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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.
221

Estudo de coeficientes de correlação para medidas de proximidade em dados de expressão gênica / A study of correlation coefficients as proximity measures for gene expression data

Jaskowiak, Pablo Andretta 02 March 2011 (has links)
O desenvolvimento da tecnologia de microarray tornou possível a mediçao dos níveis de expressão de centenas ou até mesmo milhares de genes simultaneamente para diversas condições experimentais. A grande quantidade de dados disponível gerou a demanda por métodos computacionais que permitam sua análise de forma eficiente e automatizada. Em muitos dos métodos computacionais empregados durante a análise de dados de expressão gênica é necessária a escolha de uma medida de proximidade apropriada entre genes ou amostras. Dentre as medidas de proximidade disponíveis, coeficientes de correlação têm sido amplamente empregados, em virtude da sua capacidade em capturar similaridades entre tendências das sequências numéricas comparadas (genes ou amostras). O presente trabalho possui como objetivo comparar diferentes medidas de correlação para as três principais tarefas envolvidas na análise de dados de expressão gênica: agrupamento, seleção de atributos e classificação. Dessa forma, é apresentada nesta dissertação uma visão geral da análise de dados de expressão gênica e das diferentes medidas de correlação consideradas para tal comparação. São apresentados também resultados empíricos obtidos a partir da comparação dos coeficientes de correlação para agrupamento de genes, agrupamento de amostras, seleção de genes para o problema de classificação de amostras e classificação de amostras / The development of microarray technology made possible the expression level measurement of hundreds or even thousands of genes simultaneously for various experimental conditions. The huge amount of available data generated the need for computational methods that allow its analysis in an effcient and automated way. In many of the computational methods employed during gene expression data analysis the choice of a proximity measure is necessary. Among the proximity measures available, correlation coefficients have been widely employed because of their ability to capture similarity trends among the compared numeric sequences (genes or samples). The present work has as objective to compare different correlation measures for the three major tasks involved in the analysis of gene expression data: clustering, feature selection and classification. To this extent, in this dissertation an overview of gene expression data analysis and the different correlation measures considered for this comparison are presented. In the present work are also presented empirical results obtained from the comparison of correlation coefficients for gene clustering, sample clustering, gene selection for sample classification and sample classification
222

Efeito da aquisição de leitura combinatória no responder diferencial às unidades mínimas em leitura recombinativa / Effect of combinatorial reading acquisition in the differential response to minimal units in recombinative reading

