Automatic Unbounded Verification of Alloy Specifications with Prover9

Alloy is an increasingly popular lightweight specification language based on relational logic. Alloy models can be automatically verified within a bounded scope using off-the-shelf SAT solvers. Since false assertions can usually be disproved using small counter-examples, this approach suffices for most applications. Unfortunately, it can sometimes lead to a false sense of security, and in critical applications a more traditional unbounded proof may be required. The automatic theorem prover Prover9 has been shown to be particularly effective for proving theorems of relation algebras [7], a quantifier-free (or point-free) axiomatization of a fragment of relational logic. In this paper we propose a translation from Alloy specifications to fork algebras (an extension of relation algebras with the same expressive power as relational logic) which enables their unbounded verification in Prover9. This translation covers not only logic assertions, but also the structural aspects (namely type declarations), and was successfully implemented and applied to several examples

THE ETHICAL DILEMMA OF EXPATRIATES IN EMERGING ECONOMIES: A LIMINAL PERSPECTIVE

Adjustment to emerging economies is benefited if Western expatriates recognise they are experiencing a liminal situation, which can lead to the instrumental utilisation of coping strategies as equivalent to rites of passage between distinct ethical frameworks. Given the characteristics ascribed to rites, the ethical dilemma resulting from the simultaneous demand to abide by local rules and to respect Western ethical principles is more easily solved. Consequently, effective and sustainable adjustment is favoured. Implications for organisations and individuals are discussed. JEL codes:

The regulation of collaborative economy in the european union

The paper distinguishes between sharing economy and collaborative economy, focusing on the legal framework of collaborative platforms (such as Uber or Airbnb) according to EU law. Case-law from the Court of Justice of the European Union (CJEU) and the position of the European Commission are analyzed in this regard. It is concluded that there is no harmonization, within the European Union, of the legal regime applicable to certain collaborative platforms. As such, specific regulation of collaborative platforms has followed different paths within the Member States

Validating the Hybrid ERTMS/ETCS level 3 concept with electrum

This paper reports on the development of a formal model for the Hybrid ERTMS/ETCS Level 3 concept in Electrum, a lightweight formal specification language that extends Alloy with mutable relations and temporal logic operators. We show how Electrum and its Analyzer can be used to perform scenario exploration to validate this model, namely to check that all the operational scenarios described in the reference document are admissible, and to reason about expected safety properties, which can be easily specified and model checked for arbitrary track configurations. We also show how the Analyzer can be used to depict scenarios (and counter-examples) in a graphical notation that is logic-agnostic, making them understandable by stakeholders without expertise in formal specification.The authors would like to thank David Chemouil for the support provided during the model checking of the model. This work is financed by the ERDF – European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 and by National Funds through the Portuguese funding agency, FCT - Fundação para a Ciência e a Tecnologia within project POCI-01-0145-FEDER-016826

Automated Reusable Tests for Mitigating Secure Pattern Interpretation Errors

The importance of software security has increased along with the number and severity of incidents in recent years. Security is a multidisciplinary aspect of the software development lifecycle, operation, and user utilization. Being a complex and specialized area of software engineering, it is often sidestepped in software development methodologies and processes. We address software security at the design level by adopting design patterns that encapsulate reusable solutions for recurring security problems. Design patterns can help development teams implement the best-proven solutions for a specialized problem domain. However, from the analysis of three secure pattern implementations by 70 junior programmers, we detected several structural errors resulting from their interpretation. We propose reusable unit testing test cases based on annotations to avoid secure pattern interpretation errors and provide an example for one popular secure pattern. Providing these test cases to the same group of programmers, they implemented the pattern without errors. The reason is annotations build a framework that disciplines programmers to incorporate secure patterns in their applications and ensure automatic testing.info:eu-repo/semantics/publishedVersio

