22 research outputs found
Revue de presse - jeudi 9 octobre 2014
No full text• Mettre la finance au service du climat / Pascal Canfin, Eric Loiselet, Jean-Pierre Sicard, Stéphane Voisin, Kepler Cheuvreux & Philippe Zaouati, Le Monde économie, 9/10/2014 http://www.lemonde.fr/economie/article/2014/10/07/mettre-la-finance-au-service-du-climat_4502137_3234.html La loi sur la transition énergétique doit inciter les investisseurs à « décarboner » leurs portefeuilles... • Risques mondiaux : l'indifférence toute rationnelle des marchés / Nouriel Roubini, président de Roubin..
Influence of surrounding plates on 3D subduction dynamics
No full textInternational audienceOur 3D modelling study shows that the presence of lithospheric plates around a subducting plate has a significant influence on subduction dynamics, in particular on trench retreat rate, slab dip, and lateral shortening of the subducting plate. Neighbouring plates prevent unrealistic plate behaviour with no need for complex rheologies. Because, at the Earth's surface, plates form a continuous shell, they should not be neglected
Diabetes mellitus and optic atrophy: A study of Wolfram syndrome in the Lebanese population
No full textWolfram syndrome (WFS) is a rare hereditary neurodegenerative disorder also known as DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness). WFS seems to be a heterogeneous disease that has not yet been fully characterized in terms of clinical features and pathophysiological mechanisms because the number of patients in most series was small. In this study we describe 31 Lebanese WFS patients belonging to 17 families; this, to our knowledge, is the largest number of patients reported in one series so far. Criteria for diagnosis of WFS were the presence of insulin-dependent diabetes mellitus and optic atrophy unexplained by any other disease. Central diabetes insipidus was found in 87percent of the patients, and sensorineural deafness confirmed by audiograms was present in 64.5percent. Other less frequent features included neurological and psychiatric abnormalities, urodynamic abnormalities, limited joint motility, cardiovascular and gastrointestinal autonomic neuropathy, hypergonadotropic hypogonadism in males, and diabetic microvascular disease. New features, not reported in previous descriptions, such as heart malformations and anterior pituitary dysfunction, were recognized in some of the patients and participated in the morbidity and mortality of the disease. Genetic analysis revealed WFS1 gene mutations in three families (23.5percent), whereas no abnormalities were detected in mitochondrial DNA. In conclusion, WFS is a devastating disease for the patients and their families. More information about WFS will lead to a better understanding of this disease and hopefully to improvement in means of its prevention and treatment.ALDENHOVEL HBG, 1991, NEUROPEDIATRICS, V22, P103; Al-Sheyyab M, 2001, EUR J PEDIATR, V160, P243, DOI 10.1007-s004310000704; BARRETT TG, 1995, LANCET, V346, P1458, DOI 10.1016-S0140-6736(95)92473-6; Barrett TG, 2000, J MED GENET, V37, P463, DOI 10.1136-jmg.37.6.463; Barrientos A, 1996, AM J HUM GENET, V58, P963; Barrientos A, 1996, J CLIN INVEST, V97, P1570, DOI 10.1172-JCI118581; Baz P, 1999, DIABETES CARE, V22, P1376; Bekir NA, 2000, ACTA OPHTHALMOL SCAN, V78, P480, DOI 10.1034-j.1600-0420.2000.078004480.x; BUNDEY S, 1992, J INHERIT METAB DIS, V15, P315, DOI 10.1007-BF02435965; Collier DA, 1996, AM J HUM GENET, V59, P855; COX RW, 1993, DIABETES CARE, V16, P662; CURADO FJA, 2000, ACTAS UROL ESP, V24, P504; El-Shanti H, 2000, AM J HUM GENET, V66, P1229, DOI 10.1086-302858; Evans KL, 2000, AM J MED GENET, V96, P158, DOI 10.1002-(SICI)1096-8628(20000403)96:2158::AID-AJMG63.0.CO;2-8; Genis D, 1997, ACTA NEUROPATHOL, V93, P426; Gomez-Zaera M, 2001, MOL GENET METAB, V72, P72, DOI 10.1006-mgme.2000.3107; GUNN T, 1976, J PEDIATR, V89, P565, DOI 10.1016-S0022-3476(76)80387-3; Gupta K L, 1994, J Assoc Physicians India, V42, P831; Hardy C, 1999, AM J HUM GENET, V65, P1279, DOI 10.1086-302609; HOFFMANN S, 1997, GENOMICS, V39, P8; HOMAN MR, 1987, DIABETES CARE, V10, P664; Inoue H, 1998, NAT GENET, V20, P143, DOI 10.1038-2441; Kato T, 2001, NEUROSCI RES, V40, P105, DOI 10.1016-S0168-0102(01)00221-8; KINSLEY BT, 1995, DIABETES CARE, V18, P1566, DOI 10.2337-diacare.18.12.1566; Krittiyawong Sirinate, 2000, Journal of the Medical Association of Thailand, V83, P1283; Krolewski AS, 1996, ENDOCRIN METAB CLIN, V25, P217, DOI 10.1016-S0889-8529(05)70322-4; LEIVASANTANA C, 1993, REV NEUROL, V149, P26; LIM M C L, 1990, Annals Academy of Medicine Singapore, V19, P548; Middle F, 2000, AM J MED GENET, V96, P154, DOI 10.1002-(SICI)1096-8628(20000403)96:2154::AID-AJMG53.0.CO;2-F; Ohata T, 1998, HUM GENET, V103, P470, DOI 10.1007-s004390050852; POLYMEROPOULOS MH, 1994, NAT GENET, V8, P95, DOI 10.1038-ng0994-95; ROCCHINI AP, 1995, MOSS ADAMS HEART DIS, P43; Sam W, 2001, CLIN GENET, V59, P136, DOI 10.1034-j.1399-0004.2001.590214.x; Seshiah V, 1987, J Assoc Physicians India, V35, P528; SOLIMAN AT, 1995, ARCH DIS CHILD, V73, P251; Swift M, 2000, BIOL PSYCHIAT, V47, P787, DOI 10.1016-S0006-3223(00)00244-4; SWIFT RG, 1990, LANCET, V336, P667, DOI 10.1016-0140-6736(90)92157-D; Swift RG, 1998, MOL PSYCHIATR, V3, P86, DOI 10.1038-sj.mp.4000344; Takeda K, 2001, HUM MOL GENET, V10, P477, DOI 10.1093-hmg-10.5.477; Tanizawa Y, 2000, Rinsho Byori, V48, P941; Tekgul S, 1999, J UROLOGY, V161, P616, DOI 10.1016-S0022-5347(01)61982-7; Tessa A, 2001, Hum Mutat, V17, P348, DOI 10.1002-humu.32; Torres R, 2001, MOL PSYCHIATR, V6, P39, DOI 10.1038-sj.mp.4000787; Wolfram D. J., 1938, MAYO CLIN P, V13, P71557565
