For years, researchers have studied the movement of cells and mathematicians have attempted to model the movement of the cell using various methods. This work is an extension of the work done by Zheltukhin and Lui (2011), Mathematical Biosciences 229:30-40, who simulated the stress and displacement of a one-dimensional cell using a model based on viscoelastic theory. The report is divided into three main parts. The first part considers viscoelastic models with a first-order constitutive equation and uses the standard linear model as an example. The second part extends the results of the first to models with second-order constitutive equations. In this part, the two examples studied are Burger model and a Kelvin-Voigt element connected with a dashpot in series. In the third part, the effects of substrate with variable stiffness are explored. Here, the effective adhesion coefficient is changed from a constant to a spatially-dependent function. Numerical results are generated using two different functions for the adhesion coefficient. Results of this thesis show that stress on the cell varies greatly across each part of the cell depending on the constitute equation we use, while the position and velocity of the cell remain essentially unchanged from a large-scale point of view.

The flow of blood in the human body is a very important component in un-derstanding a number of different ailments such as atherosclerosis and a falseaneurysm. In this thesis, we have utilized Poiseuille’s solution to Navier-Stokesequations with a Newtonian, incompressible fluid flowing laminar with zero ac-celeration in a pipe with non-flexible walls in order to study blood flow in anarterial tree. In order to study and simulate a larger arterial tree we have uti-lized a primitive building block, a bifurcation with one inlet and two outlets,joined together forming a tree. By prescribing an inlet flow and the pressureat every outlet at the bottom of the tree we have shown that we may solvethe system by fixed-point iteration, the Matlab functionfsolve, and Newton’smethod. This way of using primitive building blocks offers a flexible way to doanalysis as it makes it possible to easily change the shape of the tree as well asadding new building blocks such as a block that represents arteriosclerosis.

Orientador: Marcos Yutaka Shiino / Coorientador: Alberto Noriyuki Kojima / Banca: Vinícius Anéas Rodrigues / Banca: Vivian Silveira dos Santos Bardini / Resumo: A introdução da zircônia na Odontologia deu-se pela necessidade de melhores propriedades mecânicas dos materiais cerâmicos, pois com a crescente demanda estética, os cerâmicos tornaram-se materiais de largo uso, devido às suas propriedades estéticas e mecânicas. Em busca dessas propriedades, vários estudos analisaram a taxa de sobrevivência de restaurações zircônia-porcelana, relatando como uma das causas de falha a fratura precoce da porcelana de cobertura e o aumento significativo nos relatos clínicos de lascamento da porcelana de recobrimento aplicada sobre "coping" de zircônia. Diante desse problema, o objetivo deste trabalho foi determinar a tensão de falha no lascamento a partir de casos de clínicos e experimentais pertinentes a esse fenômeno em próteses fixas livres de metal .Foram coletados dados de artigos dos últimos 15 anos, por meio das bases de dados Pubmed e Google Schoolar, sendo selecionados para essa revisão os que obtiveram melhor abordagem do assunto, dando ênfase às possíveis causas de falhas nas restaurações cerâmicas dos casos clínicos e os ensaios realizados, visando um melhor entendimento desse fenômeno, via análise quantitativa e qualitativa, para melhor utilização e aproveitamento desse material na Odontologia. Para determinação da tensão de falha, foi empregada a mecânica da fratura linear elástica e determinado o fator de correção da trinca com base nas dimensões da trinca.Com a presente pesquisa, nota-se que amplitude de tensão influencia no proce... