124299 research outputs found

    Modelling water isotopologues (1H2H16O^1H^2H^{16}O,1H2^1H_217O^{17}O) in the coupled numerical climate model iLOVECLIM (version 1.1.5)

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    International audienceStable water isotopes are used to infer changes in the hydrological cycle for different climate periods and various climatic archives. Following previous developments of δ18O in the coupled climate model of intermediate complexity, iLOVECLIM, we present here the implementation of the 1H2H16O and 1H217O water isotopes in the different components of this model and calculate the associated secondary markers deuterium excess (d-excess) and oxygen-17 excess (17O-excess) in the atmosphere and ocean. So far, the latter has only been modelled by the atmospheric model LMDZ4. Results of a 5000-year equilibrium simulation under preindustrial conditions are analysed and compared to observations and several isotope-enabled models for the atmosphere and ocean components. In the atmospheric component, the model correctly reproduces the first-order global distribution of the δ2H and d-excess as observed in the data (R=0.56 for δ2H and 0.36 for d-excess), even if local differences are observed. The model–data correlation is within the range of other water-isotope-enabled general circulation models. The main isotopic effects and the latitudinal gradient are properly modelled, similarly to previous water-isotope-enabled general circulation model simulations, despite a simplified atmospheric component in iLOVECLIM. One exception is observed in Antarctica where the model does not correctly estimate the water isotope composition, a consequence of the non-conservative behaviour of the advection scheme at a very low moisture content. The modelled 17O-excess presents a too-important dispersion of the values in comparison to the observations and is not correctly reproduced in the model, mainly because of the complex processes involved in the 17O-excess isotopic value. For the ocean, the model simulates an adequate isotopic ratio in comparison to the observations, except for local areas such as the surface of the Arabian Sea, a part of the Arctic and the western equatorial Indian Ocean. Data–model evaluation also presents a good match for the δ2H over the entire water column in the Atlantic Ocean, reflecting the influence of the different water masses

    Proteomic analyses of the Arabidopsis cap-binding complex define core set and TOR-dependent protein components

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    The eukaryotic cap-binding complex (CBC) is a hub for regulations affecting mRNA behaviour including translation, degradation and storage. Beside the core eukaryotic translation initiation factors, other proteins, many of which are yet unknown, are thought to interact stably or transiently with the CBC depending on cell status. The prototype of these regulators is the animal eIF4E binding protein (4E-BP), a direct target of the TOR (Target of Rapamycin) kinase that competes with the cap-binding protein eIF4E, thus repressing translation. In plants, no functional homologs of 4E-BP have so far been characterized. In this work we performed several deep proteomic analyses of the Arabidopsis CBC after cap-affinity purification from wild-type plants. We also investigated the CBC in eIF4E mutant plants, Arabidopsis lines with lower TOR activity, or during infection with eIF4E-dependent potyviruses, conditions which are all affecting translation at the initiation level. These analyses allowed us to define a limited core set of CBC components, which were detected in all samples. Interestingly, we identified proteins, like AGO1 or VCS, which were always detected in conditions where either TOR or mRNA translation were reduced. Meta-analysis of these data revealed several new plant interactors of the CBC, potentially defining pathways related to mRNA stability and degradation, metabolism and viral life cycle. A search for eIF4E binding motifs identified several new potential 4E-BP relatives in plants

    Update on the seismogenic potential of the Upper Rhine Graben southern region

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    International audienceAbstract. The Upper Rhine Graben (URG), located in France and Germany, is bordered by north–south-trending faults, some of which are considered active, posing a potential threat to the dense population and infrastructures on the Alsace plain. The largest historical earthquake in the region was the M6.5±0.5 Basel earthquake in 1356. Current seismicity (M>2.5 since 1960) is mostly diffuse and located within the graben. We build upon previous seismic hazard studies of the URG by exploring uncertainties in greater detail and revisiting a number of assumptions. We first take into account the limited evidence of neotectonic activity and then explore tectonic scenarios that have not been taken into account previously, exploring uncertainties for Mmax, its recurrence time, the b value, and the moment released aseismically or through aftershocks. Uncertainties in faults' moment deficit rates, on the observed seismic events' magnitude–frequency distribution and on the moment–area scaling law of earthquakes, are also explored. Assuming a purely dip-slip normal faulting mechanism associated with a simplified model with three main faults, Mmax maximum probability is estimated at Mw 6.1. Considering this scenario, there would be a 99 % probability that Mmax is less than 7.3. In contrast, with a strike-slip assumption associated with a four-main-fault model, consistent with recent paleoseismological studies and the present-day stress field, Mmax is estimated at Mw 6.8. Based on this scenario, there would be a 99 % probability that Mmax is less than 7.6

    Modélisation du bain de fusion

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    Sommaire1 Contexte2 Equations de bilan en m ́ecanique des fluides3 Solidification4 Surface libre5 Conclusions – BibliographieDoctoralCette présentation sera consacrée à la description et à la modélisation des principaux phénomènes physiques se produisant dans un bain de métal liquide. Ce bain ne reste en général pas statique car il peut être soumis à des forces motrices d'origines diverses (capillaires, électromagnétiques, etc.). Les écoulements ainsi engendrés peuvent alors avoir une influence importante sur la fabricabilité et la fiabilité de pièces métalliques obtenues par des procédés mettant en œuvre un chauffage tels que la fabrication additive et le soudage

