703 research outputs found

    Influence of the solar EUV flux on the Martian plasma environment

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    The interaction of the solar wind with the Martian atmosphere and ionosphere is investigated by using three-dimensional, global and multi-species hybrid simulations. In the present work we focus on the influence of the solar EUV flux on the Martian plasma environment by comparing simulations done for conditions representative of the extrema of the solar cycle. The dynamics of four ionic species (H<sup>+</sup>, He<sup>++</sup>, O<sup>+</sup>, O<sub>2</sub><sup>+</sup>), originating either from the solar wind or from the planetary plasma, is treated fully kinetically in the simulation model in order to characterize the distribution of each component of the plasma, both at solar maximum and at solar minimum. The solar EUV flux controls the ionization frequencies of the exospheric species, atomic hydrogen and oxygen, as well as the density, the temperature, and thus the extension of the exosphere. Ionization by photons and by electron impacts, and the main charge exchange reactions are self-consistently included in the simulation model. Simulation results are in reasonable agreement with the observations made by Phobos-2 and Mars Global Surveyor (MGS) spacecraft: 1) the interaction creates a cavity, void of solar wind ions (H<sup>+</sup>, He<sup>++</sup>), which depends weakly upon the phase of the solar cycle, 2) the motional electric field of the solar wind flow creates strong asymmetries in the Martian environment, 3) the spatial distribution of the different components of the planetary plasma depends strongly upon the phase of the solar cycle. The fluxes of the escaping planetary ions are computed from the simulated data and results for solar maximum are compared with estimates based on the measurements made by experiments ASPERA and TAUS on board Phobos-2

    SYNTAX II and SYNTAX III trials: What is the take home message for surgeons?

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    Percutaneous coronary intervention (PCI) has evolved greatly in the last 40 years since its introduction by Andreas Grüntzig in 1977. Since then, we've observed an evolution in balloons, the development of stents, changes in stent structure, development of drug eluting stents, improvements in strut design, thickness and even their polymeric coating. Most recently we saw the rise and "fall" of bioabsorbable scaffolds for PCI. Trials with the most diverse devices for PCI and diagnostic techniques have been conducted. Two of the most recent trials were reported in the last year and deserve special attention-SYNTAX II and SYNTAX III. These trials are completely different in design but present valuable information for doctors managing coronary artery disease (CAD). Both trials take into account contemporary technology for assessing and treating CAD. The first uses so-called "state-of-the-art" PCI and compares the outcomes of that approach with the outcomes of the PCI arm of the pivotal SYNTAX trial. SYNTAX III Revolution on the other hand does not focus on clinical endpoints: it is a blinded trial that does not randomize patients but randomizes doctors ("the heart team") to make a decision on the best treatment for complex CAD. This decision was based either on multi-slice CT with physiological assessment using FFRCT or on conventional angiography. In this review we bring the most important aspects of those trials and the key messages for surgeons together; also, what the surgeon may expect in the future after the publication of these interesting concepts

    Electron densities in the upper ionosphere of Mars from the excitation of electron plasma oscillations

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94727/1/jgra19333.pd

    Homogenous recycling of transuranium elements from irradiated fast reactor fuel by the EURO-GANEX solvent extraction process

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    The EURO-GANEX process was developed forco-separating transuranium elements from irradiatednuclear fuels. A hot flow-sheet trial was performed in acounter-current centrifugal contactor setup, using a genuinehigh active feed solution. Irradiated mixed (carbide,nitride) U80Pu20 fast reactor fuel containing 20 % Pu wasthermally treated to oxidise it to the oxide form which wasthen dissolved in HNO3. From this solution uranium wasseparated to >99.9 % in a primary solvent extraction cycleusing 1.0 mol/L DEHiBA (N,N-di(2-ethylhexyl)isobutyramidein TPH (hydrogenated tetrapropene) as the organicphase. The raffinate solution from this process, containing10 g/L Pu, was further processed in a second cycle of solventextraction. In this EURO-GANEX flow-sheet, TRU andfission product lanthanides were firstly co-extracted intoa solvent composed of 0.2 mol/L TODGA (N,N,N′,N′-tetran-octyl diglycolamide) and 0.5 mol/L DMDOHEMA (N,N′-dimethyl-N,N′-dioctyl-2-(2-hexyloxy-ethyl) malonamide)dissolved in Exxsol D80, separating them from most otherfission and corrosion products. Subsequently, the TRUwere selectively stripped from the collected loaded solventusing a solution containing 0.055 mol/L SO3-Ph-BTP(2,6-bis(5,6-di(3-sulphophenyl)-1,2,4-triazin-3-yl)pyridinetetrasodium salt) and 1 mol/L AHA (acetohydroxamicacid) in 0.5 mol/L HNO3; lanthanides were finally strippedusing 0.01 mol/L HNO3. Approximately 99.9 % of the TRUand less than 0.1 % of the lanthanides were found in theproduct solution, which also contained the major fractionsof Zr and Mo

    Uso da tomografia computadorizada para estudo do ambiente solo-semente de soja sob sistema de plantio direto.

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    bitstream/CNPDIA-2009-09/11890/1/CT93_2008.pd

    Temporal variability of waves at the proton cyclotron frequency upstream from Mars: Implications for Mars distant hydrogen exosphere

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    We report on the temporal variability of the occurrence of waves at the local proton cyclotron frequency upstream from the Martian bow shock from Mars Global Surveyor observations during the first aerobraking and science phasing orbit periods. Observations at high southern latitudes during minimum-to-mean solar activity show that the wave occurrence rate is significantly higher around perihelion/ southern summer solstice than around the spring and autumn equinoxes. A similar trend is observed in the hydrogen (H) exospheric density profiles over the Martian dayside and South Pole obtained from a model including UV thermospheric heating effects. In spite of the complexity in the ion pickup and plasma wave generation and evolution processes, these results support the idea that variations in the occurrence of waves could be used to study the temporal evolution of the distant Martian H corona and its coupling with the thermosphere at altitudes currently inaccessible to direct measurements.Fil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Romanelli, Norberto Julio. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Chaufray, J. Y.. LATMOS; FranciaFil: Gomez, Daniel Osvaldo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Mazelle, C.. IRAP; FranciaFil: Delva, M.. IWF-ÖAW; AustriaFil: Modolo, R.. LATMOS; FranciaFil: González Galindo, F.. Instituto de Astrofísica de Andalucía; EspañaFil: Brain, D. A.. University of Colorado Boulder; Estados Unido
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