Showing papers by "University of Nice Sophia Antipolis published in 1980"
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TL;DR: In this paper, it is shown on examples that the distance between nearby states is related to quantum fluctuations; in particular, in the particular case of the harmonic oscillator group the condition of zero curvature appears to be identical to that of non dispersion of wave packets.
Abstract: A metric tensor is defined from the underlying Hilbert space structure for any submanifold of quantum states. The case where the manifold is generated by the action of a Lie group on a fixed state vector (generalized coherent states manifold hereafter noted G.C.S.M.) is studied in details; the geometrical properties of some wellknown G.C.S.M. are reviewed and an explicit expression for the scalar Riemannian curvature is given in the general case. The physical meaning of such Riemannian structures (which have been recently introduced to describe collective manifolds in nuclear physics) is discussed. It is shown on examples that the distance between nearby states is related to quantum fluctuations; in the particular case of the harmonic oscillator group the condition of zero curvature appears to be identical to that of non dispersion of wave packets.
520 citations
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TL;DR: In this paper, the conditions at the geographic South Pole enable modes of global solar oscillations and theoretical models of the internal solar structure to be identified, and a model of the global solar structure is proposed.
Abstract: Observing conditions at the geographic South Pole enable modes of global solar oscillations and theoretical models of the internal solar structure to be identified.
216 citations
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TL;DR: In this article, a criterion is given which allows one to construct one-parameter families of Volterra equations displaying numerically chaotic behavior, and a criterion for constructing one parameter family of oneparameter family of VOLTERRA equations is given.
144 citations
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TL;DR: In this article, the authors compute the differential cross section dσ/dQ2 dy for lepton pair production up to first order in the strong coupling constant α s. They show that, in the region where the theory applies and where the statistical accuracy of the experiments is good, the ratio of the QCD correction to the Drell-Yan cross section is approximately constant.
80 citations
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64 citations
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01 Jan 1980TL;DR: The dependence of the solution of boundary-value problems of structural mechanics on design variables that specify material properties and distribution is characterized in this article, and the results establish continuity (in fact, differentiability) of static structural response with respect to distributed design variables and design parameters.
Abstract: The dependence of the solution of boundary-value problems of structural mechanics on design variables that specify material properties and distribution is characterized. Prototype problems treated include beams, plates, and plane elastic solids. Symmetry and positive definiteness properties of the elliptic differential operators that govern system response are used to show that their inverses, hence the displacement fields, are Frechet differentiable with respect to design variables. Formulas for the derivatives are given and used to obtain computable formulas for design sensitivity coefficients (first variation) of integrals that arise in optimal design formulations. The results establish an extension of the concept of “well-posed” problems of structural mechanics to include continuity (in fact, differentiability” of static structural response with respect to distributed design variables and design parameters
55 citations
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01 Jan 1980TL;DR: In this article, a complete classification of the resulting bifurcation diagrams is presented, with emphasis on the cases which exhibit tertiary bifurbation, and existence theorems for the secondary and tertiary solutions and asymptotic formulae for the invariant torus.
Abstract: Non linear interactions between a Hopf bifurcation and a pitchfork-type stationary bifurcation can produce secondary bifurcations of periodic solutions, and tertiary bifurcations of periodic or aperiodic solutions lying on an invariant torus. A complete classification of the resulting bifurcation diagrams is presented, with emphasis on the cases which exhibit tertiary bifurcation. Calculations involving successive transformations to polar normal forms lead to existence theorems for the secondary and tertiary solutions and asymptotic formulae for the invariant torus.
50 citations
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TL;DR: Dissociation indicates that growth-factor-stimulated glycolysis is not involved in the control of initiation of DNA synthesis and cell proliferation, and the rapid activation of phosphofructokinase by purified growth factors is necessary for the initiation of cell proliferation.
