pinecone/core-2020-05-10-deduplication huggingface dataset:
Paleo-erosion rates in Central Asia since 9 Ma: A transient increase at the onset of Quaternary glaciations?

International audienceErosion is a fundamental player of the interactions existing between internal geodynamics and climate, in particular through its influence on the carbon dioxide budget. However, long term (> 1 Ma) erosion rates, estimated indirectly from sediment budget, remain poorly constrained. While some studies suggest that worldwide erosion rates increased at the Plio-Pleistocene climatic transition (~ 4-2 Ma), the validity of this observation and its significance is a matter of debate due to potential biases of the sedimentary record and to the influence of sea level fall on the global sedimentary flux to marginal basins. In the present study, we estimate erosion rates over the last ~ 9 Ma using in situ produced cosmogenic 10Be concentrations measured in magnetostratigraphically dated continental sediments. We focus on an intracontinental endorheic watershed draining the northern Tianshan in Central Asia, a key region regarding the ongoing debate. While erosion rates between 0.1 and 1 mm*yr− 1 are derived from most of our record, they reach values as high as ~ 2.5 mm*yr− 1 from 2.5 to 1.7 Ma. Then, after 1.7 Ma, recent and modern erosion rates fell below 1 mm*yr− 1. This temporary increase is correlated with the onset of Quaternary ice ages and suggests that global climate had a significant and transient impact on erosion
How Test Generation Helps Software Specification and Deductive Verification in Frama-C

International audienceThis paper describes an incremental methodology of deductive verification assisted by test generation and illustrates its benefits   by a set of frequent verification scenarios.  We present  StaDy, a new integration of the concolic test generator PathCrawler within the software analysis platform FramaC. This new plugin treats a complete formal specification of a C program  during test generation and provides the validation engineer with a helpful feedback   at all stages of the specification and verification tasks
Experimental and numerical study of crack healing in a nuclear glass

International audiencea b s t r a c t An experimental study of thermally or water-induced crack healing in an inactive borosil-icate glass, chemically analogous to that used in France for the vitrification of nuclear waste was carried out. Partial welding of glass plates was observed after annealing in air at 425 °C (77 °C below T g) when at least 20 MPa compressive stress was applied, while annealing at 450 °C under 20 MPa led to a complete disappearance of the interface. Closure of indenta-tion-induced cracks was observed during annealing at 400 °C in an ESEM as a result of viscous relaxation of residual stresses but it did not constitute a sufficient proof of crack healing. DCDC specimens were thus pre-cracked in an ESEM and then either annealed at various temperatures (350–490 °C) in secondary vacuum or in air, or left in water at 70–90 °C, sometimes under a compressive stress normal to the crack face. The specimens were then reloaded in the ESEM and the crack opening displacements under a given load were compared to those measured during pre-cracking. The cracks were bridged by an alteration layer over a distance from the crack tip which decreased as loading increased. The restraining effect of these bridges on crack opening was assessed via finite element simulations, using interface elements. The tensile strength of the bridging layer was estimated as 27–39 MPa after vacuum annealing at 400 °C, 11–20 MPa after 15 days in water at 90 °C and 44–78 MPa after 11 days in water at 70 °C under 5 MPa normal compression. Partially healed cracks did not resume propagation from their former crack tip, but due to branch cracks re-initiated a few hundred microns behind it which grow avoiding the healed area. This behaviour was explained using finite element simulations
Twenty Parameters Families of Solutions to the NLS Equation and the Eleventh Peregrine Breather

International audienceThe Peregrine breather of order eleven (P11 breather) solution to the focusing one-dimensional nonlinear Schrödinger equation (NLS) is explicitly constructed here. Deformations of the Peregrine breather of order 11 with 20 real parameters solutions to the NLS equation are also given: when all parameters are equal to 0 we recover the famous P11 breather. We obtain new families of quasi-rational solutions to the NLS equation in terms of explicit quotients of polynomials of degree 132 in x and t by a product of an exponential depending on t. We study these solutions by giving patterns of their modulus in the (x; t) plane, in function of the different parameters
DUST FROM COMET 209P/LINEAR DURING ITS 2014 RETURN: PARENT BODY OF A NEW METEOR SHOWER, THE MAY CAMELOPARDALIDS

