Showing papers by "University of Nice Sophia Antipolis published in 1986"
TL;DR: In this paper, spectral methods (Fourier Galerkin, Fourier pseudospectral, Chebyshev Tau, Chebyhev collocation, spectral element) and standard finite differences are applied to solve the Burgers equation with small viscosity (v = 1 100 π ).
202 citations
TL;DR: It is shown that serum-stimulated ribosomal protein S6 phosphorylation, protein synthesis activation and DNA synthesis re-initiation are pH-regulated events that display a similar threshold pHo value in CCL39 cells, indicating that growth factor-induced alkalinization has a permissive effect on the pleiotypic response.
121 citations
TL;DR: It is shown that the competition between periodicities can lead to a commensurate-incommensurate transition mediated by solitons as in equilibrium systems.
Abstract: We consider the effect of a spatially periodic forcing at the onset of one-dimensional periodic patterns in nonequilibrium systems. It is shown that the competition between periodicities can lead to a commensurate-incommensurate transition mediated by solitons as in equilibrium systems. This result is in agreement with a recent experiment.
108 citations
103 citations
TL;DR: In this article, three groups of dikes and sills can be distinguished, based on their field relationships, petrography, geochemistry and ages, and the oldest Group I, represent the feeder dikes to the Seamount Series, intruded between 2.9 and 4.0 Ma B.P. They were originally steep, with a N05°W strike and perpendicular to the originally nearly flat bedding of the layered Seamount series.
101 citations
TL;DR: Dynamic behavior of Brownian particles close to a wall is studied by photon correlation from an evanescent wave with variable penetration depth and new effects to the light-scattering study of surface dynamics are discussed.
Abstract: Dynamic behavior of Brownian particles close to a wall is studied by photon correlation from an evanescent wave with variable penetration depth. Surface correlation spectra strongly differ from the bulk measurements and are completely interpreted in terms of the combined wall's mirror effect and evanescent-wave geometry. Relevance of these new effects to the light-scattering study of surface dynamics is discussed.
88 citations
TL;DR: In this article, it was shown that out of eight phytoplankton cultures investigated, η increased with decreasing γ in three, and the highest value of η, found at γ = 0.017 s−1, was ∼400 times that found at unstated but probably high (102-5 x 103 s− 1) values of γ by Miyaki and Koizumi.
Abstract: Bulk Theological properties of sea water sometimes change in phytoplankton blooms1–7, when the water has been described as viscous1, slimey2,3, ropey2–4 or like egg white4. Fishing nets have been clogged2,5,7 and broken2, and bubbles6 or solids2,4,5 have been trapped. Turbulent viscosity, however, can be reduced8. It has been suggested1,2,6 that phytoplankton mucus may kill marine animals by ‘clogging’ their gills. Yet oceanographers consider the sea to be newtonian, that is without rigidity and with dynamic viscosity, η, independent of shear rate, γ. I show here that out of eight phytoplankton cultures investigated, η increased with decreasing γ in three, and the highest value of η, found at γ = 0.017 s−1, was ∼400 times that found at unstated but probably high (102-5 x 103 s−1) values of γ by Miyaki and Koizumi9. Finite values of dynamic rigidity, G′′, were also observed. The characteristic length, L, and time, t, of Kolmogorov eddies10 are extremely sensitive to simulated γ-dependent η, and as the scales of many oceanic processes depend on L and r, the lack of rheometrical data at ambient γ could be detrimental to the modelling of these processes.
84 citations
TL;DR: Many hundreds of isolated plastids, in a good state of preservation in their living host, the planktonic ciliate Tontonia appendiculariformis (Oligotrichina), have been studied by electron microscopy and there is evidence that the outermost third plastid membrane arises from the host ciliate.
Abstract: Many hundreds of isolated plastids, in a good state of preservation in their living host, the planktonic ciliate Tontonia appendiculariformis (Oligotrichina), have been studied by electron microscopy. These distinctive plastids, located at the periphery of the host's body, which do not belong to complete symbiotic algae, are described in detail. All are bounded by three membranes. Although degenerating plastids were observed none were ever seen in division. Their possible origin, the significance of the three plastid membranes, and the degree of the symbiosis established are discussed. From their organization, these plastids may have originated from several species of chromophyte algae, such as Dinophyceae, Prymnesiophyceae, and Bacillariophyceae or Chrysophyceae. Because of their absence of division and of their possible degeneration, they are probably not integrated genetically. However, they appear to survive for some time and to remain functional. There is evidence that the outermost third plastid membrane arises from the host ciliate. Finally, hypotheses are proposed to explain the incorporation of the plastids into the ciliate, and their possible role in building cortical polysaccharide plates.
