Verbreitung einiger B-Vitamine in Kleingewässern aus der Umgebung von Bern und Untersuchungen über die Abgabe von B-Vitaminen durch Algen     

H. Clémençon 《Aquatic Sciences - Research Across Boundaries》1963,25(2):157-165

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Kolmogorov entropy as a measure of disorder in some non-integrable Hamiltonian systems     

R. Gonczi  Ch. Froeschlé  Cl. Froeschlé 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):117-124

This paper is devoted to study the stochastic behaviour of some Hamiltonian systems with closed velocity curves. We investigate Hamiltonians already studied by Ali and Somorjai (1). These authors, by discussing Poincaré's surfaces of section for several energy values, gave a qualitative evaluation of the stochasticity of the systems.Here we present a quantitative study of this stochastic behaviour. For each energy we compute the Lyapunov characteristic exponents of fifty orbits chosen at random, in order to calculate the Kolmogorov entropy by Pesin's formula. Our results are in agreement with those of Ali and Somorjai: the disorder does not increase monotonically with increasing energy. However, we find that the largest entropy does not necessarily correspond to the maximum of the stochastic volume. The Kolmogorov entropy thus appears to be a good measure of the degree of disorder of dynamical systems.  相似文献   

Thrust sheet motion and earthquake mechanisms     

J.Cl. De Bremaecker 《Earth and Planetary Science Letters》1987,83(1-4)

The mechanism of thrust sheet motion and that of earthquake generation are two aspects of the same phenomenon. Studies of earthquake mechanisms show that only a part of the thrust fault, generally less than 10km in length, is in motion at any given instant; this part sweeps the length of the fault, moving at approximately 3 km/s. Since shear fracture propagation is inherently a dynamic phenomenon, it cannot be understood on the basis of the equations of static equilibrium. The previously proposed mechanisms all rest on such an equilibrium, which necessarily implies that the motion of a thrust sheet occurs simultaneously over its whole length; since the latter may exceed 100 km, the motion becomes a mechanical “enigma”. This enigma vanishes once the dynamic nature of the problem is recognized. The proposed mechanism also suggests that solution features on the fault result from the dissolution of barriers, thus explaining the motion of only part of a thrust sheet.  相似文献   

The lead isotope geochemistry and geochronology of late-kinematic intrusives from the Abitibi greenstone belt,and the implications for late Archaean crustal evolution     

Clément Gariépy  Claude J Allègre 《Geochimica et cosmochimica acta》1985,49(11):2371-2383

Pb isotope abundances are reported for six late-kinematic granitoid intrusives from the Quebec sector of the Abitibi greenstone belt. Leaching experiments on K-feldspar separates reveal the presence of radiogenic Pb, attributed to in situ decay of U and Th. Pb-Pb mineral isochrons were constructed with the K-feldspar data plus results obtained on the total-rock, sphene, apatite and other mineral phases; five localities show no evidence of post-emplacement disturbance and yield ages ranging from 2616 ± 19 to 2718 ± 12 Ma. These ages, which are corroborated by U-Pb dating of small populations of sphene, imply that the orogenic events in the Abitibi belt were terminated 2700–2710 Ma ago, and followed by a period of granitization which lasted for 80 to 100 Ma.The initial Pb isotope composition of the magmas shows that their source regions were isotopically heterogeneous; the time integrated ${}^{238}\text{U}{}^{204}\text{Pb}$ values for the source regions vary from 7.62 to 7.92 and the K-feldspar data indicate that similar heterogeneities were present at the scale of a single intrusion. The range of isotopic composition spans the compositional domain of the mantle, defined by sulfides associated with komatiites and some galenas, and that of the continental crust, defined by sulfides associated with Abitibi iron-formations. Consequently, the granitoid magmas are interpreted as partial melts of a continental crust comprising juvenile, mantle-derived rocks and non-negligible amounts of earlier formed sialic material. The Pb isotope data for the latter are consistent with the presence in the area of 3.0 to 3.4 Ga old sialic crust. The episode of crustal anatexis occurred as a consequence to the orogenic events which resulted in burial of altered supracrustal rocks rich in water and heat-producing elements.  相似文献   

