981 research outputs found

    Risk of Dengue for Tourists and Teams during the World Cup 2014 in Brazil

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    Abstract:Background:This year, Brazil will host about 600,000 foreign visitors during the 2014 FIFA World Cup. The concern of possible dengue transmission during this event has been raised given the high transmission rates reported in the past by this country.Methodology/Principal Findings:We used dengue incidence rates reported by each host city during previous years (2001-2013) to estimate the risk of dengue during the World Cup for tourists and teams. Two statistical models were used: a percentile rank (PR) and an Empirical Bayes (EB) model. Expected IR's during the games were generally low (<10/100,000) but predictions varied across locations and between models. Based on current ticket allocations, the mean number of expected symptomatic dengue cases ranged from 26 (PR, 10th-100th percentile: 5-334 cases) to 59 (EB, 95% credible interval: 30-77 cases) among foreign tourists but none are expected among teams. These numbers will highly depend on actual travel schedules and dengue immunity among visitors. Sensitivity analysis for both models indicated that the expected number of cases could be as low as 4 or 5 with 100,000 visitors and as high as 38 or 70 with 800,000 visitors (PR and EB, respectively).Conclusion/Significance:The risk of dengue among tourists during the World Cup is expected to be small due to immunity among the Brazil host population provided by last year's epidemic with the same DENV serotypes. Quantitative risk estimates by different groups and methodologies should be made routinely for mass gathering events. © 2014 van Panhuis et al

    Accuracy assessment of Precise Point Positioning with multi-constellation GNSS data under ionospheric scintillation effects

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    GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS) with full 16 operational capacity. The integration of GPS, GLONASS and future GNSS constellations can 17 provide better accuracy and more reliability in geodetic positioning, in particular for kinematic 18 Precise Point Positioning (PPP), where the satellite geometry is considered a limiting factor to 19 achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic 20 positioning in urban areas or under conditions of strong atmospheric effects such as for instance 21 ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even 22 loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is 23 characterized by rapid changes in amplitude and phase of the signal, which are more severe in 24 equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the 25 PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial 26 region under varied scintillation conditions. The GNSS data were processed in kinematic PPP 27 mode and the analyses show accuracy improvements of up to 60% under conditions of strong 28 scintillation when using multi-constellation data instead of GPS data alone. The concepts and 29 analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP 30 with GPS and GLONASS data integration as well as accuracy assessment with data collected 31 under ionospheric scintillation effects are presented

    A CDCL-style calculus for solving non-linear constraints

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    In this paper we propose a novel approach for checking satisfiability of non-linear constraints over the reals, called ksmt. The procedure is based on conflict resolution in CDCL style calculus, using a composition of symbolical and numerical methods. To deal with the non-linear components in case of conflicts we use numerically constructed restricted linearisations. This approach covers a large number of computable non-linear real functions such as polynomials, rational or trigonometrical functions and beyond. A prototypical implementation has been evaluated on several non-linear SMT-LIB examples and the results have been compared with state-of-the-art SMT solvers.Comment: 17 pages, 3 figures; accepted at FroCoS 2019; software available at <http://informatik.uni-trier.de/~brausse/ksmt/

    Light controlled spin polarization in asymmetric n-type resonant tunneling diode

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    The authors have observed a strong dependence of the circular polarization degree from the quantum well emission in an asymmetric n-type GaAs/AlAs/AlGaAs resonant tunneling diode on both the laser excitation intensity and the applied bias voltage. The sign of the circular polarization can be reversed by increasing the light excitation intensity when the structure is biased with voltages slightly larger than the first electron resonance. The variation of polarization is associated with a large density of photogenerated holes accumulated in the quantum well, which is enhanced due to the asymmetry of the structure. (C) 2007 American Institute of Physics.91

    Exploration of the Eucalyptus globulus gene pool

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    The first Europeans to discover Eucalyptus globulus were French explorers in 1792. Its seed was rapidly spread throughout the world in the 19th century and this was the species by which much of the world first knew the genus. However, it was in the industrial forests of the 20th century that this species, once considered the ‘Prince of Eucalypts’, achieved greatest prominence due to its fast growth and superior pulp qualities. Formal breeding first commenced in 1966 in Portugal and in the late 1980’s large base population trials from open-pollinated seed collections from native stands were established in many countries. These trials have provided unprecedented insights into the quantitative genetic control of numerous traits of economic and ecological importance and how this variation is spatially distributed in the native range of the species. However with large, fully pedigreed breeding populations becoming available for quantitative analysis and the rapidly expanding knowledge of DNA sequence variation, we are now at the threshold of a new understanding of this important eucalypt gene pool. Indications of the significance of non-additive genetic effects are becoming available. The E. globulus chloroplast genome has now been sequenced and several genome maps have been published. Studies of the variation in nuclear microsatellites and the lignin biosynthesis gene CCR confirm the complex, spatially structured nature of the native gene pool. Strong spatial structuring of the chloroplast genome has provided a tool for tracking seed migration and the geographic origin of exotic landraces. Highly divergent lineages of chloroplast DNA have been discovered and studies of the hypervariable JLA+ region argue that some components of the E. globulus gene pool have been assimilated from other species following hybridisation

