The interaction of two surface vortices near a topographic slope in a stratified ocean

We study the influence of bottom topography on the interaction of two identical vortices in a two-layer, quasi-geostrophic model. The two vortices have piecewise-uniform potential vorticity, and are lying in the upper layer of the model. The topography is a smooth bottom slope. For two cyclones, topography modifies the merger critical distance and the merger efficiency: the topographic wave and vortices can advect the two cyclones along the shelf when they are initially far from it, or towards the shelf when they are initially closer to it. They can also advect the two cyclones towards each other, and thus favour merger. The topographic wave and vortices exert a deformation on these cyclones, which filament. Regimes of partial vortex merger or of vortex splitting are then observed. The interaction of the vorticity poles in the two layers are analysed to explain the evolution of the two upper layer cyclones. For taller topography, two new regimes appear: vortex drift and splitting, and filamentation and asymmetric merger. They are due to the hetonic coupling of lower layer vorticity with the upper vortices, or to the strong shear that the former exert on the latter. The interaction of two anticyclones shows regimes of co-rotation or merger, but specifically, it leads to the drift of the two vortices away from the slope, via a hetonic coupling with opposite signed vorticity in the lower layer. This vorticity originates in the breaking of the topographic wave. The analysis of passive tracer evolution confirms the inshore or offshore drift of the fluid, the formation of tracer fronts along filaments and its mixing in regions of vortex merger. The trajectories of particles indicates how the fluid initially in the vortices is finally partitioned.Publisher PDFPeer reviewe

Introduction: Contemporary Victoriana: Victorian Literature and Popular Cultures

“For most of us, the odour of defunct Victoriana is so unpleasant […] that we are content to leave the past where we find it” (Ezra Pound, 1918). “It is not that what is past casts its light on what is present, or what is present its light on what is past; rather, image is that wherein what has been comes together in a flash with the now to form a constellation” (Benjamin 462). In Alan Hollinghurst’s 2011 novel The Stranger’s Child, the reference to Alfred, Lord Tennyson partakes of the gener..

Wideband frequency characterization of a shape memory polymer

International audienceThis study is an experimental evaluation of the mechanical properties of shape memory polymer Veriflex R under different tests conditions. Veriflex R was chosen because of its easy accessibility and its properties similar to epoxy resins which make it very suitable for use in a wide variety of technical applications. Dynamic mechanical analysis (DMA) has been used to determine the evolution of the viscoelastic properties versus temperature and frequency under harmonic loading. The time-temperature superposition principle has been found to be valid for this material. This is illustrated here through the use of the master curves. Furthermore a modal analysis on a Veriflex R rectangular plate has been performed in order to reach higher frequencies than the DMA, and a finite element model was employed to find the viscoelastic properties of the material. A correlation between these two experimental methods allowed to highlight a disparity of results explained by the deterioration of the Veriflex R over time

Prédiction des propriétés de rétention en eau des sols d'un bassin versant à l'aide de fonctions de pédotransfert : influence de la densité apparente et de la teneur en éléments grossiers

L'objectif est d'étudier la qualité de l'estimation des propriétés de rétention en eau faite à l'aide de fonctions de pédotransfert (FPT) pour les sols d'un bassin versant de 250 hectares. Ce bassin versant, situé à proximité de Mantes-la-Jolie, au nord-est de Paris, possède des sols limoneux à limoneux-argileux profonds sur la moitié de sa surface, l'autre moitié correspondant à des sols caillouteux. Après une prospection pédologique détaillée, 15 horizons types ont été définis (Tableau 1), puis 22 unités typologiques de sol (UTS) correspondant à la superposition de plusieurs horizons types et enfin 11 unités cartographiques de sols (UCS) regroupant plusieurs UTS (Tableau 2). Les propriétés de rétention en eau des horizons types ont été déterminées au laboratoire pour 8 valeurs de potentiels variant de –10 à –15000 hPa et, en parallèle, estimées à l'aide des FPT proposées par Hall et al. (1977), Jamagne et al. (1977), Rawls et al. (1982), Vereecken (1989), Bastet (1999) et Bruand et al. (2002) pour des valeurs de potentiel appartenant à ce même domaine. L'aptitude des FPT à rendre compte des variations des propriétés de rétention en eau mesurées pour les horizons types est très variable selon les FPT considérées (Tableau 4). Comme d'autres études l'ont déjà montré (Bastet, 1999, Tietje et Tapkenhinrichs, 1993, Wösten et al., 2001), la proximité géographique de la zone d'étude par rapport à celles ayant servi de base aux FPT et la similitude des matériaux parentaux sont des éléments importants à prendre en compte pour apprécier l'aptitude potentielle de FPT à estimer les propriétés de rétention en eau de sol. Une classification par texture, ou par texture et densité apparente, préalablement à l'établissement de FPT, permet d'améliorer la qualité des estimations. La texture et la densité apparente apparaissent donc comme des grandeurs déterminantes pour estimer correctement les propriétés de rétention en eau des horizons de sols étudiés. Toutefois, la densité apparente à l'échelle de l'horizon peut conduire à prendre en compte un volume de pores qui ne contribuent pas à la réserve en eau du sol, car de trop grande taille, et donc conduire certaines FPT à surestimer largement les valeurs de teneurs en eau. Pour les sols qui possèdent des éléments grossiers, dont la présence n'est pas prise en compte par les FPT, une correction des teneurs en eau mesurées et calculées, visant à les exprimer par rapport à la seule fraction fine (< 2 mm) des horizons, ne permet toutefois à aucune FPT de donner des résultats satisfaisants pour les sols caillouteux. Ces sols caillouteux, le plus souvent peu épais, sont ceux pour lesquels la mesure des propriétés de rétention en eau demeure la plus difficile à obtenir, aucune méthodologie adaptée n'étant disponible à l'heure actuelle

