Model checking a decentralized storage deduplication protocol

Fifth Latin-American Symposium on Dependable Computing (LADC)Deduplication of live storage volumes in a cloud computing environment is better done by post-processing: by delaying discovery and removal of duplicate data after I/O requests have been concluded, impact in latency can be minimized. When compared to traditional deduplication in backup systems, which can be done in-line and in a centralized fashion, distribution and concurrency lead to increased complexity. This paper outlines a deduplication algorithm for a typical cloud infrastructure with a common storage pool and summarizes how model-checking with the TLA+ toolset was used to uncover and correct some subtle concurrency issues

DEDIS: distributed exact deduplication for primary storage infrastructures

Deduplication is now widely accepted as an efficient technique for reducing storage costs at the expense of some processing overhead, being increasingly sought in primary storage systems and cloud computing infrastructures holding Virtual Machine (VM) volumes. Besides a large number of duplicates that can be found across static VM images, dynamic general purpose data from VM volumes allows space savings from 58% up to 80% if deduplicated in a cluster-wide fashion. However, some of these volumes persist latency sensitive data which limits the overhead that can be incurred in I/O operations. Therefore, this problem must be addressed by a cluster-wide distributed deduplication system for such primary storage volumes.(undefined

Distributed exact deduplication for primary storage infrastructures

Lecture Notes in Computer Science, Volume 8460, 2014Deduplication of primary storage volumes in a cloud computing environment is increasingly desirable, as the resulting space savings contribute to the cost effectiveness of a large scale multi-tenant infrastructure. However, traditional archival and backup deduplication systems impose prohibitive overhead for latency-sensitive applications deployed at these infrastructures while, current primary deduplication systems rely on special cluster filesystems, centralized components, or restrictive workload assumptions. We present DEDIS, a fully-distributed and dependable system that performs exact and cluster-wide background deduplication of primary storage. DEDIS does not depend on data locality and works on top of any unsophisticated storage backend, centralized or distributed, that exports a basic shared block device interface. The evaluation of an open-source prototype shows that DEDIS scales out and adds negligible overhead even when deduplication and intensive storage I/O run simultaneously.(undefined

Development of a brand and implementation of a promotional campaign for the products of Ria de Aveiro focus on brand identity and brand positioning

Directed internshipBetween June and December of 2012 I did an internship at Jervis Pereira, a communication and marketing consulting company. In May 2012, Jervis had been hired by Comunidade Intermunicipal da Região de Aveiro to respond to the following briefing: “develop and implement a promotional campaign for the products of Ria de Aveiro”. As this project fit my interest for Maritime Business, my field of study during the Masters program, and as I participated as an intern in all the steps of the project, I decided, in accordance with my advisor Professor Catherine da Silveira, to focus my Masters Thesis, and this Work Project Report, on the development of the new brand “Ria de Aveiro” and its respective brand identity, brand positioning and brand elements

