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Submitted by Nathália Faria da Silva (nathaliafsilva.ufv@gmail.com) on 2017-06-13T18:17:32Z No. of bitstreams: 1 resumo.pdf: 17263 bytes, checksum: 8e51a65fe7d8eecb448411acb64cf05b (MD5) / Made available in DSpace on 2017-06-13T18:17:32Z (GMT). No. of bitstreams: 1 resumo.pdf: 17263 bytes, checksum: 8e51a65fe7d8eecb448411acb64cf05b (MD5) Previous issue date: 2003-02-20 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / A estirpe probiótica Lactobacillus UFV H2b20, previamente classificada como Lactobacillus acidophilus por suas características de fermentação de açúcares, apresentou-se mais semelhante à espécie Lactobacillus delbrueckii, quanto à seqüência de rDNA 16S, o que levou ao questionamento acerca da identidade da linhagem. Para o esclarecimento da real classificação da linhagem, o método de hibridização DNA-DNA foi empregado. A linhagem apresentou 75,2% e 77,4% de reassociação com L. delbrueckii subsp. lactis (ATCC 12315) e L. delbrueckii subsp. delbrueckii (ATCC 9649), respectivamente. Dado que a homologia de 70% ou mais, por esse método, tem sido usada como padrão para agrupamento de bactérias em uma mesma espécie, sugere-se, aqui, que Lactobacillus UFV H2b20 seja, daqui para frente, denominado L. delbrueckii UFV H2b20. Identificada a linhagem, outro objetivo do trabalho era desenvolver um protocolo para detecção in situ de L. delbrueckii. Uma sonda de 26 nucleotídeos (SA) foi construída e testada com outras espécies de Lactobacillus relacionadas geneticamente entre si. Estes estudos demonstraram que a seqüência de assinatura (SA) estava presente em L. delbrueckii UFV H2b20, L. delbrueckii UFV H2b21, L. delbrueckii subsp. delbrueckii e L. delbrueckii subsp. lactis, o que indica ser ela eficaz para ser usada como sonda para rRNA 16S espécie-específica pelo método de FISH. A hipótese de existência de polimorfismos, levantada em trabalhos prévios no rDNA 16S da linhagem, foi confirmada após as análises dos segmentos de DNA clonados e selecionados do banco genômico construído para a linhagem L. delbrueckii UFV H2b20. As seqüências analisadas demonstraram, também, presença de segmentos correspondentes a quatro genes codificadores de rRNA 16S distintos, e seis segmentos distintos para uma mesma região de rRNA 23S, indicando seis operons putativos. Há evidência de, pelo menos, um operon putativo completo seguido de região codificadora de seis tRNAs. Não se detectou região espaçadora longa entre rDNA 16 e 23S. / Lactobacillus UFV H2b20, a probiotic strain, previously identified as Lactobacillus acidophilus due to its sugar fermentation pattern, was found to be more closely related to Lactobacillus delbrueckii regarding its 16S rDNA sequence. It was demonstrated by DNA-DNA hybridization that this strain presented 75.2% and 77.4% of reassociation with L. delbrueckii subsp. lactis ATCC 12315 and L. delbrueckii subsp. delbrueckii ATCC 9649, respectively. These results place Lactobacillus UFV H2b20 within the L. delbrueckii species, for 70% reassociation as measured by the method used has been a standard to cluster bacteria within the same species. A protocol for in situ detection of L. delbrueckii was developed by means of Fluorescent in situ Hybridization, FISH. A probe consisting of 26 nucleotides labeled with rhodamine was designed based on the signature sequence within the rDNA, and was tested against genetically related Lactobacillus species. A species- specific method was obtained capable of discriminating L. delbrueckii strains from other Lactobacillus species. Previous studies raised the hypothesis of polymorphism among the copies of 16S rDNA in L. delbrueckii UFV H2b20. This was confirmed by sequence analysis of rDNA from a gene library of this strain cloned in phage lambda and subcloned in pBluescript. Sequence analyses of cloned fragments demonstrated the presence of at least four distinct genes encoding 16S rRNAs. Distinct fragments containing 23S rRNA related genes indicated six putative rrn operons. One complete putative rrn operon displays a region encoding 6 different tRNAs. Long spacer regions between 16S and 23S rDNA were not detected.

Le premier objectif de la thèse est de présenter un test d'ajustement pour les modèles paramétriques couramment utilisés en l'analyse de survie, la fiabilité, les sciences sociales, l'ingénierie, la santé publique et la démographie, en présence de censure à droite. Nous développons un logiciel en langue R pour les modèles paramétrique. Le modèle de Birnbaum-Saunders (BS) est utilisé pour la test d'ajustement pour les modèles AFT paramétriques et en analyse de système redondant. L'autre contribution porte sur l'analyse de système redondant composé avec une composante en état hot et l'autre en réserve fonctionnent en état warm pour augmenter la fiabilité de systeme. Nous calculons la fiabilité du système en termes de Fonction de répartition et nous donnons l'intervalle de confiance asymptotique. / This is an increasing importance in survival analysis and reliability to select a suitable basic model for further inquiries of the data. Little deviation in basic model can cause serious problems in final results. The presence of censoring and accelerated stresses make this task more difficult. Chi-square type goodness of fit tests are most commonly used for model selection. Many modifications in chi-square tests have been proposed by various researcher. The first aim of the thesis is to present a goodness of fit test for wide rage of parametric models (shape-scale families) commonly used in survival analysis, social sciences, engineering, public health and demography, in presence of right censoring. We give the explicit forms of the quadratic form of the test statistic (NRR test) for various models and apply the test on real data. We develop a computer program in R-language for all models. A separate section is dedicated for the test in demography. We focus on the Birnbaum-Saunders (BS) distribution for goodness of fit test for parametric AFT-model and analysis of redundant system.The other purpose of the thesis is to give the analysis of redundant system. To ensure high reliability of the main components of the systems, standby units are used. The main component is replaced by the standby unit automatically, if it fails. The standby unit can be in warm, hot, or cold state. We give the procedure of one main and (n-1) standby units placed in hot state, and give the detailed analysis of one main and one standby unit using BS parametric family. We use Sedyakin's physical principal and the approach of accelerated failure time model for the analysis of redundant system. This approach is different from the traditional ones in the literature but difficulties in calculations. We calculate the reliability of the system in terms of distribution function (unreliability function) and asymptotic confidence interval.