排序方式： 共有50条查询结果，搜索用时 31 毫秒
11.
Martin Laporte Zhaojun Shao Patrick Berrebi Mohamed Laabir Eric Abadie Nicolas Faivre Fabien Rieuvilleneuve Estelle Masseret 《Marine pollution bulletin》2014
Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic species. Finally, the haplotypic diversity ranged from 0.000 to 0.791 and 0.000 to 0.942 for A. catenella and A. tamarense respectively. 相似文献
12.
Stephen J. Eaton David M. Hodgson Natasha L. M. Barlow Estelle E. J. Mortimer Claire L. Mellett 《第四纪科学杂志》2020,35(6):760-775
Offshore stratigraphic records from the North Sea contain information to reconstruct palaeo-ice-sheet extent and understand sedimentary processes and landscape response to Pleistocene glacial–interglacial cycles. We document three major Middle to Late Pleistocene stratigraphic packages over a 401-km2 area (Norfolk Vanguard/Boreas Offshore Wind Farm), offshore East Anglia, UK, through the integration of 2D seismic, borehole and cone penetration test data. The lowermost unit is predominantly fluviatile [Yarmouth Roads Formation, Marine Isotope Stage (MIS) 19–13], including three northward-draining valleys. The middle unit (Swarte Bank Formation) records the southernmost extent of tunnel valley-fills in this area of the North Sea, providing evidence for subglacial conditions most likely during the Anglian stage (MIS 12) glaciation. The Yarmouth Roads and Swarte Bank deposits are truncated and overlain by low-energy estuarine silts and clays (Brown Bank Formation; MIS 5d–4). Smaller scale features, including dune-scale bedforms, and abrupt changes in cone penetration test parameters, provide evidence for episodic changes in relative sea level within MIS 5. The landscape evolution recorded in deposits of ~MIS 19–5 are strongly related to glacial–interglacial cycles, although a distinctive aspect of this low-relief ice-marginal setting are opposing sediment transport directions under contrasting sedimentary process regimes. 相似文献
13.
A deterministic method for sensitivity analysis is developed and applied to a mathematical model for the simulation of flow in porous media. The method is based on the singular value decomposition (SVD) of the Jacobian matrix of the model. It is a local approach to sensitivity analysis providing a hierarchical classification of the directions in both the input space and of those in the output space reflecting the degree of sensitiveness of the latter to the former. Its low computational cost, in comparison with that of statistical approaches, allows the study of the variability of the results of the sensitivity analysis due to the variations of the input parameters of the model, and thus it can provide a quality criterion for the validity of more classical probabilistic global approaches. For the example treated here, however, this variability is weak, and deterministic and statistical methods yield similar sensitivity results. 相似文献
14.
Estelle Asseo Alain Riazuelo 《Monthly notices of the Royal Astronomical Society》2000,318(4):983-1004
The properties of waves able to propagate in a relativistic pair plasma are at the basis of the interpretation of several astrophysical observations. For instance, they are invoked in relation to radio emission processes in pulsar magnetospheres and to radiation mechanisms for relativistic radio jets. In such physical environments, pair plasma particles probably have relativistic, or even ultrarelativistic, temperatures. Besides, the presence of an extremely strong magnetic field in the emission region constrains the particles to one-dimensional motion: all the charged particles strictly move along magnetic field lines.
