Showing papers by "Pierre-and-Marie-Curie University published in 1984"
TL;DR: On resout des equations differentielles stochastiques a conditions aux limites reflechissantes par une approche directe basee sur le probleme de Skorokhod as discussed by the authors.
Abstract: On resout des equations differentielles stochastiques a conditions aux limites reflechissantes par une approche directe basee sur le probleme de Skorokhod
896 citations
TL;DR: In this article, a new condition on g, called W 1,p-quasiconvexity is introduced which generalizes in a natural way the quasiconvxity condition of C. B. Morrey, it being shown in particular necessary for sequential weak lower semicontinuity of I Ω and for the existence of minimizers for certain related integrals.
497 citations
TL;DR: In this article, the Western Mediterranean Sea is explained as a marginal basin, generated by a N-NW subduction of the African-Apulian plates beneath the European plate.
397 citations
365 citations
TL;DR: In this article, a three dimensional model of elastic periodic plate when the thickness e of the plate and the size ω of the periods are small is studied and convergence proof is carried out.
Abstract: This paper is devoted to the study of a three dimensional model of elastic periodic plate when the thickness e of the plate and the size ω of the periods are small. In the three studied limits (e 0 then ω 0), (ω 0 then e 0) and lately (e and ω 0 together) the three dimensional equation of elasticity are approached by the two dimensional general equations of a linear anisotropic plate, the stretching and bending being coupled. This study points out the importance of the ratio of the two small parameters, indeed the moduli occuring in the two dimensional equations are different in the three limits. In each case a convergence proof is carried out.
332 citations
TL;DR: The results indicate that 5-HT1 receptors are heterogeneous, and that [3H]PAT recognizes only a 5-ht1 subclass (called 5- HT1A).
267 citations
TL;DR: In this paper, the authors present and compare algorithms for computing joins and semijoins of relations in a multiprocessor database machine, and compare the performance of these algorithms.
Abstract: This paper presents and analyzes algorithms for computing joins and semijoins of relations in a multiprocessor database machine. First, a model of the multiprocessor architecture is described, incorporating parameters defining I/O, CPU, and message transmission times that permit calculation of the execution times of these algorithms. Then, three join algorithms are presented and compared. It is shown that, for a given configuration, each algorithm has an application domain defined by the characteristics of the operand and result relations. Since a semijoin operator is useful for decreasing I/O and transmission times in a multiprocessor system, we present and compare two equi-semijoin algorithms and one non-equi-semijoin algorithm. The execution times of these algorithms are generally linearly proportional to the size of the operand and result relations, and inversely proportional to the number of processors. We then compare a method which consists of joining two relations to a method whereby one joins their semijoins. Finally, it is shown that the latter method, using semijoins, is generally better. The various algorithms presented are implemented in the SABRE database system; an evaluation model selects the best algorithm for performing a join according to the results presented here. A first version of the SABRE system is currently operational at INRIA.
256 citations
TL;DR: In this paper, the natural isotopic composition of suspended particulate organic nitrogen was determined in the Southern Bight of the North Sea and in the Scheldt estuary and these data show that δ 15 N constitutes a convenient tracer of the origin of the suspended matter.
235 citations
TL;DR: In this paper, the authors show that wave front discontinuities (critical or stopping phases) are radiated every time an isochrone becomes tangent to a barrier, leading to what they call the critical ray approximation which is given in a closed form.
Abstract: We study high-frequency radiation from a dislocation model of rupture propagation at the earthquake source. We demonstrate that in this case all the radiation emanates from the rupture front and, by a change of variables, that at any instant of time the high-frequency waves reaching an observer come from a line on the fault plane that we call isochrone. An asymptotic approximation to near-source velocity and acceleration is obtained that involves a simple integration along the isochrones for every time step. It is shown that wave front discontinuities (critical or stopping phases) are radiated every time an isochrone becomes tangent to a barrier. This leads to what we call the critical ray approximation which is given in a closed form. The previous results are compared with discrete wavenumber synthetics obtained by Bouchon (1982) for the Gilroy 6 recording of the Coyote Lake earthquake of 1980. The fit between the asymptotic and full numerical method is extremely good. The critical ray approximation permits the identification of different phases in Bouchon's synthetics and the prediction of the behavior of the signal in the vicinity of their arrival time.
