A wavelet-based detection and characterization of damped transient waves occurring in geophysical time-series: theory and application to the search for the translational oscillations of the inner core

International audienceGeophysical time-series with non-stationary behaviour which contain transient excitations need specific tools to be analysed. Especially, it is difficult to detect and characterize transient excitations with attenuation by diffusion when their intensity is low compared to noise. This is a typical question in the search for the elusive translational motion of the inner core, the so-called Slichter triplet. This detection remains a non-trivial problem since the amplitude of the Slichter triplet is expected to be weak. Moreover, the characteristics (period, time of excitation and quality factor) of these low-intensity damped transient waves are poorly constrained. To improve the detection and characterization of such causal damped transient waves, we introduce a new continuous wavelet-based method using correlations with causal damped sinusoids that serve as the wavelet basis. This causal damped wavelet (CDW) method presents the advantage to give a direct estimate of the quality factor of the transient wave. After some synthetic tests, we present an application of the method to the time-varying gravity data recorded by superconducting gravimeters in the search for the Slichter triplet. No evidence of the Slichter triplet has been found in the 1-yr gravity data considered. However, we show that, thanks to the 3-D representation of our CDW method, it is possible to have a complete overview of the data set content and to constrain the detected events in terms of amplitude, quality factor, frequency and time

On the Rebound: Modeling Earth's Ever-Changing Shape

A new modeling tool easily computes the elastic response of changes in loading on Earth's surface to high resolution. Scientists test this tool using finely detailed data on glaciers' mass changes

Parallel Monte-Carlo Simulations on GPU and Xeon Phi for Stratospheric Balloon Envelope Drift Descent Analysis

International audienceA performance evaluation of parallel Monte-Carlo simulations on GPU and MIC is presented and the application to stratospheric balloon envelope drift descent is considered. The experiments show that GPU and MIC permit one to decrease computing time by a factor of 4 and 2, respectively, as compared to a parallel code implemented on a two sockets CPU (E5-2680-v2) which allows us to use these devices in operational conditions

The infrapatellar fat pad induces inflammatory and degradative effects in articular cells but not through leptin or adiponectin

International audienceBased on a novel approach suggesting a role of adipose tissue in osteoarthritis (OA), we aimed to determine whether the infrapatellar fat pad (IFP) may affect joint cell functions through adipokines.The conditioned media of IFP and subcutaneous adipose tissue from OA patients were used to determine the production of leptin and adiponectin, and to stimulate chondrocytes and fibroblast-like synoviocytes (FLS). Blocking experiments were carried out to evaluate the contribution of adipokines to IFP effects. The gene expression of inflammatory and degradative proteins, growth factors and components of the extracellular matrix, and the production of inflammatory mediators and metalloproteases were determined to evaluate cell response to fat-conditioned media.IFP releases elevated amounts of leptin and adiponectin independently of the body mass index and the gender. The conditioned media from IFP strongly induce the expression of inflammatory genes in both articular cells and the expression of degradative genes in chondrocytes, but remain ineffective in regulating the expression of aggrecan, type 2 collagen or growth factors. Blocking leptin or adiponectin does not change the cell response to IFP. A great variability between patients is found when compared the inflammatory activity of paired samples of IFP and subcutaneous adipose tissue.IFP may trigger both cartilage destruction and inflammation of the synovium, but not through leptin or adiponectin. The data suggest also that IFP may have specific inflammatory phenotypic features independent from the general phenotype found in obesity

The infrapatellar fat pad induces inflammatory and degradative effects in articular cells but not through leptin or adiponectin.

International audienceBased on a novel approach suggesting a role of adipose tissue in osteoarthritis (OA), we aimed to determine whether the infrapatellar fat pad (IFP) may affect joint cell functions through adipokines.The conditioned media of IFP and subcutaneous adipose tissue from OA patients were used to determine the production of leptin and adiponectin, and to stimulate chondrocytes and fibroblast-like synoviocytes (FLS). Blocking experiments were carried out to evaluate the contribution of adipokines to IFP effects. The gene expression of inflammatory and degradative proteins, growth factors and components of the extracellular matrix, and the production of inflammatory mediators and metalloproteases were determined to evaluate cell response to fat-conditioned media.IFP releases elevated amounts of leptin and adiponectin independently of the body mass index and the gender. The conditioned media from IFP strongly induce the expression of inflammatory genes in both articular cells and the expression of degradative genes in chondrocytes, but remain ineffective in regulating the expression of aggrecan, type 2 collagen or growth factors. Blocking leptin or adiponectin does not change the cell response to IFP. A great variability between patients is found when compared the inflammatory activity of paired samples of IFP and subcutaneous adipose tissue.IFP may trigger both cartilage destruction and inflammation of the synovium, but not through leptin or adiponectin. The data suggest also that IFP may have specific inflammatory phenotypic features independent from the general phenotype found in obesity

