1,163 research outputs found

    Mantle dynamics and volcanism emplacement in the Azores

    Get PDF
    The Azores plateau is a triangular shaped topographic feature encompassing the boundary zone where three major tectonic plates (EU, NU and NA) meet. The eastern side of the plateau is delimited by two major tectonic discontinuities: the Mid Atlantic Ridge, and the Terceira Rift, a recently formed ultra-slow-spreading ridge. The origin of the plateau is still under debate. One hypothesis argues that the plateau would have been formed by successive NE jumps of the oblique spreading axis, where the present TR is the latest stage. Other hypotheses invoke the northward jump of the Azores triple junction, during which the Azores region would have been transferred from the Eurasian plate to the Nubian plate. For some authors, the presence of the Azores plume, a low seismic velocity zone in the mantle beneath, is required to explain the observations: the anomalously shallow seafloor depth as well as the geochemistry of the basaltic lavas erupted within the plateau. Here we use a highly resolved tomography model to quantify the influence of this plume and the surrounding mantle.We model the convection pattern, the induced dynamic topography and stresses, and compare them with the surface observations. The dynamic topography shows two maxima: one northwest of St. Miguel, the other encompassing the Terceira, Graciosa, S. Jorge, Faial and Pico islands. Both swells are approximately located on the Terceira Ridge. The convection pattern displays two distinct upwelling towards these two groups of Islands. This may explain the difference in the geochemical signatures, in particular the unique isotopic ratios observed in some lavas from S. Miguel. The stresses induced by the underlying mantle convection are compared with the surface observations (topographic features, seismic and GPS velocities). The modeled and observed tresses fairly correlate west of our study area but their directions depart east

    The evolution of civil servants’ and managers’ recruitment and performance evaluation processes in Portuguese public administration

    Get PDF
    At the beginning of the 21st Century, new legal regulations have dictated deep changes in recruitment/selection and evaluation processes, both for employees and managers in Portuguese public administration. This paper addresses the application of these new legal documents as well as a new selection and evaluation philosophy that the Portuguese public administration seeks to instil into human resources management

    Annexin A2: The Importance of Being Redox Sensitive

    Get PDF
    Hydrogen peroxide (H2O2) is an important second messenger in cellular signal transduction. H2O2-dependent signalling regulates many cellular processes, such as proliferation, differentiation, migration and apoptosis. Nevertheless, H2O2 is an oxidant and a major contributor to DNA damage, protein oxidation and lipid peroxidation, which can ultimately result in cell death and/or tumourigenesis. For this reason, cells have developed complex antioxidant systems to scavenge ROS. Recently, our laboratory identified the protein, annexin A2, as a novel cellular redox regulatory protein. Annexin A2 possesses a reactive cysteine residue (Cys-8) that is readily oxidized by H2O2 and subsequently reduced by the thioredoxin system, thereby enabling annexin A2 to participate in multiple redox cycles. Thus, a single molecule of annexin A2 can inactivate several molecules of H2O2. In this report, we will review the studies detailing the reactivity of annexin A2 thiols and the importance of these reactive cysteine(s) in regulating annexin A2 structure and function. We will also focus on the recent reports that establish novel functions for annexin A2, namely as a protein reductase and as a cellular redox regulatory protein. We will further discuss the importance of annexin A2 redox regulatory function in disease, with a particular focus on tumour progression.European Union Seventh Framework Programme (FP7) [PCOFUND-GA-2009-246542]; Foundation for Science and Technology of Portugal; Natural Sciences and Engineering Research Council of Canada (NSERC)info:eu-repo/semantics/publishedVersio

    Quality of life measurements in patients with osteoporosis and fractures

    Get PDF
    To review all specific questionnaires regarding quality of life in osteoporosis and to describe their distinctive indications, we searched Medline, the Scientific Electronic Library Online database, and the Latin-American and Caribbean Health Sciences Literature database. Nine specific questionnaires related to osteoporosis quality of life were found: 1) the Women's Health Questionnaire, 2) Osteoporosis Quality of Life Questionnaire, 3) Osteoporosis Assessment Questionnaire, 4) Osteoporosis Functional Disability Questionnaire, 5) Quality of Life Questionnaire of the European Foundation for Osteoporosis, 6) Osteoporosis-Targeted Quality of Life Questionnaire, 7) Japanese Osteoporosis Quality of Life Questionnaire, 8) the 16-item Assessment of Health-Related Quality of Life in Osteoporosis, and 9) the Quality of Life Questionnaire in Osteoporosis (QUALIOST TM). The Quality of Life Questionnaire of the European Foundation for Osteoporosis is the osteoporosis-specific questionnaire most commonly used in the literature. The Quality of Life Questionnaire of the European Foundation for Osteoporosis and the Osteoporosis Quality of Life Questionnaire are targeted more toward fracture assessment, and the Osteoporosis Functional Disability Questionnaire can be used for longitudinal studies involving exercise. In the present study, the authors summarize all of the specific questionnaires for osteoporosis and demonstrate that these questionnaires should be selected based on the objectives to be evaluated. Osteoporosis-specific quality of life questionnaires should be validated in the language of the country of origin before being used