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The introduction of zirconia in dentistry was due to the need for better mechanical properties of ceramic materials, because of an increasing aesthetic demand. Ceramics became widely used materials due to their aesthetic and mechanical properties. Aiming at these properties, several studies have analyzed the survival rate of zirconia-porcelain restorations, reporting as one of the causes of failure. Early porcelain fracture coverage and a significant increase in clinical reports of veneering porcelain applied over "coping "of zirconia. In view of this problem, the objective of this work was to determine the failure causes of chipping from clinical and experimental cases associated to this phenomenon in fixed metal free prostheses. Data from articles of the last 15 years were collected through the Pubmed and Google Schoolar databases. Those who obtained the best approach to the subject were selected for this analysis, emphasizing the possible causes of failures in the ceramic restorations of the clinical cases and the tests performed. Aiming for a better understanding of this phenomenon, via quantitative and qualitative analysis, to better use this material in dentistry. To determine the failure causes, linear elastic fracture mechanics were used and the crack correction factor was determined based on the crack dimensions. With the present research, it is noticed that stress amplitude influences in the fracture process, although it has not pointed exactly the cause of the frac... (Complete abstract click electronic access below) / Mestre

Orientador: Rodrigo Máximo de Araújo / Banca: Vinícius Anéas Rodrigues / Banca : Eduardo Galera da Silva / Resumo: O objetivo desse estudo foi avaliar a adaptação marginal de copings cerâmicos obtidos pelos métodos de moldagem convencional e escaneamento. Os modelos foram separados em 3 grupos para avaliação e todas as coroas foram confeccionadas sobre um modelo mestre previamente fabricado em CoCr. Grupo 1: Com o auxílio de uma moldeira individual cilíndrica de acrílico foram reproduzidas 10 moldagens com silicona de adição (Panasil) no modelo mestre pela técnica de moldagem dupla e replicados dez modelos físicos em gesso pedra Fuji Rock.Sobre esses modelos foi realizado o enceramento dos copings, confecção dos sprues de cera e sobre eles foi realizada a injeção da cerâmica Grupo 2: foram realizadas 10 moldagens diretas com scanner extraoral (Swing Dental Scanner) no modelo mestre. As imagens foram obtidas através do software Exocad e copings em IPS-Emax CAD foram confeccionados em fresadora (Ceramill Motion 2) para posterior sinterização da cerâmica. Grupo 3: foram realizadas 10 moldagens diretas com scanner intraoral (CEREC Bluecam) no modelo mestre. As imagens foram obtidas através do software Exocad. Copings em IPS-Emax CAD foram confeccionados em fresadora (Ceramill Motion 2) para posterior sinterização da cerâmica. Os copings de cerâmica não foram cimentados no modelo mestre, apenas posicionados e mantidos com pressão constante de 1,4 a 1,5 kg durante a medição, com a ajuda de um delineador adaptado para esse trabalho, onde oito pontos eletivos foram usados como referência para med... (Resumo completo, clicar acesso eletrônico abaixo) / The objective of the study was to evaluate the marginal adaptation of ceramic crowns obtained by conventional molding and scanning methods. The models were separated into 3 groups for evaluation and all the crowns were made on a master model previously manufactured in CoCr. For group 1: With the aid of a single cylindrical acrylic tray the master model was molded 10 times with Panasil in the master model by the technique of double molding and replicated ten physical models in stone gypsum Fuji Rock. On these models was done the waxing of the copings, making the sprues of wax and on them was carried out the injection of the ceramics In group 2, 10 direct impressions were performed with the Swing Dental Scanner (Korea) extra oral scanner in the master model. The images were obtained through the software Exocad (GmbH) and copings in IPS-Emax CAD were made in the Ceramill Motion 2 (Amanngirrbach) mill for subsequent sintering of the ceramics. In group 3, 10 direct impressions were performed with the CEREC Bluecam intraoral scanner (Sirona Dental Systems) in the master model. The images were obtained through the Exocad (GmbH) software. IPS-Emax CAD copings were made in the Ceramill Motion 2 (Amanngirrbach) mill for subsequent sintering of the ceramic. Ceramic copings were not cemented in the master model, only positioned and maintained with a constant pressure of 1.4 to 1.5 kg during the measurement, with the aid of an eyeliner adapted for this work, where eight elective points were used as reference to measure the vertical distance between the end line of the master model and the end line of the copings. The margin at each point was measured 3 times with stereo microscope Discovery V20 (ZEISS). The mean was calculated and submitted to the ANOVA variance test "with a significance level of 5% and the following results were obtained: 66.15μm for group 1; 67.48μm for group ...(Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Este trabalho visa identificar possíveis vantagens que as empresas obtêm ao contribuir com campanhas políticas. Para isso, foi utilizada uma extensa base de dados com informações de doações a candidatos aos cargos de deputado, senador e presidente nas eleições de 2006 e 2010. As variáveis de interesse analisadas foram o retorno anormal cumulativo à época da divulgação do resultado das eleições e o retorno sobre o patrimônio líquido no ano posterior a cada eleição. Foram estimadas regressões de dados em painel através de mínimos quadrados ordinários, e incluídos efeitos fixos de ano e setor das empresas. Os resultados indicam que não apenas o mercado antecipa benefícios futuros para as empresas que contribuíram com campanhas – o que se reflete em retornos anormais cumulativos positivos à época da eleição – mas também estas empresas apresentam retornos sobre o patrimônio líquido superiores aos daquelas que não participaram do processo político. Além disso, doações a candidatos vencedores geram retorno superior aos de doações a candidatos perdedores; o que vai ao encontro da hipótese de retribuição de favores. De forma similar, contribuições a candidatos filiados à coligação do presidente eleito também apresentaram impacto superior quando comparadas com doações a candidatos da oposição. / This paper aims to identify potential benefits that companies obtain by contributing to political campaigns. We used an extensive database with information on donations to House, Senate and Presidency candidates in the 2006 and 2010 elections. The variables of interest analyzed were the cumulative abnormal return by the time the results of each election became know and the return on equity in the year following the election. Panel regressions were estimated as ordinary least squares (OLS), and fixed effects of year and industry were included. The results indicate that not only the market anticipates future benefits for companies that contributed to campaigns - which is reflected in positive cumulative abnormal returns at the announcement of the election results - but these companies also have higher returns on equity than those that were not involved in the political process. In addition, donations to winning candidates generate higher returns than donations to losing candidates; which supports the return of favors hypothesis. Similarly, contributions to candidates affiliated to the president’s coalition's also had higher impact when compared to donations to the oposition candidates.

Ao modelar-se depósitos minerais é comum enfrentarmos o problema de estimar múltiplos atributos possivelmente correlacionados, onde algumas variáveis são amostradas menos densamente do que outras. A falta de dados impõe um problema que requer atenção antes de qualquer modelagem subsequente. Precisamos, ao final, de modelos que sejam estatisticamente representativos. A maioria dos conjuntos de dados de problemas práticos são amostrados de maneira heterotópica e, para obter resultados coerentes, é preciso entender os motivos pelos quais alguns dados faltam e quais são os mecanismos que influenciaram a ausência de informações. A teoria de dados faltantes relaciona as amostras ausentes com aquelas medidas através de três mecanismos distintos: Faltante Completamente Aleatório (Missing Completely At Random - MCAR), Faltante Aleatório (Missing At Random - MAR) e Faltante Não Aleatório (Missing Not At Random - MNAR). O último mecanismo é extremamente complexo e a literatura recomenda ser tratado inicialmente como um mecanismo MAR. E após uma transformação fixa deve ser aplicada aos valores complementados para que estes se transformem em valores MNAR Embora existam métodos estatísticos clássicos para lidar com dados faltantes, tais abordagens ignoram a correlação espacial, uma característica que ocorre naturalmente em dados