Showing papers by "Pierre-and-Marie-Curie University published in 1986"
TL;DR: In this paper, a characterization of compact sets in Lp (0, T; B) is given, where 1⩽P⩾∞ and B is a Banach space.
Abstract: A characterization of compact sets in Lp (0, T; B) is given, where 1⩽P⩾∞ and B is a Banach space. For the existence of solutions in nonlinear boundary value problems by the compactness method, the point is to obtain compactness in a space Lp (0,T; B) from estimates with values in some spaces X, Y or B where X⊂B⊂Y with compact imbedding X→B. Using the present characterization for this kind of situations, sufficient conditions for compactness are given with optimal parameters. As an example, it is proved that if {fn} is bounded in Lq(0,T; B) and in L
loc
1
(0, T; X) and if {∂fn/∂t} is bounded in L
loc
1
(0, T; Y) then {fn} is relatively compact in Lp(0,T; B), ∀p
3,681 citations
TL;DR: Whether anxiety reduction or increased impulsivity is more likely to account for animal behavioral changes associated with decreased serotonergic transmission is investigated, as well as the effects of manipulating central serotonin in experimental anxiety paradigms in animals (punishment, extinction, novelty).
Abstract: Animal research suggests that central serotonergic neurons are involved in behavioral suppression, particularly anxiety-related inhibition. The hypothesis linking decreased serotonin transmission to reduced anxiety as the mechanism in the anxiolytic activity of benzodiazepines conflicts with most clinical observations. Serotonin antagonists show no marked capacity to alleviate anxiety. On the other hand, clinical signs of reduced serotonergic transmission (low 5-HIAA levels in the cerebrospinal fluid) are frequently associated with aggressiveness, suicide attempts, and increased anxiety. The target article attempts to reconcile such human and animal findings by investigating whether anxiety reduction or increased impulsivity is more Likely to account for animal behavioral changes associated with decreased serotonergic transmission. The effects of manipulating central serotonin in experimental anxiety paradigms in animals (punishment, extinction, novelty) are reviewed and compared with the effects of antianxiety drugs. Anxiety seems neither necessary nor sufficient to induce control by serotonergic neurons on behavior. Further evidence suggests that behavioral effects of anxiolytics thought to be mediated by decreases in anxiety are not caused by the ability of these drugs to reduce serotonin transmission. Blockade of serotonin transmission, especially at the level of the substantia nigra, results in a shift of behavior toward facilitation of responding. This behavioral shift is particularly marked when there is competition between acting and restraining response tendencies and when obstacles prevent the immediate attainment of an anticipated reward. It is proposed that serotonergic neurons are involved not only in behavioral arousal but also in enabling the organism to arrange or tolerate delay before acting. Decreases in serotonin transmission seem to be associated with the increased performance of behaviors that are usually suppressed, though not necessarily because of the alleviation of anxiety, which might contribute to the suppression.
974 citations
TL;DR: Although pore formation is apparently involved in the toxicity of amphotericin B and nystatin, it is not the sole factor which contributes to cell death, since K+ leakage induced by these antibiotics is separate from their lethal action.
693 citations
TL;DR: In this paper, a canonical r - s matrix type approach for integrable two-dimensional models of non-ultralocal type is developed, where the L -matrices algebra and the monodromy matrices' algebras are given in terms of the usual r-matrix and of the new s -matrix.
277 citations
TL;DR: A theoretical modeling is proposed to predict the efficiency factors for attenuation, total scattering, and backscattering for spherical and homogeneous phytoplanktonic cells in suspension to evaluate the reliability of the model for algal cells of various indices and morphologies.
Abstract: A theoretical modeling is proposed to predict the efficiency factors for attenuation, total scattering, and backscattering for spherical and homogeneous phytoplanktonic cells in suspension. The input parameters of this modeling are the actual size distribution, the spectral values of absorption by the living cells, and an adjustable value of the real part of the refractive index. The variations in these parameters lead to very diverse spectral behavior of the efficiency factors. Theoretical predictions are compared to experimental results for some species to evaluate the reliability of the model for algal cells of various indices and morphologies.
274 citations
TL;DR: It is shown how such self-oriented hierarchies are always H -oriented provided they have a minimal number of levels which is determined by the value of p 0 and their stability is studied against increases in p 0 .
222 citations
TL;DR: In this article, the authors examined the system consisting of two quarks and two antiquarks with equal or unequal masses and showed that the virtual meson-meson components of the wave function can be solved by empirical or systematic variational methods.