197 citations
TL;DR: Regional quantitative analysis performed in this study did not show significant differences in the percentage of either kind of synapses in the various striatal regions, however, regional Differences in the synaptic organization might explain the divergent data.
174 citations
TL;DR: In this article, the internal motion of a small element of fluid in inviscid and incompressible flows by neglecting the actions of the other elements which constitutes the whole fluid is studied.
Abstract: We look at the internal motion of a small element of fluid in inviscid and incompressible flows by neglecting the actions of the other elements which constitutes the whole fluid. This free motion of the elements leads, in a finite time, to the divergence of the velocity field in the element and to its flattening in a plane.
TL;DR: Electrophoresis on sodium dodecyl sulfate/polyacrylamide gel showed that the protein is homogeneous and has an apparent molecular weight of 9000 +/- 1000, in agreement with the value calculated from the amino acid composition.
Abstract: A phospholipid transfer protein has been purified 195-fold from an extract of spinach leaves. This protein is capable of transferring phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol and phosphatidyl-ethanolamine from liposomes to mitochondria. In addition to this protein, a minor part of the total activity was associated with a less purified fraction.
The pure protein has an isoelectric point of 9.0 ± 0.2 determined by a chromatofocusing technique. Electrophoresis on sodium dodecyl sulfate/polyacrylamide gel showed that the protein is homogeneous and has an apparent molecular weight of 9000 ± 1000, in agreement with the value (8832) calculated from the amino acid composition. This composition is characterized by a high amount of alanine and glycine and by the absence of phenylalanine, whereas arginine, glutamine, histidine and methionine are minor components.
The spinach protein is also able to transfer phosphatidylcholine and phosphatidylglycerol from liposomes to intact chloroplasts. This observation reinforces the hypothesis that plastid phospholipids are partly imported from outside the organelle by a transfer process.
TL;DR: In this paper, the main question was to relate Prim U(g) with the Springer correspondence, and a partial solution to (iii) was given in [21] sufficient, e.g., to treat g of type A.
TL;DR: It is shown how one can apply a lemma of Kushner and Clark to obtain properties of stochastic algorithms, including algorithms considered by Ljung as well as algorithms of the form \theta_{n+1} = \theTA_{n} - \gamma_{n-1} V_{n +1}(\theta_n, Z) , where Z is a stationary ergodic process.
Abstract: Two general classes of stochastic algorithms are considered, including algorithms considered by Ljung as well as algorithms of the form \theta_{n+1} = \theta_{n} - \gamma_{n+1} V_{n+1}(\theta_{n}, Z) , where Z is a stationary ergodic process. It is shown how one can apply a lemma of Kushner and Clark to obtain properties of these algorithms. This is done by using in particular Martingale arguments in the generalized Ljung case. In these various situations the convergence is obtained by the method of the associated ordinary differential equation, under the classical boundedness assumptions. In the case of linear algorithms, the boundedness assumptions are dropped.
TL;DR: In this paper, the existence of a metrique d'Einstein-Kahler on a variete Kahlerienne compacte a lere classe de Chern positive (C 1 > 0) is investigated.
TL;DR: In this paper, the authors examined the sedimentation rate, the clarification and the height of the sedimented bed in connection with some operative conditions (stirring), some physicochemical measurements (adsorption isotherms, electrokinetic potential), and the characteristics of the flocculant (M w, cationicity).
TL;DR: Evidence that the substantia nigra pars reticulata influences the responsiveness of these cells to their peripheral sensory inputs suggests that the basal ganglia and in particular the SNr are involved in the integrative sensorimotor processes underlying head orienting movements.
