On the numerical modelling of the Jet Erosion Test

International audienceEvaluating the erodibility of a soil, both in terms of erosion threshold (initiation) and erosion rate (progression), is critical for the evaluation of the safety of water retaining structures. Indeed different soils can erode at different rates. However, the relationship between the erosion parameters and the geotechnical and chemical properties of soils remains largely unknown. The jet erosion test appears to be an efficient and simple means for quantifying the two erosion parameters involved. The first parameter is the critical stress while the second parameter is the erosion coefficient. A simplified model of this test has been drawn up by G. Hanson et al. to interpret the experimental curves. Few attempts have been made so far to model the whole process, however. The aim of this study is to simulate the impinging jet and to take into account the erosion of the soil by means of computational fluid dynamics (CFD) numerical modelling. The key point was the time dependence of the problem, due to erosion processes, however the turbulent flow could be considered as steady because of the assumption of low kinetics erosion assumption. The results of the present modelling study are compared to the simplified model and to experimental data. This comparison is a first confirmation of the validity of the simplified model as a means of assessing the critical stress and the erosion coefficient with jet erosion tests

Fréteval – Le Château

Date de l'opération : 1988 - 1991 (FP) ; 1985 - 1987 (FP) Inventeur(s) : Leymarios Claude ; Courivaud Sylvie ; Bouclet P ; Masquilier Amaury Les trois premières campagnes de fouilles ont essentiellement porté sur la Haute-Cour, à l'ouest du château (Bouclet, Masquillier, Riquier, 1990, 1992; Leymarios, 1985, 1988, 1989). Plusieurs structures ont été étudiées : un four à pain, un ensemble de bâtiments au nord de la plate-forme et les vestiges d'une tourelle d'angle (Fig. n°1 : Le Château. pla..

Caractérisation des sables et morphologie du fond du lac du barrage hydroélectrique de Taabo (Côte d\'Ivoire)

Une analyse sédimentologique et minéralogique réalisée sur un cycle hydrologique entre octobre 2004 et août 2005 a permis d\'évaluer les charges solides en suspension et de caractériser les sédiments du lac du barrage de Taabo. La concentration moyenne en matières en suspension (12 mg.L-1) et la turbidité moyenne (20 NTU) montrent que les eaux du lac sont relativement peu chargées. Ces charges en suspension sont composées d\'une fraction inorganique et d\'une fraction organique. Les sables qui composent les sédiments de ce lac sont majoritairement moyens à grossiers et médiocrement classés avec une moyenne granulométrique de 451,48 μm et un indice de classement moyen de 1,13. Les vases et les sables fins occupent les zones profondes du lac et les zones envahies par les végétaux aquatiques. Les sables moyens sont localisés aux voisinages des berges tandis que les sables grossiers sont situés aux voisinages des îles et de la digue. Le cortège minéralogique des sédiments est caractérisé de minéraux lourds (l\'amphibole, la tourmaline, le diopside et l\'épidote) et de minéraux légers (le quartz et les feldspaths). Par ailleurs, cette étude a permis de réaliser la première carte bathymétrique du lac de Taabo 26 ans après sa mise en eau.A sedimentological and mineralogical study carried out on a hydrological cycle from October 2004 to August 2005 has permitted to assess the solid suspended matters and to characterize the sediments of the Taabo dam lake. The average of suspended matters concentration (12 mg.L -1) and the average of turbidity (20 NTU) reveal that the lake is relatively little loaded with suspended matters. These suspended matters are compound of an inorganic fraction and an organic fraction. Sands size in the sediments of this lake are from middle to coarse and badly classified. The grain size average is 451,48 μm; the standard deviation average is 1,13. Muds and fine sands are found in the deeper zones of the lake and also in the zones invaded by the aquatic plants. Middle sands are located near banks while coarse sands are located aside the islands and the dam. The minerals found in the sediments are characterized by heavy minerals (the amphibole, tourmaline, diopside and epidote) and light minerals (quartz and feldspars). Elsewhere, this study has permitted to carry out the first bathymetric Map of this lake 26 years after its setting in water. Keywords: keywordBarrage, lac, granulométrie, minéralogie, bathymétrie, Taabo./Dam, lake, grain size, mineralogy, bathymetry, Taabo.Sciences & Nature Vol. 4 (1) 2007: pp. 93-10

Feed-back on the development of a small scale Contact Erosion Test in the laboratory (characteristic size ~ 30 cm)

To determine the hydraulic load requested to initiate contact erosion process, tests are performed with an apparatus called the “Contact Erosion Test”. This device originally results from research carried out by Grenoble University, Électricité de France and Compagnie Nationale du Rhône, at the scale of ~60 cm. It has been adapted to a smaller scale in geophyConsult laboratory to conduct tests on samples extracted from core drilling. The instrumentation was improved to enable a better control of the hydraulic loading and avoid biases. The test protocol was modified, especially to better constrain the soil density at the interface. From the first series of test, we drew conclusions on the test repeatability and on the influence of parameters of the soil state. Discrepancies with previous results obtained at the scale of ~60 cm were identified. Therefore, a new erosion test campaign was planned to confirm and determine the reasons for these differences

Cytotoxic polyfunctionality maturation of cytomegalovirus-pp65-specific CD4 + and CD8 + T-cell responses in older adults positively correlates with response size

