456 research outputs found
The French Atlantic littoral and the Massif Armoricain, part 1
The author has identified the following significant results. For interpretation of Isle of Jersey imagery, two types of taxons were defined according to their variability in time. On the whole, taxons with a similar spectral signature were opposed to those with strongly varying spectral signature. The taxon types were low diachronic variations and strong diachronic variation. Imagery interpretation was restricted to the landward part of the Fromentine area, including the sand beaches which were often difficult to spectrally separate from the barren coastal dunes in the southern part of Noirmoutier Island as well as along the Breton marsh. From 1972 to 1976, sandbanks reduced in area. Two high river discharge images showed over a two year period an identical outline for the Bilho bank to seaward, whereas upstream, the bank has receeded in the same time to a line joining Paimboeuf to Montoir. The Brillantes bank has receeded at both ends, partly due to dredging operations in the access channel to Donges harbor
The combustion behavior of epoxyâbased multifunctional electrolytes
Multifunctional or structural electrolytes are characterized by ionic conductivity high enough to be used in the electrochemical devices and mechanical performance suitable for the structural applications. Preliminary insights are provided into the combustion behavior of structural biâcontinuous electrolytes based on bisphenol A diglycidyl ether (DGEBA), synthesized using the techniques of reaction induced phase separation and emulsion templating. The effect of the composition of the structural electrolytes and external heat flux on the behavior of the formulations were studied using a cone calorimeter with gases formed during testing analyzed using FTIR. The composition of the formulations investigated was changed by varying the type and amount of the ion conductive part of the biâcontinuous electrolyte. Two ionic liquids, 1âethylâ3âmethylimidazolium bis(fluorosulfonyl)imide (EMIMâTFSI) and 1âbutylâ3âmethylimidazolium tetrafluoroborate (BMIMâBF4), as well as a deep eutectic solvent (DES) based on ethylene glycol and choline chloride, were used. The results obtained confirm that time to ignition, heat release rate (HRR), total mass loss, as well as the composition of the gases released during tests depend on the composition of the formulations. Addition of liquid electrolyte is found to reduce the time to ignition by up to 10% and the burning time by between 28% and 60% with the added benefit of reducing the HRR by at least 34%. Gaseous products such as CO2, CO, H2O, CH4, C2H2, N2O, NO, and HCN were detected for all formulations with the gases SO2, NH3, HCl, C2H4, and NH3 found to be for certain formulations only
Special Geometry of Euclidean Supersymmetry III: the local r-map, instantons and black holes
We define and study projective special para-Kahler manifolds and show that
they appear as target manifolds when reducing five-dimensional vector
multiplets coupled to supergravity with respect to time. The dimensional
reductions with respect to time and space are carried out in a uniform way
using an epsilon-complex notation. We explain the relation of our formalism to
other formalisms of special geometry used in the literature. In the second part
of the paper we investigate instanton solutions and their dimensional lifting
to black holes. We show that the instanton action, which can be defined after
dualising axions into tensor fields, agrees with the ADM mass of the
corresponding black hole. The relation between actions via Wick rotation, Hodge
dualisation and analytic continuation of axions is discussed.Comment: 72 pages, 2 figure
Can a âstate of the artâ chemistry transport model simulate Amazonian tropospheric chemistry?