International audienceWe report a new observation of the Jupiter family comet 209P/LINEAR during its 2014 return. The comet is recognized as a dust source of a new meteor shower, the May Camelopardalids. 209P/LINEAR was apparently inactive at a heliocentric distance r h = 1.6 AU and showed weak activity at r h 1.4 AU. We found an active region of <0.001% of the entire nuclear surface during the comet's dormant phase. An edge-on image suggests that particles up to 1 cm in size (with an uncertainty of factor 3–5) were ejected following a differential power-law size distribution with index q = −3.25 ± 0.10. We derived a mass-loss rate of 2–10 kg s −1 during the active phase and a total mass of ≈5 × 10 7 kg during the 2014 return. The ejection terminal velocity of millimeter-to centimeter-sized particles was 1–4 m s −1 , which is comparable to the escape velocity from the nucleus (1.4 m s −1). These results imply that such large meteoric particles marginally escaped from the highly dormant comet nucleus via the gas drag force only within a few months of the perihelion passage
Quaternary global change: review and issues(Special issue in memory of Hugues Faure)

International audienceThe French National Committee of INQUA, the IGCP Project n° 459 (Carbon Cycle and Hydrology in the Paleo Terrestrial Environments),the CNRS (Centre National de la Recherche Scientifique), the CCGM (Commission de la Carte Géologique du Monde), the IRD (Institut de Recherche pour le Développement), and the BRGM (Bureau de Recherches Géologiques et Minières) have organized in June 2004 a special International Colloquium dedicated to the memory of Hugues Faure who passed away in May 2003. It was the occasion to make a review and to emphasize new results and issues on the different topics initiated by Hugues and his collaborators. It was also a chance for all his colleagues and friends to remember a rare human being and a great scientist, passionately involved in the observation and understanding of the planet, which he called "the real world", and assuming his destiny up to the end. The Scientific committee of this colloquium has decided to publish a special issue of Global and Planetary Change with some selected papers presented during this colloquium. This GPC special issue includes some of the papers presented at this colloquium and some invited papers from scientific personalities who wished to contribute to this special volume. The general theme of the special publication in honour to Hugues Faure is the Quaternary and the Global Changes. It will focus on the global cycles and Quaternary climate (3 papers), sea-level fluctuations, tectonics and climate variations (3 papers), climate changes in terrestrial records (9 papers), and man, environment and global change (4 papers). A total of 20 contributions, including a foreword on Hugues Faure, are proposed by the participants of this colloquium
Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley

International audienceAquifer overexploitation could significantly impact crop production in the United States because 60% of irrigation relies on groundwater. Groundwater depletion in the irrigated High Plains and California Central Valley accounts for ∼50% of groundwater depletion in the United States since 1900. A newly developed High Plains recharge map shows that high recharge in the northern High Plains results in sustainable pumpage, whereas lower recharge in the central and southern High Plains has resulted in focused depletion of 330 km3 of fossil groundwater, mostly recharged during the past 13,000 y. Depletion is highly localized with about a third of depletion occurring in 4% of the High Plains land area. Extrapolation of the current depletion rate suggests that 35% of the southern High Plains will be unable to support irrigation within the next 30 y. Reducing irrigation withdrawals could extend the lifespan of the aquifer but would not result in sustainable management of this fossil groundwater. The Central Valley is a more dynamic, engineered system, with north/south diversions of surface water since the 1950s contributing to ∼7× higher recharge. However, these diversions are regulated because of impacts on endangered species. A newly developed Central Valley Hydrologic Model shows that groundwater depletion since the 1960s, totaling 80 km3, occurs mostly in the south (Tulare Basin) and primarily during droughts. Increasing water storage through artificial recharge of excess surface water in aquifers by up to 3 km3 shows promise for coping with droughts and improving sustainability of groundwater resources in the Central Valley
Late Holocene sea-cliff retreat recorded by 10Be profiles across a coastal platform: Theory and example from the English Channel