Ariene Coelho Souza 17 September 2013 (has links)
O objetivo deste experimento foi investigar se um treino com palavras monossilábicas que produziria leitura combinatória em um procedimento inicial geraria a aquisição de unidades mínimas e leitura recombinativa em um treino e teste posterior com palavras dissílabas. Participaram do experimento 10 crianças típicas com idades entre quatro e cinco anos. O procedimento consistiu em 12 fases subdivididas em pré-testes, treinos, testes, anagramas e pós-testes às quais os participantes foram expostos duas vezes em seqüência: Etapas I e II. Em cada etapa foi apresentado um conjunto distinto de estímulos de treino e teste. Na Etapa I os estímulos foram divididos entre duas condições experimentais, cada uma com cinco participantes: Condição M (Treino com Palavras Monossilábicas) e Condição D (Treino com Palavras Dissílabas). As palavras de testes foram as mesmas palavras dissílabas para ambas as condições. A diferença foi que para os participantes da Condição M era medida a Leitura Combinatória e para os da Condição D era medida a Leitura Recombinativa. Na Etapa II todos os participantes foram expostos ao mesmo conjunto de treino e teste de palavras dissílabas. Em ambas as etapas foram treinadas relações auditivo-visuais entre palavras oralmente apresentadas (conjunto A), impressas (conjunto C) e suas respectivas figuras (conjunto B). Posteriormente, foi testada a leitura oral e com compreensão das palavras de treino e das palavras de teste formadas pela combinação (Condição M na Etapa I) ou recombinação das unidades menores que compunham as palavras de treino (Condição D na Etapa I e todos os participantes na Etapa II). Os resultados mostraram que apenas os participantes que passaram pela Condição M na Etapa I apresentaram leitura recombinativa na Etapa II. Assim, o responder diferencial às unidades silábicas produzido pelo treino com palavras monossilábicas e emergência de leitura combinatória na Etapa I facilitou a aquisição das unidades menores e leitura recombinativa oral na Etapa II. Os dados sugerem que o processo comportamental envolvido na leitura combinatória e recombinativa é o mesmo: discriminação de estímulos. Em função disto, observou-se que uma história prévia de responder diferencialmente às unidades silábicas (leitura combinatória) pode favorecer o responder diferencial aos elementos componentes das palavras, quaisquer que sejam (propriedade silábica da língua portuguesa) aumentando a velocidade de aquisição do desempenho recombinativo / The objective of this study was to investigate if the combinatorial reading emergence, from an initial direct training with syllables, via monosyllables words, would produce the discrimination of smaller units in an ulterior training (with others disyllables words) promoting the identification of syllables units and posterior emergence of recombinative reading under control of this components. Participated 10 typical children aged 4 to 5 years. The procedure consisted in 12 phases subdivided in pre-tests; training, tests, constructedresponse tasks and post-tests in which the participants were exposed twice in sequence: Stage I and II. Each stage presented a distinct set of training and tests stimuli. In the Stage I the stimuli were divided in two experimental conditions each with five participants: Condition M (training of Monosyllable words) and Condition D (training of Dissyllable words). The test words were the same for both conditions. The difference was that participants of Condition M had the combinatorial reading measured while the participants of Condition D participants had the recombinative reading measured. In the Stage II all the participants were exposed to the same training and test sets of the disyllables words. Auditory-visual relations between dictated words (Set A), print words (Set C) and their respective pictures (Set B) were trained. Subsequently, oral and comprehension reading of