Environmental Assessment of Soil for Monitoring: Volume IIb Survey of National Networks

The ENVASSO Project (Contract 022713) was funded 2006-8, under the European Commission 6th Framework Programme of Research, with the objective of defining and documenting a soil monitoring system appropriate for soil protection at continental level. The ENVASSO Consortium, comprising 37 partners drawn from 25 EU Member States, reviewed almost 300 soil indicators, identified existing soil inventories and monitoring programmes in the Member States, designed and programmed a database management system to capture, store and supply soil profile data, and drafted procedures and protocols appropriate for inclusion in a European soil monitoring network of sites that are geo-referenced and at which a qualified sampling process is or could be conducted. This volume (IIb), a Survey of National Networks, is the second of two reports that together constitute the most comprehensive study to date of the soil inventory and monitoring activities in the European Union. It contains comprehensive fact sheets for each national network, listing the purpose, sampling strategy adopted, analytical methods used and the number of monitoring sites.JRC.H.7-Climate Risk Managemen

Mesure de gradients de déformations par fibre optique = Strain gradient measurement with optical fiber

National audienceCet article porte sur l'utilisation de fibre optique à réseau de Bragg pour mesurer des profils de déformations non uniformes. Les réseaux de Bragg permettent facilement de mesurer des déformations uniformes, notre méthode est donc expliquée pour mesurer des gradients de déformations. Cette méthode est ensuite testée sur une éprouvette en résine, et les résultats comparés à une simulation numériques. Des fibres optiques à réseau de Bragg sont ensuite insérés dans des éprouvettes en composites stratifiés afin de caractériser les variations de déformations à travers les plis soumis à des sollicitations de flexion

A new method for unveiling Open Clusters in Gaia: new nearby Open Clusters confirmed by DR2

Context. The publication of the Gaia Data Release 2 (Gaia DR2) opens a new era in astronomy. It includes precise astrometric data (positions, proper motions, and parallaxes) for more than 1.3 billion sources, mostly stars. To analyse such a vast amount of new data, the use of data-mining techniques and machine-learning algorithms is mandatory. Aims. A great example of the application of such techniques and algorithms is the search for open clusters (OCs), groups of stars that were born and move together, located in the disc. Our aim is to develop a method to automatically explore the data space, requiring minimal manual intervention. Methods. We explore the performance of a density-based clustering algorithm, DBSCAN, to find clusters in the data together with a supervised learning method such as an artificial neural network (ANN) to automatically distinguish between real OCs and statistical clusters. Results. The development and implementation of this method in a five-dimensional space (l, b, ϖ, μα*, μδ) with the Tycho-Gaia Astrometric Solution (TGAS) data, and a posterior validation using Gaia DR2 data, lead to the proposal of a set of new nearby OCs. Conclusions. We have developed a method to find OCs in astrometric data, designed to be applied to the full Gaia DR2 archive

Long-term disease-free survival in advanced melanomas treated with nitrosoureas: mechanisms and new perspectives

BACKGROUND: Median survival of metastatic malignant melanoma is 6.0 to 7.5 months, with a 5-year survival of ~6.0%. Although long-term complete remissions are rare, few reports describe cases after chemotherapy. Fifty-three patients with metastatic melanoma were treated with Cystemustine, a chloroethyl nitrosourea (CENU) (60 or 90 mg/m(2)). CASE PRESENTATION: We describe 5 cases, presenting with complete response with long-term disease-free survival of long-term remission of 14, 12, 9, 7 and 6 years after Cystemustine therapy alone. CONCLUSION: Long-term survival has already been described in literature, but in all cases they have been obtained after chemotherapy associated with or followed by surgery. But despite these noteworthy and encouraging but also rare results, it appears essential to increase cystemustine efficiency

Soil erosion processes in european vineyards: a qualitative comparison of rainfall simulation measurements in Germany, Spain and France

Small portable rainfall simulators are considered a useful tool to analyze soil erosion processes in cultivated lands. European research groups in Spain (Valencia, Málaga, Lleida, Madrid and La Rioja), France (Reims) and Germany (Trier) have used different rainfall simulators (varying in drop size distribution and fall velocities, kinetic energy, plot forms and sizes, and field of application) to study soil loss, surface flow, runoff and infiltration coefficients in different experimental plots (Valencia, Montes de Málaga, Penedès, Campo Real and La Rioja in Spain, Champagne in France and Mosel-Ruwer valley in Germany). The measurements and experiments developed by these research teams give an overview of the variety of methodologies used in rainfall simulations to study the problem of soil erosion and describe the erosion features in different climatic environments, management practices and soil types. The aims of this study are: (i) to investigate where, how and why researchers from different wine-growing regions applied rainfall simulations with successful results as a tool to measure soil erosion processes; (ii) to make a qualitative comparison about the general soil erosion processes in European terroirs; (iii) to demonstrate the importance of the development of standard method for measurement of soil erosion processes in vineyards, using rainfall simulators; and (iv) and to analyze the key factors that should be taken into account to carry out rainfall simulations. The rainfall simulations in all cases allowed infiltration capacity, susceptibility of the soil to detachment and generation of sediment loads to runoff to be determined. Despite using small plots, the experiments were useful to analyze the influence of soil cover to reduce soil erosion, to make comparisons between different locations, and to evaluate the influence of different soil characteristics. The comparative analysis of the studies performed in different study areas points out the need to define an operational methodology to carry out rainfall simulations, which allows us to obtain representative and comparable results and to avoid errors in the interpretation in order to achieve comparable information about runoff and soil los