Controlling instabilities along a 3DVar analysis cycle by assimilating in the unstable subspace: a comparison with the EnKF

Abstract. A hybrid scheme obtained by combining 3DVar with the Assimilation in the Unstable Subspace (3DVar-AUS) is tested in a QG model, under perfect model conditions, with a fixed observational network, with and without observational noise. The AUS scheme, originally formulated to assimilate adaptive observations, is used here to assimilate the fixed observations that are found in the region of local maxima of BDAS vectors (Bred vectors subject to assimilation), while the remaining observations are assimilated by 3DVar. The performance of the hybrid scheme is compared with that of 3DVar and of an EnKF. The improvement gained by 3DVar-AUS and the EnKF with respect to 3DVar alone is similar in the present model and observational configuration, while 3DVar-AUS outperforms the EnKF during the forecast stage. The 3DVar-AUS algorithm is easy to implement and the results obtained in the idealized conditions of this study encourage further investigation toward an implementation in more realistic contexts

Avances en el manejo eficiente del olivar surbonaerense

Cinco años de vinculación entre la Cámara de Productores Olivícolas “Sur Oliva”, con sede en la cabecera del partido surbonaerense de Coronel Dorrego, el Programa Nacional de Reconversión Productiva (Cambio Rural) dependiente de la Chacra Experimental Integrada Barrow del Instituto Nacional de Tecnología Agropecuaria y las asignaturas Propiedades Edáficas y Fertilidad (módulo Física de Suelo), Fruticultura, Utilización de Residuos Orgánicos, Zoología Agrícola y Patología Vegetal del Departamento de Agronomía de la Universidad Nacional del Sur han consolidado un grupo de trabajo interdisciplinario y una vía de comunicación con el medio productivo. Se comenzó con la detección de problemáticas que originaron distintas líneas de investigación con la participación de estudiantes y graduados y el apoyo de organismos provinciales (Comisión de Investigaciones Científicas) y municipales. Luego surgieron actividades de asistencia técnica a productores y se instalaron parcelas experimentales en una de las fincas, las cuales generan conocimientos y experiencias, que también enriquecen la labor docente con la incorporación curricular de nuevos contenidos. La difusión de resultados y conclusiones se canaliza a través de revistas, jornadas y reuniones científicas, y mediante el contacto directo con integrantes del sistema productivo. También se publicó material en la revista “AgroUNS”, órgano de difusión del Departamento de Agronomía

Correlation between homogeneous propane pyrolysis and pyrocarbon deposition

International audiencePyrocarbon deposition through propane pyrolysis is studied in a 1-D hot-wall CVD furnace. The gas-phase pyrolysis is modelled with a partially reduced kinetic mechanism leading to polycyclic aromatic compounds (PAHs). The C2-C4 and C3 reaction paths are in competition for benzene formation. There is also an independent C3-C5 path leading to naphthalene. The gas-phase concentrations are correlated with experimental data including in-situ FTIR spectra intensities, pyro- carbon deposition rates, and pyrocarbon nanotextures. Rough Laminar pyrocarbon deposition appears to be more related to PAHs than Smooth Laminar pyrocarbon

Is there something of the MCT in orientationally disordered crystals ?

Molecular Dynamics simulations have been performed on the orientationally disordered crystal chloroadamantane: a model system where dynamics are almost completely controlled by rotations. A critical temperature T_c = 225 K as predicted by the Mode Coupling Theory can be clearly determined both in the alpha and beta dynamical regimes. This investigation also shows the existence of a second remarkable dynamical crossover at the temperature T_x > T_c consistent with a previous NMR and MD study [1]. This allows us to confirm clearly the existence of a 'landscape-influenced' regime occurring in the temperature range [T_c-T_x] as recently proposed [2,3].Comment: 4 pages, 5 figures, REVTEX

Treatment of endometriosis by aromatase inhibitors: efficacy and side effects

The recent demonstration that aromatase is expressed at higher levels in endometriosis implants than in normal endometrium has led to pilot studies using inhibitor aromatasis in patients with endometriosis. We conducted a systematic review of the literature and studied the efficacy of aromatase inhibitors on endometriosis. There were seventeen studies (case reports/series) evaluating outcomes of aromatase inhibitors. Studies suggest that aromatase inhibitors alone or co-administered with progestins, oral contraceptives or gonadotrophin releasing hormone (GnRH) agonist could reduce pain and endometriosis. There is only one randomized controlled trial comparing aromatase inhibitor+GnRH agonist and GnRH agonist and one study with eighty patients. Side-effects profiles of aromatase inhibitor regimens are favorable; it does not appear a significant bone loss. Aromatase inhibitors seem to have a promising effect on endometriosis but randomized controlled trials are needed to prove their effects and their safety

CVD and CVI of pyrocarbon from various precursors

International audienceThe control of pyrocarbon (pyC) chemical vapor infiltration (CVI) is a key issue in the processing of high-performance C/C composites with applications in aerospace parts and braking technology. For years, the precise investigation of deposition kinetics and pyC nanometerscale anisotropy has been rehearsed in chemical vapor deposition (CVD) and several variants of CVI with various pore sizes, and using mostly propane, propylene, and methane as source precursors. A literature survey and the analysis of recent experimental data have helped to understand better the role of gas-phase intermediate species in the various nanotextural transitions; a coherent modeling frame, which is suitable for propane, propylene, and methane—the latter having a neatly lower reactivity—has been set up and tested against experimental results from independent teams. The relation between nanotexture and processing conditions is then explained