We take anisotropic effects and relativistic effects into account by choosing one-dimensional relativistic Jűttner–Synge distribution functions to characterize the distribution of electrons and/or positrons in a relativistic, anisotropic pair plasma. The dielectric tensor, from which the dispersion relation associated with plane wave perturbations of such a pair plasma is derived, involves specific coefficients that depend on the distribution function of particles. A precise determination of these coefficients, using the relativistic one-dimensional Jűttner–Synge distribution function, allows us to obtain the appropriate dispersion relation. The properties of waves able to propagate in anisotropic relativistic pair plasmas are deduced from this dispersion relation. The conditions in which a beam and a plasma, both ultrarelativistic, may interact and trigger off a two-stream instability are obtained from this same dispersion relation. Two astrophysical applications are discussed. 相似文献
We take anisotropic effects and relativistic effects into account by choosing one-dimensional relativistic Jűttner–Synge distribution functions to characterize the distribution of electrons and/or positrons in a relativistic, anisotropic pair plasma. The dielectric tensor, from which the dispersion relation associated with plane wave perturbations of such a pair plasma is derived, involves specific coefficients that depend on the distribution function of particles. A precise determination of these coefficients, using the relativistic one-dimensional Jűttner–Synge distribution function, allows us to obtain the appropriate dispersion relation. The properties of waves able to propagate in anisotropic relativistic pair plasmas are deduced from this dispersion relation. The conditions in which a beam and a plasma, both ultrarelativistic, may interact and trigger off a two-stream instability are obtained from this same dispersion relation. Two astrophysical applications are discussed. 相似文献
15.
High‐resolution evolution of terrigenous sediment yields in the Provence Basin during the last 6 Ma: relation with climate and tectonics 
下载免费PDF全文
下载免费PDF全文 Estelle Leroux Marina Rabineau Daniel Aslanian Christian Gorini Stéphane Molliex Francois Bache Cécile Robin Laurence Droz Maryline Moulin Jeffrey Poort Jean‐Loup Rubino Jean‐Pierre Suc 《Basin Research》2017,29(3):305-339
Basin‐wide correlation of Messinian units and Plio‐Quaternary chronostratigraphic markers (5.3 Ma, 2.6 Ma, 0.9 Ma and 0.45 Ma), the mapping of total sediment thickness and the determination of overall sedimentary volumes enabled us to provide a high‐resolution quantitative history of sediment volumes for the last 6 Ma along the Gulf of Lions margin. The results point to (i) a dramatic increase in terrigenous sediment input during the Messinian Salinity Crisis. This increased sedimentation reflects enhanced regional fluvial erosion related to the dramatic fall of Mediterranean base‐level. Stronger weathering due to a regional wetter climate probably also increased erosional fluxes. (ii) A sediment input three times higher during the Plio‐Quaternary compared to the Miocene seems in agreement with published measurements from World's ocean. However, the timing of this increase being uncertain, it implies that the trigger(s) also remain(s) uncertain. (iii) A decrease in detrital volume around 2.6 Ma is attributed to a regional change in the drainage pattern of rivers in the northwestern Alps. (iv) This study also highlights the Mid‐Pleistocene Revolution around 0.9 Ma, which resulted in an almost doubling of sediment input in the Provencal Basin. 相似文献
16.
Analytical Procedures for the Measurement of Boron Isotope Compositions by Ion Microprobe in Meteorites and Mantle Rocks 总被引：3，自引：1，他引：3
Marc Chaussidon François Robert Denis Mangin Pascal Hanon Estelle F. Rose 《Geostandards and Geoanalytical Research》1997,21(1):7-17
An analytical procedure has been developed to measure in situ the 11 B/10 B ratio in terrestrial basaltic rocks and meteoritic chondrules having B concentration of less than 1 μg g?1 using a small radius ims3f ion microprobe. The central difficulties for these measurements are (i) the removal of the trace amount of B contamination introduced in the sample during polishing, (ii) the precise calibration of instrumental mass fractionation of B isotopes and (iii) the low count rates of 10 B and 11 B. Contamination experiments conducted with isotopically labelled B enriched in 10 B showed that ultrasonic cleaning in bi-distilled water (< 1 ng g?1 B) and pre-sputtering of the analysed area decrease B contamination to the level of 0.01 μg g?1. Analyses of isotope standards spanning a range of 11 B/10 B between 3.93 and 4.20 showed that instrumental mass fractionation was constant within? during one session of analyses. Repeated analyses of a standard glass showed a reproducibility of instrumental mass fractionation between February 1991 and October 1996 of 1.3. Taking into account all sources of error, boron isotope measurements are accurate to within 5 for meteoritic samples having B contents in the range 0.1 to 1 μg g?1. A slightly better accuracy of 1.5 can be achieved for basaltic glasses which can be sputtered with very intense primary beams. 相似文献
17.
