Journal of Next-Generation Research 5.0
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Brittle deformation during Alpine basal accretion and the origin of seismicity nests above the subduction interface
No full textInternational audienceGeophysical observations on active subduction zones have evidenced high seismicity clusters at 20–40 km depth in the fore-arc region whose origin remains controversial. We report here field observations of pervasive pseudotachylyte networks (interpreted as evidence for paleo-seismicity) in the now-exhumed Valpelline continental unit (Dent Blanche complex, NW. Alps, Italy), a tectonic sliver accreted to the upper plate at c. 30 km depth during the Paleocene Alpine subduction. Pre-alpine granulite-facies paragneiss from the core of the Valpelline unit are crosscut by widespread, mm to cm-thick pseudotachylyte veins. Co-seismic heating and subsequent cooling led to the formation of Ti-rich garnet rims, ilmenite needles, Ca-rich plagioclase, biotite microliths and hercynite micro-crystals. 39Ar–40Ar dating yields a 51–54 Ma age range for these veins, thus suggesting that frictional melting events occurred near peak burial conditions while the Valpelline unit was already inserted inside the duplex structure. In contrast, the base of the Valpelline unit underwent synchronous ductile and brittle, seismic deformation under water-bearing conditions followed by a re-equilibration at c. 40 Ma (39Ar–40Ar on retrograded pseudotachylyte veins) during exhumation-related deformation. Calculated rheological profiles suggest that pseudotachylyte veins from the dry core of the granulite unit record upper plate micro-seismicity (Mw 2–3) formed under very high differential stresses (>500 MPa) while the sheared base of the unit underwent repeated brittle–ductile deformation at much lower differential stresses (<40 MPa) in a fluid-saturated environment. These results demonstrate that some of the seismicity clusters nested along and above the plate interface may reflect the presence of stiff tectonic slivers rheologically analogous to the Valpelline unit acting as repeatedly breaking asperities in the basal accretion region of active subduction zones
Scientific rationale for Uranus and Neptune in situ explorations
No full textInternational audienceThe ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Presumed to have a small rocky core, a deep interior comprising ~70% heavy elements surrounded by a more dilute outer envelope of H2 and He, Uranus and Neptune are fundamentally different from the better-explored gas giants Jupiter and Saturn. Because of the lack of dedicated exploration missions, our knowledge of the composition and atmospheric processes of these distant worlds is primarily derived from remote sensing from Earth-based observatories and space telescopes. As a result, Uranus's and Neptune's physical and atmospheric properties remain poorly constrained and their roles in the evolution of the Solar System not well understood. Exploration of an ice giant system is therefore a high-priority science objective as these systems (including the magnetosphere, satellites, rings, atmosphere, and interior) challenge our understanding of planetary formation and evolution. Here we describe the main scientific goals to be addressed by a future in situ exploration of an ice giant. An atmospheric entry probe targeting the 10-bar level, about 5 scale heights beneath the tropopause, would yield insight into two broad themes: i) the formation history of the ice giants and, in a broader extent, that of the Solar System, and ii) the processes at play in planetary atmospheres. The probe would descend under parachute to measure composition, structure, and dynamics, with data returned to Earth using a Carrier Relay Spacecraft as a relay station. In addition, possible mission concepts and partnerships are presented, and a strawman ice-giant probe payload is described. An ice-giant atmospheric probe could represent a significant ESA contribution to a future NASA ice-giant flagship mission
Passerelles. Enseigner les mathématiques par leur histoire au cycle 3
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A bias-corrected CMIP5 dataset for Africa using the CDF-t method : a contribution to agricultural impact studies
