On the number of central configurations in the N-body problem     

Jaume Llibre 《Celestial Mechanics and Dynamical Astronomy》1990,50(1):89-96

Central configurations are critical points of the potential function of the n-body problem restricted to the topological sphere where the moment of inertia is equal to constant. For a given set of positive masses m ₁,..., m _n we denote by N(m ₁, ..., m _n, k) the number of central configurations' of the n-body problem in ^k modulus dilatations and rotations. If m _{n 1},..., m _n, k) is finite, then we give a bound of N(m ₁,..., m _n, k) which only depends of n and k.  相似文献   

On the restrited three-body problem when the mass parameter is small     

Jaume Llibre 《Celestial Mechanics and Dynamical Astronomy》1982,28(1-2):83-105

We study some aspects of the restricted three-body problem when the mass parameter is sufficiently small. First, we describe the global flow of the two-body rotating problem, =0, and we use it for the analysis of the collision and parabolic orbits when 0. Also we show that for any fixed value of the Jacobian constant and for any >0, there exists a ₀>0 such that if the mass parameter [0,₀], then the set of bounded orbits which are not contained in the closure of the set of symmetric periodic orbits has Lebesgue measure less than .Paper presented at the 1981 Oberwolfach Conference on Mathematical Methods in Celestial Mechanics.  相似文献   

Electrical resistivity model of the crust and upper mantle from a magnetotelluric survey through the central Pyrenees   总被引：2，自引：0，他引：2  

Jaume Pous  Juanjo Ledo  Alex Marcuello  Marc Daignières 《Geophysical Journal International》1995,121(3):750-762

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Escaped introduced sea bass (Dicentrarchus labrax) infected by Sphaerospora testicularis (Myxozoa) reach maturity in coastal habitats off Canary Islands     

Kilian Toledo‐Guedes  Pablo Sanchez‐Jerez  Jaume Mora‐Vidal  Dominique Girard  Alberto Brito 《Marine Ecology》2012,33(1):26-31

Aquaculture activities have introduced European sea bass (Dicentrarchus labrax) along the coasts of some of the Canary Islands. We present the first record of simultaneous male and female gonad maturation of escaped sea bass in the wild, indicating that this species is finding its essential fish habitat (EFH). Individuals with ripe gonads were only caught during January and February 2009, although the maturation and spawning season may last from November to February in the studied area (Tenerife island). Bass infected by Sphaerospora testicularis were found and the incidence of the parasite was checked. This represents the southernmost record of the parasite, probably introduced together with sea bass stock. The results are discussed from the point of view of risk assessment and the ecology of invasions being valuable for aquaculture management in Central North Atlantic and Mediterranean areas.  相似文献   

Modelling Gravitational Instabilities: Slab Break–off and Rayleigh–Taylor Diapirism     

Sergio Zlotnik  Manel Fernández  Pedro Díez  Jaume Vergés 《Pure and Applied Geophysics》2008,165(8):1491-1510

A non-standard new code to solve multiphase viscous thermo–mechanical problems applied to geophysics is presented. Two numerical methodologies employed in the code are described: A level set technique to track the position of the materials and an enrichment of the solution to allow the strain rate to be discontinuous across the interface. These techniques have low computational cost and can be used in standard desktop PCs. Examples of phase tracking with level set are presented in two and three dimensions to study slab detachment in subduction processes and Rayleigh–Taylor instabilities, respectively. The modelling of slab detachment processes includes realistic rheology with viscosity depending on temperature, pressure and strain rate; shear and adiabatic heating mechanisms; density including mineral phase changes and varying thermal conductivity. Detachment models show a first prolonged period of thermal diffusion until a fast necking of the subducting slab results in the break–off. The influence of several numerical and physical parameters on the detachment process is analyzed: The shear heating exerts a major influence accelerating the detachment process, reducing the onset time to one half and lubricating the sinking of the detached slab. The adiabatic heating term acts as a thermal stabilizer. If the mantle temperature follows an adiabatic gradient, neglecting this heating term must be included, otherwise all temperature contrasts are overestimated. As expected, the phase change at 410 km depth (olivine–spinel transition) facilitates the detachment process due to the increase in negative buoyancy. Finally, simple plume simulations are used to show how the presented numerical methodologies can be extended to three dimensions.  相似文献   

Three- and four-term approximate expansions of the Haverkamp formulation to estimate soil hydraulic properties from disc infiltrometer measurements     

David Moret-Fernández  Borja Latorre  Maria V. López  Yolanda Pueyo  Laurent Lassabatere  Rafael Angulo-Jaramilo  Mehdi Rahmati  Jaume Tormo  José M. Nicolau 《水文研究》2020,34(26):5543-5556