Generic and homophobic bullying in school context

Objetivo: Tendo em conta a reduzida literatura sobre o bullying homofóbico em Portugal, os objetivos deste estudo foram descrever a sua prevalência, comparativamente ao bullying genérico, na perspetiva das vítimas; comparar as diferenças de género e compreender a relação entre o bullying homofóbico e os sentimentos de infelicidade e humilhação e a denúncia por parte das vítimas. Método: Participaram 171 (7º ano), 160 (8º) e 156 (9º) alunos (52.0% feminino e 48.0% masculino), entre os 11 e os 17 anos, aos quais foi aplicado um questionário de autorrelato em formato digital, avaliando-se: género, vitimação, sentimentos infelicidade/humilhação e denúncia. Resultados: Um total de 33.0% dos alunos foram vítimas de bullying genérico, maioritariamente no 8º ano. Rapazes e raparigas registaram índices de vitimação semelhantes. Quanto ao bullying homofóbico, a prevalência aumentou do 7º para o 9º ano e os rapazes apresentaram maior frequência de vitimação comparativamente às raparigas, havendo diferenças estatisticamente significativas no 9º ano. À medida que as situações de vitimação homofóbica aumentam, maior foi o sentimento de infelicidade e humilhação nas vítimas e maior a denúncia. Conclusão: Estes dados reforçam a necessidade de ações e programas de prevenção nas escolas, enquadrados numa perspetiva sistémica, privilegiando a intervenção dos observadores de situações de bullying.Aim: Given the little scientific information about homophobic bullying in Portugal, the purpose of this study was to assess its prevalence, in comparison to generic bullying, from the perspective of the victims; to compare differences related to gender and to understand the association between homophobic bullying and feelings of unhappiness and humiliation and victim’s reporting. Method: A total of 171 (7th grade), 160 (8th) and 156 (9th) students (52.0% female/48.0% male), between 11 and 17 years old, completed a self-report questionnaire in digital format, assessing: gender, victimization, feelings of unhappiness and humiliation and victim’s reporting. Results: Of these students 33.0% were victims of bullying, mostly in the 8th grade. Boys and girls were equally likely to be victims. On the other hand, homophobic bullying situations in school increased from the 7th to the 9th grade and male students were more frequently bullied than females, showing statistically significant differences in the 9th grade. The more frequent the homophobic bullying episodes became, the greater the feelings of unhappiness and humiliation and more frequent the reporting. Conclusion: These findings strengthen the need to promote actions and programs aiming at prevention in schools, from a systemic perspective, emphasizing the intervention of observers of bullying episodes.CIEC - Centro de Investigação em Estudos da Criança, IE, UMinho (UI 317 da FCT), Portugal. Projeto Estratégico UID/CED/00317/2013, financiado através dos Fundos Nacionais da FCT (Fundação para a Ciência e a Tecnologia), cofinanciado pelo Fundo Europeu de Desenvolvimento Regional (FEDER) através do COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) com a referência POCI-01-0145-FEDER-007562info:eu-repo/semantics/publishedVersio

Broadband access technologies

Broadband technologies have view great growth over the past decade. But, the main part of this development and growth has been in the core networks, and the capacity of the access network to delivery broadband services remains as a challenge ("last mile problem"). The access network remains a bottleneck in terms of the bandwidth and service quality it affords the end user. By other side, the access network is much more spread geographically and covers larger areas. Then, this part of the network is usually the most expensive component in terms of capital investment and OAM cost. Some studies reefer that this networks required 70% of the total investment. Several access technologies can be used in this part of the network, which can be used to resolve the bandwidth bottleneck and the investment problem: xDSL, HFC, FTTx, FWA, WiMAX, PLC, Satellite, etc. This paper presents a methodology and a tool that compare and evaluate broadband access technologies. The paper presents a techno-economic analysis of eight broadband technologies for access networks: digital subscriber line (DSL), hybrid fiber coax (HFC), power line communications (PLC), fiber to the home (FTTH), fiber to the curb (FTTC), fiber to the cabinet (FTTCab), and wireless alternatives such as WiMAX and satellite. Several actors (such operators, service providers, …) could use this tool to compare different technological solutions, forecast deployment costs, compare different scenarios, etc

Ozone therapy for herpes zoster : case report

info:eu-repo/semantics/publishedVersio

Características dos profissionais em sistemas de informação: região de Trás-os-Montes (Portugal)

The profile of the Information Systems Professionals remains a constant challenge for schools and employers. Constant environmental, technological and organizational changes may raise difficulties in keeping the curriculum of Information Systems updated. Thus, the knowledge and the abilities demanded of professionals are in constant transformation. School plays an essential role in the process of providing professionals with the necessary skills to operate in the Information Society. Their competence depends, largely, on an appropriate curriculum that must be adequate to the organizations necessities. This paper identifies the skills required for the IS professionals in the organizations located in the region of “Trás-os-Montes” (Portugal). This work is based in a survey, realized in 51 organizations from “Trás-os-Montes”. The main objective was the identification of the skills expected from the employers for the IS professional. The study show that the soft skills are the most required

Towards a characterization of BPM tools' simulation support: the case of BPMN process models