    Update and synthesis of the available archaeological and geochronological data for the Lower Paleolithic site of Loreto at Venosa (Basilicata, Italy)

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    International audienceAbstract In the Basilicata region, located in southern Italy and known for hosting among the first occurrences of the Acheulean culture in southwestern Europe, the Lower Paleolithic site of Loreto at Venosa is located less than a kilometer from the emblematic site of Notarchirico and less than 25 km from Cimitero di Atella. The Loreto site has not been studied as thoroughly as the two other sites and, although geological investigations have been carried out in the Venosa basin, no direct numerical dating has ever been published for the three archaeological levels brought to light during the excavation campaigns. We present a multi-method geochronological approach combining ESR/U-series, ESR, and 40 Ar/ 39 Ar permitting to refine the age of the most ancient archaeological level (A) of the Loreto site. These data allow us to propose an MIS 13 age for this level, in accordance with previous hypotheses based on geological and paleontological data. We also propose a technical review of the lithic tools preserved in the collection of the National Archaeological Museum of Venosa to integrate Loreto in the evolution scheme of the European Acheulean techno-complex emergence and diffusion

    Mirror symmetry at far edges of stability: The cases of <math><mmultiscripts><mi mathvariant="normal">C</mi><mprescripts/><none/><mn>8</mn></mmultiscripts></math> and <math><mmultiscripts><mi>He</mi><mprescripts/><none/><mn>8</mn></mmultiscripts></math>

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    International audienceMissing mass spectroscopy of the unbound C8 nucleus was performed by the one-neutron transfer C9(p,d)C8 reaction at 55 MeV/nucleon. Besides the known ground state, two new resonant states were observed, the first at an excitation energy of 3.40(25) MeV with a width of 3.0(5) MeV, the second at 18.6(5) MeV with a width of 3.9(11) MeV. Spin and parity Jπ=2+ were assigned to the first resonance from the distorted-wave Born approximation analysis of the experimental differential cross section. The excitation energy of the 2+ resonance in C8 supports the persistence of the subshell closure at the semimagic number Z = 6, as is the case for N = 6. The mirror energy difference relative to the 2+ state in He8, ΔEx=−0.14(25) MeV, is compatible with zero. Both states represent resonances in the continuum, unbound by about 1.4 and 6.9 MeV, respectively, above the particle thresholds. A simple theoretical model emphasizes the difference in unboundedness to account for a symmetry in mirror energies. This unique system is expected to provide a salient test of theoretical models, which include the treatment of the continuum

    Unassisted Solar Syngas Production by a Molecular Dye-Cobalt Catalyst Assembly in a Tandem Photoelectrochemical Cell

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    International audiencecological transition requires the development of carbon capture and utilization technologies powered by renewable energies. Direct solar conversion of CO2 in photoelectrochemical cells is a promising approach to produce syngas, en route to fuels and chemicals. We report here on a dyad based on a Ru-based metallorganic dye and a tetraazamacrocyclic cobalt catalyst grafted on NiO to form efficient molecular photocathodes for CO-rich syngas production (ratio of CO/H-2 > 80:20) from a CO2-saturated aqueous bicarbonate buffer. After integration with a BiVO4/CoPi photoanode in a tandem photoelectrochemical cell in a Z-scheme configuration, syngas could be produced from CO2 water with Faradaic efficiencies (FE) of 62 % and 14 % for CO and H-2, respectively, under visible light and in the absence of any applied bias, equating to a solar to fuel conversion efficiency of 1.3 x 10(-2) %

    Continuum coupling correlation energy -- the Gamow shell model study

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    International audienceThe Gamow shell model provides the open quantum system formulation of nuclear shell model. In the coupled-channel representation, Gamow shell model provides the unified theory of nuclear structure and reactions which is well suited for the study of resonances and clusterization. In this work, we apply this approach to study the continuum-coupling correlation energy for selected near-threshold states of 7^7Li, 7^7Be

    Theoretical analysis of the dimensionality of ultrasonic attenuation in polycrystalline materials with elongated grains

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    International audienceIn the present work, the grain scattering-induced attenuation coefficient is obtained for longitudinal bulk waves in untextured cubic polycrystalline materials with elongated grains using proposed 2D and 3D theoretical models. These models are obtained based on previously developed 2D and 3D models for equiaxed grains. Comparison of the 2D and 3D models allows an analysis of the dimensionality of grain scattering-induced attenuation, which involves more complex mechanisms with elongated grains. In the higher stochastic scattering regime, both 3D and 2D longitudinal attenuations are found to be dependent on the grain size parallel to the wave propagation. In the Rayleigh scattering regime the 3D attenuation is volume dependent and in contrast, the 2D longitudinal attenuation is found to be cross-section dependent and is therefore helpful for identifying the 3D grain shape/rotation


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