SIMD Monte-Carlo Numerical Simulations Accelerated on GPU and Xeon Phi

International audienceThe efficiency of a pleasingly parallel application is studied for several computing platforms. A real world problem, i.e., Monte-Carlo numerical simulations of stratospheric balloon envelope drift descent is considered. We detail the optimization of the SIMD parallel codes on the K40 and K80 GPUs as well as on the Intel Xeon Phi. We emphasize on loop and task parallelism, multi-threading and vectorization, respectively. The experiments show that GPU and MIC permit one to decrease computing time by non negligeable factors, as compared to a parallel code implemented on a two sockets CPU (E5-2680-v2) which finally allows us to use these devices in operational condition

Three-dimensional gravity anomaly inversion in the Pyrenees using compressional seismic velocity model as structural similarity constraints

International audienceWe explore here the benefits of using constraints from seismic tomography in gravity data inversion and how inverted density distributions can be improved by doing so. The methodology is applied to a real field case in which we reconstruct the density structure of the Pyrenees along a southwest-northeast transect going from the Ebro basin in Spain to the Arzacq basin in France. We recover the distribution of densities by inverting gravity anomalies under constraints coming from seismic tomography. We initiate the inversion from a prior density model obtained by scaling a pre-existing compressional seismic velocity Vp model using a Nafe-Drake relationship : the Vp model resulting from a full-waveform inversion of teleseismic data. Gravity data inversions enforce structural similarities between Vp and density by minimizing the norm of the cross-gradient between the density and Vp models. We also compare models obtained from 2.5D and 3D inversions. Our results demonstrate that structural constraints allow us to better recover the density contrasts close to the surface and at depth, without degrading the gravity data misfit. The final density model provides valuable information on the geological structures and on the thermal state and composition of the western region of the Pyrenean lithosphere

The New IERS Special Bureau for Loading (SBL)

Currently, the establishment of the International Earth Rotation Service (IERS) Special Bureau for Loading (SBL) is in progress as part of the IERS Global Geophysical Fluids Center (GGFC). The main purpose of the SBL is to provide reliable, consistent model predictions of loading signals that have been thoroughly tested and validated. The products will describe at least the surface deformation, gravity signal and geo-center variations due to the various surface loading processes in reference frames relevant for direct comparison with existing geodetic observing techniques. To achieve these goals, major scientific advances are required with respect to the Earth model, the theory and algorithms used to model deformations of the Earth as well as improvements in the observational data related to surface loading

Identifying 2010 Xynthia Storm Signature in GNSS-R-Based Tide Records

In this study, three months of records (January–March 2010) that were acquired by a geodetic Global Navigation Satellite Systems (GNSS) station from the permanent network of RGP (Réseau GNSS Permanent), which was deployed by the French Geographic Institute (IGNF), located in Socoa, in the south of the Bay of Biscay, were used to determine the tide components and identify the signature of storms on the signal to noise ratio (SNR) during winter 2010. The Xynthia storm hit the French Atlantic coast on the 28th of February 2010, causing large floods and damages from the Gironde to the Loire estuaries. Blind separation of the tide components and of the storm signature was achieved while using both a singular spectrum analysis (SSA) and a continuous wavelet transform (CWT). A correlation of 0.98/0.97 and root mean square error (RMSE) of 0.21/0.28 m between the tide gauge records of Socoa and our estimates of the sea surface height (SSH) using the SSA and the CWT, respectively, were found. Correlations of 0.76 and 0.7 were also obtained between one of the modes from the SSA and atmospheric pressure from a meteorological station and a mode of the SSA. Particularly, a correlation reaches to 0.76 when using both the tide residual that is associated to surges and atmospheric pressure variation