70 research outputs found

    Numerical study of ground vortex formation

    Get PDF
    It is well known that under certain conditions, a tornado-like vortex is formed between an air inlet and a nearby solid wall. When a gas-turbine engine is operated / manoeuvred near a ground plane at static or near-static conditions, a strong vortex is often observed to form between the ground and the inlet. This so called inlet vortex (or ground vortex) can cause severe operational difficulties. With CFD tools, the ground vortex phenomenon has been simulated on a 1/1th scale model. Calculations have been performed under cross-wind ground vortice mode of formation. The effect of the height of the intake to the ground and the effect of the cross-flow velocity have been studied in term of velocities and turbulent kinetic energy, after which the study of the appearance and location of the vortice have been made. The cross-flow test showed the formation of one vortice at an upstream location. The study of the effect of cross-flow velocity and the effect of the height of the intake showed that are fulcral parameters for the appearance and strength of the vortice

    Critical Zone Storage Controls on the Water Ages of Ecohydrological Outputs

    Get PDF
    Acknowledgments: This work was supported by the European Research Council (ERC, project GA 335910 VeWa). M.P. Maneta acknowledges support from the NASA Ecological Forecasting Program Award #80NSSC19K00181 and NASA EPSCoR #80NSSC18M0025M. The authors are thankful to V. Ivanov, two anonymous reviewers, and E. Anguelova, whose comments and suggestions considerably improved the manuscript. Open access funding enabled and organized by Projekt DEAL. Funding Information EC | FP7 | FP7 Ideas: European Research Council (FP7 Ideas). Grant Number: GA 335910 VeWa National Aeronautics and Space Administration (NASA). Grant Numbers: #80NSSC19K00181, #80NSSC18M0025M NASA EPSCoR. Grant Number: #80NSSC18M0025M NASA Ecological Forecasting Program. Grant Number: #80NSSC19K00181 European Research Council. Grant Number: GA 335910 Open access funding enabled and organized by Projekt DEAL.Peer reviewedPublisher PD

    Changes to Snowpack Energy State from Spring Storm Events, Columbia River Headwaters, Montana

    Get PDF
    The generation and release of meltwater during the spring snowmelt season can be delayed because of spring storm episodes with snow accumulation and/or sustained subfreezing temperatures. The delayed release of snowmelt often extends beyond the particular storm event because of changes to the internal state of energy in the snowpack that prevents transmission of meltwater. Following a storm, two energy deficits internal to the snowpack must be overcome before surface melt can drain and exit the snowpack: 1) cold content created by heat lost during the episode must be removed and 2) dry pore space must be filled with liquid water to residual saturation. This study investigates the role of these two processes in spring snowmelt following past storm episodes in western Montana. The analysis addresses;10 yr of historical snowpack and air temperature data from 33 stations in the Columbia River headwaters. Results indicate that the addition of pore space has a greater impact on delaying snowmelt than does the addition of cold content, with snow accumulation events responsible for 86% of the collective energy deficit imposed on the snowpack during storm episodes. Nearly all refreezing events occur within one month of peak snowpack, but accumulation events are common up to 50 days later. Under standardized conditions representing clear weather during the spring season, these energy deficits could all be overcome in a matter of hours

    Economic impacts of regional water scarcity in the SĂŁo Francisco River Basin, Brazil: an application of a linked hydro-economic model.

    Get PDF
    This paper presents a linked hydro-economic model and uses it to examine the regional effects of water use regulations and product price changes on the agriculture of the SĂŁo Francisco River Basin, Brazil. The effects of weather on surface water availability are explicitly addressed using the hydrological model MIKE-Basin. Farmers? adjustments to changes in precipitation, surface water availability, and other factors are quantified using an economic model based on non-linear programming techniques. The models are externally linked. Results show that regional impacts, at the sub-basin level, vary depending on the location of each sub-basin relative to river flows. The effects of water use regulations and of exogenous price shocks on agriculture depend on weather, location, productmix and production technology. Implications of these results for policies designed to manage agriculture and water use are discussed

    A spatially distributed hydroeconomic model to assess the effects of drought on land use, farm profits, and agricultural employment.

    Get PDF
    In this paper a high-resolution linked hydroeconomic model is demonstrated for drought conditions in a Brazilian river basin.Doi: 10.1029/2008WR00753

    A parsimonious crop-water productivity index: an application to Brazil.