International audienceWe explore a new method for documenting the long term retreat rate of sea cliffs based on measurements and modeling of 10Be concentration transects across present-day shore platforms. The proposed forward numerical model relies on a scenario of sea level rise since the last deglaciation, and predicts the shape of 10Be concentration transects as a function of prescribed cliff recession and vertical coastal platform downwearing rates. Two independent transect features allow fitting the long-term recession rate model to field observations: a sharp 10Be concentration drop predicted at the former stationary location of the cliff during the last glacial period ~100 ka ago, and a characteristic dome shape whose magnitude is directly related to the recession rate of the cliff. A retreating chalk cliff site from the English Channel coast of France, at Mesnil Val, where the 7 m tidal range broadly exposes the shore platform, was selected to test the proposed method. Although retreat rates were too high to pinpoint the predicted 10Be concentration drop at the last glacial cliff position, the 10Be-concentration of the flints sampled across the shore platform are consistent with the expected dome shape. When modeled using the proper tidal range and proposed Holocene sea level rise history, the 10Be data yield a cliff retreat rate since the mid-Holocene of 11-13 cm/yr. This is consistent with a 30-year-long measurement record, strongly supporting the utility of the 10Be method
Neodymium isotopic composition of the oceans: A compilation of seawater data

International audienceA global compilation of the neodymium isotopic composition of seawater is presented. With 880 data points, it confirms the gradual εNd increase for intermediate/deep water masses from the northwest North Atlantic, via the Austral and Indian oceans, to the Pacific. This confirms the usefulness of this tracer for studying large scale oceanic circulation. The compilation stresses the need for documenting the oceans south of 30°S, from which less than 4% of the data are derived. The associated neodymium concentrations display heterogeneous vertical gradients among major oceanic basins. In addition to particle remineralization along the global thermohaline circulation, the database suggests that basin size differences also contribute to that heterogeneity
Impact of three different TiO2 morphologies on hydrogen evolution by methanol assisted water splitting: Nanoparticles, nanotubes and aerogels

International audienceIncreasing the activity of a photocatalyst goes through the improvement of both its absorption (light) and adsorption (reactant) properties. For a given semiconducting material, the charge carrier separation is also a very important step. Properly combining chosen phases is one option to improve this separation (example of the commercial P25) and depositing platinum on the surface of the catalyst, another one. In some cases, coupling both may nevertheless lead to a decrease of photoactivity or at least limit the potentiality of the catalyst. A third option, consisting in modifying the morphology of the photoactive phase, has shown very promising results. In this study, we have elaborated, characterized and evaluated the hydrogen evolution potentiality (through methanol assisted water splitting) of different TiO2 morphologies: nanoparticles, nanotubes and aerogels. These materials have shown different behaviours depending on both their composition and morphology. Different types of separation processes have been claimed to account for the observed different photoactivities, with more or less pronounced synergetic effects, due to: the use of Pt as a co-catalyst, the mixture of different TiO2 phases (anatase and TiO2(B) or rutile) and the specific morphology of the samples (nanotubes or aerogels). Among all the tested samples, the TiO2 aerogel supported Pt one exhibited very promising performances, three times as active as P25 supported Pt, which is already much more active than pure P25 in our testing conditions
The Gaia Mission and the Asteroids. A perspective from space astrometry and photometry for asteroids studies and science.