Abstract: In the framework of simple non-relativistic potential models, we examine the system consisting of two quarks and two antiquarks with equal or unequal masses. We search for possible bound states below the threshold for the spontaneous dissociation into two mesons. We solve the four body problem by empirical or systematic variational methods and we include explicitly the virtual meson-meson components of the wave function. With standard twobody potentials, there is no proliferation of multiquarks. With unequal quark masses, we obtain however exotic\(\left( {\bar Q\bar Qqq} \right)\) bound states with a baryonic antidiquark-quark-quark structure very analogous to the heavy flavoured (Q′qq) baryons.
190 citations
TL;DR: It is hypothesize that β‐turns including the basic amino acids doublets, flanked by highly ordered secondary structures (either β‐sheet or α‐helix) may constitute a minimal requirement for the recognition by the endoproteases involved in the processing of these precursors.
172 citations
TL;DR: The electrostatic self-force acting on a point test charge in the space-time describing a static, cylindrically symmetric cosmic string is determined and a repulsive interaction is found.
Abstract: We determine the electrostatic self-force acting on a point test charge in the space-time describing a static, cylindrically symmetric cosmic string. We find a repulsive interaction.
167 citations
TL;DR: An infinite number of canonical representations for integrable classical field theories of non-ultralocal type are constructed from graded Kac-Moody algebras as mentioned in this paper.
165 citations
TL;DR: In this paper, a model of a confined atom in a self-consistent field has been developed to describe the high-density effects on atomic bound states in plasmas and a suitable quantum-mechanical impact calculation has been performed to obtain linewidths and line shifts.
Abstract: A model of a confined atom in a self-consistent field has been developed to describe the high-density effects on atomic bound states in plasmas. Numerical values, asymptotic behaviors, and scaling laws are given for energy levels and spectral line shifts. Concurrently, a suitable quantum-mechanical impact calculation has been performed to obtain linewidths and line shifts. For a typical electron temperature and density of laser plasma, it has been shown that line shifts given by the two approaches are in agreement within 10%.
TL;DR: In this article, the optical \ensuremath{\Gamma} phonon and the stress-strain relations in diamond were investigated for general uniaxial and hydrostatic stresses up to several megabar.
Abstract: The optical \ensuremath{\Gamma} phonon and the stress-strain relations in diamond are investigated for general uniaxial and hydrostatic stresses up to several megabar. Theoretical calculations are carried out using ab initio pseudopotentials within local-density-functional theory. Second-, third-, and fourth-order elastic constants are evaluated, including the internal-strain effect. The splittings and shifts of the \ensuremath{\Gamma} phonon are predicted up to cubic order in the macroscopic strain. A number of quantities are predicted, and where experimental results are available good agreement is found. At large uniaxial stresses (\ensuremath{\sim}4 Mbar) the electronic band gap collapses, and a phonon instability of the metallic diamond structure is found for compressions along the [110] and [111] crystal axes.
TL;DR: In this paper, the existence of stationary states for Dirac nonlinear Dirac equations of the form:======¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯\/\/\/\/\/\/\/\/\/\/\/▬▬▬▬▬▬•
Abstract: We prove the existence of stationary states for nonlinear Dirac equations of the form:
$$i\gamma ^\mu \partial _\mu \psi - m\psi + F(\bar \psi \psi )\psi = 0.$$
We seek solutions which are separable in spherical coordinates and we use a shooting method for solving the associated problem of ordinary differential equations.
TL;DR: The transition to chaos in ''the hydrogen atom in a magnetic field'' is numerically studied and shown to lead to well-defined signature on the energy-level fluctuations.
Abstract: The transition to chaos in "the hydrogen atom in a magnetic field" is numerically studied and shown to lead to well-defined signature on the energy-level fluctuations. Upon an increase in the energy, the calculated statistics evolve from Poisson to Gaussian orthogonal ensemble according to the regular or chaotic character of the classical motion. Several methods are employed to test the generic nature of these distributions.
TL;DR: A hybrid gene that can be translated on yeast cytosolic ribosomes is constructed by fusing the encoding presequence of subunit 9 of the Neurospora ATPase to a restriction fragment containing the bI4 maturase coding sequence, and it is revealed that the resulting protein is imported into mitochondria, which was revealed by its ability to restore to respiratory competence a yeast mutant defective in the bBI4maturase.
