Memoria social, identidad, poder y conflicto

Este texto trata sobre las relaciones entre identidad, memoria, poder y conflicto. Partiendo de un análisis de la memoria de dos ancianos, los propios abuelos maternos del autor, se enfoca el papel del género, la familia, la posición social y la biografía (trayectoria) en la producción de la memoria. Después de pasar revista de un modo sintético a los esquemas y procesos de la memoria, se aborda la relación entre memoria, identidad social, poder y conflicto en un espacio rural portugués que el autor estudió

Long-distance nationalism, boundaries and the experience of racism among Santomean migrants in Portugal

This study will pay attention to modalities of the expression and reproduction of long-distance nationalism among immigrants from S. Tomé and Príncipe in Lisbon – commemorations and conversations and narratives – that are also dimensions of social memory.info:eu-repo/semantics/publishedVersio

Performance Assessment of Routing Protocols for IoT/6LoWPAN Networks

The Internet of Things (IoT) proposes a disruptive communication paradigm that allows smart objects to exchange data among themselves to reach a common goal. IoT application scenarios are multiple and can range from a simple smart home lighting system to fully controlled automated manufacturing chains. In the majority of IoT deployments, things are equipped with small devices that can suffer from severe hardware and energy restrictions that are responsible for performing data processing and wireless communication tasks. Thus, due to their features, communication networks that are used by these devices are generally categorized as Low Power and Lossy Networks (LLNs). The considerable variation in IoT applications represents a critical issue to LLN networks, which should offer support to different requirements as well as keeping reasonable quality-of-service (QoS) levels. Based on this challenge, routing protocols represent a key issue in IoT scenarios deployment. Routing protocols are responsible for creating paths among devices and their interactions. Hence, network performance and features are highly dependent on protocol behavior. Also, based on the adopted protocol, the support for some specific requirements of IoT applications may or may not be provided. Thus, a routing protocol should be projected to attend the needs of the applications considering the limitations of the device that will execute them. Looking to attend the demand of routing protocols for LLNs and, consequently, for IoT networks, the Internet Engineering Task Force (IETF) has designed and standardized the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). This protocol, although being robust and offering features to fulfill the need of several applications, still presents several faults and weaknesses (mainly related to its high complexity and memory requirement), which limits its adoption in IoT scenarios. An alternative to RPL, the Lightweight On-demand Ad Hoc Distancevector Routing Protocol – Next Generation (LOADng) has emerged as a less complicated routing solution for LLNs. However, the cost of its simplicity is paid for with the absence of adequate support for a critical set of features required for many IoT environments. Thus, based on the challenging open issues related to routing in IoT networks, this thesis aims to study and propose contributions to better attend the network requirements of IoT scenarios. A comprehensive survey, reviewing state-of-the-art routing protocols adopted for IoT, identified the strengths and weaknesses of current solutions available in the literature. Based on the identified limitations, a set of improvements is designed to overcome these issues and enhance IoT network performance. The novel solutions are proposed to include reliable and efficient support to attend the needs of IoT applications, such as mobility, heterogeneity, and different traffic patterns. Moreover, mechanisms to improve the network performance in IoT scenarios, which integrate devices with different communication technologies, are introduced. The studies conducted to assess the performance of the proposed solutions showed the high potential of the proposed solutions. When the approaches presented in this thesis were compared with others available in the literature, they presented very promising results considering the metrics related to the Quality of Service (QoS), network and energy efficiency, and memory usage as well as adding new features to the base protocols. Hence, it is believed that the proposed improvements contribute to the state-of-the-art of routing solutions for IoT networks, increasing the performance and adoption of enhanced protocols.A Internet das Coisas, do inglês Internet of Things (IoT), propõe um paradigma de comunicação disruptivo para possibilitar que dispositivos, que podem ser dotados de comportamentos autónomos ou inteligentes, troquem dados entre eles buscando alcançar um objetivo comum. Os cenários de aplicação do IoT são muito variados e podem abranger desde um simples sistema de iluminação para casa até o controle total de uma linha de produção industrial. Na maioria das instalações IoT, as “coisas” são equipadas com um pequeno dispositivo, responsável por realizar as tarefas de comunicação e processamento de dados, que pode sofrer com severas restrições de hardware e energia. Assim, devido às suas características, a rede de comunicação criada por esses dispositivos é geralmente categorizada como uma Low Power and Lossy Network (LLN). A grande variedade de cenários IoT representam uma questão crucial para as LLNs, que devem oferecer suporte aos diferentes requisitos das aplicações, além de manter níveis de qualidade de serviço, do inglês Quality of Service (QoS), adequados. Baseado neste desafio, os protocolos de encaminhamento constituem um aspecto chave na implementação de cenários IoT. Os protocolos de encaminhamento são responsáveis por criar os caminhos entre os dispositivos e permitir suas interações. Assim, o desempenho e as características da rede são altamente dependentes do comportamento destes protocolos. Adicionalmente, com base no protocolo adotado, o suporte a alguns requisitos específicos das aplicações de IoT podem ou não ser fornecidos. Portanto, estes protocolos devem ser projetados para atender as necessidades das aplicações assim como considerando as limitações do hardware no qual serão executados. Procurando atender às necessidades dos protocolos de encaminhamento em LLNs e, consequentemente, das redes IoT, a Internet Engineering Task Force (IETF) desenvolveu e padronizou o IPv6 Routing Protocol for Low Power and Lossy Networks (RPL). O protocolo, embora seja robusto e ofereça recursos para atender às necessidades de diferentes aplicações, apresenta algumas falhas e fraquezas (principalmente relacionadas com a sua alta complexidade e necessidade de memória) que limitam sua adoção em cenários IoT. Em alternativa ao RPL, o Lightweight On-demand Ad hoc Distance-vector Routing Protocol – Next Generation (LOADng) emergiu como uma solução de encaminhamento menos complexa para as LLNs. Contudo, o preço da simplicidade é pago com a falta de suporte adequado para um conjunto de recursos essenciais necessários em muitos ambientes IoT. Assim, inspirado pelas desafiadoras questões ainda em aberto relacionadas com o encaminhamento em redes IoT, esta tese tem como objetivo estudar e propor contribuições para melhor atender os requisitos de rede em cenários IoT. Uma profunda e abrangente revisão do estado da arte sobre os protocolos de encaminhamento adotados em IoT identificou os pontos fortes e limitações das soluções atuais. Com base nas debilidades encontradas, um conjunto de soluções de melhoria é proposto para superar carências existentes e melhorar o desempenho das redes IoT. As novas soluções são propostas para incluir um suporte confiável e eficiente capaz atender às necessidades das aplicações IoT relacionadas com suporte à mobilidade, heterogeneidade dos dispositivos e diferentes padrões de tráfego. Além disso, são introduzidos mecanismos para melhorar o desempenho da rede em cenários IoT que integram dispositivos com diferentes tecnologias de comunicação. Os vários estudos realizados para mensurar o desempenho das soluções propostas mostraram o grande potencial do conjunto de melhorias introduzidas. Quando comparadas com outras abordagens existentes na literatura, as soluções propostas nesta tese demonstraram um aumento do desempenho consistente para métricas relacionadas a qualidade de serviço, uso de memória, eficiência energética e de rede, além de adicionar novas funcionalidades aos protocolos base. Portanto, acredita-se que as melhorias propostas contribuiem para o avanço do estado da arte em soluções de encaminhamento para redes IoT e aumentar a adoção e utilização dos protocolos estudados

