Browsing by Issue Date, starting with "2019-07-25"
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- Towards a Formally Verified Space Mission Software using SPARKPublication . Neto, Paulo Miguel Ferreira; Sousa, Simão Patricio Melo deThis research work is in the scope of the Master course in Computer Science of University of Beira Interior dissertation and introduces the research undertaken in a Master Thesis done in collaboration with Critical Software, SA. This document presents the effort for verification and validation of ExoMars Trace Gas Orbiter Central Software that was fully implemented by Critical Software in cooperation with Thales Alenia Space, for an European Space Agency exploration of Mars atmosphere mission. The work was an Ada implemented code reformulation to SPARK aiming the capability evaluation of code analysis and Design-by-Contract techniques for validation and verification of a spacecraft on board software. On Safety Mission-Critical systems the importance of secure and reliable software path to the introduction of new high integrity development methods as an efficient and low cost alternative of software testing. As Edger Dijsktra said, testing software only detect the presence of bugs but not prove his absence and, besides that, it is a late detection. There is an increased need of safety and functional properties assurance before the system deployment. Design-by-Contract approach is a kind of formal code verification, based on Hoare Logic, that can reduce the costs in two ways, because it gave earlier high guarantees that code is free of runtime errors and run as expected, in the development phase where bugs correction is cheaper. SPARK toolset is used to perform formal code verification for Ada programming language, mostly used on Safety Mission-Critical systems development. SPARK analysis is targeted for assurance of correct information flow and the correct behaviour of programs execution.
- Reconhecimento de faces em diferentes graus de alexitimiaPublication . Monteiro, Sandra Cristina da Silva; Rodrigues, Paulo Joaquim Fonseca da Silva Farinha; Nascimento, Carla Sofia Lucas doO reconhecimento de identidade tem vindo a demonstrar-se uma tarefa fundamental, não só ao nível das relações interpessoais, mas também no desempenho de determinadas profissões que exigem um rápido processamento cognitivo na identificação de duas faces como sendo a mesma ou faces diferentes, como é o caso dos seguranças aeroportuários. Um estudo anterior encontrou, como resultados complementares, que indivíduos alexitimicos tendem a processar esta informação mais rapidamente que indivíduos não alexitimicos. Deste modo, a presente investigação propõe-se a estudar as diferenças na velocidade de processamento de reconhecimento de faces e emoções entre indivíduos alexitimicos e não alexitimicos. Para tal utilizamos a Toronto Alexithymia Scale (TAS) para avaliar os níveis de alexitimia da amostra e recorremos à Radboud Faces Database (RaFD), uma base de dados de fotografias de pessoas reais que correspondiam a determinadas características adequadas a esta investigação, para construir a experiência que permitiu a recolha dos dados. O principal objetivo consistiu em comparar as pontuações obtidas no TAS com a Taxa de Acerto e o Tempo de Resposta Médio da amostra. Desta feita, pretendemos verificar possíveis diferenças na velocidade do reconhecimento de faces e emoções entre sujeitos alexitimicos e não alexitimicos. Assim, relativamente aos resultados, é possível concluir que nenhum deles é estatisticamente significativo, o que sugere que não existem diferenças entre os grupos. Por fim, em relação à discussão, nenhuma das hipóteses colocadas se comprova após as análises efetuadas, o que os permitiu realizar algumas reflecções e sugestões que consideramos pertinentes.
- Determination of the main compounds of Ayahuasca and the study of their cytotoxicity in dopaminergic neuronsPublication . Simão, Ana Aysa Rocha da; Cristovão, Ana Clara Braz; Alba, Maria Eugénia GallardoAyahuasca is a psychoactive beverage prepared traditionally from a mixture of the leaves and stems of Psychotria viridis and Banisteriopsis caapi, respectively, being originally consumed by indigenous Amazonian tribes for ritual and medicinal purposes. Over the years, its use has spread to other populations as a source of personal growth and spiritual connection. Also, the recreational use of the isolated compounds has become prominent. The main compounds of this tea-like preparation are N,N-dimethyltryptamine (DMT) and ß-Carbolines (B-CA) or harmala alkaloids, such as: harmine, tetrahydroharmine and harmaline. The latter are monoamineoxidase (MAO) inhibitors, thus allowing DMT to exert its psychoactive and hallucinogenic effects on the central nervous system (CNS). Although consumers defend its use, its metabolic effects and those on the CNS are not fully understood yet. The majority of studies regarding the effects of this beverage as a whole or as individual compounds are based on in vivo, clinical trials or even on surveys. Therefore, one of the objectives of this work was to develop an analytical method using gaschromatography coupled to a mass spectrometry (GC-MS) was developed to identify such compounds on five varieties of available commercial teas (P. viridis, B. caapi; P. harmala; Mimosa tenuiflora and DC AB). The developed method was fully validated in line with international guidelines for bioanalytical method validation. Linearity was obtained in a range of 0.2-20 µg/mL for all compounds, except for DMT (0.04-4 µg/mL), with determination coefficients above 0.99. In respect to precision and accuracy, the obtained coefficients of variation (CVs) were within the acceptable values (= 20 % for lowest limit of quantification (LLOQ) and = for other concentrations), both for intra- and inter-day. Recoveries ranged from 37 – 97 %. The method was considered suitable for quantify such compounds on real tea samples and P. viridis presented the highest DMT content, while P. harmala presented the highest content of B-CA. Alongside, the in vitro toxicity caused by DMT and ß-Carbolines on N27 rat dopaminergic neurons was evaluated, as well as the toxicity of harmalol, the main metabolite of harmaline. Likewise, all of the teas prepared were tested in cells. Overall, the results show that at the highest concentrations studied all compounds individually and when combined in the tea mixture exert neurotoxicity on N27 dopaminergic cells in a dose-dependent manner. This is the first study to investigate cytotoxicity of Ayahuasca compounds and commercial teas on dopaminergic cells and use GC-MS to quantify these compounds in five different teas, as well as two tea mixtures.