ARP Caso ARP Nº 17

39 year old female, presenting at ER with aphasia and right hemiparesis. A few hours later, develops mild hemoptysis. Thoracic CT performed to exclude pulmonary embolism. Patient taking immunosupressants for suspected demyelinating disease (multiple sclerosis?), due to relapsing-remitting but progressive episodes of limb weakness and numbness and impaired and blurred vision

Caso Clínico ARP Nº17: Arterite de Takayasu

39 year old female, presenting at ER with aphasia and right hemiparesis. A few hours later, develops mild hemoptysis. Thoracic CT performed to exclude pulmonary embolism. Patient taking immunosupressants for suspected demyelinating disease (multiple sclerosis?), due to relapsing-remitting but progressive episodes of limb weakness and numbness and impaired and blurred vision

Preliminary Specification of Services and Protocols

This document describes the preliminary specification of services and protocols for the Crutial Architecture. The Crutial Architecture definition, first addressed in Crutial Project Technical Report D4 (January 2007), intends to reply to a grand challenge of computer science and control engineering: how to achieve resilience of critical information infrastructures, in particular in the electrical sector. The definitions herein elaborate on the major architectural options and components established in the Preliminary Architecture Specification (D4), with special relevance to the Crutial middleware building blocks, and are based on the fault, synchrony and topological models defined in the same document. The document, in general lines, describes the Runtime Support Services and APIs, and the Middleware Services and APIs. Then, it delves into the protocols, describing: Runtime Support Protocols, and Middleware Services Protocols. The Runtime Support Services and APIs chapter features as a main component, the Proactive-Reactive Recovery Service, whose aim is to guarantee perpetual execution of any components it protects. The Middleware Services and APIs chapter describes our approach to intrusion-tolerant middleware. The middleware comprises several layers. The Multipoint Network layer is the lowest layer of CRUTIAL's middleware, and features an abstraction of basic communication services, such as provided by standard protocols, like IP, IPsec, UDP, TCP and SSL/TLS. The Communication Support Services feature two important building blocks: the Randomized Intrusion-Tolerant Services (RITAS), and the Overlay Protection Layer (OPL) against DoS attacks. The Activity Support Services currently defined comprise the CIS Protection service, and the Access Control and Authorization service. Protection as described in this report is implemented by mechanisms and protocols residing on a device called Crutial Information Switch (CIS). The Access Control and Authorization service is implemented through PolyOrBAC, which defines the rules for information exchange and collaboration between sub-modules of the architecture, corresponding in fact to different facilities of the CII's organizations.The Monitoring and Failure Detection layer contains a preliminary definition of the middleware services devoted to monitoring and failure detection activities. The remaining chapters describe the protocols implementing the above-mentioned services: Runtime Support Protocols, and Middleware Services Protocol

How to Tolerate Half Less One Byzantine Nodes in Practical Distributed System

The application of dependability concepts and approaches to the design of secure distributed systems is raising a considerable amount of interest in both communities under the designation of intrusion tolerance. However, practical intrusion-tolerant replicated systems based on the state machine approach can handle at most f Byzantine components out of a total of n=3f+1, which is the maximum resilience in asynchronous systems. This paper extends the normal asynchronous system with a special distributed oracle called TTCB. Using this extended system we manage to implement an intrusion-tolerant service, based on the state machine approach (SMA), with 2f+1 replicas only. Albeit a few other papers in the literature present intrusion-tolerant services based on the SMA, this is the first time the number of replicas is reduced from 3f+1 to 2f+1. Another interesting characteristic of the described service is a low time complexit

The Design of a COTS Real-Time Distributed Security Kernel (Extended Version)

