Microseismic activity and fluid fault interactions: some results from the Corinth Rift Laboratory (CRL), Greece

International audienceThe Gulf of Corinth, in western-central Greece, is one of the fastest continental rifts in theworld. In its western section near the city of Aigion, the previous work has outlined theexistence of a shallow dipping seismogenic zone between 5 and 12 km. This seismic activityhas been monitored with a network of 12 three-component stations for the period 2000–2007. Three, few months long, seismic swarms have been observed. They mobilize a complexstructural fault system that associates both shallow dipping elements and subvertical structureswith very different azimuths, some of which extend to depths greater than that of the shallowdipping zone. The swarm activity associates intensely active, short crises (a few days) withmore quiescent periods. The long-term growth velocity of the seismically activated domainsis compatible with a fluid diffusion process. Its characteristics are discussed in the context ofthe results from the 1000 m deep AIG10 well that intersects the Aigion Fault at 760 m. Thevertical growth directions of the seismically activated volumes outline two different sources forthe fluid and imply non-steady pressure conditions within the seismic domain. The diffusivityalong the cataclastic zone of the faults is in the order of 1 m2s−1, while faults act as hydraulicbarrier in the direction perpendicular to their strike. If the vertical direction is a principalstress component, the high pore pressure values that must be reached to induce slip on theshallowly dipping planes can result only from transitory dynamic conditions. It is argued thatthe shallow dipping active seismic zone is only local and does not correspond to a 100 kmscale decollement zone. We propose to associate the localization process with deep fluid fluxesthat have progressively modified the local stress field and may be the cause for the quiescenceof the West Heliki Fault presently observed

Anisotropic and inhomogeneous Coulomb screening in the Thomas-Fermi approximation: Application to quantum dot-wetting layer system and Auger relaxation

International audienceA model for anisotropic and inhomogeneous Coulomb screening due to 2D and 3D carriers, is proposed in the Thomas–Fermi approximation. Analytical expressions for the screened interaction potentials and scattering matrix elements are obtained. This model is applied to the Auger relaxation of carriers in an InAs/InP quantum dot (QD) – wetting layer (WL) system. The influences of the QD morphology and carriers densities on screening and Auger effects are studied. 2D–2D scattering is found to be the most important process, depending especially on QD morphology. A smearing effect is associated to the wetting layer wavefunction extension along the growth axis. The screened potential is similar to a potential screened by 3D carriers

Procédés Limités par le Transfert de Rayonnement en Milieu Hétérogène: Étude des couplages cinétiques et énergétiques dans les photo-bioréacteurs par une approche thermodynamique

L'étude présente des approches théoriques et expérimentales permettant de modéliser les procédés physiquement limités par le transfert de rayonnement dans des milieux potentiellement complexes (semi-transparents, diffusants et participants). Les propriétés optiques et radiatives des particules de formes quelconques sont d'abord calculées, comme paramètres d'entrée pour la résolution de l'équation linéaire de Boltzmann (ou Équation des Transferts Radiatifs) conduisant à la connaissance du champ de radiation. Le couplage thermocinétique est ensuite formulé dans le cas concret des photo-bioréacteurs. Le modèle de connaissance prédictif et réifié obtenu est alors utilisé pour simuler, concevoir, optimiser ou contrôler divers photo-bioréacteurs

Semianalytical model for simulation of electronic properties of narrow-gap strained semiconductor quantum nanostructures

International audienceA complete semianalytical model is proposed for the simulation of the electronic, mechanical, and piezoelectric properties of narrow-gap strained semiconductor quantum nanostructures. A transverse isotropic approximation for the strain and an axial approximation for the strained 8x8 Hamiltonian are proposed. It is applied extensively to the case of InAs/InP quantum dots (QDs). Symmetry analysis shows that there does exist a nonvanishing splitting on the electron P states due to the coupling with valence band. This splitting, which was not considered before, is found to be smaller in InAs/GaAs QD than in InAs/InP QD. Analytic expressions for the first and second order piezoelectric polarizations are used to evaluate the perturbation of electronic states

