Associação entre polimorfismo inserção/delecção da enzima conversora da angiotensina na diabetes mellitus tipo 2: estudo da população portuguesa

A Diabetes mellitus tipo 2 (DM2) é uma patologia de etiologia múltipla à qual estão associados vários factores genéticos. A Enzima Conversora da Angiotensina (ECA) tem sido alvo de vários estudos pela sua relação com factores pró-inflamatórios, pró-oxidantes e pró-fibrose, sendo o polimorfismo de Inserção/Delecção o mais estudado. Neste contexto, o objectivo deste estudo é assim verificar a distribuição deste polimorfismo numa amostra de indivíduos de nacionalidade portuguesa e verificar a sua possível associação com a DM2. Para tal, foram analisadas 87 amostras (controlos n =24 e diabéticos n =63) de indivíduos de nacionalidade portuguesa. As amostras foram submetidas a um processo de extracção de ADN, sendo posteriormente amplificadas por Polymerase Chain Reaction e analisadas por eletroforese em gel de agarose a 1%. Observou-se uma prevalência de 8% (n=7) com genótipo I/I, 38% (n=33) com genótipo I/D e 54% (n=47) com genótipo D/D. A amostra em estudo demonstrou assim estar sob o equilíbrio Hardy-Weinberg. Observou-se também uma associação entre níveis mais elevados de glicemia e o genótipo I/I (p=0,019). Na análise da utilização de insulina no controlo dos níveis de glicemia na DM2, observou-se uma maior proporção de indivíduos com genótipo D/D. Este estudo demonstra a importância do investimento da caracterização genética em patologias metabólicas multifactoriais como a DM2.

Evaluating P-NET message's response time with fixed priority queuing at application process level

P-NET is a multi-master fieldbus standard based on a virtual token passing scheme. In P-NET each master is allowed to transmit only one message per token visit. In the worst-case, the communication response time can be derived considering that, in each token cycle, all stations use the token to transmit a message. In this paper, we define a more sophisticated P-NET model, which considers the actual token utilisation. We then analyse the possibility of implementing a local priority-based scheduling policy to improve the real-time behaviour of P-NET.

Supporting real-time distributed computer-controlled systems with multi-hop P-NET networks

Fieldbus communication networks aim to interconnect sensors, actuators and controllers within process control applications. Therefore, they constitute the foundation upon which real-time distributed computer-controlled systems can be implemented. P-NET is a fieldbus communication standard, which uses a virtual token-passing medium-access-control mechanism. In this paper pre-run-time schedulability conditions for supporting real-time traffic with P-NET networks are established. Essentially, formulae to evaluate the upper bound of the end-to-end communication delay in P-NET messages are provided. Using this upper bound, a feasibility test is then provided to check the timing requirements for accessing remote process variables. This paper also shows how P-NET network segmentation can significantly reduce the end-to-end communication delays for messages with stringent timing requirements.

Communication response time in P-NET networks: worst-case analysis considering the actual token utilisation

Fieldbus networks aim at the interconnection of field devices such as sensors, actuators and small controllers. Therefore, they are an effective technology upon which Distributed Computer Controlled Systems (DCCS) can be built. DCCS impose strict timeliness requirements to the communication network. In essence, by timeliness requirements we mean that traffic must be sent and received within a bounded interval, otherwise a timing fault is said to occur. P-NET is a multi-master fieldbus standard based on a virtual token passing scheme. In P-NET each master is allowed to transmit only one message per token visit, which means that in the worst-case the communication response time could be derived considering that the token is fully utilised by all stations. However, such analysis can be proved to be quite pessimistic. In this paper we propose a more sophisticated P-NET timing analysis model, which considers the actual token utilisation by different masters. The major contribution of this model is to provide a less pessimistic, and thus more accurate, analysis for the evaluation of the worst-case communication response time in P-NET fieldbus networks.

Adding local priority-based dispatching mechanisms to P-NET networks: a fixed priority approach

In this paper we address the real-time capabilities of P-NET, which is a multi-master fieldbus standard based on a virtual token passing scheme. We show how P-NET’s medium access control (MAC) protocol is able to guarantee a bounded access time to message requests. We then propose a model for implementing fixed prioritybased dispatching mechanisms at each master’s application level. In this way, we diminish the impact of the first-come-first-served (FCFS) policy that P-NET uses at the data link layer. The proposed model rises several issues well known within the real-time systems community: message release jitter; pre-run-time schedulability analysis in non pre-emptive contexts; non-independence of tasks at the application level. We identify these issues in the proposed model and show how results available for priority-based task dispatching can be adapted to encompass priority-based message dispatching in P-NET networks.

Aplicação de Internet of Things em casas inteligentes - Serviço Aplicacional

Engenharia Informática, Área de Especialização em Arquiteturas, Sistemas e Redes

Global and Partitioned Multiprocessor Fixed Priority Scheduling with Deferred Pre-emption

This article introduces schedulability analysis for global fixed priority scheduling with deferred preemption (gFPDS) for homogeneous multiprocessor systems. gFPDS is a superset of global fixed priority pre-emptive scheduling (gFPPS) and global fixed priority non-pre-emptive scheduling (gFPNS). We show how schedulability can be improved using gFPDS via appropriate choice of priority assignment and final non-pre-emptive region lengths, and provide algorithms which optimize schedulability in this way. Via an experimental evaluation we compare the performance of multiprocessor scheduling using global approaches: gFPDS, gFPPS, and gFPNS, and also partitioned approaches employing FPDS, FPPS, and FPNS on each processor.