Application of acoustic full waveform inversion to retrieve high-resolution temperature and salinity profiles from synthetic seismic data

14 pages, 14 figuresRecent works show that multichannel seismic (MCS) systems are able to provide detailed information on the oceans' fine structure. The aim of this paper is to analyze whether 1-D full waveform inversion algorithms are suitable to recover the extremely weak acoustic impedance contrasts associated to the oceans' fine structure, as well as their potential to image meso-scale objects such as meddies. We limited our analysis to synthetic, noise-free data, in order to identify some methodological issues related to this approach under idealistic conditions (e.g., 1-D wave propagation, noise-free data, known source wavelet). We first discuss the influence of the starting model in the context of the multi-scale strategy that we have implemented. Then we show that it is possible to retrieve not only sound speed but also salinity and temperature contrasts within reasonable bounds from the seismic data using Neural Network relationships trained with regional oceanographic data sets. Potentially, the vertical resolution of the obtained models, which depends on the maximum frequency inverted, is of the order of 5–10 m, whereas the root mean square error of the inverted properties is shown to be ∼0.5 m/s for sound speed, 0.1°C for temperature, and 0.06 for salinity. To conclude this study, we have inverted synthetic data simulated along an oceanographic transect acquired during the EU-funded Geophysical Oceanography (GO) project. The results demonstrate the applicability of the method for synthetic data, as well as its potential to define oceanographic features along 2-D transects at full ocean depth with excellent lateral resolutionThe authors are grateful to REPSOL for supporting this work through the Kaleidoscope project. Likewise, we also acknowledge the EU‐funded GO‐project (EC‐NEST‐15603) as well as German funded POSEIDON CRUISE (P350) for providing the experimental dataset. Part of the work has been done in the framework of projects MEDOC (Ref CTM2007‐66179‐C02‐02/MAR) and POSEIDON (Ref CTM2010‐21569), both funded by the Spanish MICINNPeer reviewe

Calibrage autonome et correction d'un système aéroporté pour la mesure du vent horizontal

International audienc

Hexanoic, Octanoic and Decanoic Acids Promote Basal and Insulin-Induced Phosphorylation of the Akt-mTOR Axis and a Balanced Lipid Metabolism in the HepG2 Hepatoma Cell Line

Metabolic illnesses such as non-alcoholic fatty liver disease (NAFLD) are in constant increase worldwide. Highly consumed long chain fatty acids (LCFA) are among the most obesogenic and steatogenic nutrients. Hepatic steatosis is associated with several complications such as insulin resistance. Growing evidence points to medium chain fatty acids (MCFA), more efficiently oxidized than LCFA, as a promising dietary alternative against NAFLD. However, reports on the hepatic effects of MCFA are sometimes conflicting. In this study we exposed HepG2 cells, a human hepatocellular model, to 0.25 mM of hexanoic (C6), or octanoic (C8), and decanoic (C10) acids separately or in a C8 + C10 equimolar mix reflecting commercially available MCFA-rich oils. We found that C6, a poorly studied MCFA, as well as C8 and C10 did not provoke the deleterious lipid anabolism runaway typically induced by LCFA palmitate. MCFA tended, instead, to promote a balanced metabolic profile and were generally non-cytotoxic. Accordingly, mitochondrial integrity was mostly preserved following MCFA treatment. However, treatments with C8 induced a mitochondrial membrane potential decrease, suggesting prolonged exposure to this lipid could be problematic. Finally, MCFA treatments maintained optimal insulin sensitivity and even fostered basal and insulin-dependent phosphorylation of the Akt-mTOR pathway. Overall, MCFA could constitute an effective nutritional tool to manage liver steatosis and hepatic insulin resistance

Systeme de mesures physiques et microphysiques embarque

SIGLEAvailable from CEN Saclay, Service de Documentation, 91191 Gif-sur-Yvette Cedex (France) / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Les avions français de recherche atmosphérique et de télédétection : bilan et perspectives

International audienceWe are planning to replace the French airplanes used for atmospheric research and remote sensing, and we wish to describe some of the current systems (aircraft, instrumentation and data processing) and give some examples of their use. The last part of the article looks the future. It is a summary of proposals made by the Scientific Committee for Atmospheric and Remote Sensing Research Aircraft of future needs, and infers the specifications required for the future aircraft and their instrumentation.Alors que nous sommes en train de planifier le remplacement des avions français utilisés par la communauté scientifique en recherche atmosphérique et en télédétection, nous avons voulu présenter un état des lieux montrant les moyens disponibles (les avions, leur instrumentation et leurs filières de traitement des données) et quelques exemples de travaux scientifiques ayant bénéficié de ces outils. La dernière partie de l'article est tournée vers l'avenir. Elle présente une synthèse des travaux prospectifs réalisés par le Conseil scientifique des avions de recherche atmosphérique et de télédétection pour évaluer les besoins futurs de la communauté scientifique et en déduire les qualités et les performances requises pour les futurs avions de recherche et leur instrumentation