TL;DR: Oxygen and carbon isotope stratigraphies can be established for deep Mediterranean records and the major events of the last 150 ka are easily identifiable as discussed by the authors, however, the five substages of stage 5 or the 18 ka event (stage 2) are only recorded by Globigerina bulloides and benthic foraminifera, suggesting that the cooling affected only winter SST.
TL;DR: In this paper, the Davie Ridge is interpreted as a remnant transform fault that controlled the late Jurassic/early Cretaceous drift of Madagascar and the opening of the Somali Basin.
Abstract: The continental margin of northern Mozambique is edged by a north-south trending alignment of submarine peaks forming the Davie Ridge (Fig. la). From earlier studies1–5, the ridge has been interpreted as a remnant transform fault that controlled the late Jurassic/early Cretaceous drift of Madagascar and the opening of the Somali Basin6–8. During MD40-MACAMO cruise (June 1984), 7,500 km of water gun seismic reflexion lines have been implemented throughout the region where two flat-bottomed troughs, the north-south trending Kerimbas and Lacerda deep grabens, interrupt the continental slope alongside the ridge. These grabens cut into Tertiary sediments correspond westward, to a Miocene tilting or a recent normal fault; and eastward, to an old discontinuity several times reactivated and located above an abrupt uplift of the Moho. The two grabens are separated from each other by a rigid region of thickened crust, affected by intense seismicity and supporting volcanoes. We report here that the eastern branch of the East African Rift joins the submerged grabens across the Tanzanian continental shelf (Fig. 1b).
TL;DR: In this article, intersection properties of multi-dimensional random walks were studied and a central limit theorem for the range of a two-dimensional recurrent random walk was proved. But the results were only applied to the case of two independent Brownian motions.
Abstract: We study intersection properties of multi-dimensional random walks. LetX andY be two independent random walks with values in ℤd (d≦3), satisfying suitable moment assumptions, and letIn denote the number of common points to the paths ofX andY up to timen. The sequence (In), suitably normalized, is shown to converge in distribution towards the “intersection local time” of two independent Brownian motions. Results are applied to the proof of a central limit theorem for the range of a two-dimensional recurrent random walk, thus answering a question raised by N. C. Jain and W. E. Pruitt.
TL;DR: It can be stated that in dense solid argon there is no way to reproduce the experimental results with any pair potential and that many-body exchange potentials have to be incorporated for an accurate description.
Abstract: Brillouin scattering was measured at room temperature in liquid and solid argon in a diamond-anvil cell at pressures up to 33 GPa. In the fluid, our results agree well with those obtained by ultrasonic methods. In the solid, the elastic anisotropy and the use of the experimental equation of state allowed us to determine limiting values for all the elastic constants as a function of pressure. We also performed self-consistent phonon calculations using various pair potentials proposed for argon. From the comparison between calculation and experiment it can be stated that in dense solid argon there is no way to reproduce the experimental results with any pair potential and that many-body exchange potentials have to be incorporated for an accurate description.
TL;DR: In this article, the growth of very thin oxide films exhibits particular features which are discussed in this paper, and the effect of hydrogenated impurities is also discussed; this difference is possibly associated with the transport of oxygen atoms through the silica network.
Abstract: The thermal oxidation of silicon is generally modelled by Deal and Grove's theory based on the assumption that the oxygen molecules dissolve in silicon in interstitial positions and migrate to the Si-SiO2 interface where they react with the silicon substrate. Experimental results for oxidation in dry oxygen agree with this theory only for thick oxide films. The growth of very thin oxide films exhibits particular features which are discussed in this paper. For these films, the growth mechanism is different from that of thick films; this difference is possibly associated with the transport of oxygen atoms through the silica network. The effect of hydrogenated impurities is also discussed.
TL;DR: It is shown that DNA exists in a positively superhelical state in the genome of the virus-like particle SSV-1, present in Sulfolobus.