the training and the test words was tested. The latter were formed by combination (Condition M in Stage I) and recombination (Condition D in Stage I and all participants at the Stage II) of the minimal units of the training words. The results showed that only that participants exposed to Condition M, presented recombinative reading in the Stage II. Thus, the differential response to syllabic units produced by monosyllabic words training and the emergence of combinatorial reading in the Stage I facilitated the acquisition of minimal units and recombinative oral reading at the Stage II. Data suggest that behavioral process involved in Combinatorial and Recombinative Reading is the same: stimuli discrimination. Consequently, it was observed that a previous history in differentially respond to syllabic units (combinatorial reading) could favor the differential respond to elements that composed the words whatever the elements are (syllabic propriety of portuguese language) increasing the speed of acquisition of recombinative performance
223

Abordagem não-paramétrica para cálculo do tamanho da amostra com base em questionários ou escalas de avaliação na área de saúde / Non-parametric approach for calculation of sample size based on questionnaires or scales of assessment in the health care

Euro de Barros Couto Junior 01 October 2009 (has links)
Este texto sugere sobre como calcular um tamanho de amostra com base no uso de um instrumento de coleta de dados formado por itens categóricos. Os argumentos para esta sugestão estão embasados nas teorias da Combinatória e da Paraconsistência. O propósito é sugerir um procedimento de cálculo simples e prático para obter um tamanho de amostra aceitável para coletar informações, organizá-las e analisar dados de uma aplicação de um instrumento de coleta de dados médicos baseado, exclusivamente, em itens discretos (itens categóricos), ou seja, cada item do instrumento é considerado como uma variável não-paramétrica com um número finito de categorias. Na Área de Saúde, é muito comum usar instrumentos para levantamento com base nesse tipo de itens: protocolos clínicos, registros hospitalares, questionários, escalas e outras ferramentas para inquirição consideram uma sequência organizada de itens categóricos. Uma fórmula para o cálculo do tamanho da amostra foi proposta para tamanhos de população desconhecidos e um ajuste dessa fórmula foi proposto para populações de tamanho conhecido. Pôde-se verificar, com exemplos práticos, a possibilidade de uso de ambas as fórmulas, o que permitiu considerar a praticidade de uso nos casos em que se tem disponível pouca ou nenhuma informação sobre a população de onde a amostra será coletada. / This text suggests how to calculate a sample size based on the use of a data collection instrument consisting of categorical items. The arguments for this suggestion are based on theories of Combinatorics and Paraconsistency. The purpose is to suggest a practical and simple calculation procedure to obtain an acceptable sample size to collect information, organize it and analyze data from an application of an instrument for collecting medical data, based exclusively on discrete items (categorical items), i.e., each item of the instrument is considered as a non-parametric variable with finite number of categories. In the health care it is very common to use survey instruments on the basis of such items: clinical protocols, hospital registers, questionnaires, scales and other tools for hearing consider a sequence of items organized categorically. A formula for calculating the sample size was proposed for a population of unknown size, and an adjusted formula has been proposed for population of known size. It was seen, with practical examples, the possibility of using both formulas, allowing to consider the practicality of the use in cases that have little or no information available about the population from which the sample is collected
224