90 pagesThe Gaia space mission to be operated in early 2012 by the European Space Agency (ESA), will make a huge step in our knowledge of the Sun's neighbor-hood, up to the Magellanic clouds. Somewhat closer, Gaia will also provide ma jor improvements in the science of asteroids, and more generally to our Solar System, either directly or indirectly. Gaia is a scanning survey telescope aimed to perform high accuracy astrometry and photometry. More speciﬁcally it will provide physical and dynamical characterization of asteroids, a better knowledge of the solar system composition, formation and evolution, local test of the general relativity, and linking the dynamical reference frame to the kinematical ICRS. We develop here the general aspects of asteroid observations and the scientiﬁc harvest in perspective of what was achieved in the pre-Gaia era. In this lecture we focus on the determination of size of asteroids, shape and rotation, taxonomy, orbits and their improvements with historical highlight, and also the dynamical model in general
Interaction of magma with sedimentary wall rock and magnetite ore genesis in the Panzhihua mafic intrusion, SW China

International audienceIn SW China, several large magmatic Fe-Ti-V oxide ore deposits are hosted by gabbroic intrusions associated with the Emeishan flood basalts. The Panzhihua gabbroic intrusion, a little deformed sill that contains a large titanomagnetite deposit at its base, concordantly intrudes late- Proterozoic dolostones. Mineralogical and chemical studies of the contact aureole in the footwall dolostones demonstrates that the metamorphism was largely isochemical, but for the release of large quantities of CO2 as the rocks were converted to marble and skarns during intrusion of the gabbroic magma. Petrological modelling of the crystallization of the intrusion, using H2O-poor Emeishan basalt as parent magma, shows that under normal conditions Fe-Ti-oxides crystallize at a late stage, after the crystallization of abundant olivine, clinopyroxene and plagioclase. In order for titanomagnetite to separate efficiently to form the ore deposit, this mineral must have crystallized earlier and close to the liquidus. We propose that CO2-rich fluids released during decarbonatization of sedimentary floor rocks passed up through the magma. Redox equilibria calculations show that when magma with the composition of Emeishan basalt is fluxed by a CO2-rich gas phase, its equilibrium oxygen fugacity (fO2) increases from FMQ to FMQ+1.5. From experimental constraints on magnetite saturation in basaltic magma under controlled fO2, such an oxidizing event would allow magnetite to crystallize near to the liquidus, leading to the formation of the deposit
Wetland monitoring using classification trees and SPOT-5 seasonal time series

International audienceMultiseason reflectance data from radiometrically and geometrically corrected multispectral SPOT-5 images of 10-m resolution were combined with thorough field campaigns and land cover digitizing using a binary classification tree algorithm to estimate the area of marshes covered with common reeds (Phragmites australis) and submerged macrophytes (Potamogeton pectinatus, P. pusillus, Myriophyllum spicatum, Ruppia maritima, Chara sp.) over an area of 145,000 ha. Accuracy of these models was estimated by cross-validation and by calculating the percentage of correctly classified pixels on the resulting maps. Robustness of this approach was assessed by applying these models to an independent set of images using independent field data for validation. Biophysical parameters of both habitat types were used to interpret the misclassifications. The resulting trees provided a cross-validation accuracy of 98.7% for common reed and 97.4% for submerged macrophytes. Variables discriminating reed marshes from other land covers were the difference in the near-infrared band between March and June, the Optimized Soil Adjusted Vegetation Index of December, and the Normalized Difference Water Index (NDWI) of September. Submerged macrophyte beds were discriminated with the shortwave-infrared band of December, the NDWI of September, the red band of September and the Simple Ratio index of March. Mapping validations provided accuracies of 98.6% (2005) and 98.1% (2006) for common reed, and 86.7% (2005) and 85.9% (2006) for submerged macrophytes. The combination of multispectral and multiseasonal satellite data thus discriminated these wetland vegetation types efficiently. Misclassifications were partly explained by digitizing inaccuracies, and were not related to biophysical parameters for reedbeds. The classification accuracy of submerged macrophytes was influenced by the proportion of plants showing on the water surface, percent cover of submerged species, water turbidity, and salinity. Classification trees applied to time series of SPOT-5 images appear as a powerful and reliable tool for monitoring wetland vegetation experiencing different hydrological regimes even with a small training sample (N=25) when initially combined with thorough field measurements
A low δ7Li lower crustal component: Evidence from an alkalic intraplate volcanic series (Chaîne des Puys, French Massif Central)