Estelle Auzanneau M. W. Schmidt D. Vielzeuf J. A. D Connolly 《Contributions to Mineralogy and Petrology》2010,159(1):1-24
Phengite chemistry has been investigated in experiments on a natural SiO2–TiO2-saturated greywacke and a natural SiO2–TiO2–Al2SiO5-saturated pelite, at 1.5–8.0 GPa and 800–1,050°C. High Ti-contents (0.3–3.7 wt %), Ti-enrichment with temperature, and a
strong inverse correlation of Ti-content with pressure are the important features of both experimental series. The changes
in composition with pressure result from the Tschermak substitution (Si + R2+ = AlIV + AlVI) coupled with the substitution: AlVI + Si = Ti + AlIV. The latter exchange is best described using the end-member Ti-phengite (KMgTi[Si3Al]O10(OH)2, TiP). In the rutile-quartz/coesite saturated experiments, the aluminoceladonite component increases with pressure while
the muscovite, paragonite and Ti-phengite components decrease. A thermodynamic model combining data obtained in this and previous
experimental studies are derived to use the equilibrium MgCel + Rt = TiP + Cs/Qz as a thermobarometer in felsic and basic
rocks. Phengite, rutile and quartz/coesite are common phases in HT-(U)HP metamorphic rocks, and are often preserved from regression
by entrapment in zircon or garnet, thus providing an opportunity to determine the T–P conditions of crystallization of these rocks. Two applications on natural examples (Sulu belt and Kokchetav massif) are presented
and discussed. This study demonstrates that Ti is a significant constituent of phengites that could have significant effects
on phase relationships and melting rates with decreasing P or increasing T in the continental crust. 相似文献
18.
Estelle Turpin Christa Fittschen Alexandre Tomas Pascal Devolder 《Journal of Atmospheric Chemistry》2003,46(1):1-13
We have determined the 2-oxo-propyl CH3C(O)CH2 (sometimes called 1-methylvinoxy or acetonyl) radical yield for the reaction of acetone with OH radical relative to the 2-oxo-propyl yields for the reactions of F- and Cl atoms with acetone using the Discharge Flow technique. The 2-oxo-propyl radical has been monitored by Laser Induced Fluorescence LIF at short reaction times in the systems: OH + acetone (R1), F + acetone (R2), and Cl + acetone (R3). From these measurements we have deduced the branching ratio for the 2-oxo-propyl radical formation in the title reaction to be in the range 0.8 R 1. 相似文献
19.
Shear modulus and damping ratio of grouted sand 总被引：2，自引：0，他引：2
Estelle Delfosse-Ribay Irini Djeran-Maigre Richard Cabrillac Daniel Gouvenot 《Soil Dynamics and Earthquake Engineering》2004,24(6):461-471
An experimental comparative study of three different grouted sands in terms of their effects on the values of two dynamic properties is presented. The dynamic properties studied are the shear modulus and the damping ratio which are determined with resonant column tests and cyclic triaxial tests. The behaviour of a pure Fontainebleau sand is compared with the behaviour of a Fontainebleau sand grouted with a silicate grout, a micro-fine cement grout and a mineral grout. The effects of the grouting treatment, the type of grout, the confining pressure, and the strains, on the shear modulus and the damping ratio are studied. The test results have shown that grouting improves the stiffness of the sand especially for small strains. Whatever the type of material, confining stress improves the shear modulus whereas it has a negligible effect on the damping ratio. When strain increases, the shear modulus decreases and the damping ratio increases. 相似文献
20.
Jacq Kévin Ployon Estelle Rapuc William Blanchet Claire Pignol Cécile Coquin Didier Fanget Bernard 《Journal of Paleolimnology》2021,66(3):249-260
Journal of Paleolimnology - Images of sediment cores are often acquired to preserve primary color information, before such profiles are altered by subsequent sampling and destructive analyses. In... 相似文献