152 research outputs found

    Assessing recharge and discharge across the prairie pothole landscape: application of spatial hydrological data and statistical analysis in a groundwater flow model

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    Quantifying the spatial and temporal dynamics between groundwater recharge, discharge, and wetlands is a necessary step to develop effective water management strategies. Wetlands in the northern Great Plains play a role in flood control, water supply, and regional ecology. The water budget of a wetland in the northern prairies is often an unequal balance between moisture input and output in which the permanence of a wetland depends on its groundwater budget. Identifying and quantifying groundwater recharge and discharge zones has applications in predicting the spatial and temporal distribution of wetlands. The current work involved the application of a groundwater model to the watershed of the North Branch of the Turtle River in Nelson County, North Dakota. The model identified the spatial distribution of recharge and discharge zones by estimating the local configuration of the water table. Model input parameters were developed using geographic information systems (GIS). The model was modified to integrate a statistical component to spatially correlate the modeled configuration of the water table with observed water table conditions. The statistical package compared the model output arrays indicating shallow water table with the spatial distribution of observed wetlands and hydric soils. Within the watershed, recharge and discharge zones were mapped, the configuration of the water table was estimated, and areas with a shallow water table identified. Model output was found to be strongly controlled by the initial topographic profile of the landscape. The magnitude of groundwater flux was considered less reliable than the pattern of flux due to the difficulty in accurately quantifying and discretizing the physical parameters that control the rate of groundwater movement. The model and methods presented provide a means to model the groundwater hydrology of prairie pothole wetlands

    Impact of sown fallows on the Xiphinema index populations in different soil types

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    The nematode Xiphinema index is, economically, the major virus vector in viticulture, transmitting specifically the Grapevine Fanleaf Virus (GFLV), the most severe grapevine virus disease worldwide. The management of this disease has long been to use soil fumigation, harmful for both the applicator and the environment. The objective of this study was to evaluate an alternative approach using plants to reduce vector nematode populations between uprooting and replanting. Of thirty botanical species, tested in previous greenhouse trials, the seven best performing plants were evaluated for their capacity to reduce X. index populations in soil compared to bare soil in 5 field trials on different soil types in Bordeaux and Burgundy. In most trials, sown fallows reduced the number of X. index nematodes more efficiently than bare soil. All plants tested in field, except Trifolium pratense, showed their efficacy in field on survival of nematodes X. index but this efficiency varied according to species and site. The best results were obtained with Medicago hybride, Tagetes minuta, Avena sativa and Vicia villosa. Over the following years we will be evaluating if a decrease of the populations of the nematode vector does lead to a significant drop or delay of GFLV contamination for the newly planted vines

    Non-linear dynamic analysis of anisotropic cylindrical shells containing a flowing fluid

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    Basic theory -- Matrix construction : no fluid -- Analytical formulation : with fluid -- Analysis of free vibrations -- The algorithm

    Un nouvel indicateur intégré d’évaluation des dégâts occasionnés aux grappes par des bioagresseurs majeurs au vignoble

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    Communication faite au cours du colloque DinABio2013, 13 et 14 novembre 2013; Tours, FranceAn original and integrative evaluation indicator has been developed to quantify the cumulated damage from major pests and diseases affecting grape bunches: downy mildew, powdery mildew, gray mould and tortricid moths. It made it possible to estimate the associated crop losses and to relate them to the plant protection strategy in different modes of production (organic farming, in-transition, conventional). Thus, overall plant losses were higher in 2012 than in 2011. The in-transition growers’ strategy, with reduced copper doses but increased numbers of sprays, led to a 20% increase in average severity on bunches (essentially due to Downy mildew). The more pragmatic approach of experienced organic growers and conventional ones (higher doses and fewer sprays) reduced the yield losses. The proposed indicator is used for two purposes, i) evaluating the quantitative losses due to pest attacksand ii) differentiating them from other non-pest ones. A more detailed analysis including the impact on performance will be achieved and published soon.Un indicateur d’évaluation, l’IEDG (Indicateur d’Evaluation des Dégâts sur Grappes), a été mis au point pour quantifier les dégâts cumulés dus aux principaux bioagresseurs affectant les grappes de raisin : mildiou, oïdium, pourriture grise et tordeuses. Il permet d’estimer la perte de récolte imputable au cortège parasitaire et de faire le lien avec la stratégie phytosanitaire adoptée (caractérisée ici par l’IFT) et le mode de production (AB, conversion, conventionnel). Ainsi, les pertes sanitaires ont été supérieures en 2012 par rapport à 2011. La stratégie phytosanitaire des viticulteurs en conversion, basée sur des réductions de dose de cuivre de près de 80% et des passages plus nombreux dans les parcelles, n’a pas été efficiente en 2012 avec des sévérités proches de 20% sur grappe, essentiellement dues au mildiou. L’utilisation de doses d’applications supérieures et moins de passages dans les parcelles limite les dommages chez les autres viticulteurs. L’indicateur proposé permet d’évaluer les pertes quantitatives générées par les attaques de bioagresseurs et de les différencier des autres pertes non parasitaires. Une analyse plus fine incluant l’effet région et l’impact sur le rendement devra être réalisée

    A new integrative assessment indicator for damage caused by major pests and diseases in the vineyard