geológicos. A metodologia adequada para tratar com a falta de dados geológicos é a atualização bayesiana, em que se inserem valores sob mecanismo MAR considerando a correlação espacial. No presente estudo, a atualização bayesiana foi combinada com transformações fixas para tratar o mecanismo de falta de dados MNAR em dados geológicos. A transformação fixa aqui empregada é baseada no erro de inserção gerado em um cenário MAR no conjunto de dados. Assim, com o conjunto completo resultante foi utilizado em uma simulação sequencial gaussiana dos teores de uma base de dados multivariada, apresentando resultados satisfatórios, superiores aos obtidos por meio da cossimulação sequencial gaussiana, não inserindo qualquer viés no modelo final. / When modeling mineral deposits, it is common to face the problem of estimating multiple attributes possibly correlated where some variables are more densely sampled then others. Missing data imposes a problem that requires attention prior to any subsequent modeling. The later requires estimation models statistically representative. Most practical data sets are often heterotopically sampled, and to obtain coherent results one must understand the reasons why there are missing data and what are the mechanisms that cause the absence of information. The theory of missing data relates the missing samples to those measured through three different mechanisms: Missing Completely At Random (MCAR), Missing At Random (MAR), and Missing Not At Random (MNAR). The last mechanism is quite complex to deal with, and the literature recommends being treated as a MAR mechanism and after a fixed transform should be applied to the imputed values so that these turn into MNAR imputed values. Even though there are classical statistical methods to deal with missing data, such approaches ignore spatial correlation, a feature that occurs naturally in geological data. The adequate methodology to deal with missing geologic data is Bayesian Updating, which approaches the MAR mechanism and accounts for spatial correlation. In the present study, bayesian updating was used combined with fixed transforms to treat MNAR missing data mechanism in geologic data. The fixed transform herein used is based on the error of MAR imputation on the data set. The resulting complete set was then used on a sequential gaussian simulation of the grades on a multivariate data set, presenting satisfactory results, superior to those obtained through sequential gaussian cossimulation, not inserting any biases on the final model.

Nos últimos anos, o value-at-risk tem se tornado uma ferramenta amplamente utilizada nas principais instituições financeiras, inclusive no Brasil. Dentre suas vantagens, destaca-se a possibilidade de se resumir em um único número os riscos de mercado incorridos e incorporar neste valor tanto a exposição da instituição quanto a volatilidade do mercado. O objetivo principal deste estudo é verificar a eficácia dos modelos mais conhecidos de value-at-risk - RiskMetrics(TM) e Simulação Histórica - na mensuração dos riscos de mercado de carteiras de renda fixa compostas por instrumentos pré-fixados em reais. No âmbito da alocação de capital para atendimento aos órgãos de regulamentação, o estudo estende-se também ao modelo adotado pelo Banco Central do Brasil. No decorrer do estudo, discute-se ainda as vantagens e desvantagens apresentadas, bem como o impacto que as peculiaridades do mercado brasileiro exercem sobre as hipóteses assumidas em cada um dos modelos. / Value-at-Risk (VaR) has become the primary tool for the systematic measuring and monitoring of market risk in most financial institutions. VaR is a statistical measure that comprises not only the exposure but also the market volatility in a single number. The main purpose of this work is to evaluate the performance of the well-known value-at-risk models - RiskMetrics(TM) and Historical Simulation - in the Brazilian fixed-income market. In the scope of capital allocation related to banking regulation, this study also extends briefly to the model adopted by the Brazilian Central Bank. Additionally, the underlying assumptions of these models are analyzed in the Brazilian financial market context. Also, this study discusses the advantages and disadvantages presented by the RiskMetrics and the Historical Simulation models.

