A distributed auctioneer for resource allocation in decentralized systems

In decentralized systems, nodes often need to coordinate to access shared resources in a fair manner. One approach to perform such arbitration is to rely on auction mechanisms. Although there is an extensive literature that studies auctions, most of these works assume the existence of a central, trusted auctioneer. Unfortunately, in fully decentralized systems, where the nodes that need to cooperate operate under separate spheres of control, such central trusted entity may not exist. Notable examples of such decentralized systems include community networks, clouds of clouds, cooperative nano data centres, among others. In this paper, we make theoretical and practical contributions to distribute the role of the auctioneer. From the theoretical perspective, we propose a framework of distributed simulations of the auctioneer that are Nash equilibria resilient to coalitions and asynchrony. From the practical perspective, our protocols leverage the distributed nature of the simulations to parallelise the execution. We have implemented a prototype that instantiates the framework for bandwidth allocation in community networks, and evaluated it in a real distributed setting.Peer ReviewedPostprint (author's final draft

Towards incentive-compatible pricing for bandwidth reservation in community network clouds

Community network clouds provide for applications of local interest deployed within community networks through collaborative efforts to provision cloud infrastructures. They complement the traditional large-scale public cloud providers similar to the model of decentralised edge clouds by bringing both content and computation closer to the users at the edges of the network. Services and applications within community network clouds require connectivity to the Internet and to the resources external to the community network, and here the current besteffort model of volunteers contributing gateway access in the community networks falls short. We model the problem of reserving the bandwidth at such gateways for guaranteeing quality-of-service for the cloud applications, and evaluate different pricing mechanisms for their suitability in ensuring maximal social welfare and eliciting truthful requests from the users. We find second-price auction based mechanisms, including Vickrey and generalised second price auctions, suitable for the bandwidth allocation problem at the gateways in the community networks.Peer ReviewedPostprint (author's final draft

Análise e descrição do nível de atividade física, aptidão física e da composição corporal de alunos de licenciatura e mestrado da Universidade do Minho

Bons níveis de aptidão física estão, geralmente, relacionados com bons níveis de atividade física. Estes fatores associam-se de forma positiva com a saúde, nomeadamente na prevenção de certos tipos de doenças, tais como as relacionadas como doenças hipocinéticas. Outro bem comum aliado à prática assenta num melhor bem-estar físico e psicológico. Assim, o propósito deste projeto assenta na análise e descrição do Nível de Atividade Física (NAF) e da Aptidão Física (ApF) e de dados antropométricos de alunos de Licenciatura e de Mestrado da Universidade do Minho, com idade compreendidas entre os 18 e 25 anos de idade. Proceder-se-á à aplicação de um questionário para conhecer e identificar o NAF nesta amostra; à avaliação antropométrica, determinando o peso, a altura e as pregas de adiposidade subcutânea; e a ApF será avaliada a partir de testes de força, resistência muscular e capacidade aeróbica. Pretende-se verificar se existem diferenças entre os grupos da amostra. Em função dos resultados obtidos será desenhado um programa de atividade física, realçando os seus benefícios para a promoção da saúde, a ser aplicado aos grupos de menor AF com o intuito de melhorar os níveis de aptidão física.CIEC - Centro de Investigação em Estudos da Criança, UM (UI 317 da FCT

Convênios e Contratos de Repasse do Governo Federal: Uma Análise Comparativa das Aplicações FiscalizaBR e SISCONV

O incentivo do governo federal brasileiro à transparência dos dadospúblicos e ao controle social se tornou cada vez mais evidente após ainstauração da Lei de Acesso à Informação. Devido a essa lei, novasferramentas de busca e novas formas de visualizações têm sido propostas para que o cidadão possa realizar o controle social de maneira eficiente. Este trabalho apresenta a aplicação móvel FiscalizaBR, cujo objetivo é facilitar o acesso, a busca e a visualização das informações sobre contratos e convênios do Governo Brasileiro. Por meio de estudo experimental, constatou-se que a aplicação proposta apresentou valores para efetividade e eficiência maiores do que os de outra aplicação existente com a mesma finalidad

Amber in Portugal: state of the art

XXXIV Jornadas de Paleontología y IV Congreso Ibérico de Paleontología (Villareal, Portugal. Sep 2018) p 279-287Portuguese amber has received very little attention from the paleontological and geological points of view. To our knowledge, only twelve amber outcrops or amber-bearing areas have been detected in Portugal. The first outcrops were cited in times as old as 1867 and 1910, and although some of them were considered Jurassic in age, most likely the amber came from Cretaceous deposits. The Portuguese outcrops are poor in amber and, thus far, only a dipteran (Nematocera) insect has been found as bioinclusion (Cascais amber); the area of Estoril-Cascais, near Lisbon, provides amber interesting from the paleoentomological standpoint. In contrast, prehistoric amber from Portugal, namely as diverse types of beads and pendants, has been researched in some detail during the last decades. The 25 archeological localities known occur from north to south, ranging in ages from the Neolithic through the Chalcolithic to the Late Bronze Age. Further research is required to prospect the known paleontological localities, and also to look for new ones, in order to obtain stratigraphically contextualized samples and to perform the first infrared and/or Raman spectroscopy analyses. This will allow comparing these with the infrared and/or Raman spectra of archeological pieces to shed light on the origin of the amber as a raw material during prehistoric times. The potential discovery of a paleontological locality yielding abundant bioinclusions would be of great interest, as it would allow taxonomic and paleoecological comparisons with the rich Cretaceous outcrops from the north and northeastern Iberian PeninsulaMuseo Geominero, Instituto Geológico y Minero de EspañaDepartament de Dinàmica de la Terra i del Oceà and Institut de Recerca de la Biodiversitat (IRBio). Facultat de Ciències de laTerra. Universitat de BarcelonaDepartamento de Prehistoria, Historia Antigua y Arqueología. Universidad de SalamancaDepartamento de Biodiversidad, Ecología y Evolución, Facultad de Biología, Universidad ComplutenseMuseo de Ciencias Naturales de ÁlavaDepartamento de Prehistoria y Arqueología, Universidad de GranadaOxford University Museum of Natural HistoryInstitute of Environmental Science and Technology (ICTA)Facultad de Ciencias, Universidad Autónoma de MadridDepartamento de História, Estudos Europeus, Arqueologia e Artes, Faculdade de Letras, Universidade de Coimbra, Instituto de Arqueologi