Tracking and orbit determination performance of the GRAS instrument on MetOp-A
No full textThe global navigation satellite system receiver for atmospheric sounding (GRAS) on MetOp-A is the first European GPS receiver providing dual-frequency navigation and occultation measurements from a spaceborne platform on a routine basis. The receiver is based on ESA’s AGGA-2 correlator chip, which implements a high-quality tracking scheme for semi-codeless P(Y) code tracking on the L1 and L2 frequency. Data collected with the zenith antenna on MetOp-A have been used to perform an in-flight characterization of the GRAS instrument with focus on the tracking and navigation performance. Besides an assessment of the receiver noise and systematic measurement errors, the study addresses the precise orbit determination accuracy achievable with the GRAS receiver. A consistency on the 5 cm level is demonstrated for reduced dynamics orbit solutions computed independently by four different agencies and software packages. With purely kinematic solutions, 10 cm accuracy is obtained. As a part of the analysis, an empirical antenna offset correction and preliminary phase center correction map are derived, which notably reduce the carrier phase residuals and improve the consistency of kinematic orbit determination results.Delft Institute of earth Observation and Space SystemsAerospace Engineerin
Molecular biology of hearing
No full textThe inner ear is our most sensitive sensory organ and can be subdivided into three functional units: organ of Corti, stria vascularis and spiral ganglion. The appropriate stimulus for the organ of hearing is sound, which travels through the external auditory canal to the middle ear where it is transmitted to the inner ear. The inner ear houses the hair cells, the sensory cells of hearing. The inner hair cells are capable of mechanotransduction, the transformation of mechanical force into an electrical signal, which is the basic principle of hearing. The stria vascularis generates the endocochlear potential and maintains the ionic homeostasis of the endolymph. The dendrites of the spiral ganglion form synaptic contacts with the hair cells. The spiral ganglion is composed of neurons that transmit the electrical signals from the cochlea to the central nervous system. In recent years there has been significant progress in research on the molecular basis of hearing. An increasing number of genes and proteins related to hearing are being identified and characterized. The growing knowledge of these genes contributes not only to greater appreciation of the mechanism of hearing but also to a deeper understanding of the molecular basis of hereditary hearing loss. This basic research is a prerequisite for the development of molecular diagnostics and novel therapies for hearing loss
Subducting slabs: jellyfishes in the Earth mantle
No full textInternational audienceThe constantly improving resolution of geophysical data, seismic tomography and seismicity in particular, shows that the lithosphere does not subduct as a slab of uniform thickness but is rather thinned in the upper mantle and thickened around the transition zone between the upper and lower mantle. This observation has traditionally been interpreted as evidence for the buckling and piling of slabs at the boundary between the upper and lower mantle, where a strong contrast in viscosity may exist and cause resistance to the penetration of slabs into the lower mantle. The distribution and character of seismicity reveal, however, that slabs undergo vertical extension in the upper mantle and compression near the transition zone. In this paper, we demonstrate that during the subduction process, the shape of low viscosity slabs (1 to 100 times more viscous than the surrounding mantle) evolves toward an inverted plume shape that we coin jellyfish. Results of a 3D numerical model show that the leading tip of slabs deform toward a rounded head skirted by lateral tentacles that emerge from the sides of the jellyfish head. The head is linked to the body of the subducting slab by a thin tail. A complete parametric study reveals that subducting slabs may achieve a variety of shapes, in good agreement with the diversity of natural slab shapes evidenced by seismic tomography. Our work also suggests that the slab to mantle viscosity ratio in the Earth is most likely to be lower than 100. However, the sensitivity of slab shapes to upper and lower mantle viscosities and densities, which remain poorly constrained by independent evidence, precludes any systematic deciphering of the observations
Overview of R&D on 3D Geological Modelling at BRGM
