1,484 research outputs found

    Contribution of multi-temporal remote sensing images to characterize landslide slip surface ‒ Application to the La Clapière landslide (France)

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    Landslide activity is partly controlled by the geometry of the slip surface. This activity is traduced at the surface by displacements and topographic variations. Consequently, multi-temporal remote sensing images can be used in order to characterize the geometry of landslide slip surface and its spatial and temporal evolution. Differential Digital Elevation Models (DEMs) are obtained by subtracting two DEMs of different years. A method of multi-temporal images correlation allows to generate displacement maps that can be interpreted in terms of velocity and direction of movements. These data are then used to characterize qualitatively the geometry of the slip surface of the la Clapière landslide (French Southern Alps). Distribution of displacement vectors and of topographic variations are in accordance with a curved slip surface, characterizing a preferential rotational behaviour of this landslide. On the other hand, a spatial and temporal evolution of the geometry of the slip surface is pointed out. Indeed, a propagation of the slip surface under the Iglière bar, in the W part of the landslide, is suspected and can be linked to the acceleration of the landslide in 1987. This study shows the high potential of multi-temporal remote sensing images for slip surface characterization. Although this method could not replace in situ investigations, it can really help to well distribute geophysical profiles or boreholes on unstable areas

    Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade

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    Upgraded spectroscopic hardware and an improved impurity concentration calculation allow accurate determination of boron density in the ASDEX Upgrade tokamak. A database of boron measurements is compared to quasilinear and nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational effects over a range of H-mode plasma regimes. The peaking of the measured boron profiles shows a strong anti-correlation with the plasma rotation gradient, via a relationship explained and reproduced by the theory. It is demonstrated that the rotodiffusive impurity flux driven by the rotation gradient is required for the modelling to reproduce the hollow boron profiles at higher rotation gradients. The nonlinear simulations validate the quasilinear approach, and, with the addition of perpendicular flow shear, demonstrate that each symmetry breaking mechanism that causes momentum transport also couples to rotodiffusion. At lower rotation gradients, the parallel compressive convection is required to match the most peaked boron profiles. The sensitivities of both datasets to possible errors is investigated, and quantitative agreement is found within the estimated uncertainties. The approach used can be considered a template for mitigating uncertainty in quantitative comparisons between simulation and experiment.Comment: 19 pages, 11 figures, accepted in Nuclear Fusio

    On three-manifolds dominated by circle bundles

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    We determine which three-manifolds are dominated by products. The result is that a closed, oriented, connected three-manifold is dominated by a product if and only if it is finitely covered either by a product or by a connected sum of copies of the product of the two-sphere and the circle. This characterization can also be formulated in terms of Thurston geometries, or in terms of purely algebraic properties of the fundamental group. We also determine which three-manifolds are dominated by non-trivial circle bundles, and which three-manifold groups are presentable by products.Comment: 12 pages; to appear in Math. Zeitschrift; ISSN 1103-467

    Evaluation of New Pasture Legume Species in Terms of Summer Feeding Value and Effects on Wool Production.

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    86KA71, Pasture legumes improve the feeding value of summer pastures in a mediterranean-type environment by maintaining the protein intake of grazing animals over the dry summer period, much of which comes from the ingestion of legume burr (A.D. Wilson and N.L. Hindley, 1968). Some of the most important species of pasture legumes to have been released commercially are Trifolium subterraneum (sub.clover), Medicago truncatula (barrel medic) and Medicago polymorpha (burr medic) (D.B. Purser, G.B. Taylor and W.J. Collins, 1987). What little information is available on the feeding value of these species suggests that barrel medic pod (H. Brownlee, 1973) and dry sub.clover pasture (D.B. Purser, unpublished data, as quoted in D.B. Purser et al., 1987) do not supply sufficient nutrients to permit the maintenance of body weight. Field observations however, have shown that sheep grazing burr medic pastures over summer are more productive than sheep grazing sub.clover or grass pastures. There is a wide range in pod structure and chemical composition between and within the different species of pasture legumes and this is likely to affect their feeding value. It is particularly relevant to consider the pod\u27s content of seed because it is the seed that provides the main source of nutrients, especially lipids and proteins (G.D. Denney, J.P. Hogan and J.R. Lindsay, 1979). Preliminary research at Katanning (Western Australia) has shown that the pod:seed ratio of barrel medic is only approximately 35% whereas the pod:seed ratio of the burr medics Circle Valley and Serena is approximately 50%. This finding suggests that the quality of burr medic pod is likely to be superior to the quality of barrel medic pod

    Prevalence of glaucoma in the Lao People's Democratic Republic: the Vientiane Eye Study

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    First published March 18, 2021.AIMS: To determine the prevalence and subtypes of glaucoma in Vientiane Province. METHODS: We conducted a population-based study of 1264 participants aged ≥40 years of age from urban and rural areas of Vientiane Province. Data collection included Snellen visual acuity, slip lamp examination, tonometry, gonioscopy, dilated stereoscopic disc examination and perimetry. Glaucoma was categorised by clinical subtype. RESULTS: The mean age of the 1264 participants was 57.6 years; 91.9% of eyes had a gradable disc. The prevalence of glaucoma of any category in at least one eye was 1.54% (95% CI 0.66% to 3.59%). The overall prevalence of primary open-angle glaucoma, primary angle-closure glaucoma and secondary glaucoma was 0.62% (95% CI 0.19% to 1.98%), 0.55% (95% CI 0.12% to 2.54%) and 0.37% (95% CI 0.07% to 1.86%); 12 (66.7%) of participants with glaucoma were at least unilaterally blinded by WHO definition. CONCLUSIONS: The prevalence of glaucoma in the Vientiane Eye Study is relatively low compared with the prevalence reported in other studies from Asian regions; however, the median age in this study was low, reflecting the age group of the population and the rapid urbanisation occurring in the Lao People's Democratic Republic. Nevertheless, glaucoma remains a blinding disease in this population.Brad Guo, Yiran Tan, Stephen Nygaard, Cesar Carrillo, Kham Od Nouansavanh, Kitar Souksamone, Robert J Casso

    Exploring Pompeii: discovering hospitality through research synergy

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    Hospitality research continues to broaden through an ever-increasing dialogue and alignment with a greater number of academic disciplines. This paper demonstrates how an enhanced understanding of hospitality can be achieved through synergy between archaeology, the classics and sociology. It focuses on classical Roman life, in particular Pompeii, to illustrate the potential for research synergy and collaboration, to advance the debate on hospitality research and to encourage divergence in research approaches. It demonstrates evidence of commercial hospitality activities through the excavation hotels, bars and taverns, restaurants and fast food sites. The paper also provides an example of the benefits to be gained from multidisciplinary analysis of hospitality and tourism
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