Consensus in high performance computing

Dissertação de mestrado integrado em Informatics EngineeringFor a long time, developers and scientists designed consensus solutions that sacrificed thread scalability or load balance to decrease the latency. The appearance of networking and memory with microseconds requests reshaped how high-throughput consensus solutions are designed today. Today’s protocols must be multi-threaded to scale and seize the high hardware-level parallelism available. Moreover, their focus should be on not overloading the system instead of decreasing the latency. In the last decade, storage devices underwent an enormous development in their performance. The NVMe devices bought the request’s latency of solid-state devices to the microseconds range. Additionally, the software available to manage and operate these devices kept up with the hardware development. Libraries such as the Storage Performance Tool Kit (SPDK) appeared to ease the development of high-performance storage applications. In this context, this work aimed to answer a fundamental question: can NVMe Devices and SPDK improve the existing consensus-related work? This dissertation describes a solution for the distributed consensus problem that combines Disk Paxos (a consensus algorithm that relies upon writing and reading in a network of storage devices to achieve a distributed agreement) with NVMe Devices and SPDK. We conceived this solution using C++ and conducted a performance evaluation that, in the end, compared our solution with LibPaxos. Our findings describe the issues and benefits of the usage of these technologies to solve consensus. With our approach, we increase the understanding of the potential of these new technologies in enabling better solutions for the consensus problem in the future.Durante bastante tempo, as abordagens adotadas para resolver o consenso distribuído sacrificavam a escalabilidade do número de “threads” ou o balanceamento da carga com o objetivo de diminuir a latência da solução. O aparecimento de redes e latências de memória, com pedidos na ordem dos microssegundos, alterou a forma como os algoritmos de alto desempenho são desenhos, hoje em dia. Os protocolos atuais têm de ser “multithreaded” para conseguirem escalar e aproveitar o elevado paralelismo existente do hardware disponível. Para além disso, o foco dos protocolos deve residir em evitar a sobrecarga do sistema e não na redução da latência. Na última década, houve um grande desenvolvimento nos dispositivos de armazenamento. Os discos “NVMe” introduziram latências na gama dos microssegundos aumentando significativamente o desempenho dos discos de armazenamento. Adicionalmente, o “software” disponível, para gerir e operar sobre estes dispositivos, também acompanhou o seu desenvolvimento. Bibliotecas, como o “Storage Performance Tool Kit (SPDK)”, apareceram para facilitar o desenvolvimento de aplicações de armazenamento de alto desempenho. Neste contexto, este trabalho teve, como principal objetivo, responder à seguinte questão: Podem os dispositivos NVMe e o SPDK melhorar o trabalho existente sobre o consenso distribuído? Esta dissertação descreve uma solução para o consenso distribuído que combina o Disk Paxos, um algoritmo que resolve o consenso distribuído, através de leituras e escritas numa rede partilhada de discos, com os dispositivos NVMe e a biblioteca SPDK. Esta solução foi desenvolvida em C++ e foi realizada uma análise de desempenho que, na sua fase final, compara a mesma com outra solução existente, o LibPaxos. A análise desenvolvida descreve os problemas e os benefícios de usar estas tecnologias para resolver o problema de consenso distribuído. Com esta abordagem, foi possível explorar e descobrir o potencial que as tecnologias usadas têm para possibilitar o desenvolvimento de melhores soluções no futuro

A notícia: realidade ou ficção literária?