Procedimento go/no-go com estímulos compostos e relações condicionais emergentes em crianças com autismo / Go/no-go procedure with compound stimuli and emergent conditional relations in children with autism

Cassia Leal da Hora 18 February 2009 (has links)
O procedimento matching-to-sample (MTS) tem sido amplamente utilizado para o estabelecimento de relações condicionais emergentes. Nesse procedimento, respostas de escolha são emitidas em diferentes localizações. Tal característica pode favorecer o estabelecimento de um controle inadvertido pela localização. No procedimento go/no-go com estímulos compostos, respostas são emitidas em uma única localização. Com o objetivo de avaliar se relações condicionais emergentes poderiam ser produzidas em crianças com autismo a partir do procedimento go/no-go com estímulos compostos, sem o estabelecimento de controle inadvertido pela localização, foram realizados dois estudos. No Estudo 1, quatro crianças autistas, que apresentaram controle pela localização no procedimento MTS, foram submetidas ao treino das relações AB e BC com o procedimento go/no-go com estímulos compostos no qual, respostas emitidas na presença dos estímulos compostos A1B1, A2B2, B1C1 e B2C2 eram seguidas de reforço e respostas na presença de compostos A1B2, A2B1, B1C2 e B2C1 não eram. Em seguida, os participantes realizaram testes para verificar a emergência de relações que não foram diretamente treinadas (BA, CB, AC e CA). Os resultados mostraram que apenas um dos quatro participantes atingiu critério de aprendizado no treino das relações condicionais e exibiu desempenhos consistentes com a emergência de relações de simetria, transitividade e equivalência após a reapresentação de sessões de treino e testes. Todos os participantes apresentaram o padrão de responder em todos os compostos apresentados. Como decorrência do Estudo 1, foi realizado um segundo estudo que pretendeu verificar se relações condicionais emergentes podem ser estabelecidas em indivíduos com diagnóstico de autismo a partir de um treino com o procedimento go/no-go com estímulos compostos em que a duração dos estímulos compostos aos quais o participante não deveria responder foi gradualmente aumentada com o objetivo de evitar respostas diante deles. Para tanto, outras três crianças diagnosticadas com autismo foram submetidas às mesmas fases experimentais do Estudo 1 dentre as quais algumas diferiam pela manipulação na duração dos compostos. Os resultados mostraram que apenas um dos participantes atingiu critério para realização dos testes de Simetria, mas não exibiu desempenho consistente com a emergência de tais relações. Os outros dois participantes não atingiram critério de aprendizagem na fase de Pré-treino ou de Treino, devido ao estabelecimento do padrão de responder em todos os compostos. Os resultados indicam ainda que o procedimento de aumento gradual na duração dos estímulos favoreceu o aprendizado das relações condicionais para um dos participantes, mas pode gerar o estabelecimento do controle inadvertido pela duração dos estímulos. Os participantes que realizaram o treino com o procedimento MTS não atingiram critério de aprendizagem e exibiram desempenhos indicativos do estabelecimento de controle inadvertido pela localização. Concluiu-se que o procedimento go/no-go com estímulos compostos, embora tenha permitido o estabelecimento de desempenhos emergentes para um dos participantes, pode gerar um padrão de responder em todos os compostos mesmo com o procedimento de aumento gradual na duração dos compostos diante dos quais o participante não deve responder. / Matching-to-sample procedure is widely used for establishing emergent conditional relations. However, adventitious control by location, rather than the conditional control, can be established with this procedure in individuals with autism. With the go/no-go procedure with compound stimuli, participants responses are emitted in a single location. Aiming to assess whether emergent conditional relations could be established in autistic children with a go/no-go procedure with compound stimuli, without the establishment adventitious control by location, two studies were conducted. Study 1 sought to verify if the go/no-go procedure with compound stimuli would establish emergent conditional relations in children diagnosed with autism who had control by the location in training with Matching-to-sample procedure. Four autistic children, who showed adventitious control by location in a matching-to-sample task, were submitted to AB and BC training with the go/no-go procedure with compound stimuli. Responses emitted in the presence of A1B1, A2B2, B1C1 and B2C2 compounds were followed by reinforcers and responses emitted in the presence of A1B2, A2B1, B1C2 and B2C1 were not. After that, participants were submitted to tests to verify emergence of conditional relations (BA, CB, AC and CA) that were not directly trained. The results showed that only one of the four participants met the learning criterion in training and exhibited emergent performances in tests only after retraining the baseline relations. In most of the training sessions, all participants responded to all compounds stimuli. These results show that refrain from responding is difficult to be established with the go/no-go procedure in children with autism. Study 2 was conducted to verify if refrain from responding would be established in children with autism if the duration of compounds that should not control responding in training was gradually increased. Other three children diagnosed with autism were submitted to the same procedure as conducted in Study 1, except that during pre-training and training duration of some compounds were gradually increased in some sessions. Results showed that only one participant met the learning criteria in training, but did not showed emergent performances in tests. The other two participants responded to all compounds in most of the sessions. The results indicate that the gradual increase of stimuli duration did not established refrain from responding for some participants and produced adventitious control by stimuli duration for most of them. Although one participant showed emergent performances with the go/no-go procedure with compound stimuli, this procedure can produce responses to all compounds stimuli even when some compounds duration is gradually increased.
225