<p>General Aviation (GA) is a category of aircraft operations, exclusive of all military and commercial operations. According to Federal Aviation Administration (FAA), fixed-wing aircraft (also known as airplanes) account for 76.2% of all the estimated registered GA fleet in the United States. Out of all the GA accidents that the National Transportation Safety Board (NTSB) investigated in 2017, 87.7% of the accidents involved fixed-wing aircraft. The NTSB reports on all GA accidents and records the accident details in their database. The NTSB database has an abundance of accident data, but the data is not always logically complete and has missing information. Many researchers have conducted several studies to provide GA fixed-wing accident causation using the NTSB accident data. The quantitative analyses conducted by the researchers focused on a chain of events approach and identified the most frequent events in accidents. However, these studies provided little insight into why the events in the accidents happened. In contrast, the qualitative analyses conducted an in-depth study of limited accidents from the NTSB database. This approach helps in providing new findings but is difficult to apply to large scale datasets. Therefore, our understanding of GA fixed-wing accident causation is limited. This research uses a state-based approach, developed by Rao (2016), to provide a potentially better understanding of causes for GA fixed-wing accidents. I analyzed 10,500 fixed-wing accidents in 1982–2017 that involved inflight loss of control (LOC-I) using the state-based approach. I investigated the causes of LOC-I using both a conventional approach and a state-based approach. I analyzed fatal, non-fatal and overall LOC-I accidents in three timeframes: 1989–1998, 1999–2008 and 2008–2017. This multi-year analysis helped in discerning changes in the causation trends in the last three decades. A mapping of the LOC-I state definition to the NTSB codes helped in identifying 2350 more accidents in the database that were not discernible using the conventional approach. The conventional analysis revealed “directional control not maintained” as the top cause for the LOC-I accidents, which provides little information about how loss of control happened in accidents. The state-based analysis highlighted some important findings that contribute to LOC-I accidents that were not discernible using the conventional approach. The state-based analysis identified preflight mechanical issue as one of the new causes for LOC-I with a presence in 5.1% of LOC-I accidents in 2009–2017. It also helped in inferring some of the missing information in the accident data by modeling the accidents in a logical order. Using the logic rules in the state-based approach, I inferred that the pilot’s tendency to hit objects or terrain caused loss of control in 19.9% of LOC-I accidents in 2009–2017. Further, the logic rules helped in inferring that 7.5% of LOC-I accidents in 2009–2017 involved hazardous condition of an aircraft before the start of flight. A comparison of the findings from state-based approach with the GAJSC (General Aviation Joint Steering Committee) safety enhancements revealed that the state-based approach encompassed all the potential issues addressed in the safety enhancements. Additionally, a state-based analyses of larger datasets of fatal and non-fatal accidents suggested some new potential issues (such as improper maintenance) that were not explicitly addressed in the GAJSC safety enhancements. </p>

This thesis makes two main contributions to the literature. The first is to establish the existence of a capital supply channel, in particular a bank lending channel of monetary policy transmission in the UK using a clean measure of bank loan supply. In this study we exploit the revealed debt preferences of debt issuing firms by using the Becker and Ivashina (2014) fixed effects framework to isolate the impact of credit supply. By conditioning the sample on non-financial firms whose debt issuance is observed, we are able to eliminate the effects of credit demand and to isolate a clean measure for bank loan supply. In this thesis, we find that the tendency by unconstrained, non-financial firms to substitute corporate bonds for bank loans at different points of the financial cycle reflects changes in bank loan supply. We also find that the patterns of substitutability are consistent among more granular classifications of heterogeneous debt. Our results reveal that among unconstrained firms, the proportion of new bank loan issuance declines, while the proportions of corporate bonds and program debt issuance tend to increase, when faced with unfavourable credit market conditions. We then create a loan to bond substitution measure based on observed substitution behaviour of unconstrained firms. We find that this measure explains the out of sample bank loan issuance behaviour of constrained firms. As a result we conclude that the measure is able to cleanly capture changes in bank loan supply. We extend the study to examine the impact of bank loan supply on the financing, hiring and investment decisions of UK non-financial corporations. We find that bank loan supply disruptions significantly and disproportionately affect the hiring and inventory investment decisions of bank dependent firms relative to those of non-bank dependent firms. The propensity to invest or hire among bank dependent UK non-financial firms declines relative to non-bank dependent firms when bank loan supply deteriorates. Moreover, the fixed investment decisions of non-bank dependent firms tend to decline following adverse bank loan supply shocks. These results confirm the existence of a bank lending channel among UK non-financial firms, and the findings are in line with the narrow credit view of monetary policy transmission. Our second central contribution is to analyse the impact of orthogonal QE shocks, credit supply shocks, credit demand shocks, and monetary policy shocks on the aggregate debt issuance behaviour of UK non-financial firms. Using structural vector error correction models (SVECM), we show that QE shocks increase corporate bond issuance and compress term spreads, but have no effect on the policy rate. Moreover, we observe that unexpected increases in the monetary policy rate lead to a decline in corporate bonds in the short term. While credit supply shocks move aggregate bank lending and aggregate corporate bond issuance in the same direction, corporate bond issuance responds with a lag to fluctuation in credit supply. This implies that adverse credit supply shocks may produce amplified negative effects on capital supply as both corporate bonds and bank loan decline. We also establish a counterfactual for corporate bonds and bank loan issues based on our structural model. We find that the QE policies result in the Bank of England averting a decline in corporate bond issuance of between 3% and 10% during the QE period. Our findings in this thesis point towards the existence of a portfolio balance channel of QE that operates in the UK corporate bond markets during the QE period.