Abstract: Reports from several laboratories have suggested increased rates of glycolysis play an essential part in the initiation of DNA synthesis. This is based on observations that aerobic glycolysis: (1) occurs at low rate in resting mammalian cells and at very high rate in tumour cells; (2) increases rapidly after DNA synthesis is initiated by addition of serum or purified growth factors, and (3) correlates with the expression of the transformed phenotype. Also, specific inhibitors of aerobic glycolysis prevent the initiation of DNA synthesis. To determine whether the rapid activation of phosphofructokinase--and therefore glycolysis--by purified growth factors is necessary for the initiation of cell proliferation, we have isolated and studied two classes of glycolytic mutants. The first, isolated from Chinese hamster fibroblasts, has a total block in the glycolytic pathway. The second, from hamster and Fisher rat fibroblasts maintains a permanent high rate of glycolysis. We have found that both classes of mutants retain normal control of DNA synthesis in response to serum. This dissociation indicates that growth-factor-stimulated glycolysis is not involved in the control of initiation of DNA synthesis and cell proliferation.
44 citations
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TL;DR: In this article, an isolated dipolar system made of Stockmayer molecules has been simulated using a 2-D electrostatics dipolar interaction and the autocorrelation function (ACF) of the moment of the disc was extracted from the runs, together with the ACF of a small inner disc (either microscopic or multimolecular).
Abstract: Molecular dynamics (MD) simulations of an isolated dipolar system (made of Stockmayer molecules) has been performed. A two dimensional system has been adopted, using a ‘2-D electrostatics’ dipolar interaction. The isolated system was a disc in vacuo. The autocorrelation function (ACF) of the moment of the disc was extracted from our runs, together with the ACF of the moment of a small inner disc (‘microscopic’ or ‘multimolecular’ ACF). Comparison of these two ACF has allowed us to compute the response function of the annulus between the two discs. The behaviour of the latter was that predicted by the theory of Fatuzzo and Mason. It is thus shown, for the first time, that one can obtain, by numerical simulation of a few hundred molecules, reliable values of the complex permittivity of highly polar fluids, despite the long range character of the dipolar interaction. Its behaviour is surprisingly realistic when compared with that of real 3-D polar liquids. Monomolecular ACF have also been extracted from the ...
44 citations
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TL;DR: In this paper, the authors present some recent mathematical results leading to a qualitative explanation of what can happen when a self-oscillating periodic flow with frequency wI loses its stability and is superseded by a quasi-periodic flow with two fundamental frequencies, wI and w2.
Abstract: The recent experimental results of Collub and Benson'.' and Libchaber and M a ~ r e r ' ~ on convection in small boxes lead them to consider four main routes to turbulent convection.2 Two qualitative features common to all these routes as the Rayleigh number increases, are that a breaking of spatial symmetry leads to a steady convection, and (after this bifurcation or after a second one of the same type) that a Hopf bifurcation gives a self-oscillating flow. Both these phenomena are now well known and belong in standard studies of mathematics, even though it is very difficult to check whether we have realized the mathematical conditions for obtaining these types of bifurcations in practice. The phenomenon of period-doubling (see Reference 5 , Chapter 2, or Reference 6, Chapter XI) of a self-oscillating flow is equally well understood. Our goal is to present some recent mathematical results leading to a qualitative explanation of what can happen when a self-oscillating periodic flow with frequency wI loses its stability and is superseded by a quasi-periodic flow with two fundamental frequencies, wI and w2. In the next section, we shall give some results on frequency lockings between ol and w2, which are not real bifurcations, and we shall explain why it is impossible to see these lockings close to the bifurcation point. In the third section, we shall describe a mathematical mechanism that could explain the occurrence of a very small frequency, wI. In the last section, we shall give an idea of what might be happening when a third frequency is observed, even though the bifurcation of a flow with two frequencies into a flow with three frequencies is absolutely not generic, following Chcnciner and I o o s s . ~ ~ * It should be clear that what we are saying consists of conjectures, since a real proof on the actual equations of fluid dynamics of what is observed in experiments would involve such lengthy computations that we will have to wait quite a while to discover the answer. However, a number of relativity simple examples seem to show that these conjectures are reasonable. Moreover, the mathematical phenomena described in the next section seem to be observed in References 1-3 and 9, those of the third section in References 2 and 4, and those of the last section in Reference 2.