Learning optimal environments using projected stochastic gradient ascent

In this work, we propose a new methodology for jointly sizing a dynamical system and designing its control law. First, the problem is formalized by considering parametrized reinforcement learning environments and parametrized policies. The objective of the optimization problem is to jointly find a control policy and an environment over the joint hypothesis space of parameters such that the sum of rewards gathered by the policy in this environment is maximal. The optimization problem is then addressed by generalizing the direct policy search algorithms to an algorithm we call Direct Environment Search with (projected stochastic) Gradient Ascent (DESGA). We illustrate the performance of DESGA on two benchmarks. First, we consider a parametrized space of Mass-Spring-Damper (MSD) environments and control policies. Then, we use our algorithm for optimizing the size of the components and the operation of a small-scale autonomous energy system, i.e. a solar off-grid microgrid, composed of photovoltaic panels, batteries, etc. On both benchmarks, we compare the results of the execution of DESGA with a theoretical upper-bound on the expected return. Furthermore, the performance of DESGA is compared to an alternative algorithm. The latter performs a grid discretization of the environment's hypothesis space and applies the REINFORCE algorithm to identify pairs of environments and policies resulting in a high expected return. The choice of this algorithm is also discussed and motivated. On both benchmarks, we show that DESGA and the alternative algorithm result in a set of parameters for which the expected return is nearly equal to its theoretical upper-bound. Nevertheless, the execution of DESGA is much less computationally costly

Polyclonal B-cell lymphocytosis with binucleated lymphocytes (PPBL)

Persistent polyclonal B-cell lymphocytosis (PPBL) is a rare and recently described entity. The review of the literature show PPBL is diagnosed predominantly but not exclusively in women, usually smokers. PPBL is recognized by a moderate, chronic and absolute lymphocytosis (>4 × 109/l) in the peripheral blood. In 10% of cases without lymphocytosis, the PPBL diagnosis has to be suggested by peripheral blood examination showing in all cases atypical binucleated lymphocytes. A polyclonal serum IgM is also associated and HLA-DR7 expression is present in most cases. Contrary to B-cell chronic lymphoproliferative disorders (B-CLPD), peripheral B cells are polyclonal with kappa and lambda light-chain expression and no clonal rearrangement of immunoglobulin heavy chain genes is usually demonstrated. The detection of an extra isochromosome for the long arm of chromosome 3 +i(3)(q10) has to be considered as a specific marker of PPBL. We performed conventional cytogenetic analysis (CCA) in 111 patients with typical PPBL we followed-up more than 4 years. +i(3q) was detected in 34% (33/98), PCC in 8% (8/98) and both abnormalities in 31% (30/98). CCA showed neither +i(3q) nor PCC in 28% (27/98). Fluorescence in situ hybridization (FISH) was also performed in 84 cases and +i(3q) was detected in 71% (60/84). When combining both procedures in 84 patients, +i(3q) was detected in 17 patients with negative CCA and was confirmed in 43 patients with positive CCA. CCA and FISH were both negative in 24 cases. Whether patients with PPBL are at increased risk of hematological malignancy remains unclear. After a median follow-up of 4.4 years, most PPBL patients presented a stable clinical and biological course. Six patients died from pulmonary cancer, myocardial infarction, cerebral aneurysm rupture or diffuse large B-cell lymphoma. Two patients had IgM monoclonal gammopathy of undetermined significance (MGUS) at the time of PPBL diagnosis and two other patients developed IgM MGUS respectively 12 and 22 years after PPBL diagnosis. A malignant non Hodgkin's lymphoma (NHL) appeared in 3 additional patients: two patients presented diffuse large B cell lymphoma and 1 patient a splenic marginal zone lymphoma. In conclusion, the possibility of PPBL to evolve toward a clonal proliferation, malignant lymphoma or secondary solid cancer lead us to consider PPBL not as a benign pathology. We recommend a careful and continued clinical and biological long-term follow-up in all PPBL patients