Abstract: We have established in previous electrophysiological studies that the substantia nigra pars reticulata (SNr) exerts a potent inhibitory influence on cells located in the intermediate and deep tectal strata. The present study demonstrates that, in the rat, the tectospinal neurons constitute one of the cellular populations of the tectum on which the SN exerts its influence.
TL;DR: In this article, the presence of argon (≃ 1%) in purified air samples may, in some circumstances, modify the apparent isotope ratio of atmospheric N2, which seems to be essentially an instrumental, presumably pressure-related, effect.
Abstract: Small differences in natural isotope ratios between two compounds can be measured easily and with high precision by using mass spectrometers fitted with double (or triple) ion collectors and dual inlet systems equipped for rapid switching between reference and sample1–3. The parameter used to describe these differences in natural 15N abundance is: where R is the isotopic ratio of m/z = 29(14N15N+) to m/z = 28(14N14N+). Although an international standard for nitrogen has not yet been defined, atmospheric N2 had been chosen through practical experience, even before the worldwide homogeneity of its isotopic composition was demonstrated4–7. However, the presence of argon (≃1%) in purified air samples may, in some circumstances, modify the apparent isotope ratio of atmospheric N2. Two different mass spectrometers in our laboratory have been used to assess the magnitude of this ‘argon effect’, which seems to be essentially an instrumental, presumably pressure-related, effect. Therefore, on mass spectrometers showing this argon effect it is imperative that a correction be applied to measurements of δ15N of atmospheric N2. However, in some circumstances (different mass spectrometers, different tuning of the same instrument) this effect can be non-existent or negligible and might require no correction whatsoever.
TL;DR: A transition to a new form of ice occurs at 44 GPa as discussed by the authors, which is the tenth known solid form of O and may be the expected "symmetric-ice" structure.
Abstract: ${\mathrm{H}}_{2}$O at 300 K has been studied up to 67 GPa by Brillouin scattering. A transition to a new form of ice occurs at 44 GPa. This is the tenth known solid form of ${\mathrm{H}}_{2}$O and may be the expected "symmetric-ice" structure.
TL;DR: In this paper, the chemical shift of xenon adsorbed in a zeolite is related to the st.129 Xe can be used as a probe for determining zeolites properties.
TL;DR: The importance of noradrenaline in the control of the level of the uncoupling protein responsible for the high thermogenic capacity of brown adipose tissue mitochondria was examined in this article.
TL;DR: The electrophysiological study established that the thalamic nuclei medio-dorsal/central-lateral, paracentral, ventral-medial and the zona incerta receive ascending collaterals of the tecto-spinal neurons.
01 Jan 1984
TL;DR: It was studies of this type that showed the important role of the midgut epithelium in ionic regulation and mineral accumulation in insects belonging to several different orders.
Abstract: Within the digestive tract, the ingested food is broken down into simpler molecules by the action of enzymes and thus rendered absorbable through the gut wall. The midgut is composed of a long straight tube which often contains blind pouches (caeca). It is the main site of production of digestive enzymes and of absorption. In many insect species, it secretes a peritrophic membrane which is permeable to the digestive enzymes and to the products of digestion. In most insects, the structure of the midgut seems to be rather uniform, and thus the same cells are both secretory and absorptive. However, ultrastructural and cytochemical studies have shown a variety of differences which are related sometimes to cycles of cellular activities. In other cases, the midgut exhibits a clear division into functional segments or a mixture of different kinds of specialized cells may be present. Physiological experiments combined with ultrastructural and cytochemical investigations have sometimes clearly established the functions of these segments, or cells. It was studies of this type that showed the important role of the midgut epithelium in ionic regulation and mineral accumulation in insects belonging to several different orders. The transfer of fluid and ions through the wall of the midgut sometimes leads to curious arrangements that bring into contact a midgut segment with the Malpighian tubules, and concurrently certain specialized gut cells lose their digestive function in order to undertake an absorptive role.