Due to the increasing acceptance of BPM (Business Process Management), nowadays BPM tools are extensively used in organizations. Core to BPM are the process modeling languages, of which BPMN is the one that has been receiving most attention these days. Once a business process is described using BPMN, one can use a process simulation approach in order to discover its optimized form. This paper analyzes the business process modeling and simulation areas, identifying I the elements that must be present in the BPMN language in order to allow processes to be simulated. During this analysis a set of existing BPM tools, which support BPMN, are compared regarding their limitations in terms of simulation capabilities. In this context, a platform to support the characterization of BPM tools regarding process simulation capabilities has been developed, which might be useful to users ii ho want to select the most adequate BPM tool taking into account their simulation needs.This work has been supported by FCT - Fundação para a Ciência e Tecnologia, within the Project Scope: UID/CEC/00319/2019

Superchannel transmission over flexible-grid optical networks

Superchannels have been proposed as a cost-effective solution to cope with the future data capacity demand in long-haul transport networks. However, in superchannels, the spectrum of the subchannels is tightly packed and the crosstalk between subchannels can become a performance constraint. Along its path in the optical network, a superchannel passes through several reconfigurable optical add-drop multiplexers (ROADMs). The cumulative filtering effect of the cascaded wavelength selective switches (WSSs), inside the ROADMs, reduces the available bandwidth and leads to signal distortion. The subchannels performance is significantly dependent on the intercarrier spacing. If too large, the edge subchannels suffer a higher distortion from the filtering cascade. If too narrow, it creates a considerable intercarrier crosstalk between the subchannels. In this work, we perform the exhaustive assessment of the optical signal-to-noise ratio (OSNR) penalties due to the optical filtering and intercarrier crosstalk between subchannels using different M-ary quadrature amplitude modulation (M-QAM) formats, symbol rates, roll-off factors, number of traversed WSSs, WSS bandwidths, number of subchannels and intercarrier spacing. We provide a procedure to obtain optimized values of these parameters that guarantee an OSNR penalty below 1.5 dB for all subchannels after 20 WSSs. Two WSS filter spectral models are compared, named analytical and super-Gaussian. We have shown the use of the computationally much faster performance metric, the error vector magnitude (EVM) penalty, and concluded that it provides a more pessimistic performance estimate than the OSNR penalty, to estimate the distortion due to the filters cascade.O uso de super-canais tem sido proposto como uma boa relação custo-benefício para suportar a futura procura de capacidade de dados nas redes de transporte a longa distância. Contudo, nos super-canais, o espectro dos sub-canais está muito compactado e a interferência entre sub-canais pode tornar-se uma limitação. Enquanto atravessa a rede óptica, um super-canal passa através de vários multiplexadores ópticos reconfiguráveis de inserção e extracção (ROADMs, em inglês). O efeito acumulado da filtragem de uma cascata de filtros baseados em comutadores selectivos no comprimento-de-onda (WSS em inglês) que se encontram dentro dos ROADMs, reduz a largura-de-banda disponível e causa distorção no sinal óptico. A performance dos sub-canais é significativamente dependente do espaçamento entre sub-canais, da interferência entre sub-canais e da filtragem nos WSS’s. Neste trabalho, avalia-se exaustivamente a penalidade na relação sinal-ruído óptica (OSNR, em inglês) devido a filtragem óptica e interferência entre sub-canais, usando diferentes formatos de modulação M-QAM, ritmos de símbolos, factores de excesso de banda, número de WSS’s, larguras-de-banda dos WSS’s, número de sub-canais e espaçamento entre portadoras. Fornece-se um procedimento para obter valores optimizados para estes parâmetros que garantem que a penalidade na OSNR é menor que 1.5 dB em todos os sub-canais depois de 20 WSS’s. Comparam-se também dois modelos espectrais para o filtro WSS, denominados analítico e super-Gaussiano. Investiga-se o uso da penalidade da EVM, computacionalmente muito mais rápida, como métrica de desempenho e conclui-se que fornece resultados mais pessimistas que a penalidade da OSNR para estimar a distorção da cascata de filtros