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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Climate Warming, Wildfire Hazard, and Wildfire Occurrence in Coastal Eastern Spain   总被引：25，自引：0，他引：25  

Josep Piñol  Jaume Terradas  Francisco Lloret 《Climatic change》1998,38(3):345-357

A climatic series (1941 to 1994) from a Mediterranean locality of NE Spain was used to calculate two wildfire hazard indices based on daily meteorological data. Both fire hazard indices increased over this period, as a consequence of increasing mean daily maximum temperature and decreasing minimum daily relative humidity. These trends were observed in both mean values of the indices and in the number of very high risk days. Annual data on the number of wildfires and burned area also show an increase from 1968 to 1994, and are significantly correlated with both fire hazard indices. Although other non-meteorological causes (e.g., human activities, fuel accumulation) have likely contributed to the observed increase of wildfires, an effect of climatic warming on wildfire occurrence is supported by this relationship.  相似文献   

Impacts of Tourism Development on Water Demand and Beach Degradation on the Island of Mallorca (Spain)   总被引：4，自引：0，他引：4  

Celso Garcia  Jaume Servera 《Geografiska Annaler: Series A, Physical Geography》2003,85(3-4):287-300

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Untangling the Palaeocene climatic rhythm: an astronomically calibrated Early Palaeocene magnetostratigraphy and biostratigraphy at Zumaia (Basque basin, northern Spain)     

Jaume Dinarès-Turell  Juan Ignacio Baceta  Xabier Orue-Etxebarria  Stefano Lorito 《Earth and Planetary Science Letters》2003,216(4):483-500

The magnetostratigraphy of a 54-m-long section above the Cretaceous-Tertiary boundary at the sea-cliff section of Zumaia in the Basque basin (northern Spain) has been established. The section encompasses the entire Danian and the lower part of the Selandian stages as indicated by calcareous plankton biostratigraphy. The studied interval consists of (hemi)pelagic limestone-marl alternations in the form of couplets and bundles, which range from centimetre/decimetre to metre scale respectively and a few thin-bedded calcareous turbidites. The magnetostratigraphy, based on samples from about 200 stratigraphic levels, allows the identification of six reversal boundaries from chron C29r to C26r at a bed level. The spatial (or temporal) evolution of periodicities from a lithologically coded series is studied with the continuous wavelet transform technique. A preliminary age model based on the standard CK95 GPTS indicates that the basic lithologic carbonate-marl couplet corresponds to the 19-23-kyr precession cycle (21-31-cm cycle in the depth domain) and that a bundle cycle (usually groups of four to six basic couplets) with global periodicity centred at 1.22 m corresponds to the ∼110-kyr eccentricity cycle. We have tuned the bundle cycles to the Va03_R7 eccentricity orbital solution [Astrophys. J. 592 (2003) 620-630] following an initial match of a node of the ∼2.4-Ma eccentricity modulatory cycle in the target time series to particularly carbonate-rich bundles from the upper part of the Zumaia section that displays significant power of a 4.4-m-period cycle corresponding to the ∼404-kyr eccentricity cycle. Consistency between lithologic patterns and characteristics in the eccentricity target is reasonably met although the ∼404-kyr eccentricity cycle is not persistent throughout. The tuning, however, appears robust as it brings the age of the K/T boundary at ∼65.8 Ma. It is argued that a sea-level signal (tectonically driven?) is superimposed on the climatic forcing at the Milankovitch band masking the full expression of the low-frequency astronomical periods. We provide a cycle-tuned duration for all intervening Early Palaeocene polarity chrons and estimate relative ages for bioevents. The cycle-tuned chronology indicates that the CK95 GPTS overestimates the duration of chrons C28 and C27 by 20 and 26% respectively. Our data may prove useful to better constrain Early Palaeocene biostratigraphy of calcareous plankton and in the redefinition of the boundary between the Danian and Selandian stages.  相似文献   

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   

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   

A modified Archie’s law for two conducting phases     

Paul W.J. Glover  Malcolm J. Hole  Jaume Pous 《Earth and Planetary Science Letters》2000,180(3-4):369-383

Many types of mixing model are used widely within the earth sciences to determine the electrical properties of porous media consisting of solid and fluid phases of known conductivities, volume fractions and distributions (i.e. phase connectivities). Most models are valid for two or more conducting phases. However, of the simple models only Archie’s law includes a variable term, the Archie cementation exponent m, that describes the connectivity of the phases. Unfortunately, Archie’s law is only valid for one conducting phase distributed within a non-conducting phase, which makes it inapplicable in instances where the rock matrix has a significant conductivity such as for clay-rich rocks and in calculations involving partial melting. More complex models exist which account for multiple conducting phases and control over phase conductivity. We have adapted the conventional Archie’s law to produce a simple modified Archie’s law that can be used with two conducting phases of any conductivity and any volume fraction, while retaining the ability to model variable connectivities within those phases that result from variations in their distribution. The modified model has two exponents (m and p) that describe the connectivity of each of the two phases. The exponents are related through an equation that depends also on the volume fractions of the two phases. The modified and the conventional versions of Archie’s law have been tested on a granular analogue porous medium with a conducting matrix and a pore space saturated with a range of saline fluids with different salinities and conductivities. The new model describes the experimentally determined electrical behaviour of the system extremely well, improving greatly on the conventional Archie’s law.  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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