Controle por unidades verbais mínimas e extensão da unidade ensinada: o efeito do treino de fonemas na emergência da leitura recombinativa / Minimal verbal units control and extension of the unit taught: effect of the phoneme training upon the emergence of recombinative reading

Luana Zeolla Inhauser 14 November 2012 (has links)
A leitura é uma habilidade complexa que envolve uma rede de relações entre estímulos e entre estímulos e respostas. Para que um repertório de leitura seja considerado proficiente, o leitor deve apresentar a leitura de novas palavras, não diretamente ensinadas e formadas pela recombinação de unidades aprendidas previamente em outras relações (leitura recombinativa). Um requisito fundamental para o desenvolvimento da leitura recombinativa é, portanto, o estabelecimento de um responder diferencial sob controle das unidades menores, como por exemplo, sílabas, letras ou fonemas, componentes das palavras. O objetivo do presente trabalho foi investigar o efeito do treino direto de fonemas, combinado com um treino de palavras, sobre a emergência da leitura recombinativa de palavras inteiras. Verificou-se também se o momento de inserção do treino de fonemas no procedimento de ensino, se prévio (Condição I) ou sobreposto (Condição II) ao treino de palavras, foi uma variável relevante para a emergência da leitura recombinativa. Os participantes do estudo foram 12 estudantes universitários, com idades entre 18 e 37 anos, e que foram distribuídos igualmente entre três Condições Experimentais: a) Condição I Treino Prévio de Fonemas; b) Condição II Treino Sobreposto de Fonemas; c) Condição IIITreino de palavras. A Condição III foi realizada com o objetivo permitir uma comparação entre o desempenho dos participantes que foram submetidos ao treino de fonemas (Condições I e II) com o dos participantes que foram expostos somente ao treino de palavra (Condição III). Os estímulos utilizados no estudo consistiram de palavras faladas (A) e palavras escritas com um pseudoalfabeto (C), bem como de fonemas e letras do pseudoalfabeto, correspondentes a estes fonemas. Os procedimentos empregados tanto para o treino de fonemas como para o treino de palavras inteiras foram os procedimentos de MTS (relação AC) e de Nomeação Oral (relação CD). Os testes para verificar a emergência da leitura recombinativa foram os mesmos nas três Condições Experimentais e consistiram em testes parciais de leitura oral (Testes CD) e de leitura receptiva (Testes AC), e em um Teste Final de Leitura Oral. Os resultados demonstraram que o treino direto de fonemas (Condições I e II) foi eficaz em estabelecer leitura recombinativa com elevados índices de acertos e pouca variabilidade intra e inter-participantes. O momento de inserção do treino de fonemas no procedimento de ensino foi uma variável relevante e possibilitou a observação de resultados distintos entre os participantes submetidos às Condições I e II. Os resultados sugerem que os participantes submetidos a Condição II (Sobreposto) foram os que apresentaram maior velocidade na recombinação e índices mais elevados de leitura recombinativa, enquanto os participantes submetidos a Condição I (Prévio) foram os que apresentaram menor variabilidade entre si / Reading is a complex skill that involves a network of relationships between stimuli and between stimuli and responses. A repertoire of proficient reading is considered when the reader is able to read new words, not directly taught and composed by the recombination of units previously learned in other relationships (recombinative reading). An essential requirement for the development of recombinative reading is thus establishing a differential responding under the control of smaller units, such as syllables, phonemes or letters, components of the words. The objective of this study was to investigate the effect of direct training of phonemes, combined with a training of words, upon the emergence of recombinative reading of whole words. It was also verified the effect of the moment of insertion of phoneme training in the teaching procedure, prior (Condition I) and overlapping (Condition II) to word training. The participants were 12 college students, aged between 18 and 37 years, which were equally distributed among three Experimental Conditions: a) Condition I Prior Phoneme Training, b) Condition II Overlapping Phoneme Training; c) Condition III Word Training. Condition III was conducted in order to allow a comparison between the performance of participants who were submitted to phoneme training (Condition I and II) and the performance of participants who were exposed only to word training (Condition III). The stimuli used in the study consisted of spoken pseudowords (A) and printed pseudowords (C), as well phonemes and letters form the pseudo-alphabet corresponding to these phonemes. The procedures applied for both phoneme and word training were MTS (AC relation) and Oral Naming (CD relation). Tests to verify the emergence of recombinative reading were the same in all three Experimental Conditions and consisted of partial tests of oral reading (Tests C\'D) and receptive reading (Tests A\'C\'), as well as of a Final Test of Oral Reading. The results showed that the direct training of phonemes (Conditions I and II) was effective in establishing recombinative reading with high scores and low variability within and among participants. Regarding the moment of the insertion of phoneme training on the procedure, the conclusion is that this is an important variable and enables the observation of different results among participants submitted to Conditions I and II. The results suggest that participants undergoing Condition II (Overlapping) were those with greater recombinative speed and higher rates of recombinative reading, while participants submitted to Condition I (Prior) presented the lowest variability among themselves
226

Simplifying Sample Preparation using Fabric Phase Sorptive Extraction: Analysis of Trace Targeted Pollutant Residues in Environmental, Biological and Food Samples