No full textInternational audienceThe objective of this paper is to present a new dataset of bias-corrected CMIP5 global climatemodel (GCM) daily data over Africa. This dataset was obtained using the cumulative distribution function transform (CDF-t) method, a method that has been applied to several regions and contexts but never to Africa. Here CDF-t has been applied over the period 1950–2099 combining Historical runs and climate change scenarios for six variables: precipitation, mean near-surface air temperature, near-surface maximum air temperature, near-surface minimum air temperature, surface downwelling shortwave radiation, and wind speed, which are critical variables for agricultural purposes. WFDEI has been used as the reference dataset to correct the GCMs. Evaluation of the results over West Africa has been carried out on a list of priority user-based metrics that were discussed and selected with stakeholders. It includes simulated yield using a crop model simulating maize growth. These bias-corrected GCM data have been compared with another available dataset of bias-corrected GCMs using WATCH Forcing Data as the reference dataset. The impact of WFD, WFDEI, and also EWEMBI reference datasets has been also examined in detail. It is shown that CDF-t is very effective at removing the biases and reducing the high inter-GCM scattering. Differences with other bias-corrected GCM data are mainly due to thedifferences among the reference datasets. This is particularly true for surface downwelling shortwave radiation, which has a significant impact in terms of simulated maize yields. Projections of future yields over West Africa are quite different, depending on the bias-correction method used. However all these projections show a similar relative decreasing trend over the 21st century
Comparison of Spectroscopic Strategies to Determine Molecular Geometries and the Impact of Nuclear versus Atomic Masses: The Example of HCO + and HOC +
No full textInternational audienceWe compare a recently proposed mixed experimental/theoretical procedure for the derivation of molecular equilibrium structures with several commonly used spectroscopic approaches using experimental data for several isotopologues. We also examine the sensitivity of the results from these approaches to the replacement of the commonly employed atomic masses with nuclear masses. This point is of particular importance for ionic species like HCO + and HOC + which serve as numerical reference cases. The scatter of molecular equilibrium geometries derived by different approaches is found to exceed stated statistical uncertainties by about an order of magnitude
IMPACT DE LA DETTE PUBLIQUE SUR L'INVESTISSEMENT: CAS DE LA COMMUNAUTÉ ECONOMIQUE DES PAYS DES GRANDS LACS
No full textThe CEPGL and its member states, like most low-income countries, have a very large public external debt and a weakness in terms of investment. Hence the question of asking "What impact can the public debt have on public and private investment? ". To carry out this study, two models were specified on the basis of the existing theoretical and empirical literature and according to the specificities of the economy of the CEPGL and its member countries. After preliminary tests (individual effects tests and Hausman specification test) which led to INVPRI estimation through the FMOLS and MCO and INVPUB estimation by the GLS, it appears that of this study, that public investment positively impacts private investment andvice versa, the government-backed stock of public debt, on the other hand, has a negative impact on private investment, contrary to its positive relationship with the private sector public investment. As for the servicing of the public debt and guaranteed by the State, it negatively influences the investment (public and private long-term) contrary to its impact on long-term private investment.La CEPGL et ses Etats membres comme la plupart des pays à faible revenu, accusent une dette extérieure publique très importante et une faiblesse en termes d’investissements. D’où la question de se demander « Quel peut être l’impact de la dette publique sur l’investissementpublic et privé ? ». Pour mener à bien cette étude, deux modèles ont été spécifiés sur la base de la littérature théorique et empirique existante et en fonction des spécificités de l’économie de la CEPGL et de ses pays membres. Après des tests préliminaires (tests des effets individuels et test de spécification de Hausman) qui nous ont amené à l’estimation de l’INVPRI par le truchement du FMOLS et du MCO et l’estimation de l’INVPUB par les GLS, il ressort de cette étude que l’investissement public impacte positivement l’investissement privé et vice-versa, le stock de la dette publique et garantie par l’Etat, pour sa part, impact négativement l’investissement privé contrairement à sa relation positive avec l’investissement public. Quant à ce qui est du service de la dette publique et garantie par l’Etat, il influence négativement l’investissement (public et privé de long terme) contrairement à son impact sur l’investissement privé de long term
