Digitally programmable delay-locked-loop with adaptive charge pump current for UWB radar system

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para obtenção do grau de Mestre em Engenharia Electrotécnica e Computadores

Relative abelian kernels of some classes of transformation monoids

Bulletin of the Australian Mathematical Society, nº 73 (2006), p. 375-404

Estudo da expressão génica da Legionella pneumophila estirpe paris após co-cultura em Acanthamoeba castellanii

RESUMO: A Legionella é um bacilo Gram-negativo que replica dentro de protozoários como Acanthamoeba castellanii (A. castellanii) e no interior de macrófagos alveolares humanos, podendo resultar numa pneumonia grave. A Legionella em meio líquido tem um ciclo de vida bifásico, apresentando traços replicativos na fase exponencial e expressando factores transmissíveis na fase estacionária. Estudos recentes demonstraram que a Legionella precisa de assegurar um tempo preciso no seu ciclo de vida para efectuar com êxito a infecção das células hospedeiras. Muitos modelos de estudo foram desenvolvidos a fim de aumentar o conhecimento sobre o ciclo de vida intracelular e identificar os genes necessários para a modulação da célula hospedeira. Embora o conhecimento sobre a interacção bactéria-hospedeiro ainda seja limitado, parece que esta interacção gera um conjunto de características de virulência permitindo que a bactéria infecte células fagocíticas humanas e cause doença. O objectivo do presente projecto de investigação foi investigar e seleccionar genes críticos para a infecciosidade da Legionella pneumophila estirpe Paris (Lp Paris), desenhar e optimizar uma técnica de PCR em tempo real para o estudo da expressão génica e comparar o perfil de expressão da Lp Paris antes e depois da co-cultura em A. castellanii. Os resultados mostraram que oito dos 12 genes em estudo alteraram a sua expressão relativa após co-cultura em A. castellanii quando os ensaios foram realizados com culturas de Lp Paris na fase estacionária precoce (cinco foram induzidos e três reprimidos) Quando os ensaios foram realizados com culturas de Lp Paris na fase estacionária tardia 11 genes apresentaram repressão na sua expressão relativa. Analisando os resultados, concluímos que o perfil de expressão de Lp Paris foi modificado pela interacção com A. castellanii, no entanto essa mudança foi dependente da fase do seu ciclo de vida.-------ABSTRACT: Legionella is a pathogenic Gram-negative bacterium that replicates not only within aquatic protozoa like Acanthamoeba castellanii (A. castellanii), but also within human alveolar macrophages, which can result in a severe pneumonia. Legionella has a biphasic life cycle in broth, where exponential phase cultures display replicative traits and stationary bacteria express transmissive factors. Recent studies demonstrated that for successful infection of host cells, Legionella needs to ensure a precise timing of its life cycle. Many models of study were developed in order to learn about the intracellular life cycle and to identify the genes necessary for the host cell modulation. Although knowledge about the bacteria-host interaction is still limited, it appears that this interaction generate a pool of virulence traits, allowing the bacterium to infect human phagocytic cells and cause disease. The purpose of the present study was to investigate and select de critical genes for the infectivity of Legionella pneumophila strain Paris (Lp Paris), design and optimize a real time PCR technique for gene expression study and compare the expression profile of Lp Paris before and after co- culture of A. castellanii. The results show that eight of 12 genes in study changed its relative expression after coculture in A. castellanii when we performed the intracellular assays with early stationary phase Lp Paris cultures (five were induced and tree were repressed). When we performed the intracellular assays with late stationary phase Lp Paris cultures 11 genes showed a repressed relative expression. Analysing the results, we conclude that the expression profile of Lp Paris was modified by interaction with A. castellanii but this change was dependent of the timing of its life cycle.

Making sense of the experimental evidence on endogenous timing in duopoly markets

The prediction of asymmetric equilibria with Stackelberg outcomes is clearly the most frequent result in the endogenous timing literature. Several experiments have tried to validate this prediction empirically, but failed to find support for it. By contrast, the experiments find that simultaneous-move outcomes are modal and that behavior in endogenous timing games is quite heterogeneous. This paper generalizes Saloner’s (1987) and Hamilton and Slutsky’s (1990) endogenous timing games by assuming that players are averse to inequality in payoffs. We explore the theoretical implications of inequity aversion and compare them to the empirical evidence. We find that this explanation is able to organize most of the experimental evidence on endogenous timing games. However, inequity aversion is not able to explain delay in Hamilton and Slutsky’s endogenous timing games.

Forecasts of relative performance in tournaments: Evidence from the field

This paper uses a field experiment to investigate the quality of individuals’ forecasts of relative performance in tournaments. We ask players in luck-based (poker) and skill-based (chess) tournaments to make point forecasts of rank. The main finding of the paper is that players’ forecasts in both types of tournaments are biased towards overestimation of relative performance. However, the size of the biases found is not as large as the ones often reported in the psychology literature. We also find support for the “unskilled and unaware hypothesis” in chess: high skilled chess players make better forecasts than low skilled chess players. Finally, we find that chess players’ forecasts of relative performance are not efficient.

Exploiting the cointrgration between vix and CDS in a credit market timing model

We investigate the cointegration between VIX and CDS indices, and the possibility of exploiting it in an existing credit market timing investment model. We find cointegration over most of the sample period and the leadership of VIX over the CDS in the price discovery process. We present two methods for including cointegration into the model. Both strategies improve the in-sample and out-of-sample model performances, even though out-of-sample results are weaker. We find that in-sample better performances are explained by a stronger cointegration, concluding that in the presence of cointegration our strategies can be profitable in an investment model that considers transaction costs.

Fatigue life assessment of endodontic instruments subjected to multi planar curvature

This present study aimed to investigate the fatigue life of unused (new) endodontic instruments made of NiTi with control memory by Coltene™ and subjected to the multi curvature of a mandibular first molar root canal. Additionally, the instrument‟s structural behaviour was analysed through non-linear finite element analysis (FEA). The fatigue life of twelve Hyflex™ CM files was assessed while were forced to adopt a stance with multiple radius of curvature, similar to the ones usually found in a mandibular first molar root canal; nine of them were subjected to Pecking motion, a relative movement of axial type. To achieve this, it was designed an experimental setup with the aim of timing the instruments until fracture while worked inside a stainless steel mandibular first molar model with relative axial motion to simulate the pecking motion. Additionally, the model‟s root canal multi-curvature was confirmed by radiography. The non-linear finite element analysis was conducted using the computer aided design software package SolidWorks™ Simulation, in order to define the imposed displacement required by the FEA, it was necessary to model an endodontic instrument with simplified geometry using SolidWorks™ and subsequently analyse the geometry of the root canal CAD model. The experimental results shown that the instruments subjected to pecking motion displayed higher fatigue life values and higher lengths of fractured tips than those with only rotational relative movement. The finite element non-linear analyses shown, for identical conditions, maximum values for the first principal stress lower than the yield strength of the material and those were located in similar positions to the instrument‟s fracture location determined by the experimental testing results.