44 citations
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TL;DR: It does not seem that a coupling between agonist binding and guanylate cyclase stimulation is necessarily involved, but differentiation of a physiological response to muscarinic agents seems to be clearly linked to molecular events which occur after ligand binding to the mus carinic receptor.
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TL;DR: In this article, the mean squared moment of an inner disc, as a function of the diameter of the disc, is fitted with a single dielectric constant, which is thus determined.
Abstract: Molecular dynamics simulation of a sample of a two-dimensional fluid of Stockmayer molecules (i.e. particles interacting via a central Lennard-Jones interaction plus a point dipole interaction) are reported. The dipolar interaction adopted is that required by two-dimensional electrostatics, so that the convergence problem is conserved. The sample (≈13 molecular diameters in size) is kept in vacuo by a steep circular potential barrier. It is first shown that for distances greater than 3 to 5 molecular diameters the macroscopic laws of electrostatics apply, by checking that the mean squared moment of an inner disc, as a function of the diameter of the disc, can be fitted with a single dielectric constant, which is thus determined. The Kirkwood correlation factor for an infinite sample is then evaluated. For highly polar systems, it is greater than unity. Also the radial vector correlation function h Δ(r), which describes the weight of in an expansion of the angle-dependent pair distribution f...
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TL;DR: In this article, drop calorimetric measurements of HT-H273 were reported for glassy and liquid albite and potassium tetrasilicate for the temperature interval 600-1500 K. Analysis of these observations as well as data for 13 other stable and supercooled silicate liquids suggests strongly that the isobaric heat capacities of these liquids are equal and thus temperature independent.
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TL;DR: La famille des Udoteacees (Caulerpales), comprend plus de 120 especes reparties dans toutes les mers tropicales and subtropicales.
Abstract: La famille des Udoteacees (Caulerpales), comprend plus de 120 especes reparties dans toutes les mers tropicales et subtropicales. Les connaissances sur la reproduction et le cycle de cette famille ...
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TL;DR: In this article, the authors classify discontinuous transitions to chaotic behavior occurring after a single bifurcation in real endomorphisms, which can be extended to more realistic dynamical systems, relying on the possible existence of the hysteresis mechanism.
Abstract: We study and classify discontinuous transitions to chaotic behaviour occurring after a single bifurcation in real endomorphisms. This classification which can be extended to more realistic dynamical systems, relies on the possible existence of the hysteresis mechanism. We discuss the intermittency phenomenon as an evidence for transitions without hysteresis.
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TL;DR: Recurrent patterns of hybridizaton were observed in independently isolated rat cell lines, indicating that the sites of the integrative recombinations were close enough, both in the viral and the cellular sequences, not to be distinguished at the level of sensitivity of the technique.
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TL;DR: In this paper, a typical model for doubly periodic flows is constructed, which presents numerically a transition to chaotic behavior after the frequency locking phenomenon, and two types of transitions to turbulence are observed.
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TL;DR: [3H]Phencyclidine has a tendency to adsorb to filters used in binding experiments, and the spinal binding techniques that should be used to overcome this difficulty are described.
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28 Sep 1980TL;DR: In a previous paper [Andr80] the notion of the behaviour of a place-transition net on a subset of transitions was introduced and the behaviour-equivalence (B-Equivalence) was defined and properties preserved by this equivalence were exhibited.
Abstract: In a previous paper [Andr80] we introduced the notion of the behaviour of a place-transition net on a subset of transitions. The behaviour-equivalence (B-equivalence) was defined and properties preserved by this equivalence were exhibited.