    Oxidation of clofibric acid in aqueous solution using a non-thermal plasma discharge or gamma radiation

    Full text link
    In this work, we study degradation of clofibric acid (CFA) in aqueous solution using either ionizing radiation from a 60^{60}Co source or a non-thermal plasma produced by discharges in the air above the solution. The results obtained with the two technologies are compared in terms of effectiveness of CFA degradation and its by-products. In both cases the CFA degradation follows a quasi-exponential decay in time well modelled by a kinetic scheme which considers the competition between CFA and all reaction intermediates for the reactive species generated in solution as well as the amount of the end product formed. A new degradation law is deduced to explain the results. Although the end-product CO2_2 was detected and the CFA conversion found to be very high under the studied conditions, HPLC analysis reveals several degradation intermediates still bearing the aromatic ring with the chlorine substituent. The extent of mineralization is rather limited. The energy yield is found to be higher in the gamma radiation experiments.Comment: 25 pages, 7 figure

    A self-parametrization framework for meta-heuristics

    Get PDF
    Even while the scientific community has shown great interest in the analysis of meta-heuristics, the analysis of their parameterization has received little attention. It is the parameterization that will adapt a meta-heuristic to a problem, but it is still performed, mostly, empirically. There are multiple parameterization techniques; however, they are time-consuming, requiring considerable computational effort and they do not take advantage of the meta-heuristics that they parameterize. In order to approach the parameterization of meta-heuristics, in this paper, a self-parameterization framework is proposed. It will automatize the parameterization as an optimization problem, precluding the user from spending too much time on parameterization. The model will automate the parameterization through two meta-heuristics: A meta-heuristic of the solution space and one of the parameter space. To analyze the performance of the framework, a self-parameterization prototype was implemented. The prototype was compared and analyzed in a SP (scheduling problem) and in the TSP (traveling salesman problem). In the SP, the prototype found better solutions than those of the manually parameterized meta-heuristics, although the differences were not statistically significant. In the TSP, the self-parameterization prototype was more effective than the manually parameterized meta-heuristics, this time with statistically significant differences.This work was supported by national funds through the FCT - Fundação para a Ciência e Tecnologia through the R&D Units Project Scopes: UIDB/00319/2020, and EXPL/EME-SIS/1224/2021

    Study on the Impact of the NS in the Performance of Meta-Heuristics in the TSP

    Get PDF
    Meta-heuristics have been applied for a long time to the Travelling Salesman Problem (TSP) but information is still lacking in the determination of the parameters with the best performance. This paper examines the impact of the Simulated Annealing (SA) and Discrete Artificial Bee Colony (DABC) parameters in the TSP. One special consideration of this paper is how the Neighborhood Structure (NS) interact with the other parameters and impacts the performance of the meta-heuristics. NS performance has been the topic of much research, with NS proposed for the best-known problems, which seem to imply that the NS influences the performance of meta-heuristics, more that other parameters. Moreover, a comparative analysis of distinct meta-heuristics is carried out to demonstrate a non-proportional increase in the performance of the NS.This work is supported by FEDER Funds through the "Programa Operacional Factores de Competitividade - COMPETE" program and by National Funds through FCT "FundaqAo para a Ciencia e a Tecnologia" under the project: FCOMP-01-0124-FEDER-PEst-OE/EEl/U10760/2011, PEst-OE/EEI/UI0760/2014, and PEst2015-2020.info:eu-repo/semantics/publishedVersio

    Evaluation of the Simulated Annealing and the Discrete Artificial Bee Colony in the Weight Tardiness Problem with Taguchi Experiments Parameterization

    Get PDF
    Meta-Heuristics (MH) are the most used optimization techniques to approach Complex Combinatorial Problems (COPs). Their ability to move beyond the local optimums make them an especially attractive choice to solve complex computational problems, such as most scheduling problems. However, the knowledge of what Meta-Heuristics perform better in certain problems is based on experiments. Classic MH, as the Simulated Annealing (SA) has been deeply studied, but newer MH, as the Discrete Artificial Bee Colony (DABC) still need to be examined in more detail. In this paper DABC has been compared with SA in 30 academic benchmark instances of the weighted tardiness problem (1 parallel to Sigma w(j)T(j)). Both MH parameters were fine-tuned with Taguchi Experiments. In the computational study DABC performed better and the subsequent statistical study demonstrated that DABC is more prone to find near-optimum solutions. On the other hand SA appeared to be more efficient.This work is supported by FEDER Funds through the "Programa Operacional Factores de Competitividade - COMPETE" program and by National Funds through FCT "Fundacao para a Ciencia e a Tecnologia" under the project: PEst-OE/EEI/UI0760/2014, and PEst2015-2020.info:eu-repo/semantics/publishedVersio
    • …
    corecore