    Polarization resolved luminescence in asymmetric n-type GaAs/AlGaAs resonant tunneling diodes

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    We have investigated the polarized emission from a n-type GaAs/AlGaAs resonant tunneling diode under magnetic field. The GaAs contact layer emission shows a large constant negative circular polarization. A similar result is observed for the quantum well, but only when electrons are injected from the substrate, while for inverted biases, the polarization tends to become positive for small voltages and large laser excitation intensities. We believe that the quantum well polarization may be associated to the partial thermalization of minority carriers on the well subbands and is thus critically dependent on the bias-controlled density of carriers accumulated in the well.921

    Zeeman splitting and spin dynamics tuning by exciton charging in two-dimensional systems

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    Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)We report a study of magnetic responses of neutral and charged excitons in quantum wells, which are very sensitive to the strong spin hybridization of holes. This effect can be used to engineer the spin character of excitonic complexes in two-dimensional systems tuned by the magnetic field strength. Conditions for spin flip for each kind of excitonic complex is detailed and the nature of the effect discussed. Differences in the effective Zeeman splitting between neutral and charged excitons are theoretically predicted and unambiguously confirmed experimentally. Circularly polarized resolved photoluminescence has been used to study these effects under applied magnetic fields. The intertwining of spin dynamics of excitons and trions is discussed.8420Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

    Novel hydroxyapatite/carboxymethylchitosan composite scaffolds prepared through an innovative ‘‘autocatalytic’’ electroless coprecipitation route

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    A developmental composite scaffold for bone tissue engineering applications composed of hydroxyapatite (HA) and carboxymethylchitosan (CMC) was obtained using a coprecipitation method, which is based on the ‘‘autocatalytic’’ electroless deposition route. The results revealed that the pores of the scaffold were regular, interconnected, and possess a size in the range of 20–500 lm. Furthermore, the Fourier transform infra-red spectrum of the composite scaffolds exhibited all the characteristic peaks of apatite, and the appearance of typical bands from CMC, thus showing that coprecipitation of both organic and inorganic phases was effective. The X-ray diffraction pattern of composite scaffolds demonstrated that calciumphosphates consisted of crystalline HA. From microcomputed tomography analysis, it was possible to determine that composite scaffolds possess a 58.9% 6 6% of porosity. The 2D morphometric analysis demonstrated that on average the scaffolds consisted of 24% HA and 76% CMC. The mechanical properties were assessed using compressive tests, both in dry and wet states. Additionally, in vitro tests were carried out to evaluate the wateruptake capability, weight loss, and bioactive behavior of the composite scaffolds. The novel hydroxyapatite/ carboxymethylchitosan composite scaffolds showed promise whenever degradability and bioactivity are simultaneously desired, as in the case of bone tissue-engineering scaffolding applications.Contract grant sponsor: European Union (STREP Project HIPPOCRATES); contract grant number: NMP3-CT-2003-50575

    Superresonance effect from a rotating acoustic black hole and Lorentz symmetry breaking

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    We investigate the possibility of the acoustic superresonance phenomenon (analog to the superradiance in black hole physics), i.e., the amplification of a sound wave by reflection from the ergoregion of a rotating acoustic black hole with Lorentz symmetry breaking. For rotating black holes the effect of superradiance corresponds to the situation where the incident waves has reflection coefficient greater than one, and energy is extracted from them. For an acoustic Kerr-like black hole its rate of loss of mass is affected by the Lorentz symmetry breaking. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.Comment: 9 pages, version to appear in PL

    A matrix-matched reference material for validating petroleum Re-Os measurements

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    This study presents two matrix-matched reference materials developed for petroleum Re-Os measurements. We present the Re and Os mass fractions and 187Re/188Os and 187Os/188Os values (ratio of the number of atoms of the isotopes) for repeatedly measured aliquots (ca. 120–150 mg test portions) of the NIST Research Material 8505 (RM 8505) crude oil, and its asphaltene and maltene fractions, and ~ 90 g of homogeneous asphaltene powder isolated from this oil. Measurements were performed using the Carius tube-isotope dilution negative-thermal ionisation mass spectrometry methodology. The RM 8505 crude oil contains 1.98 ± 0.07 ng g−1 Re and 25.0 ± 1.1 pg g−1 Os, with Re-Os isotope amount ratios of 452 ± 6 for 187Re/188Os and 1.51 ± 0.01 for 187Os/188Os (n = 20, 95% conf.). The homogeneous asphaltene sample contains 16.52 ± 0.10 ng g−1 Re and 166.0 ± 0.9 pg g−1 total Os, and possesses isotope amount ratios of 574 ± 3 for 187Re/188Os and 1.64 ± 0.01 for 187Os/188Os (n = 24, 95% conf.). The intermediate precision of these data makes the RM 8505 whole oil and the (~ 90 g) homogenised asphaltene appropriate petroleum matrix-matched reference materials for Re-Os measurements. The asphaltene fraction of the oil is the main carrier of Re and Os of the RM 8505 whole oil, and caution is suggested in using asphaltene and maltene fractions of a single oil for Re-Os geochronology
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