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01 Jan 1980TL;DR: In this article, the methode de demonstration raffine une idee de VAN DE VEN [17], who traitait le cas des fibres uniformes de rang 2, and it was deja reprise par GRAUERT-MULICH [6], BARTH [2], ELENCWAJG [3].
Abstract: Dans un recent travail, SPINDLER [15] a demontre le resultat suivant: Si E est un fibre semi-stable sur ℙn(ℂ), alors sa restriction a une droite generale est de la forme E|L ≅ OL(a1) ⊕...⊕ 0L(ar), avec ai ≥ ai+l ≥ ai−1 (La Suite a1 ≥ a2 ≥...≥ ar s’appelle type de scindage generique de E). La methode de demonstration raffine une idee de VAN DE VEN [17], qui traitait le cas des fibres uniformes de rang 2, idee deja reprise par GRAUERT-MULICH [6], BARTH [2], ELENCWAJG [3]. Elle consiste a montrer que si E est un fibre de type de scindage generique al ≥ a2 ≥ ... ≥ ar avec ai − a.i+1 ≥ 2 pour au moins un i, il existe un sous-faisceau F ⊂ E de type de scindage generique a1 ≥ ...≥ ai.
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TL;DR: In this paper, the depolarized scattered light intensity from supercooled benzyl benzoate has been analyzed in the whole spectral range for a 90° scattering angle with a Fabry-Perot and an intensity correlation technique.
Abstract: The depolarized scattered light intensity from supercooled benzyl benzoate has been analysed in the whole spectral range for a 90° scattering angle with a Fabry-Perot and an intensity correlation technique. In particular, a detailed analysis of the central part of the spectrum of both polarized and depolarized intensities, is carried out. Our results are consistent with the local order theory and allow the experimental determination of the relaxation times and coupling coefficients of the tensorial variables introduced in that theory.
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TL;DR: In this paper, the influence of rare-earth impurities on the thermoluminescence (TL) of ZrSiO4 phosphors is studied by recording the TL curves and TL emission spectra of a number of synthetic Zr SiO4 samples, doped individually with the trivalent elements of the lanthanide series, and X-irradiated at 77 K.
Abstract: The influence of rare-earth (RE) impurities on the thermoluminescence (TL) of ZrSiO4 phosphors is studied by recording the TL curves and TL emission spectra of a number of synthetic ZrSiO4 samples, doped individually with the trivalent elements of the lanthanide series, and X-irradiated at 77 K. It is shown that Dy3+, Tb3+, Gd3+, Eu3+, and Sm3+ are the only activators of TL in ZrSiO4. The RE3+ characteristic TL peaks which appear below 350 K are situated at the same temperatures as the TL peaks related to SiO4–4 host groups or OH− impurity processes and are the result of an energy transfer mechanism from the TL emission resulting of recombination in these centres to the RE3+ emitting centres.
L'etude de l'influence des impuretes de terres rares (TR) sur la thermoluminescence (TL) des zircons a ete faite sur un certain nombre d'echantillons synthetiques de ZrSiO4 dopes par chacun des elements trivalents de la serie des lanthanides et irradies par rayons × a 77 K. Seuls Dy3+, Tb3+, Gd3+, Eu3+, et Sm3+ s'avěrent ětre des activateurs de la TL des ZrSiO4. Les pics de TL caracteristiques des TR3+ qui apparaissent en-dessous de 350 K sont situes aux měmes temperatures que celles des pics de TL interpretes par des mecanismes inherents aux groupements de reseau SiO4–4 ou aux impuretes OH− et resultent d'un transfert d'energie de l'emission de TL de ces centres vers la TR3+ emettrice.
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TL;DR: Affinities of phencyclidines for the brain receptor but not those for peripheral organs are correlated with the pharmacological activities of phen cyclidines as measured in the rotarod test.
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TL;DR: In this paper, the depolarized (V-H) and the polarized spectrum scattered by a viscous fluid was computed using hydrodynamic equations, obtained in a previous paper.