A modelagem e simulação de reatores trifásicos representa um grande desafio para simuladores de processo. Muitos estudos acadêmicos têm sido desenvolvidos com o objetivo de descrever e prever o comportamento desses equipamentos, quer seja em seu estado estacionário, quer seja as respostas dinâmicas. Várias são as abordagens aplicadas para tentar melhor refletir os fenômenos envolvidos nos reatores trifásicos, ponderando sempre o custo computacional de cada abordagem. Neste trabalho, um reator de hidrogenação seletiva de nafta de pirólise foi simulado baseado em dados publicados na literatura. O reator é do tipo leito gotejante (trifásico), e as reações consideradas são de pseudo-primeira ordem. A técnica aplicada foi a de modelagem matemática por células, onde os leitos catalíticos foram subdivididos em reatores tipo CSTR dinâmicos associados em série. A cada célula, um cálculo de flash foi associado, aperfeiçoando os balanços de massa e energia comumente empregados em reatores de leito gotejante. A abordagem termodinâmica utilizada para prever o equilíbrio líquido-vapor foi a i - i, com a equação de estado SRK associada a parâmetros de interação binária específicos para a solubilidade de hidrogênio em gasolina de pirólise. Os parâmetros de interação binária são provenientes do pacote termodinâmico do simulador iiSE. O modelo do reator foi implementado no software EMSO (Environment for Modeling, Simulation and Optimization) consistindo em cerca de 9000 equações e variáveis. Os resultados obtidos com o modelo contruído foram similares aos reportados na literatura. A aplicação de modelagem por células mostrou-se não só aplicável mas também mais robusta do que as abordagens tradicionais que utilizam equações diferenciais ordinárias. A utilização da ferramenta EMSO para a modelagem por células mostrou-se ainda mais vantajosa ao permitir a avaliação do comportamento dinâmico do reator em algumas situações hipotéticas, mas que são bem comuns na indústria. / Modeling and simulation of three-phase reactors is a challenge for process simulators. Many academic studies have been developed in order to describe and predict the behavior of these equipments for both steady states or dynamic responses. There are several approaches applied trying to reflect better the phenomena involved in three-phase reactors, always considering the computational cost of each approach. In this work a selective hydrogenation reactor for pyrolysis naphtha was simulated based on published literature data.The reactor is trickle bed type and the reactions are considered pseudofirst order. The technique used is cell-network modeling, where the catalyst beds were subdivided into dynamics CSTR reactors linked in series. To each cell there is a calculation Flash associated, enhancing mass and energy balances commonly applied in TBR. The thermodynamic approach used to predict the vapor-liquid equilibrium was i- i with SRK equation of state, associated to specific binary interaction parameters for the solubility of hydrogen in pygas from the thermodynamic simulator package iiSE. The binary interaction parameters come from the thermodynamic package of IISE simulator. The reactor model was implemented in software EMSO (Environment for Modeling, Simulation and Optimization) and consists of 9,000 equations and variables approximately. The results obtained with the model constructed here were similar to those reported in the literature. The use of cell-network modeling proved to be not only applicable but also more robust than the traditional approaches that use ordinary differential equations. The use of EMSO tool for cell-network modeling proved to be even more advantageous because allows the evaluation of some dynamic behavior of the reactor for hypothetical situations but quite common in the industry.