Measuring Earthquakes from Optical Satellite Images

Système pour l'Observation de la Terre images are used to map ground displacements induced by earthquakes. Deformations (offsets) induced by stereoscopic effect and roll, pitch, and yaw of satellite and detector artifacts are estimated and compensated. Images are then resampled in a cartographic projection with a low-bias interpolator. A subpixel correlator in the Fourier domain provides two-dimensional offset maps with independent measurements approximately every 160 m. Biases on offsets are compensated from calibration. High-frequency noise (0.125 m^-1 ) is ~0.01 pixels. Low-frequency noise (lower than 0.001 m^-1 ) exceeds 0.2 pixels and is partially compensated from modeling. Applied to the Landers earthquake, measurements show the fault with an accuracy of a few tens of meters and yields displacement on the fault with an accuracy of better than 20 cm. Comparison with a model derived from geodetic data shows that offsets bring new insights into the faulting process

Analysis of distributed multi-periodic systems to achieve consistent data matching

Distributed real-time architecture of an embedded system is often described as a set of communicating components. Such a system is data flow (for its description) and time-triggered (for its execution). This work fits in with these problematics and focuses on the control of the time compatibility of a set of interdependent data used by the system components. The architecture of a component-based system forms a graph of communicating components, where more than one path can link two components. These paths may have different timing characteristics but the flows of information which transit on these paths may need to be adequately matched, so that a component uses inputs which all (directly or indirectly) depend on the same production step. In this paper, we define this temporal data-matching property, we show how to analyze the architecture to detect situations that can cause data matching inconsistencies, and we describe an approach to manage data matching that uses queues to delay too fast paths and timestamps to recognize consistent data

Impact of rare earth element clusters on the excited state lifetime evolution under irradiation in oxide glasses

International audienceRare earth doped active glasses and fibers can be exposed to ionizing radiations in space and nuclear applications. In this work, we analyze the evolution of 2 F 5/2 excited state lifetime in Yb 3+ ions in irradiated aluminosilicate glasses by electrons and γ rays. It is found that the variation of lifetimes depends on the Yb 3+ clusters content of the glasses for irradiation doses in the 10 2 – 1.5·10 9 Gy range. In particular, glasses with high clustering show a smaller decrease in lifetime with increasing radiation dose. This behavior is well correlated to the variation in paramagnetic defects concentration determined by electron paramagnetic resonance. This effect is also observed in Yb 3+ doped phosphate and Er 3+ doped aluminosilicate glasses, inferring that clustering plays an important role in irradiation induced quenching

Two-dimensional ultrasonic computed tomography of growth bone

International audienceUltrasonography is the main first-line imaging technique used to diagnose various pediatric pathologies. Pediatric radiologists are very keen on ultrasonography since it is a non-invasive, non-irradiant, painless, inexpensive imaging modality, which is also practicable on bedside. In bone diseases, this technique has also proved to be a very effective tool to assess congenital (i.e., hip dysphasia), infectious (i.e., sub-periostal abscess), inflammatory (i.e., chronic arthritis), and even traumatic (i.e., ankle sprain) processes. However, with standard devices, this exam is not suitable for diagnosis or monitoring bone tumors, classically explored by other more effective techniques, which presented various disadvantages (cost, irradiation, sedation, accessibility). Many authors have dealt with the ultrasonic imaging of bones. Their main aim has usually been to assess the thickness of the diaphysis and to calculate the speed of sound of a wave crossing the structure. Our group has been focusing on the cross-sectional radial imaging process, using ultrasonic computed tomography. Known to be a potentially valuable method of imaging objects with a similar acoustical impedance, difficulties arise when it is proposed to obtain quantitative tomograms of more highly contrasted media (hard bone tissues). Finding solutions here involves either using non-linear schemes and/or performing extensive studies on the limitation of the initial approximation. In this paper, we recall the limits of the ultrasonic computed tomography when dealing with highly contrasted scatterers, using a high-order tomographic method. The performances and limitations are evaluated in the basis of simulated and experimental data, obtained using an ultrasonic scanner, to one geometrical-mimicking phantom and to a real children fibula. Sample thicknesses and speed-of-sound varied as a function of radial position and the experimental procedure fulfilled the criteria of the diffraction tomography. Results are promising and suggest that the geometrical and acoustical characteristics of the bones, which are known to be one of the main factors contributing to the growth bone disease, can be determined using this ultrasonic computed tomography

Laser-induced periodic alignment of Ag nanoparticles in soda-lime glass

International audienceOne-, two- or three-dimensional arrays of closely spaced silver nanoparticles may lead to new optical properties, due to short or long range coupling between their resonant surface plasmons, so that the spatially controlled growth of silver nanoparticles provides an efficient way to tune their optical properties. Towards this way, we present here the periodic pattern of a glass surface with silver nanoparticles by continuous ultraviolet laser exposure. The formation of the 160 nm period pattern is well described by an interference-based model which agrees with the experimental conclusions, mainly obtained by various forms of microscopy. Statistical approach based on the autocorrelation function gives quantitative description about the quality of the order in the periodic structure and about the nanoparticles averaged diameter (80 nm). We also present the optical extinction spectrum of the Laser Induced Periodic Surface Structure (LIPSS)-containing area of the glass, which unusually shows several bands in the visible range. The period of 160 nm of the periodic structure is short enough to allow coupling between nanoparticles, which makes it a possible candidate for plasmon-based optical applications