This technical report describes the design of a security kernel called TTCB, which has innovative features. Firstly, it is a distributed subsystem with its own secure network. Secondly, the TTCB is real-time, that is, a synchronous subsystem capable of timely behavior. These two characteristics together are uncommon in security kernels. Thirdly, the TTCB can be implemented using only COTS components. We discuss essentially three things in this paper: (1) The TTCB is a simple component providing a small set of basic secure services. It aims at building a new style of protocols to achieve intrusion tolerance, which for the most part execute in insecure, arbitrary failure environments, and resort to the TTCB only in crucial parts of their operation. (2) Besides, the TTCB is a synchronous device supplying functions that may be an enabler of a new generation of timed secure protocols, until now known to be fragile due to attacks on timing assumptions. (3) Finally, we present a design methodology that establishes our hybrid failure assumptions in a well-founded manner. It helps us to achieve a robust design, despite using exclusively COTS components, with the advantage of allowing the security kernel to be easily deployed on widely used platform

Erosão Hídrica Estrutural – EHE: Descrição de processos de modelação geográfica

Sendo o fenómeno de erosão hídrica do solo resultante de variados factores em contextos de complexidade, decorrente da sua natureza inter-relacionada, considera-se pertinente uma aproximação visando a definição de uma metodologia simples e eficaz, facilmente aplicável ao ordenamento do território. Podendo a força gravítica, ou melhor dizendo, o trabalho da força gravítica ser considerado o factor primordial em processos de erosão decorrentes do escoamento superficial, a metodologia desenvolvida integrou primeiramente esta dimensão. Considera-se o estudo dos processos erosivos numa perspectiva global ou de contexto, integrando nos procedimentos metodológicos não a erosão específica local decorrente da inclinação do terreno em cada local ou célula, mas a erosão potencial global cumulativa, em que a erosão em cada célula é influenciada por um conjunto de células e influencia outro conjunto de células. Outros modelos de previsão de perda de solo recorrem a este princípio, como o WEPP, Water Erosion Prediction Project (Flanagan, D. C., ed, 1994), e têm demonstrado bastante aderência à realidade, de acordo com os trabalhos desenvolvidos com base nos dados da Estação Experimental de Erosão de Vale Formoso (Tomás, 1997), sendo limitados pela quantidade de informação de base necessária à sua utilização. Em 2001 foi adaptado ao modelo WEPP a metodologia MIR (Minimum Information Requirement) que se baseia fundamentalmente em informação topográfica, de solo e de ocupação do solo associada a um simulador, usando um conjunto mínimo de informação para estimar a perda de solo (Brazier, 2001). A abordagem agora desenvolvida distingue-se de abordagens mais usualmente aplicadas no nosso país, que assentam na integração de classes de declive com classes de avaliação de erodibilidade do solo definidas pericialmente e de acordo com valores de referência provenientes de diversos autores. Tendo em conta estas considerações desenvolveu-se um modelo de cálculo do índice topográfico de Erosão Hídrica Estrutural (EHE) que constitui uma métrica da acção do relevo no processo de erosão hídrica integrando diversas variáveis topográficas segundo os princípios da mecânica clássica, adaptados às características do ambiente (software) de modelação

Toolbox EHE - Erosão Hídrica Estrutural

A Toolbox EHE é uma ferramenta desenvolvida em “Model Builder - ArcGIS 9.3" integrando os pressupostos metodológicos do Modelo EHE, desenvolvido por uma equipa da Escola de Ciências e Tecnologia da Universidade de Évora, visando a implementação de critérios de delimitação das Áreas de Elevado Risco de Erosão Hídrica do Solo no âmbito da Reserva Ecológica Nacional

On the Resilience of Intrusion-Tolerant Distributed Systems

The paper starts by introducing a new dimension along which distributed systems resilience may be evaluated - exhaustion-safety. A node-exhaustion-safe intrusion-tolerant distributed system is a system that assuredly does not suffer more than the assumed number of node failures (e.g., crash, Byzantine). We show that it is not possible to build this kind of systems under the asynchronous model. This result follows from the fact that in an asynchronous environment one cannot guarantee that the system terminates its execution before the occurrence of more than the assumed number of faults. After introducing exhaustion-safety, the paper proposes a new paradigm - proactive resilience - to build intrusion-tolerant distributed systems. Proactive resilience is based on architectural hybridization and hybrid distributed system modeling. The Proactive Resilience Model (PRM) is presented and shown to be a way of building node-exhaustion-safe intrusion-tolerant systems. Finally, the paper describes the design of a secret sharing system built according to the PRM. A proof-of-concept prototype of this system is shown to be highly resilient under different attack scenarios

