimai Europos gamtinių dujų tinkluose bei elektriniuose kontrolės komponentuose, naudojamuose atominėse elektrinėse. Padaryta išvada, kad sudaryta metodologija yra tinkama analizuoti mažoms imtims netiesiniuose nuo laiko priklausomuose modeliuose. Be to, analizė parodė, kad skirtingi modelio tikimo metodai gali vesti į skirtingas išvadas apie modelius ir kartais šie metodai gali neveikti dėl heteroskedastiškumo duomenyse. Dėl šios priežasties atlikta Bajesinio posteriorinio vidurkinimo procedūra, kurios rezultatas yra patikimesnis ir geriau kalibruotas, nei kad vieno modelio atveju. Taip pat nustatytas adaptyvaus Metropolis algoritmo pranašumas lyginant su Metropolis-Hastings algoritmu analizuojant labai koreliuotus parametrus bei netiesinius modelius.
99

Investigating Molecular Evolution of Rhodopsin Using Likelihood/Bayesian Phylogenetic Methods

Du, Jingjing 22 July 2010 (has links)
Rhodopsin, a visual pigment protein found in retinal photoreceptors, mediates vision at low-light levels. Recent studies focusing primarily in human and mouse have challenged the assumption of neutral evolution of synonymous substitutions in mammals. Using recently developed likelihood-based codon models accounting for mutational bias and selection, we find significant evidence for selective constraint on synonymous substitutions in mammalian rhodopsins, and a preference for cytosine at 3rd codon positions. A second project investigated adaptive evolution in rhodopsin, in view of theories of nocturnality in early mammals. We detected a significant acceleration of non-synonymous substitution rates at the origins of therian mammals, and a tendency of synonymous substitutions towards C-ending codons prior to that. These findings suggest an evolutionary scenario in which synonymous substitutions that increase mRNA stability and/or translation efficiency may have preceded adaptive non-synonymous evolution in early mammalian rhodopsins. These findings have important implications for theories of early mammalian nocturnality.
100

Approximation de la distribution a posteriori d'un modèle Gamma-Poisson hiérarchique à effets mixtes

Nembot Simo, Annick Joëlle 01 1900 (has links)
La méthode que nous présentons pour modéliser des données dites de "comptage" ou données de Poisson est basée sur la procédure nommée Modélisation multi-niveau et interactive de la régression de Poisson (PRIMM) développée par Christiansen et Morris (1997). Dans la méthode PRIMM, la régression de Poisson ne comprend que des effets fixes tandis que notre modèle intègre en plus des effets aléatoires. De même que Christiansen et Morris (1997), le modèle étudié consiste à faire de l'inférence basée sur des approximations analytiques des distributions a posteriori des paramètres, évitant ainsi d'utiliser des méthodes computationnelles comme les méthodes de Monte Carlo par chaînes de Markov (MCMC). Les approximations sont basées sur la méthode de Laplace et la théorie asymptotique liée à l'approximation normale pour les lois a posteriori. L'estimation des paramètres de la régression de Poisson est faite par la maximisation de leur densité a posteriori via l'algorithme de Newton-Raphson. Cette étude détermine également les deux premiers moments a posteriori des paramètres de la loi de Poisson dont la distribution a posteriori de chacun d'eux est approximativement une loi gamma. Des applications sur deux exemples de données ont permis de vérifier que ce modèle peut être considéré dans une certaine mesure comme une généralisation de la méthode PRIMM. En effet, le modèle s'applique aussi bien aux données de Poisson non stratifiées qu'aux données stratifiées; et dans ce dernier cas, il comporte non seulement des effets fixes mais aussi des effets aléatoires liés aux strates. Enfin, le modèle est appliqué aux données relatives à plusieurs types d'effets indésirables observés chez les participants d'un essai clinique impliquant un vaccin quadrivalent contre la rougeole, les oreillons, la rub\'eole et la varicelle. La régression de Poisson comprend l'effet fixe correspondant à la variable traitement/contrôle, ainsi que des effets aléatoires liés aux systèmes biologiques du corps humain auxquels sont attribués les effets indésirables considérés. / We propose a method for analysing count or Poisson data based on the procedure called Poisson Regression Interactive Multilevel Modeling (PRIMM) introduced by Christiansen and Morris (1997). The Poisson regression in the PRIMM method has fixed effects only, whereas our model incorporates random effects. As well as Christiansen and Morris (1997), the model studied aims at doing inference based on adequate analytical approximations of posterior distributions of the parameters. This avoids the use of computationally expensive methods such as Markov chain Monte Carlo (MCMC) methods. The approximations are based on the Laplace's method and asymptotic theory. Estimates of Poisson mixed effects regression parameters are obtained through the maximization of their joint posterior density via the Newton-Raphson algorithm. This study also provides the first two posterior moments of the Poisson parameters involved. The posterior distributon of these parameters is approximated by a gamma distribution. Applications to two datasets show that our model can be somehow considered as a generalization of the PRIMM method since it also allows clustered count data. Finally, the model is applied to data involving many types of adverse events recorded by the participants of a drug clinical trial which involved a quadrivalent vaccine containing measles, mumps, rubella and varicella. The Poisson regression incorporates the fixed effect corresponding to the covariate treatment/control as well as a random effect associated with the biological system of the body affected by the adverse events.

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