A milk urea model to better assess nitrogen excretion and feeding practice in dairy systems

A milk urea model to better assess nitrogen excretion and feeding practice in dairy systems. 20. Nitrogen Worksho

Polyester layered silicate nanohybrids by controlled grafting polymerization

peer reviewedPoly( epsilon-caprolactone) (PCL) layered silicate nanohybrids were synthesized by ring opening polymerization of epsilon-caprolactone according to a well-controlled coordination-insertion mechanism. Montmorillonites were surface-modified by non functional (trimethylhexadecylammonium) and hydroxy functional alkylammonium cations, i.e., (2-hydroxyethyl) dimethylhexadecylammonium. The hydroxy functions available at the clay surface were activated into tin( II or IV) or Al(III) alkoxide initiators for lactone polymerization, thus yielding surface-grafted PCL chains. The surface-grafted PCL chains were recovered by an ionic exchange reaction with lithium chloride and they were analyzed by size exclusion chromatography. The PCL molar mass was measured as a function of the hydroxy content of the clay that was modulated by exchanging the Na cations with mixtures of non-functional and hydroxy functional ammonium cations of different compositions. Nanohybrids were also characterized by small-angle X-ray diffraction, transmission electron microscopy and thermogravimetry. The PCL molar mass and the nanocomposite morphology (i.e., exfoliation and/or intercalation) were readily tuned by the content of the hydroxy groups available at the clay surface. Surface-grafted aluminium trialkoxide species proved highly efficient in initiating polymerization that leads to PCL chains of controlled molar mass and narrow molecular weight distribution with polydispersity indices as low as 1.2

Anatomie, animaux, vocabulaire de la vivisection

Introduction Le projet de recherche Animalhumanité visait à réunir chercheuses et chercheurs en littérature, sciences du vivant et informatique pour des travaux sur l’expérimentation et la fiction mettant l’animalité au cœur du vivant, en valorisant à la fois les fonds des collections du musée Fragonard et le fonds ancien de la bibliothèque de l’EnvA, École nationale vétérinaire d’Alfort. En raison de la non-disponibilité en version numérique des ouvrages du fonds ancien, nous nous sommes con..

A New Family of Receptor Tyrosine Kinases with a Venus Flytrap Binding Domain in Insects and Other Invertebrates Activated by Aminoacids

Background: Tyrosine kinase receptors (RTKs) comprise a large family of membrane receptors that regulate various cellular processes in cell biology of diverse organisms. We previously described an atypical RTK in the platyhelminth parasite Schistosoma mansoni, composed of an extracellular Venus flytrap module (VFT) linked through a single transmembrane domain to an intracellular tyrosine kinase domain similar to that of the insulin receptor. Methods and Findings: Here we show that this receptor is a member of a new family of RTKs found in invertebrates, and particularly in insects. Sixteen new members of this family, named Venus Kinase Receptor (VKR), were identified in many insects. Structural and phylogenetic studies performed on VFT and TK domains showed that VKR sequences formed monophyletic groups, the VFT group being close to that of GABA receptors and the TK one being close to that of insulin receptors. We show that a recombinant VKR is able to autophosphorylate on tyrosine residues, and report that it can be activated by L-arginine. This is in agreement with the high degree of conservation of the alpha amino acid binding residues found in many amino acid binding VFTs. The presence of high levels of vkr transcripts in larval forms and in female gonads indicates a putative function of VKR in reproduction and/or development. Conclusion: The identification of RTKs specific for parasites and insect vectors raises new perspectives for the control of human parasitic and infectious diseases

A Second Actin-Like MamK Protein in Magnetospirillum magneticum AMB-1 Encoded Outside the Genomic Magnetosome Island

Magnetotactic bacteria are able to swim navigating along geomagnetic field lines. They synthesize ferromagnetic nanocrystals that are embedded in cytoplasmic membrane invaginations forming magnetosomes. Regularly aligned in the cytoplasm along cytoskeleton filaments, the magnetosome chain effectively forms a compass needle bestowing on bacteria their magnetotactic behaviour. A large genomic island, conserved among magnetotactic bacteria, contains the genes potentially involved in magnetosome formation. One of the genes, mamK has been described as encoding a prokaryotic actin-like protein which when it polymerizes forms in the cytoplasm filamentous structures that provide the scaffold for magnetosome alignment. Here, we have identified a series of genes highly similar to the mam genes in the genome of Magnetospirillum magneticum AMB-1. The newly annotated genes are clustered in a genomic islet distinct and distant from the known magnetosome genomic island and most probably acquired by lateral gene transfer rather than duplication. We focused on a mamK-like gene whose product shares 54.5% identity with the actin-like MamK. Filament bundles of polymerized MamK-like protein were observed in vitro with electron microscopy and in vivo in E. coli cells expressing MamK-like-Venus fusions by fluorescence microscopy. In addition, we demonstrate that mamK-like is transcribed in AMB-1 wild-type and ΔmamK mutant cells and that the actin-like filamentous structures observed in the ΔmamK strain are probably MamK-like polymers. Thus MamK-like is a new member of the prokaryotic actin-like family. This is the first evidence of a functional mam gene encoded outside the magnetosome genomic island