Um dos objectivos da imprensa escrita, da rádio e da televisão, enquanto órgãos de informação, é fornecer relatos dos acontecimentos julgados significativos e interessantes (Traquina, 1988: 29). Estes relatos fazem parte dum discurso jornalístico de que o acontecimento constitui o referente de que se fala, o efeito de realidade da cadeia dos signos, uma espécie de ponto zero de significação (Rodrigues, 1988: 9)

Increasing availability through maintainability growth using partial Multi Criteria Decision Making (pMCDM)

In the last decades considerations about equipments' availability became an important issue, as well as its dependence on components characteristics such as reliability and maintainability. This is particularly of outstanding importance if one is dealing with high risk industrial equipments, where these factors play an important and fundamental role in risk management when safety or huge economic values are in discussion. As availability is a function of reliability, maintainability, and maintenance support activities, the main goal is to improve one or more of these factors. This paper intends to show how maintainability can influence availability and present a methodology to select the most important attributes for maintainability using a partial Multi Criteria Decision Making (pMCDM). Improvements in maintainability can be analyzed assuming it as a probability related with a restore probability density function [g(t)]

When temporary agency work is not so temporary

Theory and empirical research have provided mixed arguments and evidence for the effects of temporary agency work on workers’ well-being. One unresolved issue is how length of service in agency work affects workers’ well-being and behaviour. This study, based on Self-Determination theory, explored this question by comparing the motives for temporary agency employment and the well-being of workers who have had this employment status for different periods of time. From a sample of 3300 Portuguese temporary agency workers, the study compared three groups who had been engaged in temporary agency work for (1) up to 6 months, (2) between 7 and 12 months and (3) between 13 and 24 months. Regression analyses, controlling for background variables and job insecurity perception, showed that longer periods of temporary agency working were associated with lower autonomous and voluntary motives for temporary employment, workplace well-being and well-being outside work. Theoretical and practical implications are discussed.info:eu-repo/semantics/acceptedVersio

A national referral of an integrated network of continuing care a study case

This study aims to characterize the National Long-Term Care Network (NL-TCN) users. The Portuguese National Health Service, was restructured in 2006 with the creation of the National Long-Term Care Network to respond to new health and social needs concerning the continuity of care. Objectives- Analyse the sociodemographic profile of the network users and the review of hospital, local and regional management procedures. Methods-we used various methods of observational or experimental nature (data processing and presentation of results with the program Statistical Package for Social Sciences, version 20, descriptive statistics (frequencies, crosstabs and test chi-square)). The Pearson correlation test showed a positive correlation between time procedures at the local and regional management and hospital’s length of stay. Results- from a sample of 805 cases, 595 (74%) were admitted in the NL-TCN, a rate lower than the national average (86%). Almost half of the sample was admitted in Rehabilitation Units (46%), while nationally the highest number of admissions was in Home Care Teams (30%). The average time from hospital referral to network admission was 9.73 days with a positive correlation between referred network management procedures and hospital length of stay. Conclusions- For specialized units, the maximum waiting times were for the Long-Term and Support Units (mean 30.27 days) and the minimum waiting times were for Home Care Teams (mean 5.57 days). The average time between the local and regional management was 3.59 days. Almost 90% of referrals were orthopaedics, internal medicine and neurology and Network users were mostly elderly (average 75 years old), female and married. Most users were admitted to inpatient units (78%) and only 15% remained in their home town.CG

The temporary agency worker’s motivation profile analysis

The Self-Determination Theory (SDT) establishes that human motivations can take different forms (e.g., amotivation, extrinsic and intrinsic motivation), yet it is only recently that the theory has been advanced to explain how these different forms combine to influence temporary agency workers’ (TAWs) affective commitment and their perception over the human resources practices (HRP) applied. We tested this theory with data from seven temporary agency companies (N = 3766). Through latent profile analysis (LPA) we identified five distinct motivation profiles and found that they differed in their affective commitment to the agency and to the client-company, and in their perception of HRP. We verified that temporary agency workers in more intrinsic profiles had more positive outcomes and a better perception of the investment made by the companies, than did TAWs in more extrinsic profiles. Additionally, when TAWs were able to integrate the reasons for being in this work arrangement, the negative effect of the extrinsic motivation was attenuated, and it was possible to find moderated profiles in which TAWs also showed more positive results than TAWs with only extrinsic motives. These differences are consistent with the notion that a motivation profile provides a context that determines how the individual components are experienced. Theoretical and practical implications of this context effect are discussed.publishersversionpublishe