Abstract: Hydrodynamic equations, obtained in a previous paper, are used to compute the depolarized (V-H) and the polarized (V-V) spectrum scattered by a viscous fluid. Explicit expressions are given which can be compared directly with experiment.
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TL;DR: The adaptative regulation of glucose transport described in many fibroblast cell lines exists also in cardiac cells, according to the technique of countertransport.
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TL;DR: In this paper, it was established that a paramagnetic trap centre is associated with most TL peaks in the thermoluminescence of undoped zircons, synthesized with the methode hydrothermal method, and which are X-irradiated at 77 K.
Abstract: The 365 nm emission band observed at 100, 165, 205, 260, and 325 K in the thermoluminescence of undoped zircons, synthesized with the hydrothermal method, and which are X-irradiated at 77 K, is attributed to the SiO lattice groups. It is established that a paramagnetic trap centre is associated to most TL peaks. These traps are fairly well described by the Curie model: an electron is trapped in the field of two positive charges, one substituted to silicon, the other to a neighbouring oxygen.
La bande d'emission situee autour de 365 nm et apparaissant a 100, 165, 205, 260 et 325 K dans la thermoluminescence de zircons non dopes, synthetises par la methode hydrothermale, et ayant subi une irradiation X a 77 K, est attribuee aux groupements du reseau SiO. Il est montre qu'a un pic de thermoluminescence est en general associe un centre de piegeage paramagnetique, et que ces derniers sont assez bien representes par le modele de Curie: un electron est piege dans le champ de deux charges positives, l'une substituee a un silicium, l'autre a un oxygene voisin.
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TL;DR: Three-wave stimulated Raman scattering in optical fibers has been studied theoretically in connection with the characteristics of the fiber (core diameter, core-cladding refractive-index difference) and excitation conditions.
Abstract: Three-wave stimulated Raman scattering in optical fibers has been studied theoretically in connection with the characteristics of the fiber (core diameter, core-cladding refractive-index difference) and excitation conditions. We observe experimentally this type of scattering in a silica fiber, from which we can estimate the nonlinearity of silica and the index difference of the fiber.
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TL;DR: In this paper, the authors show that a secondary instability associated with a low frequency mode can result from the nonlinear competition between a symmetry-breaking linear instability and an oscillatory instability.
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TL;DR: In this article, the synthesis of 1-trityl-2-phenylaziridine, 1trity l 2 -carboxylates and 2-methyl carboxylate of N-triphenylmethyl-α-chloroamines with KF in acetonitrile under reflux is described.
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TL;DR: In this article, it was shown that X-irradiation can dissociate OH− groups into O− and H0, and suggested that dissociation into OH and e− also occurs.
Abstract: After X irradiation at 77 K, hydroxylated zircons show thermoluminescence (TL) peaks at 115 and 160 K, with an intense emission band around 285 nm. By correlating EPR and TL observations on hydroxylated zircons, it is shown that X-irradiation can dissociate OH− groups into O− and H0, and suggested that dissociation into OH and e− also occurs. It is proposed that recombination of O− and H0 at 115 K, and of OH and e− at 160 K, lead to the same excited state (OH−)*, which explains the similar 285 nm emission for both TL peaks.
Les courbes de thermoluminescence (TL) obtenues, apres irradiation X a 77 K, sur des zircons hydroxyles, revelent la presence de pics a 115 et 160 K, dont les spectres d'emission comportent une intense bande d'emission maximale a 285 nm. La confrontation des observations en RPE et TL montre que l'irradiation X peut decomposer le groupement OH− en O− et H0, et suggere qu'une dissociation en OH et e− peut aussi exister. Nous montrons que la recombinaison de O− et H0 a 115 K, et de OH et e− a 160 K, conduit a un měme etat excite (OH−)*, dont la desexcitation explique l'emission a 285 nm.