The World Meteorological Organization’s Fourth International Workshop on Tropical Cyclone Landfall Processes (IWTCLP-IV): A Summary
No full textInternational audienceThe Fourth International Workshop on Tropical Cyclone Landfall Processes (IWTCLP-4) was held in Macau, China from 5-7 December 2017. The workshop was organized by World Meteorological Organization’s (WMO’s) Expert Team on Tropical Cyclone Landfall Processes in partnership with WMO's Tropical Cyclone Program. The workshop provided a forum for discussion between researchers and forecasters on the current status of tropical cyclone landfall processes and on priorities and opportunities for research. More than 60 leading research scientists and warning specialists working on topics related to tropical cyclone landfall examined current knowledge, forecasting and research trends from an integrated global perspective. The workshop offered a number of recommendations for future forecasting studies and research with special regard to the varying needs of different tropical cyclone affected regions. The recommendations emanating from the workshop will be presented at the upcoming Ninth International Workshop on Tropical Cyclones (IWTC-9) (Hawaii, USA, 3-7 December 2018)
Assessing chromium mobility in natural surface waters: Colloidal contribution to the isotopically exchangeable pool of chromium (E w Cr value)
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Improving paleohydrological and diagenetic reconstructions in calcite veins and breccia of a sedimentary basin by combining Δ 47 temperature, δ 18 O water and U-Pb age
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Mortality and its determinants in antiretroviral treatment-naive HIV-infected children with suspected tuberculosis: an observational cohort study
No full textInternational audienceBACKGROUND:Tuberculosis is a major cause of morbidity and mortality in HIV-infected children, but is difficult to diagnose. We studied mortality and its determinants in antiretroviral treatment (ART)-naive HIV-infected children presenting with suspected tuberculosis.METHODS:In this observational cohort study, HIV-infected children aged 13 years or younger with suspected tuberculosis were followed up for 6 months as part of the ANRS 12229 PAANTHER 01 cohort in eight hospitals in four countries (Burkina Faso, Cambodia, Cameroon, and Vietnam). Children started ART and antituberculosis treatment at the clinician's discretion and were retrospectively classified into one of three groups by tuberculosis documentation: confirmed by culture or Xpert MTB/RIF, unconfirmed, and unlikely. We assessed mortality and associated factors using Kaplan-Meier methods and Cox proportional hazard models. The ANRS 12229 PAANTHER 01 study is registered at ClinicalTrials.gov, number NCT01331811.FINDINGS:266 (61%) of 438 children enrolled in the study between April 27, 2011, and May 31, 2014, were ART-naive and included in the analysis (40 had confirmed tuberculosis, 119 unconfirmed tuberculosis, and 107 unlikely tuberculosis). 112·5 person-years of follow-up were available. 154 children (58%) started antituberculosis treatment and 212 (80%) started ART. 50 children (19%) died. Mortality by 6 months was higher in children with confirmed tuberculosis (14 deaths; 2 month survival probability 65·0% [95% CI 50·2-79·8]) compared with unconfirmed tuberculosis (19 deaths; 83·5% [76·8-90·3]) and unlikely tuberculosis (17 deaths; 83·5% [76·3-90·7]; log-rank p=0·0141) and was lower in children with confirmed or unconfirmed tuberculosis who started antituberculosis treatment (p<0·0001 for both). In a multivariate analysis, ART started during the first month of follow-up (hazard ratio 0·08; 95% CI 0·01-0·67), confirmed tuberculosis (6·33; 2·15-18·64), young age (5·90; 2·02-17·19), CD4 less than 10% (2·63; 1·25-5·53), miliary features (4·08; 1·56-10·66), and elevated serum transaminases (4·40; 1·82-10·65) were all independently associated with mortality.INTERPRETATION:In our cohort, mortality was high in the first 6 months after suspicion of tuberculosis in ART-naive children. ART should be started early, particularly in children with factors associated with high mortality. Documented or empirical tuberculosis treatment decision should be accelerated to reduce mortality and allow early ART initiation.FUNDING:ANRS and Fondation Total