    Get PDF
    An application to the SĂŁo Francisco river basin; Site characteristics, data sources and methodology

    Assessing agriculture-water links at the basin scale: hydrologic and economic models of the SĂŁo Francisco River Basin, Brazil.

    Get PDF
    This article uses a basin-wide hydrologic model to assess the hydrologic and economic effects of expanding agriculture in the SĂŁo Francisco River Basin, Brazil

    G-CSF induces CD15(+) CD14(+) cells from granulocytes early in the physiological environment of pregnancy and the cancer immunosuppressive microenvironment

    Get PDF
    OBJECTIVES: Recombinant granulocyte colony‐stimulating factor (G‐CSF) is frequently administered to patients with cancer to enhance granulocyte recovery post‐chemotherapy. Clinical trials have also used G‐CSF to modulate myeloid cell function in pregnancy and inflammatory diseases. Although the contribution of G‐CSF to expanding normal granulocytes is well known, the effect of this cytokine on the phenotype and function of immunosuppressive granulocytic cells remains unclear. Here, we investigate the impact of physiological and iatrogenic G‐CSF on an as yet undescribed granulocyte phenotype and ensuing outcome on T cells in the settings of cancer and pregnancy. METHODS: Granulocytes from patients treated with recombinant G‐CSF, patients with late‐stage cancer and women enrolled on a trial of recombinant G‐CSF were phenotyped by flow cytometry. The ability and mechanism of polarised granulocytes to suppress T‐cell proliferation were assessed by cell proliferation assays, flow cytometry and ELISA. RESULTS: We observed that G‐CSF leads to a significant upregulation of CD14 expression on CD15(+) granulocytes. These CD15(+)CD14(+) cells are identified in the blood of patients with patients undergoing neutrophil mobilisation with recombinant G‐CSF, and physiologically in women early in pregnancy or in those treated as a part of a clinical trial. Immunohistochemistry of tumor tissue or placental tissue identified the expression of G‐CSF. The G‐CSF upregulates the release of reactive oxygen species (ROS) in CD15(+)CD14(+) cells leading to the suppression of T‐cell proliferation. CONCLUSIONS: G‐CSF induces a population of ROS(+) immunosuppressive CD15(+)CD14(+) granulocytes. Strategies for how recombinant G‐CSF can be scheduled to reduce effects on T‐cell therapies should be developed in future clinical studies

    Biophysical analysis of the plant-specific GIPC sphingolipids reveals multiple modes of membrane regulation

    Get PDF
    The plant plasma membrane (PM) is an essential barrier between the cell and the external environment, controlling signal perception and transmission. It consists of an asymmetrical lipid bilayer made up of three different lipid classes: sphingolipids, sterols, and phospholipids. The glycosyl inositol phosphoryl ceramides (GIPCs), representing up to 40% of total sphingolipids, are assumed to be almost exclusively in the outer leaflet of the PM. However, their biological role and properties are poorly defined. In this study, we investigated the role of GIPCs in membrane organization. Because GIPCs are not commercially available, we developed a protocol to extract and isolate GIPC-enriched fractions from eudicots (cauliflower and tobacco) and monocots (leek and rice). Lipidomic analysis confirmed the presence of trihydroxylated long chain bases and 2-hydroxylated very long-chain fatty acids up to 26 carbon atoms. The glycan head groups of the GIPCs from monocots and dicots were analyzed by gas chromatograph–mass spectrometry, revealing different sugar moieties. Multiple biophysics tools, namely Langmuir monolayer, ζ-Potential, light scattering, neutron reflectivity, solid state 2H-NMR, and molecular modeling, were used to investigate the physical properties of the GIPCs, as well as their interaction with free and conjugated phytosterols. We showed that GIPCs increase the thickness and electronegativity of model membranes, interact differentially with the different phytosterols species, and regulate the gel-to-fluid phase transition during temperature variations. These results unveil the multiple roles played by GIPCs in the plant PM.Vers un modĂšle intĂ©gratif de la bicouche lipidique de la membrane plasmique vĂ©gĂ©taleDĂ©veloppement d’une infrastructure française distribuĂ©e pour la mĂ©tabolomique dĂ©diĂ©e Ă  l’innovatio
    • 

    corecore