Cytomegalovirus (CMV) infection is one of the most common persistent viral infections in humans worldwide and is epidemiologically associated with many adverse health consequences during aging. Previous studies yielded conflicting results regarding whether large, CMV-specific T-cell expansions maintain their function during human aging. In the current study, we examined the in vitro CMV-pp65-reactive T-cell response by comprehensively studying five effector functions (i.e., interleukin-2, tumor necrosis factor-α, interferon-γ, perforin, and CD107a expression) in 76 seropositive individuals aged 70 years or older. Two data-driven, polyfunctionality panels (IL-2-associated and cytotoxicity-associated) derived from effector function co-expression patterns were used to analyze the results. We found that, CMV-pp65-reactive CD8 + and CD4 + T cells contained similar polyfunctional subsets, and the level of polyfunctionality was related to the size of antigen-specific response. In both CD8 + and CD4 + cells, polyfunctional cells with high cytotoxic potential accounted for a larger proportion of the total response as the total response size increased. Notably, a higher serum CMV-IgG level was positively associated with a larger T-cell response size and a higher level of cytotoxic polyfunctionality. These findings indicate that CMV-pp65-specific CD4 + and CD8 + T cell undergo simultaneous cytotoxic polyfunctionality maturation during aging

Syndrome de Parkes-Weber familial

[A familial case of Parkes-Weber syndrome]. Introduction. Parkes-Weber syndrome is usually described as a sporadic form of osteohypertrophic angiodysplasia. However, family forms of Klippel-Trenaunay syndrome have been described. We report the first familial case of Parkes-Weber syndrome. Observation. A boy born at 27 weeks and 6 days of amenorrhea with extensive plane angioma of the right lower limb, right lower part of the back and abdomen. We also noted hypertrophy of this member with venous dilatations. Arterial Doppler ultrasound of the right lower limb showed an aneurysmal varix between the vein and the common femoral artery, confirming a diagnosis of Parkes-Weber syndrome. His maternal first cousin, to years his senior, also presented Parkes-Weber syndrome of the right upper limb. Discussion. This is the first observation of a familial case of Parkes-Weber syndrome in first cousins. Vascular malformations are transmitted in autosomal dominant fashion in the majority of infected families but with incomplete penetrance and variable expressivity. Symptoms appeared to worsen from generation to generation. In each generation of this family, we noted the presence of hemangiomas or capillary malformations with aggravation in the third generation and onset of Parkes-Weber syndrome. Genetic investigation with linkage analysis for the various members in order to identify a predisposing locus yielded little of interest.Introduction: Parmi les angiodysplasies ostéohypertrophiques, le syndrome de Parkes-Weber est habituellement décrit comme sporadique. En revanche, des formes familiales du syndrome de Klippel-Trénaunay ont déjà été rapportées. Nous rapportons la première observation familiale d’un syndrome de Parkes-Weber. Observation : Un garçon, né à 27 semaines et 6 jours d’aménorrhée, était atteint d’un angiome plan étendu du membre inférieur droit, de la partie inférieure droite du dos et de l’abdomen. On notait également une hypertrophie de ce membre et des dilatations veineuses. L’échodoppler artériel du membre inférieur droit mettait en évidence une fistule artérioveineuse entre la veine et l’artère fémorale commune, permettant de poser le diagnostic de syndrome de Parkes-Weber. Sa cousine germaine du côté maternel, son aînée de 10 ans, avait également un syndrome de Parkes-Weber du membre supérieur droit. Discussion : Il s’agit de la première observation d’un cas familial, chez des cousins germains, de syndrome de Parkes-Weber. Les malformations vasculaires se transmettent sur un mode autosomique dominant dans la majorité des familles atteintes avec cependant une pénétrance incomplète et une expressivité variable. Il y aurait une aggravation des symptômes de génération en génération. Chez les membres de cette famille, nous avons constaté dans chaque génération la présence d’hémangiomes ou de malformations capillaires avec une aggravation à la troisième génération devant l’apparition du syndrome de Parkes-Weber. Une enquête génétique avec une analyse de liaison génétique pour les différents membres, à la recherche d’un locus prédisposant a été peu contributive

Radionuclides concentrations in the Loire river system resulting from routine discharges of five nuclear power plants: assessment of dose to man

Low level radioactive liquid discharges have been carried out in the Loire river since 1963. Since then, the number of power plants located on the Loire river and its tributaries has been steadily increasing to reach, in the year 2000, 14 reactors operating on 5 different sites. The question arose to evaluate to what extent the addition of several nuclear power plants on the same river system could increase the concentrations in radionuclides in the environment and affect the dose to the public. To address this issue, EDF initiated in 1998 the “Loire river and estuary radioecology” program with the focus on assessing possible accumulation of radionuclide in river bottom sediments or on river shores. The following radionuclides were considered because of their importance in power plant liquid discharges: tritium, 14C, 58Co, 60Co, $^{110{\rm m}}$Ag, 134Cs, 137Cs, 54Mn, 124Sb, and 131I. Radionuclide concentrations in the dissolved, particulate and sedimentary forms were evaluated using the CRESCENDO model. The development and validation of this model required a multi-step process. The first step was to design a 350-km long 1D hydraulic and water transport based on currently available tools and data. Next, daily tritium concentrations measured in Angers, at the downstream limit of the river, were compared with computed values. The following step was to calibrate the sediment transport model. Areas where fine particles settled (dams and river shores) were monitored to improve our understanding of sediment dynamics. Then equations representing radionuclide exchange between water and particles were derived from laboratory experiments and included in the model. After each step the computed values were compared to measure data sets to ensure the model adequately described the processes involved. In the final step, the CALVADOS model was used to calculate dose to the public at different locations along the Loire river

A RETROSPECTIVE STUDY OF THE MANAGEMENT OF ANAEMIA IN PATIENTS WITH DIALYSIS-DEPENDENT CHRONIC KIDNEY DISEASE IN FRANCE: THE AMACK STUDY

International audienc