Perceção do Funcionamento Familiar e do Suporte Social em Estudantes do Ensino Superior em Portugal Continental

Objetivo: Esta investigação pretende analisar a perceção de funcionamento familiar e a satisfação do suporte social em estudantes do ensino superior em Portugal Continental. Metodologia: Participaram 516 estudantes a estudar em Aveiro, Coimbra, Leiria e Lisboa, nos cursos de Ciências do Desporto, Enfermagem, Engenharia Mecânica, Gestão, Jornalismo/Comunicação, Medicina e Psicologia com idades compreendidas entre os 17 e os 38 anos de idade. Os instrumentos aplicados foram a Escala de Avaliação da Flexibilidade e da Coesão Familiar (FACES-IV), Escala de Satisfação com o Suporte Social (ESSS) e o questionário sócio demográfico e de dados complementares. Resultados: Os participantes avaliaram as suas famílias como equilibradas, apresentando resultados elevados na coesão equilibrada e na flexibilidade equilibrada. Os estudantes referem boa comunicação familiar, mas sentem-se insatisfeitos com as suas famílias. Relativamente à satisfação com o suporte social, estudantes percecionam elevada e média satisfação com o Suporte Social. Os alunos que apresentam perceção mais elevada de suporte social são de Psicologia e Ciências do Deporto e os que apresentam menos satisfação são os de Medicina e os alunos que frequentam o quinto ano. As variáveis associadas ao funcionamento familiar explicaram 49 % da variância do suporte social. Conclusões: O funcionamento familiar e o suporte social parecem relacionar-se de forma positiva. Este estudo traz contributos para a compreensão do papel da família e do suporte social no processo de adaptação dos jovens ao ensino superior. / Objective/Purpose: The aim of this study was to analyse the perception of the family functioning and the satisfaction with the social support in higher education students from mainland Portugal. Methods: A total of 516 students participated in this research. They studied Sports Sciences, Nursing, Mechanical Engineering, Management, Journalism/Communication, Medicine and Psychology in Aveiro, Coimbra, Leiria and Lisbon. Their ages vary between 17 and 38 years old. The instruments applied were the Family Adaptability and Cohesion Scale (FACES-IV), the Satisfaction with Social Support Scale (ESSS) and the socio-demographic and complementary data questionnaire. Results: The participants evaluated their families as balanced, presenting high results in balanced cohesion and in balanced adaptability. The students perceive good family communication and are mostly dissatisfied with their families. Concerning the satisfaction with social support, students perceived high and medium satisfaction with Social Support. The students who presented higher perception of social support study Psychology and Sports Sciences and the students with lower satisfaction study Medicine. Students attending the fifth year perceive lower satisfaction with social support. The variables associated with family functioning explain 49% of the social support variance. Conclusions: The family functioning and the social support seem to relate positively. This study brings contributes for the comprehension of the family role and social support in the process of adaptation to higher education

Low Complexity Byzantine-Resilient Consensus

The application of the tolerance paradigm to security intrusion tolerance has been raising a good deal of attention in the dependability and security communities. This paper is concerned with a novel approach to intrusion tolerance. The idea is to use privileged distributed components generically designated by wormholes to support the execution of intrusion-tolerant protocols, often called Byzantine-resilient protocols in the literature. The paper introduces the design of wormhole-aware intrusion-tolerant protocols using a classical distributed systems problem: consensus. The system where the consensus protocol runs is mostly asynchronous and can fail in an arbitrary way, except for the wormhole, which is secure and synchronous. Using the wormhole to execute a few critical steps, the protocol manages to have a low time complexity: in the best case, it runs in a single round, even if some processes are malicious. The protocol is also arguably faster than classical Byzantine protocols, because it does not use public-key cryptography in runtime. The protocol has the interesting feature of not being bound by the FLP impossibility resul