Mesa, Rodolfo 26 October 2017 (has links)
Sample preparation is an essential component of analytical methods in chemistry. It is not only necessary but also presents an opportunity to increase the effectiveness of the method significantly. There are various commercially available technologies for sample preparation, including numerous variations of LLE, SPE, and SPME. However, these technologies all present significant deficiencies, including the inability to extract directly from complex samples such as whole milk. Instrumental analysis has been improved greatly in the last two decades but still is not applicable to complex samples without sample preparation. This work presents the theory of FPSE, including the synthesis of sol-gel sorbents, coating of FPSE cellulose substrates and the mechanism of retention. Original research data presented herein introduce a comprehensive view on possible applications of FPSE in forensic chemistry and otherwise. Five distinct FPSE-based methods were rigorously developed for analysis of targeted pollutant residues. These methods were validated and compare to leading methods published in peer-reviewed literature quite favorably. Four of the methods were coupled to HPLC-UV and designed for trace or ultra-trace analysis of PAHs, BTEX, substituted phenols and nitroaromatic explosives, respectively. An additional FPSE-based method was developed and validated for direct analysis of BPA and five estrogenic EDCs in commercially purchased whole milk. This latter was coupled to both HPLC-UV and HPLC(QQQ)-MS/MS. The applicability of FPSE(PTHF) media was also tested for screening of aqueous samples and subsequent storage of analytes on the sorbent. My study included simultaneous extraction of a mixture of eight forensically significant compounds with various physicochemical properties and effective storage of each compound in frozen and ambient conditions for 32 weeks. These findings suggest that the storage ability of FPSE media can be extended as long as necessary, which is very significant in forensic laboratories where evidence often needs to be stored in a costly manner that may not be as effective in maintaining the chemical composition of the sample.
227

Improved Techniques for Protein Analysis Focusing on Membrane Proteins and Hydrophobic Peptides

Redeby, Theres January 2006 (has links)
In this thesis, the vital cell functions performed by integral membrane proteins (IMPs) are briefly discussed. Such proteins are under-represented in most protein studies due to the hydrophobic nature of IMPs, which seriously complicate their solubilization, sample handling, preparation, separation and analysis. Conventional analytical techniques include for example matrix-assisted laser desorption/ionization mass spectrometry (MALDIMS), capillary electrophoresis (CE) and reversed phase high-performance liquid chromatography (RP-HPLC). Presented here are methods and protocols, which have been developed especially for IMP and hydrophobic peptide analysis, using the abovementioned techniques. The fluorinated organic solvent hexafluoroisopropanol (HFIP) has previously been shown beneficial as an additive for solubilization of hydrophobic analytes, which are poorly soluble in commonly used organic solvents or water. In Papers I-IV, HFIP is successfully exploited as solvent for the investigated IMPs and peptides. The simple fabrication and the focusing effect of a new structured MALDI target plate are presented in Paper I. This target plate contains concentrating sample spots, specifically designed to provide increased sensitivity for hydrophobic protein and peptide MALDI-MS analysis. When replacing a regular steel target with this new structured MALDI plate, more than a five-fold increase in average sensitivity is achieved for HFIP solubilized hydrophobic peptides. The full-length IMP bacteriorhodopsin (BR) and a cyanogen bromide digest thereof are used as model samples for the development of sample handling procedures in Paper II, and the peptides were used for evaluation of the MALDI-target plate in Paper I. Furthermore, the CE separation of the peptides, fractionation onto the structured MALDI plate and following MS analysis is presented in Paper III. Nine of the ten theoretical BR peptides were detected using this method. A protocol for the purification and analysis of chloroplast membrane proteins from the green macroalga Ulva lactuca has been described in Paper IV. The highest protein yield was achieved when proteins were extracted in HFIP, directly from the chloroplasts. The MALDI-MS analysis of samples with and without previous RP-HPLC fractionation revealed proteins with molecular weights ranging between 1 and 376 kDa. In Paper V, a closed-open-closed CE system is presented, containing an open microchannel for off-line MALDI detection. The electroosmotic flow and band broadening of this system has been evaluated. / QC 20100916
228

A Novel Miniaturised Dynamic Hollow-Fibre Liquid-Phase Micro-Extraction Method for Xenobiotics in Human Plasma Samples

