3,359 research outputs found

    On the number of nonequivalent propelinear extended perfect codes

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    The paper proves that there exist an exponential number of nonequivalent propelinear extended perfect binary codes of length growing to infinity. Specifically, it is proved that all transitive extended perfect binary codes found by Potapov are propelinear. All such codes have small rank, which is one more than the rank of the extended Hamming code of the same length. We investigate the properties of these codes and show that any of them has a normalized propelinear representation

    Treatment of bimodality in proficiency test of pH in bioethanol matrix

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    The pH value in bioethanol is a quality control parameter related to its acidity and to the corrosiveness of vehicle engines when it is used as fuel. In order to verify the comparability and reliability of the measurement of pH in bioethanol matrix among some experienced chemical laboratories, reference material (RM) of bioethanol developed by Inmetro - the Brazilian National Metrology Institute - was used in a proficiency testing (PT) scheme. There was a difference of more than one unit in the value of the pH measured due to the type of internal filling electrolytic solutions (potassium chloride, KCl or lithium chloride, LiCl) from the commercial pH combination electrodes used by the participant laboratories. Therefore, bimodal distribution has occurred from the data of this PT scheme. This work aims to present the possibilities that a PT scheme provider can use to overcome the bimodality problem. Data from the PT of pH in bioethanol were treated by two different statistical approaches: kernel density model and the mixture of distributions. Application of these statistical treatments improved the initial diagnoses of PT provider, by solving bimodality problem and contributing for a better performance evaluation in measuring pH of bioethanol.Comment: 20 pages, 6 figures, Accepted for publication in Accreditation and Quality Assurance (ACQUAL

    Phenomenology Tools on Cloud Infrastructures using OpenStack

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    We present a new environment for computations in particle physics phenomenology employing recent developments in cloud computing. On this environment users can create and manage "virtual" machines on which the phenomenology codes/tools can be deployed easily in an automated way. We analyze the performance of this environment based on "virtual" machines versus the utilization of "real" physical hardware. In this way we provide a qualitative result for the influence of the host operating system on the performance of a representative set of applications for phenomenology calculations.Comment: 25 pages, 12 figures; information on memory usage included, as well as minor modifications. Version to appear in EPJ

    Primary Antiphospholipid Syndrome: Pregnancy Outcome in a Portuguese Population

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    Introduction:Women with antiphospholipid syndrome(APS) may suffer from recurrent miscarriage, fetal death, fetal growth restriction (FGR), pre-eclampsia, placental abruption, premature delivery and thrombosis. Treatment with aspirin and low molecular weight heparin (LMWH) combined with close maternal-fetal surveillance can change these outcomes. Objective: To assess maternal and perinatal outcome in a cohort of Portuguese women with primary APS. Patients and Methods: A retrospective analysis of 51 women with primary APS followed in our institution (January 1994 to December 2007). Forty one(80.4%) had past pregnancy morbidity and 35.3%(n=18) suffered previous thrombotic events. In their past they had a total of 116 pregnancies of which only 13.79 % resulted in live births. Forty four patients had positive anticardiolipin antibodies and 33 lupus anticoagulant. All women received treatment with low dose aspirin and LMWH. Results: There were a total of 67 gestations (66 single and one multiple). The live birth rate was 85.1%(57/67) with 10 pregnancy failures: seven in the first and second trimesters, one late fetal death and two medical terminations of pregnancy (one APS related). Mean (± SD) birth weight was 2837 ± 812 g and mean gestational age 37 ± 3.3 weeks. There were nine cases of FGR and 13 hypertensive complications(4 HELLP syndromes). 54.4% of the patients delivered by caesarean section. Conclusions: In our cohort, early treatment with aspirin and LMWH combined with close maternal-fetal surveillance was associated with a very high chance of a live newborn

    Bloqueio Aurículo-Ventricular Completo Congénito. Caso Clínico e Revisão da Literatura

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    Introduction: Congenital complete atrioventricular block (AVB) without cardiac malformation is a rare and potentially fatal condition. In most cases it is associated with maternal systemic lupus erythematosus through transplacental passage of antibodies anti-SSA/Ro and/or anti-SSB/La. Antenatal fluorinated-steroids have been successful in reversing first and second degree congenital AVB but inconsistent in third degree block. Case Report:The authors report a case of fetal bradycardia diagnosed at 24 weeks of gestation. The fetal echocardiogram revealed a second/third degree AVB without structural heart disease. Maternal anti-SSA/Ro antibodies were detected. There was no blockage improvement with maternal oral fluorinated-steroids. An elective cesarean section was performed at term with the delivery of a healthy girl that required an epicardical pacemaker on the 8th day of life. Conclusion: In this case, treatment with maternal fluorinated corticosteroids was not effective in preventing progression of the heart block

    Developing a site-conditions map for seismic hazard Assessment in Portugal

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    The evaluation of site effects on a broad scale is a critical issue for seismic hazard and risk assessment, land use planning and emergency planning. As characterization of site conditions based on the shear-wave velocity has become increasingly important, several methods have been proposed in the literature to estimate its average over the first thirty meters (Vs30) from more extensively available data. These methods include correlations with geologic-geographic defined units and topographic slope. In this paper we present the first steps towards the development of a site–conditions map for Portugal, based on a regional database of shear-wave velocity data, together with geological, geographic, and lithological information. We computed Vs30 for each database site and classified it according to the corresponding geological-lithological information using maps at the smallest scale available (usually 1:50000). We evaluated the consistency of Vs30 values within generalized-geological classes, and assessed the performance of expedient methodologies proposed in the literature

    Alterations in brain connectivity due to plasticity and synaptic delay

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    Brain plasticity refers to brain's ability to change neuronal connections, as a result of environmental stimuli, new experiences, or damage. In this work, we study the effects of the synaptic delay on both the coupling strengths and synchronisation in a neuronal network with synaptic plasticity. We build a network of Hodgkin-Huxley neurons, where the plasticity is given by the Hebbian rules. We verify that without time delay the excitatory synapses became stronger from the high frequency to low frequency neurons and the inhibitory synapses increases in the opposite way, when the delay is increased the network presents a non-trivial topology. Regarding the synchronisation, only for small values of the synaptic delay this phenomenon is observed

    Cerenkov angle and charge reconstruction with the RICH detector of the AMS experiment

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    The Alpha Magnetic Spectrometer (AMS) experiment to be installed on the International Space Station (ISS) will be equipped with a proximity focusing Ring Imaging Cerenkov (RICH) detector, for measurements of particle electric charge and velocity. In this note, two possible methods for reconstructing the Cerenkov angle and the electric charge with the RICH, are discussed. A Likelihood method for the Cerenkov angle reconstruction was applied leading to a velocity determination for protons with a resolution of around 0.1%. The existence of a large fraction of background photons which can vary from event to event, implied a charge reconstruction method based on an overall efficiency estimation on an event-by-event basis.Comment: Proceedings submitted to RICH 2002 (Pylos-Greece
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