A strongly conservative finite element method for the coupling of Stokes and Darcy flow

https://scholars.carroll.edu/romansarcophagus_file5/1145/thumbnail.jp

Modelling study of the impact of deep convection on the utls air composition - Part I: Analysis of ozone precursors

International audienceThe aim of this work is to study the local impact on the upper troposphere/lower stratosphere air composition of an extreme deep convective system. For this purpose, we performed a simulation of a convective cluster composed of many individual deep convective cells that occurred near Bauru (Brazil). The simulation is performed using the 3-D mesoscale model RAMS coupled on-line with a chemistry model. The comparisons with meteorological measurements show that the model produces meteorological fields generally consistent with the observations. The present paper (part I) is devoted to the analysis of the ozone precursors (CO, NOx and non-methane volatile organic compounds) and HOx in the UTLS. The simulation results show that the distribution of CO with altitude is closely related to the upward convective motions and consecutive outflow at the top of the convective cells leading to a bulge of CO between 7 km altitude and the tropopause (around 17 km altitude). The model results for CO are consistent with satellite-borne measurements at 700 hPa. The simulation also indicates enhanced amounts of NOx up to 2 ppbv in the 7–17 km altitude layer mainly produced by the lightning associated with the intense convective activity. For insoluble non-methane volatile organic compounds, the convective activity tends to significantly increase their amount in the 7–17 km layer by dynamical effects. During daytime in the presence of lightning NOx, this bulge is largely reduced in the upper part of the layer for reactive species (e.g. isoprene, ethene) because of their reactions with OH that is increased on average during daytime. Lightning NOx also impacts on the oxydizing capacity of the upper troposphere by reducing on average HOx, HO2, H2O2 and organic hydroperoxides. During the simulation time, the impact of convection on the air composition of the lower stratosphere is negligible for all ozone precursors although several of the simulated convective cells nearly reach the tropopause. There is no significant transport from the upper troposphere to the lower stratosphere, the isentropic barrier not being crossed by convection. The impact of the increase of ozone precursors and HOx in the upper troposphere on the ozone budget in the LS is discussed in part II of this series of papers

Membrane-embedded TSPO: an NMR view

Translocator Protein (18 kDa) (TSPO) is a mitochondrial transmembrane protein commonly used as a biomarker for neuroinflammation and is also a potential therapeutic target in neurodegenerative diseases. Despite intensive research efforts, the function of TSPO is still largely enigmatic. Deciphering TSPO structure in the native lipid environment is essential to gain insight into its cellular activities and to design improved diagnostic and therapeutic ligands. Here, we discuss the influence of lipid composition on the structure of mammalian TSPO embedded into lipid bilayers on the basis of solid-state NMR experiments. We further highlight that cholesterol can influence both the tertiary and quaternary TSPO structure and also influence TSPO localization in mitochondria-associated endoplasmic reticulum membranes

Emploi pratique des analyses fourragères pour l'appréciation des pâturages tropicaux

Les taux de matières sèches, de matières azotées brutes, de cellulose et de cendres constituent les éléments de calcul de la valeur bromatologique des fourrages. A partir de résultats expérimentaux, les tables hollandaises donnent directement la valeur bromatologique d'un kg de matières sèches de fourrage en fonction du taux de cellulose et de cendres pour la valeur énergétique et en fonction du taux de matières azotées brutes pour les matières azotées digestibles. Par analogie à l'unité gros bétail (U.G.B.) des pays tempérés, un animal de référence de 250 kg pour les pays tropicaux peut être adopté comme Unité-Bétail tropical (U.B.T.). La consommation journalière théorique étant évaluée à 2,5 kg de matière sèche pour 100 kg de poids vif, les besoins de l'U.B.T. sont rapportés au kg de matière sèche ingérée sous le nom d'Equivalent-Rati on exprimé en unité fourragère et matière azotée digestible. Le dépouillement de plus de 500 analyses bromatologiques de plantes fourragères tropicales a mis en évidence: l'importance des pâturages aériens comme complément de la ration en matières azotées digestibles au cours de la saison sèche tant sur steppes que sur savanes; l'importance périodique des espèces d'appoint pour assurer la nourriture du bétail sur steppes; - le nombre limité d'espèces assurant une ration d'entretien pendant une longue période sur steppes; - l'importance du temps de croissance pour les espèces vivaces de savanes, la valeur bromatologique des repousses dépendant plus de ce facteur que de la date de récolt

Delocalization of slowly damped eigenmodes on Anosov manifolds

We look at the properties of high frequency eigenmodes for the damped wave equation on a compact manifold with an Anosov geodesic flow. We study eigenmodes with spectral parameters which are asymptotically close enough to the real axis. We prove that such modes cannot be completely localized on subsets satisfying a condition of negative topological pressure. As an application, one can deduce the existence of a "strip" of logarithmic size without eigenvalues below the real axis under this dynamical assumption on the set of undamped trajectories.Comment: 28 pages; compared with version 1, minor modifications, add two reference