Ulisses NextGen

Dissertação de mestrado integrado em Informatics EngineeringNowadays data can have many different shapes and relations between itself, ontologies try to formalize the semantics subjacent to this data and make it understandable by humans and code alike. While code succeeds at parsing and interpreting this formalization traditional ontology formats can be tough for a human to understand without previously deepened knowledge of the ontologic paradigm and, even then, directly analyzing a format like RDF would be, at the very least, very tedious. This problem is not exclusive to ontologic data either as to make sense of big datasets, even in famously human readable formats like JSON, humans need visualizations and abstractions. This dissertation is a study on graph visualization of ontologic data and how abstractions can be used to convey information to the end user in meaningful ways The information gathered is then used to implement an application called "Ulisses NextGen" that can generate an easily navigable graph visualizing application with a strong focus to support ontological data but general enough to support any information that can be abstracted as a graph. The application is served as a javascript package to be used in anywhere on the web where it can be used best to reach the end user.Hoje em dia os dados podem ter muitas formas e relações diferentes entre si, as ontologias tentam formalizar a semântica subjacente a estes dados e torná-los compreensíveis tanto para o ser humano como para o código. Embora o código consiga análisar e interpretar facilmente esta formalização, os formatos tradicionais de ontologias podem ser difíceis de entender para um humano sem um con hecimento previamente aprofundado do paradigma ontológico e, mesmo assim, analisar directamente um formato como o RDF seria, no mínimo, muito tedioso. Este problema não é exclusivo dos dados ontológicos, existe tradicionalmente uma grande dificulade por parte do ser humano em interpretar grandes conjuntos de dados precisando de visualizações e abstracções. Esta dissertação é um estudo sobre a visualização gráfica de dados ontológicos e como as abstracções podem ser usadas para transmitir informação ao utilizador final de formas significativas A informação recolhida é então usada para implementar uma aplicação chamada "Ulisses NextGen" que gera um grafo facilmente navegável com um grande foco para suportar dados ontológicos mas geral o suficiente para suportar qualquer informação que possa ser abstraída como um grafo. A aplicação é servida como um pacote javascript para ser usado em qualquer lugar na web onde possa ser melhor utilizada para chegar ao utilizador final

Quantitative relational modelling with QAlloy

Alloy is a popular language and tool for formal software design. A key factor to this popularity is its relational logic, an elegant specification language with a minimal syntax and semantics. However, many software problems nowadays involve both structural and quantitative requirements, and Alloy's relational logic is not well suited to reason about the latter. This paper introduces QAlloy, an extension of Alloy with quantitative relations that add integer quantities to associations between domain elements. Having integers internalised in relations, instead of being explicit domain elements like in standard Alloy, allows quantitative requirements to be specified in QAlloy with a similar elegance to structural requirements, with the side-effect of providing basic dimensional analysis support via the type system. The QAlloy Analyzer also implements an SMT-based engine that enables quantities to be unbounded, thus avoiding many problems that may arise with the current bounded integer semantics of Alloy.FCT - Fundação para a Ciência e a Tecnologia(LA/P/0063/2020

O factor de trancrição NDT80 como regulator negativo da adesão e da formação de biofilme em Candida parapsilosis