International audienceThe intraplate volcanic suite of the Chaîne des Puys (French Massif Central) shows a complete petrologic range, from alkali basalts to trachytes. The significant variations of trace elements and radiogenic isotopes along the series strongly support the occurrence of crustal assimilation associated with fractional crystallization (AFC). The least contaminated basalts are clearly related to a HIMU-type reservoir (206Pb/204Pb > 19.6; 87Sr/86Sr < 0.7037; εNd > + 4). The behavior of radiogenic isotopes suggests that the most likely crustal contaminants are meta-sediments located in the lower crust. The Li isotopic compositions of the lavas range from high δ7Li (> + 7‰) in basalts to lighter values in more evolved lavas (down to δ7Li ≈ 0‰). The mantle component, expressed in the least evolved lavas, has a heavy Li isotopic signature, in good agreement with previous δ7Li measurements of OIB lavas with HIMU affinities. The evolution of Li isotopic compositions throughout the volcanic series is in agreement with the AFC model suggested by the Sr–Nd–Pb isotopic systems. Although the behavior of Li isotopes during assimilation processes is currently poorly constrained, our calculations suggest that at least a portion of the lower crust beneath the Chaîne des Puys is characterized by a light Li isotopic composition (δ7Li < − 5‰)
Measuring local and global vibration modes in model plants

International audienceModel plants are extensively used in biological studies, and their mechanical behaviour needs to be better understood, in relation to studies in mechanoperception for instance. We present here the ﬁrst approach to derive experimentally the modal parameters of two of these plants, Arabidopsis thaliana and Populus tremula alba. A classical sinusoidal sweep excitation is used, with a measurement of displacements based on LKT optical ﬂow tracking, followed by a Bi-Orthogonal decomposition (BOD). This allows to estimate several modal frequencies for each plant, as well as the corresponding spatial localizations of deformation. Analyzing the modal frequencies, we show that global and local modes correspond to distinct ranges of frequencies and depend diﬀerently on plant size. Possible phenotyping applications are then discussed
Optimal growth with adaptation to climate change

International audienceMany economic sectors, like housing or transportation, are exposed to climate and likely to suffer efficiency losses when climate changes. The global economy is far from dematerialized yet, these sectors represent a significant fraction of the existing capital stock. Using an optimal growth model with perfect knowledge, we examine the balance between these efficiency losses and investment in adaptation measures, which can become sunk costs when climate changes even more. Simulations remind that adaptation should be proactive rather than reactive: protection measures installed today are not designed for today's climate only, but anticipate future warmer conditions over their lifetime. While there is an over-investment compared with a no climate change baseline, the overall cost to adapt is relatively low in front of the potential losses from misadaptation. This allows to stay almost always well adapted to climate
Influence of weather and global warming in chloride ingress into concrete: a stochastic approach

International audienceReinforced concrete (RC) structures are subject to environmental actions affecting their performance, serviceability and safety. Among these actions, chloride ingress leads to corrosion and has been recognized as a critical factor reducing the service life of RC structures. This paper presents a stochastic approach to study the influence of weather conditions and global warming on chloride ingress into concrete. The assessment of chloride ingress is carried out on the basis of a comprehensive model that couples the effects of convection, chloride binding, concrete aging, temperature and humidity. A simplified model of temperature and humidity including seasonal variations and global warming is also proposed in this work. Three scenarios of global warming are defined based on: gas emissions, global population growth, introduction of new and clean technologies and use of fossil sources of energy. The proposed approach is illustrated by a numerical example where it is found that the climate changes may yield to significant lifetime reductions. These results justify the implementation of countermeasures directed to (1) reduce and/or mitigate the action of global warming on weather and (2) minimize the impact of climate changes on RC structures