TL;DR: The increase in mitochondrial uncoupling protein in brown adipose tissue during acute stimulation by exposure of animals to cold was examined and use of a cDNA probe shows that synthesis of uncoupled protein mRNA was quickly stimulated.
TL;DR: Findings in nuclear extracts of concanavalin A‐stimulated lymphocytes suggest a major role of topoisomerase II in DNA replication, together with the previous results on regenerating rat liver, suggest a big role for this enzyme inDNA replication.
TL;DR: In this paper, the authors investigated the algebras of the non-local charges and their generating functionals (the monodromy matrices) in classical and quantum non-linear σ models.
Abstract: We investigate the algebras of the non-local charges and their generating functionals (the monodromy matrices) in classical and quantum non-linear σ models. In the case of the classical chiral σ models it turns out that there exists no definition of the Poisson bracket of two monodromy matrices satisfying antisymmetry and the Jacobi identity. Thus, the classical non-local charges do not generate a Lie algebra. In the case of the quantum O(N) non-linear σ model, we explicitly determine the conserved quantum monodromy operator from a factorization principle together withP,T, and O(N) invariance. We give closed expressions for its matrix elements between asymptotic states in terms of the known two-particleS-matrix. The quantumR-matrix of the model is found. The quantum non-local charges obey a quadratic Lie algebra governed by a Yang-Baxter equation.
TL;DR: In this article, the intrinsic viscosities of cationic polyelectrolytes with a large range of compositions by the redox polymerization and copolymerization of acrylamide and aminoethyl chloride acrylate were determined by light scattering, and empirical laws between viscosity, composition in comonomers, molecular weight and ionic strength.
TL;DR: In this paper, a study of 1130 aftershocks of the 1980 Campania-Lucania earthquake is presented, where the authors use upward traveling rays to find a well-constrained fault plane solution.
Abstract: The result of a study of 1130 aftershocks of the 1980 Campania-Lucania earthquake are presented. The data were collected primarily with a dense array of portable smoked-drum seismographs deployed in the epicentral region a few days after the main shock. Tests performed on subsets of the data to establish the location accuracy are described in detail, and epicentral maps and cross-sections are presented and discussed. One hundred and sixty well-constrained fault plane solutions using upward traveling rays are presented. The distribution of aftershocks forms an elongate cloud which does not define a plane. This is not because the events are poorly located. A subset of events located with epicentral errors of less than 1 km and depth errors less than 2 km forms a similar cloud to the complete aftershock set. The aftershock mechanisms are very varied. Some are similar to the main event but many differ profoundly. These include events on shallow or vertical planes and thrust events. The latter include some events which require contraction in the direction in which the main event indicates extension. The aftershocks of all mechanisms are intermixed in space in such a way that no simple system of faults can explain them. A model to explain the aftershocks and the lack of surface ruptures in the main event is offered. It is proposed that the main shock cuts between two aseismic detachment surfaces and that the aftershocks are a consequence of the complicated deformation that such a geometry demands. Whatever interpretation is adopted, the results are a challenge to the commonly accepted view that aftershocks even approximately define simple fault planes or that aftershock mechanisms replicate the mechanism of the main shock. Defects in interpretations of the main shock and aftershocks process arise largely from a lack of information about the geometry of structures at depth in the epicentral region. Suitable deep reflection profiles could help to resolve this problem.
TL;DR: On etudie l'existence des solutions T-periodiques (TER,T>0) du systeme hamiltonien suivant: z=gH'(z)+f(t), ou g est la matrice asymetrique standard as discussed by the authors.
Abstract: On etudie l'existence des solutions T-periodiques (TER,T>0) du systeme hamiltonien suivant: z=gH'(z)+f(t), ou g est la matrice asymetrique standard
TL;DR: In this paper, it was shown that if a locally compact group G acts simplicially on a tree in such a way that the stabilizers of the vertices are amenable, then G is K-amenable.