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    An original and integrative evaluation indicator has been developed to quantify the cumulated damage from major pests and diseases affecting grape bunches: downy mildew, powdery mildew, gray mould and tortricid moths. It made it possible to estimate the associated crop losses and to relate them to the plant protection strategy in different modes of production (organic farming, in-transition, conventional). Thus, overall plant losses were higher in 2012 than in 2011. The in-transition growers’ strategy, with reduced copper doses but increased numbers of sprays, led to a 20% increase in average severity on bunches (essentially due to Downy mildew). The more pragmatic approach of experienced organic growers and conventional ones (higher doses and fewer sprays) reduced the yield losses. The proposed indicator is used for two purposes, i) evaluating the quantitative losses due to pest attacks and ii) differentiating them from other non-pest ones. A more detailed analysis including the impact on performance will be achieved and published soon

    Soil type and soil preparation influence vine development and grape composition through its impact on vine water and nitrogen status

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    The influence of soil type and preparation on vine development and grape composition was investigated in a 50 ha estate located in Saint-Emilion (Bordeaux, France) and planted predominantly with Merlot. Part of the vineyard was planted down the slopes and another part of the vineyard was planted on terraces, where soils were profoundly modified through soil preparation. Grape composition (berry weight, sugar, total acidity, malic acid and pH), vigor (pruning weight), vine nitrogen status (Yeast Available Nitrogen (YAN) in grapes) and vine water status (δ13C) was measured at a very high density grid of 10 data points per hectare. Water deficit was globally weak over the estate because of high soil water holding capacity whereas vine nitrogen status was highly variable. Vine vigor and grape composition were predominantly driven by vine nitrogen status. On terraces, where soils were deep, due to invasive soil preparation, water deficits were particularly small or non-existent and vine nitrogen status was highly variable. Grape quality potential was medium to low, except in places with low nitrogen status, but at the expense of low yields. On parcels planted down the slopes water deficits were recorded because vine rooting was limited by compact subsoils. Vine nitrogen status was homogeneous. Grape quality and yield were medium to high and relatively homogeneous. When possible, downhill plantations are to be preferred over terraces because in the latter vine yield and quality parameters are highly variable because of massive soil movements prior to plantation

    3-D Reconstruction of Urban Scenes from Sequences of Images

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    In this paper, we address the problem of the recovery of the Euclidean geometry of a scene from a sequence of images without any prior knowledge either about the parameters of the cameras, or about the motion of the camera(s). We do not require any knowledge of the absolute coordinates of some control points in the scene to achieve this goal. Using various computer vision tools, we establish correspondences between images and recover the epipolar geometry of the set of images, from which we show how to compute the complete set of perspective projection matrices for each camera position. These being known, we proceed to reconstruct the scene. This reconstruction is defined up to an unknown projective transformation (i.e. is parameterized with 15 arbitrary parameters). Next we show how to go from this reconstruction to a more constrained class of reconstructions, defined up to an unknown affine transformation (i.e. parameterized with 12 arbitrary parameters) by exploiting known geometr..

    032: Thirty months outcomes after PCI of unprotected left main coronary artery according to the SYNTAX score

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    AimsTo assess middle term outcomes according to SYNTAX score and rates of delayed surgical/bleeding events after unprotected left main (LM) coronary artery (ULMCA) PCI in an unselected patients population.MethodsConsecutive patients treated by PCI for ULMCA were included among a single center 3508 PCI database within 36 months. Syntax scores were calculated, post discharge extracardiac surgery or hemorrhage were recorded during follow-up as clinical outcomes (Death, TVR, MACCE=cardiovascular death+MI+stroke+TLR).Results102 (3.6%) patients underwent PCI of the LM, including 21 protected LM. Among the 81 patients with PCI of ULMCA, mean age was 65±13, 27% had urgent PCI for AMI or cardiogenic shock, 61% had DES.SYNTAX score was 28±14 in mean and ≤22 in 30 (37%), 23 to 32 in 22 (27%) and ≥33 in 29 (36%) patients.At 30±11 months follow up (98% of the patients), death occurred in 24 patients (30%), TVR in 16 (20%) and MACCE in 35 (43%). Clinical events according to the SYNTAX score are shown in figure. No cardiovascular death occurred in patients with syntax ≤22. MACCE rates were significantly lower when DES were used (24% vs. 64%, p<0.05) and in case of non-urgent PCI (36% vs. 71%, p<0.05).During follow-up, 20 (25%) and 12 (15%) patients underwent unplanned extracardiac surgery and/or hemorrhage, leading to antiplatelet withdrawal in 31% of the cases.ConclusionsIn unselected patients treated by PCI of ULMCA with Syntax score ≤22, outcomes were found to be excellent with no cardiovascular death observed at 30 months. DES and non-urgent PCI were associated with a better prognosis. One patient out of three underwent unplanned extracardiac surgery or hemorrhage during follow up.Figure: 30-months outcomes according to SYNTAX scor

    Persistent orocutaneous and anal fistulae induced by nicorandil: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Although nicorandil is prescribed widely, awareness of its potential to cause serious complications to the gastrointestinal tract mucosa is limited. Whilst nicorandil-induced oral and anal ulceration is well documented in the literature, nicorandil-induced fistulation is not. This is the first report in the literature of a single patient demonstrating simultaneous orocutaneous and anal fistulae during nicorandil therapy. Two separate cases of orocutaneous and anal fistulae associated nicorandil usage have previously been documented in specialist journals.</p> <p>Case presentation</p> <p>A 71-year-old Caucasian man presented with a 3-year history of concurrent orocutaneous and anal fistulae. He had been exposed to 30 mg twice-daily nicorandil therapy for 4 years. Both fistulae responded poorly to intensive and prolonged conventional treatment but healed promptly on reduction and eventual withdrawal of nicorandil therapy.</p> <p>Conclusion</p> <p>Management of resistant cases of orocutaneous and anal fistulae in patients on high-dose nicorandil therapy may be impossible without reduction or even withdrawal of nicorandil.</p
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