Abstract: The topological state of DNA is of importance in a variety of essential biological events1–4. Covalently closed circular DNA duplexes isolated from eukaryotic cells and their viruses, as well as from eubacteria and their bacteriophages are, without exception, negatively supercoiled. Little is known about the topological state of the DNA in archaebacteria, a group of organisms distinct from both ekaryotes and eubacteria5, but recently an ATP-dependent DNA topoisomerase has been isolated from the archaebacterium Sulfolobus acidocaldarius. This enzyme, termed ‘reverse gyrase’, converts relaxed or negatively supercoiled DNA into positively supercoiled forms in vitro6–9. It is not a gyrase-like type II topoisomerase, as initially reported9, but an ATP-dependent type I enzyme7,8. The function of this enzyme in vivo has not been established, largely because of the lack of data on the topological state of Sulfolobus DNA. Here we show that DNA exists in a positively superhelical state in the genome of the virus-like particle SSV-1, present in Sulfolobus.
TL;DR: The results suggest that glucose supply to the fetus may be limited in times of maternal hypoglycemia and that placental mechanism(s) may serve to buffer glucose transfer to the unborn child in conditions of hyperglycemia.
Abstract: The impact of varying maternal glucose concentrations on glucose uptake, transfer, and metabolism was investigated in the human placenta perfused in vitro. The rates of placental glucose uptake from the maternal perfusate and transfer to the fetal perfusate were significantly correlated with maternal glucose concentration up to 20 mM. Placental glucose utilization was also dependent upon maternal glucose concentration up to 17 mM. Between 3 and 53 mM maternal glucose, lactate production increased 3-fold while no change in oxygen consumption could be demonstrated. Correlatively, glucose storage was shown to increase dramatically above 10 mM maternal glucose. These results suggest that glucose supply to the fetus may be limited in times of maternal hypoglycemia and that placental mechanism(s) may serve to buffer glucose transfer to the fetus in conditions of hyperglycemia.
TL;DR: The formalisme de la fonctionnelle de la densite est applique a l'etude de la stabilite mecanique et thermodynamique de cristaux colloidaux polydisperses as mentioned in this paper.
Abstract: Le formalisme de la fonctionnelle de la densite est applique a l'etude de la stabilite mecanique et thermodynamique de cristaux colloidaux polydisperses. Les particules colloidales sont assimilees a des spheres dures avec une distribution continue, p(σ), de diametres additifs. On montre que de telles solutions solides cessent d'etre stables au-dela d'un degre de polydispersite critique, qui depend de la forme de p(σ), mais est toujours de l'ordre de 20%. Le probleme de la determination de la courbe de coexistence fluide-solide est brievement evoque
TL;DR: In this paper, a reaction model for the dissolution-passivation process of iron-chromium alloy in acidified sulfate media is proposed, where the reaction mechanism of alloy is depicted as that of iron perturbed by the chromium addition.
TL;DR: In the presence of BF3, the reaction rate of organocopper and cuprate reagents with poorly reactive epoxides is dramatically enhanced as discussed by the authors, and they show a complete stereochemical (pure anti opening) and regiochemical control.
TL;DR: In this article, the structural framework of the Taiwan-Luzon-Mindoro belt (or festoon) is described, following three major transects: the Luzon tranchs with active subduction and active island arc; the Taiwan tranch with active collision; the Mindoro tranchings with active subsurface and inactive collision.
TL;DR: In this paper, the authors apply a numerical model of the thermal evolution of a continental lithosphere undergoing extensional deformation to the Rhinegraben, and the results are in agreement with the present configuration of the rift and of its shoulders, as well as with their evolution since the Oligocene.
TL;DR: In this article, the hepatitis B virus infection of mononuclear blood cells (including lymphoid cells) is a frequent event at all stages of the viral infection which might be related to immunological abnormalities observed in HBV carriers.
TL;DR: A novel feature of vortex solutions for a spontaneously broken SU(N) theory is that their electric charge q is quantized in units of the fundamental charge e, q=mne/ \ensuremath{\surd}2N , with m-Z, and their angular momentum J is nonzero and also quantized, J=nm/2N.
Abstract: Vortex solutions for a spontaneously broken SU(N) theory are explicitly constructed. N Higgs fields in the adjoint representation are needed in order to ensure topological stability. (N-1) topologically different solutions exist with magnetic flux \ensuremath{\Phi} quantized according to the relation \ensuremath{\Phi}=(2\ensuremath{\pi}/e)n/ \ensuremath{\surd}N with n=1,2,...,N-1. When a Chern-Simons term is added, the model exhibits electrically charged vortex solutions. A novel feature of these solutions is that their electric charge q is quantized in units of the fundamental charge e, q=mne/ \ensuremath{\surd}2N , with m\ensuremath{\in}Z. In addition, their angular momentum J is nonzero and also quantized, J=nm/2N.