Mestrado em Biologia Molecular e CelularC. parapsilosis infections incidence has been increasing for the past 20 years. Its caracteristics of adhering and forming biofilms are a critical factor for infection caused by this organism, affecting from immunocompromised or transplanted patients to low-birth-weight neonates. The health-care workers are a major transmission vehicle of this fungus. The azoles class of antifungal drugs are the first and most common line of defense to treat infections by this type of yeast species. Its mode of action on the yeast cell works by inhibiting the lanoststerol 14α-demethylase, an enzyme belonging to the ergosterol biosyntethic pathway.. On a recent study it has become clear that C. parapsilosis antifungal azole resistance may display similar resistance mechanisms that the ones described for C. albicans. A resistant strain obtained after exposure to posaconazole has shown an upregulation of two transcriptional factors, Upc2 and Ndt80. The aim of this work was to assess the role of these two transcriptional factors on C. parapsilosis azole resistance. For that, it was intended to knockout both genes using the SAT1-flipper cassette. The strain obtained after disruption of one copy of NDT80 gene displayed an unexpected phenotype, concerning adhesion and biofilm formation, comparatively to the wild-type BC014 strain. It were also made susceptibility tests although with no evident changes. These results demonstrate that NDT80 gene may be a negative regulator of C. parapsilosis adherence to abiotic and biotic substrates, impairing also biofilm formation.As infecções por C. parapsilosis têm vindo a aumentar nos últimos 20 anos. As suas características intrínsecas de adesão e capacidade de formação de biofilmes são um factor critíco de infecção, sendo os pacientes transplantados ou com o sistema imunitário comprometido ou mesmo os neonatos de baixo peso o grupo de risco mais afectado. Os prestadores de cuidados de saúde são o meio de transmissão mais comum para a infecção por esta levedura. A classe dos antifúngicos azóis são a primeira linha de defesa para tratamento de infecções por este tipo de leveduras. Estes actuam inibindo a enzima lanosterol 14α-demethylase, enzima constituinte da via biossintética do ergosterol. Um estudo recente demonstrontrou que a resistência aos azoles em C. parapsilosis poderá ter os mesmos mecanismos observados e estudados em C. albicans. Uma estirpe resistente obtida após exposição a Posaconazole revelou uma sobre-expressão de 13 genes envolvidos na biossíntese do ergosterol, entre eles dois factores de transcrição, Upc2 e Ndt80. Com vista a avaliar o papel destes factores de transcrição na resistência aos azoles em C. parapsilosis, pretendeu-se efectuar a delecção dos dois genes usando a ferramenta molecular SAT1-flipper cassette. Apenas um alelo do gene NDT80 foi deletado, originando um fenótipo distinto em comparação com a estirpe original BC014, em particular na sua capacidade de adesão e de formação de biofilmes. Foram realizados testes de susceptibilidade embora sem qualquer diferença evidente entre fenótipos. Estes resultados demonstram que o gene NDT80 pode ser um regulador negativo da capacidade de adesão de C. parapsilosis, afectando também o seu potencial de formação de biofilmes

Prehospital therapeutic hypothermia in recovered cardiac arrest victims

INTRODUÇÃO A Hipotermia terapêutica consiste no arrefecimento corporal induzido com o objetivo de manter uma temperatura central de 33ºC, com a finalidade de reverter e ou prevenir os mecanismos responsáveis pela lesão neurológica de reperfusão após recuperação de circulação espontânea. Existe alguma evidência de que a hipotermia terapêutica melhora a sobrevivência e o resultado neurológico após paragem cardíaca ocorrida no préhospitalar, contudo a sua utilização não é ainda consensual em vítimas com recuperação de circulação espontânea. OBJETIVO Determinar a eficácia da Hipotermia Terapêutica induzida no Pré-Hospitalar na melhoria da sobrevivência e dos resultados neurológicos das vítimas que sofreram paragem cardíaca extrahospitalar. MÉTODOS Foi realizada uma revisão sistemática da literatura sobre estudos que avaliavam a eficácia da aplicação de hipotermia terapêutica nas vítimas de paragem cardíaca no contexto de pré-hospitalar. Cinco RCT’s, envolvendo 759 participantes, sendo 378 do grupo de hipotermia pré-hospitalar e 381 do grupo controlo. RESULTADOS A análise dos estudos revelou que existem diferenças significativas na diminuição da temperatura na admissão hospitalar quando utilizada a HTPH comparativamente à normotermia ou hipotermia terapêutica hospitalar (HTH) (IV=-1,16; IC 95%= -1,40-0,92; p<0,00001). Contudo não são observadas diferenças significativas no que se refere à sobrevivência (RR=0,97; IC 95%=0,79-1,19; p=0,76) e outcomes neurológicos favoráveis (RR=0,98; IC 95%=0,79-1,20; p=0,83). CONCLUSÕES A hipotermia terapêutica no pré-hospitalar não tem influência na sobrevivência e nos outcomes neurológicos favoráveis no momento da alta, mas apresenta benefício com relevância clinica nos valores da temperatura no momento da admissão hospitalar, pelo que se infere serem necessários mais estudos para aferir da eficácia desta medida terapêutica.info:eu-repo/semantics/publishedVersio