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Stratigraphic framework of the thrust geometry and structural inversion in the southeastern Pyrenees : La Garrotxa area     

Albert Martinez  Jaume Vergés  Eduard Clavell  John Kennedy 《Geodinamica Acta》2013,26(3):185-194

Abstract

The structure of la Garrotxa area within the Cadi unit (south-eastern Pyrenees) consists of a set of duplexes at different scales which repeat the different carbonatic litho-units of the Lower and Middle Eocene. These duplexes are folded by antiformal stacks structures with basement rocks in their cores. The north boundary of these antiformal stacks represents an inversion of pre-existent extensional faults which formed half-graben geometries. The basement rocks involved in the structure represent short-cuts formed in the footwall of the extensional faults. All thrusts of La Garrotxa area branch with the upper Garrotxa thrust. The more complex structure of La Garrotxa area than the adjacent areas within the Cadí unit, is due to the initial complex synsedimentary geometry of the sedimentary pile.

The Cadi unit overlies the Serrat unit with a hangingwall ramp geometry. This unit was deduced from the Serrat-1 well, drilled in 1987. The Serrat unit is made up of a Middle Eocene evaporitic sequence, with alternating shales and anhydrites and a 100 meters thick salt layer close to the top. The total thickness of this evaporitic Beuda sequence is 1 000 meters. The Beuda sequence clearly controlled the thrust geometry of the younger thrusts.  相似文献   

Diagenetic evolution of lower Jurassic platform carbonates flanking the Tazoult salt wall (Central High Atlas,Morocco)     

Mar Moragas  Vinyet Baqués  Anna Travé  Juan Diego Martín-Martín  Eduard Saura  Gregoire Messager  David Hunt  Jaume Vergés 《Basin Research》2020,32(3):546-566

Platform carbonates diagenesis in salt basins could be complex due to potential alterations of fluids related and non-related to diapirism. This paper presents the diagenetic history of the Hettangian to Pliensbachian platform carbonates from the Tazoult salt wall area (central High Atlas, Morocco). Low structural relief and outcrop conditions allowed to define the entire diagenetic evolution occurred in the High Atlas diapiric basins since early stages of the diapiric activity up to their tectonic inversion. Precipitation of dolomite and calcite from both warmed marine-derived and meteoric fluids characterised diagenetic stages during Pliensbachian, when the carbonate platforms were exposed and karstified. Burial diagenesis occurred from Toarcian to Middle Jurassic, due to changes of salt-induced dynamic related to increase in siliciclastic input, fast diapir rise and rapid burial of Pliensbachian platforms. During this stage, the diapir acted as a physical barrier for fluid circulation between the core and the flanking sediments. In the carbonates and breccias flanking the structures, dolomite and calcite precipitated from basinal brines, whereas carbonate slivers located in the core of the structure, were affected by the circulation of Mn-rich fluids. The final diagenetic event is characterised by the income of meteoric fluids into the system during uplift caused by Alpine orogeny. These results highlight the relevant influence of diapirism on the diagenetic modifications in salt-related basins in terms of diagenetic events and involved fluids.  相似文献   

Magnetostratigraphic and cyclostratigraphic calibration of a prospective Palaeocene/Eocene stratotype at Zumaia (Basque Basin, northern Spain)     

Jaume Dinarès-Turell  Juan Ignacio Baceta  Victoriano Pujalte  Xabier Orue-Etxebarria  Gilen Bernaola 《地学学报》2002,14(5):371-378

ABSTRACT Detailed magnetostratigraphic work at the Palaeocene/Eocene boundary interval in the Zumaia section has led to a precise delineation of the position of polarity Chron C25n from −35.0 m (or −35.7 m) to −25.2 m below the base of the Carbon Isotopic Excursion that marks the Palaeocene/Eocene boundary. This chronostratigraphic constraint suggests that the lithological carbonate–marl couplets making up most of the studied section are the expression of orbital precession cycles, and confirms the expanded and continuous nature of the section, with mean sediment accumulation rates of ∼ 2.5 cm kyr⁻¹. The new data render Zumaia a unique land-based marine section with available magnetostratigraphic data coupled to cyclostratigraphy. The revised chronostratigraphic framework presented supports previous cyclostratigraphic calibration of the latest Palaeocene geomagnetic timescale; it should facilitate better assessment of the different chemobiostratigraphic events that span this critical interval as a consequence of past climate and oceanographic change. Consequently, the Zumaia section is proposed as a candidate Global Stratotype Section and Point (GSSP) for the Palaeocene/Eocene boundary.  相似文献   

Effects of anisotropy on the two-dimensional inversion procedure     

Wiebke Heise  Jaume Pous 《Geophysical Journal International》2001,147(3):610-621

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