We present an evaluation of a nested high-resolution Goddard Earth Observing System (GEOS)-Chem chemistry transport model simulation of tropospheric chemistry over tropical South America. The model has been constrained with two isoprene emission inventories: (1) the canopy-scale Model of Emissions of Gases and Aerosols from Nature (MEGAN) and (2) a leaf-scale algorithm coupled to the Lund-Potsdam-Jena General Ecosystem Simulator (LPJ-GUESS) dynamic vegetation model, and the model has been run using two different chemical mechanisms that contain alternative treatments of isoprene photo-oxidation. Large differences of up to 100 Tg C yr^(â1) exist between the isoprene emissions predicted by each inventory, with MEGAN emissions generally higher. Based on our simulations we estimate that tropical South America (30â85°W, 14°Nâ25°S) contributes about 15â35% of total global isoprene emissions. We have quantified the model sensitivity to changes in isoprene emissions, chemistry, boundary layer mixing, and soil NO_x emissions using ground-based and airborne observations. We find GEOS-Chem has difficulty reproducing several observed chemical species; typically hydroxyl concentrations are underestimated, whilst mixing ratios of isoprene and its oxidation products are overestimated. The magnitude of model formaldehyde (HCHO) columns are most sensitive to the choice of chemical mechanism and isoprene emission inventory. We find GEOS-Chem exhibits a significant positive bias (10â100%) when compared with HCHO columns from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) and Ozone Monitoring Instrument (OMI) for the study year 2006. Simulations that use the more detailed chemical mechanism and/or lowest isoprene emissions provide the best agreement to the satellite data, since they result in lower-HCHO columns
Campagne océanographique FLUPAC à bord du N.O. l'ATALANTE 23 septembre au 29 octobre 1994. Recueil des données. Tome 1 : météo, courantologie, hydrologie, données de surface
La campagne FLUPAC du N.O. L'Atalante, qui s'est déroulée du 23 septembre au 29 octobre 1994, s'est placée dans le cadre du programme international JGOFS (JOINT GLOBAL OCEAN FLUX STUDY). Elle a comporté deux radiales et deux stations équatoriales de 6-7 jours. La premiÚre radiale, le long de 165°E, a parcouru la zone comprise entre 20°S et 6°N. La seconde s'est déroulée le long de l'équateur entre 167°E et 150°W. Les deux stations de longue durée ont eu lieu à O°-167°E et 0°-150°W. Elles ont été l'occasion d'études détaillées des flux impliqués dans le cycle du carbone de la couche superficielle (0-500 m). Le premier tome du recueil de données présente des résultats, sous forme de graphiques et de tableaux, des paramÚtres enregistrés en continu et de ceux de la sonde CTD. Les paramÚtres chimiques, la chlorophylle "a" et les observations en cytomÚtrie de flux obtenus sur l'eau de la "rosette" couplée à la sonde CTD, sont également présentés. (Résumé d'auteur
Deformation Quantization of Superintegrable Systems and Nambu Mechanics
Phase Space is the framework best suited for quantizing superintegrable
systems, naturally preserving the symmetry algebras of the respective
hamiltonian invariants. The power and simplicity of the method is fully
illustrated through new applications to nonlinear sigma models, specifically
for de Sitter N-spheres and Chiral Models, where the symmetric quantum
hamiltonians amount to compact and elegant expressions. Additional power and
elegance is provided by the use of Nambu Brackets to incorporate the extra
invariants of superintegrable models. Some new classical results are given for
these brackets, and their quantization is successfully compared to that of
Moyal, validating Nambu's original proposal.Comment: LateX2e, 18 page
Roles of marginal seas in absorbing and storing fossil fuel CO2
We review data on the absorption of anthropogenic CO2 by Northern Hemisphere marginal seas (Arctic Ocean, Mediterranean Sea, Sea of Okhotsk, and East/Japan Sea) and its transport to adjacent major basins, and consider the susceptibility to recent climatic change of key factors that influence CO2 uptake by these marginal seas. Dynamic overturning circulation is a common feature of these seas, and this effectively absorbs anthropogenic CO2 and transports it from the surface to the interior of the basins. Amongst these seas only the East/Japan Sea has no outflow of intermediate and deep water (containing anthropogenic CO2) to an adjacent major basin; the others are known to be significant sources of intermediate and deep water to the open ocean. Consequently, only the East/Japan Sea retains all the anthropogenic CO2 absorbed during the anthropocene. Investigations of the properties of the water column in these seas have revealed a consistent trend of waning water column ventilation over time, probably because of changes in local atmospheric forcing. This weakening ventilation has resulted in a decrease in transport of anthropogenic CO2 from the surface to the interior of the basins, and to the adjacent open ocean. Ongoing measurements of anthropogenic CO2, other gases and hydrographic parameters in these key marginal seas will provide information on changes in global oceanic CO2 uptake associated with the predicted increasing atmospheric CO2 and future global climate change. We also review the roles of other marginal seas with no active overturning circulation systems in absorbing and storing anthropogenic CO2. The absence of overturning circulation enables anthropogenic CO2 to penetrate only into shallow depths, resulting in less accumulation of anthropogenic CO2 in these basins. As a consequence of their proximity to populated continents, these marginal seas are particularly vulnerable to human-induced perturbations. Maintaining observation programs will make it possible to assess the effects of human-induced changes on the capacity of these seas to uptake and store anthropogenic CO2
Association of partial T2-FLAIR mismatch sign and isocitrate dehydrogenase mutation in WHO grade 4 gliomas:results from the ReSPOND consortium
Self-management practices of smokers with asthma and/or chronic obstructive pulmonary disease: a cross-sectional survey
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