Hansson, Helena January 2010 (has links)
Bioanalytical chemistry is a challenging field, often involving complex samples, such as blood, plasma, serum or urine. In many applications, sample cleanup is the most demanding and time-consuming step. In the work underlying this thesis a novel dynamic miniature extractor, known as a hollow-fibre liquid-phase microextractor (HF-LPME), was designed, evaluated and studied closely when used to clean plasma samples. Aqueous-organic-aqueous liquid extraction, in which the organic liquid is immobilised in a porous polypropylene membrane, was the principle upon which the extractor was based, and this is discussed in all the papers associated with this thesis. This type of extraction is known as supported-liquid membrane extraction (SLM). The aim of this work was the development of a dynamic system for SLM. It was essential that the system could handle small sample volumes and had the potential for hyphenations and on-line connections to, for instance, LC/electrospray-MS. The design of a miniaturised HF-LPME device is presented in Paper I. The extraction method was developed for some weakly acidic pesticides and these were also used for evaluation. In the work described in Paper II, the method was optimised on the basis of an experimental design using spiked human plasma samples. Paper III presents a detailed study of the mass-transfer over the liquid membrane. The diffusion through the membrane pores was illustrated by a computer-simulation. Not surprisingly, the more lipophilic, the greater the retention of the compounds, as a result of dispersive forces. The main focus of the work described in Paper IV was to make the HF/LPME system more versatile and user-friendly; therefore, the extractor was automated by hyphenation to a SIA system. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript.
229

Stochastic Modelling of Random Variables with an Application in Financial Risk Management.

Moldovan, Max January 2003 (has links)
The problem of determining whether or not a theoretical model is an accurate representation of an empirically observed phenomenon is one of the most challenging in the empirical scientific investigation. The following study explores the problem of stochastic model validation. Special attention is devoted to the unusual two-peaked shape of the empirically observed distributions of the conditional on realised volatility financial returns. The application of statistical hypothesis testing and simulation techniques leads to the conclusion that the conditional on realised volatility returns are distributed with a specific previously undocumented distribution. The probability density that represents this distribution is derived, characterised and applied for validation of the financial model.
230

Estudo de transições durante o processo de desenovelamento térmico da RNase A por meio da calorimetria (DSC) e espectroscopia de correlação bidimensional no infravermelho médio (2D-IR) /

Martins, Danúbia Batista. January 2011 (has links)
Orientador: Marinônio Lopes Cornélio / Banca: Antônio José da Costa Filho / Banca: André Luiz Galo / Resumo: Esse trabalho tem por objetivo estudar as transições conformacionais, induzidas termicamente, na Ribonuclease A. Esta abordagem foi realizada aplicando!se a técnica de calorimetria diferencial de varredura (DSC) e infravermelho médio com transformada de Fourier (FTIR), associando a técnica de análise de correlação bidimensional (2D! COS), variável!variável (VV) e sample sample (SS). A partir dos dados de DSC determinamos a variação de entalpia do sistema (∆Hcal) que foi de 587 kJ/mol. Também identificamos as temperaturas de pré (36, 39, 43, 49 e 59°C), pós transição (71°C) e temperatura de melting (65°C), além da determinação do ∆Hcal para cada uma das transições. A análise de correlação bidimensional sample!sample (SS) também foi capaz de identificar as mesmas temperaturas encontradas por DSC. Por sua vez, a análise de correlação bidimensional variável!variável (VV) descreveu a evolução conformacional das estruturas secundárias da proteína durante o desenovelamento térmico / Abstract: This work aims to study the thermally!induced conformational transitions in Ribonuclease A. This approach was performed by applying the technique of differential scanning calorimetry (DSC) and medium infrared Fourier transform spectroscopy (FTIR), linking the technique of correlation analysis (2D!COS), variable!variable (VV) and sample !sample (SS). From DSC data determine the enthalpy change of the system (SHcal) which was 587 kJ / mol. We identified the pre temperatures (36, 39, 43, 49 and 59 ° C), post transition (71 ° C) and melting temperature (65 ° C), besides determination of SHcal for each transition. The two!dimensional correlation analysis sample! sample (SS) was also able to identify the same temperatures found by DSC. In turn, the two!dimensional correlation analysis of variable!variable (VV) described the conformation evolution of the protein secondary structures during thermal unfolding / Mestre

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