No full textInternational audienceBRGM has invested for long in the development of methods for geological modelling. These methods have progressively moved to industrialization through « homemade » software (GDM-Multilayer, 3DGeomodeller). Considering the wide range of applications and geological settings, the choice for own developments allows better flexibility and adaptive capabilities on tools and methods. Modelling geology in complex tectonic environment: In the frame of Potential and Gradients Cokriging method (Lajaunie et al., 1997), one of critical parameters when interpolating natural objects concerns the anisotropy which in current methods is at best considered as uniform within the domain. The introduction of spatially variable anisotropies will allow to model structures such as folds whose characteristics are variable in space, intrusive systems in orogenic domains, or even meandering alluvial systems. This will contribute to increase the realism of geological models
Bridging static and dynamic modeling: an application to high energy geothermal reservoir modeling
No full textInternational audienceWhen mass and energy transfers are involved, bridging static and dynamic modeling in a seamless way is a milestone to build reliable conceptual models of the subsurface in order to efficiently exploit its resources or use it as a storage space (energy, gas, waste…). Our purpose here is to be able to build interactive conceptual models of high energy geothermal reservoirs. As these reservoirs are always located in complex geological settings (faults and fractures are ubiquitous features) and involve the circulation of hot brines over a wide range of thermodynamical parameters, we must be able:#1 to quickly build structural models involving geological bodies of any shape and with the occurrence of discontinuities,#2 to produce conformable meshes of such models,#3 to perform multiphase thermo-hydraulic simulations with phase change on these meshes without numerical artefacts.Over the years, iso-potential surface mapping has proved an efficient framework to achieve goal #1 and it is now implemented in several commercial softwares (e.g. GeoModeller). Yet, when it comes to goal #2 the implicit nature of surfaces make volumic meshing a non-trivial task. We recently used the Computational Geometry Algorithms Library (CGAL) to build conformal simplicial (tetrahedral) meshes that exactly match any geological 3D object and its boundaries or internal 2D features such as fault surfaces. A crucial issue of this process is to provide the mesher with sharp features of dimension 1 (surface intersections) to avoid local over-refinement (or even crash of the algorithm). Finally, to reach goal #3 we used the Vertex Approximate Gradient finite volume scheme which has been adapted to model mass and energy over any polyhedral meshes with the possibility to take into account objects of codimension 1 such as fault surfaces which may act as corridors for fluid flows.We think that the proposed workflow and computing tools can be easily adapted to any other thematic field than geothermal reservoir modeling both for engineering purposes and the simulation of geological processes over very large timescales
Conduction system pacing in France in 2022: A snapshot survey from the Working Group of Pacing and Electrophysiology of the French Society of Cardiology
No full textInternational audienceBackground: Conduction system pacing (CSP) is an emerging and promising approach for physiological ventricular pacing. While data from randomized controlled trials are scarce, use of His-bundle pacing (HBP) and left bundle branch area pacing (LBBAP) has increased in France.Aim: To perform a national snapshot survey for cardiac electrophysiologists to evaluate adoption of CSP in France.Methods: An online survey, distributed to every senior cardiac electrophysiologist in France, was conducted in November 2022.Results: A total of 120 electrophysiologists completed the survey. Eighty-three (69%) respondents reported experience in undertaking CSP procedures and 27 (23%) were planning to start performing CSP in the coming 2 years. The implantation techniques and criteria used for successful implantation differed significantly among operators. The most frequent indications for HBP and LBBAP were high-degree atrioventricular block with left ventricular ejection fraction (LVEF) < 40% (24 and 82%, respectively) or with LVEF ≥ 40% (27 and 74%, respectively), and after failure of a coronary sinus left ventricular lead (27 and 71%, respectively). The limitations respondents most frequently perceived when performing HBP were bad sensing/pacing parameters (45%), increased procedure duration (41%) and risk of lead dislodgement (30%). The most frequently perceived limitations to performing LBBAP were absence of guidelines or consensus (31%), lack of medical training (23%) and increased procedure duration (23%).Conclusions: Our national survey-based study supports wide adoption of CSP in France. CSP is currently used as a second-line approach for both antibradycardia and resynchronization indications, with important variations regarding implantation techniques and criteria for measuring success