The First International Workshop on Warning Criteria for Active Slides: technical issues,problems and solutions for managing early warning systems   总被引：1，自引：0，他引：1  

Catherine Cloutier  Federico Agliardi  Giovanni Battista Crosta  Paolo Frattini  Corey Froese  Michel Jaboyedoff  Jacques Locat  Clément Michoud  Hideaki Marui 《Landslides》2015,12(1):205-212

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Landslide detection and monitoring capability of boat-based mobile laser scanning along Dieppe coastal cliffs,Normandy     

Clément Michoud  Dario Carrea  Stéphane Costa  Marc-Henri Derron  Michel Jaboyedoff  Christophe Delacourt  Olivier Maquaire  Pauline Letortu  Robert Davidson 《Landslides》2015,12(2):403-418

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Stability of Titanium Dioxide Nanoparticle Agglomerates in Transitional Waters and Their Effects Towards Plankton from Lagoon of Venice (Italy)     

Clémentine Perstrimaux  Séverine Le Faucheur  Monika Mortimer  Serge Stoll  Fabrizio Bernardi Aubry  Margherita Botter  Roberto Zonta  Vera I. Slaveykova 《Aquatic Geochemistry》2015,21(2-4):343-362

The present study explores the effect of salinity and dissolved organic carbon (DOC) gradients on the stability and reactivity of titanium dioxide nanoparticle (TiO₂-NP) agglomerates in ambient water from the Lagoon of Venice and their possible effect on nauplii sampled at the same locations. In all ambient water samples, TiO₂-NPs formed rapidly micrometre-sized agglomerates. The increase in the salinity and concomitant decrease in DOC content induced the formation of larger agglomerates, with z-average hydrodynamic diameter increasing with TiO₂-NP concentration and exposure duration. Under the studied conditions, ζ-potential exhibited negative values. In line with agglomeration results, enhancement of the salinity and lower DOC resulted in less negative ζ-potential with close to 0 values in the dispersions of 100 mg L^?1 TiO₂-NPs in sea water. Two-hour exposure to micrometre-sized agglomerates of TiO₂-NPs resulted in an increase in the fluorescence of propidium iodide (PI) stained nauplii in comparison with unexposed controls, but had no effect at 24-h exposure. The increase in nauplii-associated PI fluorescence was more noticeable in dispersions containing 100 mg L^?1 than those containing 10 mg L^?1 TiO₂-NPs, suggesting membrane permeability alteration in a concentration-dependent manner. However, the PI staining results have to be interpreted with caution because of the possible dye binding to the nauplii surface without penetration of cellular membrane. The effect of TiO₂-NPs on nauplii was more pronounced at higher salinity and decreased with increasing DOC concentrations at 2 h, while no trends were found at 24-h exposure, as well as exposure to 100 mg L^?1 TiO₂-NPs.  相似文献   

Fast Update of Conditional Simulation Ensembles     

Clément Chevalier  Xavier Emery  David Ginsbourger 《Mathematical Geosciences》2015,47(7):771-789

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Seasonal variations of surface duct conditions in Ngaoundere,North Cameroon     

Samuel Kaissassou  André Lenouo  Armand Nzeukou  Clément Tchawoua  D. A. Vondou 《Meteorology and Atmospheric Physics》2015,127(6):659-674

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The Lyapunov characteristic exponents-applications to celestial mechanics     

Cl. Froeschlé 《Celestial Mechanics and Dynamical Astronomy》1984,34(1-4):95-115

After a presentation of Lyapunov characteristic exponents (LCE) we recall their basic properties and numerical methods of computation. We review some numerical computations which are concerned with LCEs and mainly related to celestial mechanics problems.  相似文献