Regularization of energy-momentum tensor correlators and parity-odd terms

We discuss the problem of regularizing correlators in conformal field theories. The only way to do it in coordinate space is to interpret them as distributions. Unfortunately except for the simplest cases we do not have tabulated mathematical results. The way out we pursue here is to go to momentum space and use Feynman diagram techniques and their regularization methods. We focus on the energy-momentum tensor correlators and, to gain insight, we compute and regularize 2-point functions in 2d with various techniques both in coordinate space and in momentum space, obtaining the same results. Then we do the same for 2-point functions in 4d. Finally we turn to 3-point function in 4d, and concentrate on the parity-odd part. We derive in particular the regularized trace and divergence of the energy-momentum tensor in a chiral fermion model. We discuss the problems related to the parity-odd trace anomaly.Comment: 40 pages, 1 figure. v2: minor changes and typos correcte

Social stress: the good, the bad, and the neurotrophic factor:understanding the brain through PET imaging and molecular biology

The growing burden of social pressure is reflected by the increasing number of stress-associated health issues around the globe. One example of a stress-related health issue is depressive disorder. Depression is considered a major global health issue, affecting every cultural, economic and age group. The work described in this thesis aimed to investigate how different social stimuli –beneficial or harmful – can affect the brain. In this context, we mimicked different environments that are usually observed in humans in animal models, which allowed us to investigate how the brain of the animal physiologically responds to different social stressors, focusing especially on memory, inflammation of the brain, and a protein involved in proper functioning and survival of brain cells: the brain-derived neurotrophic factor (BDNF).In this thesis, we describe that social environment is able to increase or decrease BDNF levels in the hippocampus, when animals were exposed for a long time to beneficial or harmful social interactions, respectively. However, when animals were exposed to acute social and physical stress, there was no effect on BDNF concentration. We also found that animals submitted to harmful social stress showed transient effects on behavior, which had normalized after two weeks. Brain inflammation, as observed by positron emission tomography, was also normalized after two weeks. We concluded that the effect of short social stress exposure was temporary, showing an effect after a few days, but normalizing a few weeks after exposure to the stressor, but long exposue to social stimuli can induce lasting modification of brain functioning

Schistosoma Mansonii aspartic protease expression and refolding trials

Schistosomiasis is a parasitic disease that causes considerable socio-economic losses in affected areas due to loss of productive capacity of affected individuals and high rates of morbidity and mortality. Therapeutic controls for this parasitic disease have shown some drawbacks with resistance emergence to praziquantel, the drug of choice for treatment, being reported in recent years. Thus, new chemotherapeutic targets are been investigated, aiming to develop drugs that are more effective, with lower cost and fewer adverse reactions. Among these new targets, aspartic proteases are among the most promising, since their involvement in other diseases such as Alzheimer's and diabetes have been proven and a chemotherapeutic arsenal for AIDS treatment has been developed based on the structure and function of the HIV1 aspartic protease. The rational design of new drugs requires knowledge of the structures of target proteins. In this study we have examined the activation of pro-enzyme, recombinant forms of two putative cathepsin D-like aspartic proteases from the helminth Schistosoma mansonii (SmCDs). Extensive folding trials were undertaken in attempts to determine the potential for activation of the proteolytic activities of the enzymes. A recombinant protein disulfide isomerase from the same organism was also prepared for use in protease folding trials. Preliminary evidence suggests that an activated form of one of the two proteases (SmCD2) may be obtained by introducing a solubilizing maltose-binding tag on the N-terminal end resulting in soluble expression of the enzyme. This result has raised the prospect of developing an in vitro screening tool to identify potential lead compounds for new drug development. Although PDI samples were purified and active in rearrange disulfide bridges of insulin, no evidence of assistance in refolding SmCDs were observed. Since PDI itself may be considered as a drug target, crystallization attempts in order to obtain its structures were done. Both crystallization of PDI and its influence in SmCDs refolding must be further be investigated in different conditions

CFT's, contact terms and anomalies

The first problem that is analysed in this thesis is the possibility of the existence of a parity-odd trace anomaly in 4d in the presence of a curved background. We show some evidence by using Feynman diagram techniques that this anomaly is present in the theory of a free chiral fermion and that it has the curious feature of having a purely imaginary coefficient in Lorentzian signature. We also analyse the theory of a free massive fermion in 3d. We compute two- and three-point functions of a gauge current and the energy-momentum tensor and, for instance, obtain the well-known result that in the IR limit we reconstruct the relevant CS action in the effective action. We then couple the model to higher spin currents and explicitly work out the spin 3 case. In the UV limit we obtain an effective action which was proposed many years ago as a possible generalization of spin 3 CS action. In the IR limit we derive a different higher spin action. This analysis can evidently be generalized to higher spins. We also discuss the conservation and properties of the correlators we obtain in the intermediate steps of our derivation

Evolution of renal transplantation activity in Portugal: public data from 2003 to 2015

Para doentes insuficientes renais, o transplante de rim, quando possível, é a terapia de substituição da função renal que garante uma menor mortalidade, a redução de problemas cardiovasculares e uma melhor qualidade de vida em comparação com a diálise, mesmo em doentes com idade avançada e com morbilidades. A análise sistemática de indicadores associados à actividade da transplantação renal permite a melhor caracterização e conhecimento dos problemas existentes. O objectivo deste trabalho é o de descrever a evolução da actividade de transplantação renal em Portugal com a informação de acesso livre que está disponível para análise. Este estudo tem por base a informação do Observatório Global em Doação e Transplantação, recolhida e produzida pela colaboração entre a Organização Mundial de Saúde e a Organización Nacional de Trasplantes, de onde recolhemos os dados disponíveis respeitantes a Portugal, para os anos entre 2003 e 2015. No período em análise verificamos que 2009 foi o ano que registou um maior número de transplantes renais. Em 2012 registou- se a maior queda do número de transplantes de rim com dador cadáver (-20.8%) em relação ao ano predecessor. Só com a disponibilização de dados para análise é possível fazer o melhor escrutínio de políticas a implementar.For patients with renal insufficiency, renal transplantation, when possible, is the renal replacement therapy that guarantees a lower mortality, a reduction of cardiovascular problems, and a better quality of life compared to dialysis; even in patients with advanced age and morbidities. The systematic analysis of indicators associated with renal transplantation activity allows a better characterization and understanding of inherent problems. The objective of this study is to describe the evolution of kidney transplant activity in Portugal with free access information that is available for analysis. This study is based on information from the Global Observatory on Donation and Transplantation, collected and produced by the collaboration between the World Health Organization and the Organización Nacional de Trasplantes, from where we collected the available data regarding to Portugal for the years between 2003 and 2015. In the analyzed period, 2009 was the year with a higher number of kidney transplants. In 2012 it was registered the highest reduction in kidney transplants from cadaveric donors (-20.8%) compared to the predecessor year.info:eu-repo/semantics/publishedVersio

Transforming Growth Factor-b1 polymorphism is not associated with chronic graft disease: evidence from a meta-analysis

Kidney transplantation has been recognised as the optimal treatment choice for most end stage renal disease patients and the increase of allograft survival rates is achieved through the refinement of novel immunosuppressive agents. Chronic Graft Disease (CGD) is a multifactorial process that likely includes a combination of immunological, apoptotic and inflammatory factors. The application of individualised immunosuppressive therapies will also depend on the identification of risk factors that can influence chronic disease. Despite being the subject of several independent studies, investigations of the relationship between transforming growth factor-b1 (TGF-b1) polymorphisms and kidney graft outcome continue to be plagued by contradictory conclusions