65 citations
TL;DR: Dr Beranek and his colleagues have previously contributed to the authors' correspondence columns and proposed an unconventional view on the role of hyperplastic capillary endothelial cells in the pathogenesis of fibrosis, finding further support in the article from Bardadin & Desmet published in the February 1985 issue of Histopathology.
Abstract: Dr Beranek and his colleagues have previously contributed to our correspondence columns and proposed an unconventional view on the role of hyperplastic capillary endothelial cells in the pathogenesis of fibrosis. These authors found further support for their hypothesis in the article from Bardadin & Desmet published in the February 1985 issue of Histopathology. Professor Desmet was invited to comment and his view, encompassing historical aspects of the topic, is also published here. Editor
56 citations
TL;DR: Upon microinjection into fertilized mouse eggs of circular molecules of plasmid pPyLT1 carrying the gene encoding the large T protein of polyoma virus within bacterial vector sequences, autonomous circular plasmids were stably maintained in low copy numbers in transgenic strains.
55 citations
TL;DR: In this paper, Andereck et al. showed that Taylor-vortex flow (TVF) can bifurcate into one of the following cellular flows: wavy vortices (WV, TW, WIB, wavy inflow boundaries (WIB), wavy outflow boundary (WOB), or WOB).
Abstract: Experiments of Andereck et al. (1986) with corotating cylinders, show that Taylor-vortex flow (TVF) can bifurcate into one of the following cellular flows: wavy vortices (WV), twisted vortices (TW), wavy inflow boundaries (WIB), wavy outflow boundaries (WOB). We describe here the structure of these different flows, showing how they result from simple symmetry breaking. Moreover we consider the codimension-two situation where WIB and WOB interact, since this is an observed physical situation.The method used in this paper is based on symmetry arguments. It differs notably from the Liapunov-Schmidt reduction used in particular by Golubitsky & Stewart (1986) on the same problem with counter-rotating cylinders. Here we take into account all the dynamics, instead of restricting the study to oscillating solutions. In addition to the standard oscillatory modes, we have a translational mode due to the indeterminacy of TVF under the shifts along the axis. We derive an amplitude-expansion procedure which allows the translational mode to depend on time. Our amplitude equations have nevertheless a simple structure because the oscillatory modes have a precise symmetry. They break, in general, the rotational invariance and they are either symmetric or antisymmetric with respect to the plane z = 0. Moreover, the most typical cases are when either of these modes has the same axial period as TVF or when their axial period is double this. This leads to four different cases which are shown to give WV, TW, WIB or WOB, all these flows being ‘rotating waves’, i.e. they are steady in a suitable rotating frame.Finally we consider the interaction between WIB and WOB that occurs when, at the onset of instability, the two critical modes arise simultaneously. In this case we show in particular that there may exist a stable quasi-periodic flow bifurcating from WIB or WOB. The two main frequencies are those of underlying WIB and WOB, while there may exist a third frequency corresponding to a slow superposed travelling wave in the axial direction.The method was used in the counter-rotating case for interacting non-axisymmetric modes (see Chossat et al. 1986). One of the original contributions here is not only to clarify the origin of all observed bifurcations from TVF, but also to handle the translational mode which may not stay small. This technique combined with centre-manifold and equivariance techniques may be helpful for many problems starting with orbits of solutions, such as the TVF considered here.
TL;DR: The results indicate that the acquisition by lipoprotein lipase of a catalytically active conformation is linked directly or indirectly to glycosylation.
TL;DR: In this paper, a new phenomenon is reported in which light satisfying a Bragg-type resonance condition gets strongly reflected by a weak coarse-period superlattice that is superimposed on a fine-period (submicron) stratified medium.
Abstract: A new phenomenon is reported in which light satisfying a Bragg-type resonance condition gets strongly reflected by a weak coarse-period (tens of microns) superlattice that is superimposed on a fine-period (submicron) stratified medium. A couple-wave theory is developed to describe this interaction.
TL;DR: The binding parameters as well as the specificity of these receptors toward neurotensin analogues reveal close similarities between the binding sites present in primary cultured neurons and those described in other membrane preprations or cells.
Abstract: The present article describes the interaction of neurotensin with specific receptors in pure primary cultured neurons and the mechanisms by which this peptide is inactivated by these cells. Neurotensin binding sites are not detectable in nondifferentiated neurons and appear during maturation. The binding at 37°C of [monoiodo-Tyr3 neurotensin to monolayers of neurons 96 h after plating is saturable and characterized by a dissociation constant of 300 pM and a maximal binding capacity of 178 fmol/mg of protein. The binding parameters as well as the specificity of these receptors toward neurotensin analogues reveal close similarities between the binding sites present in primary cultured neurons and those described in other membrane preprations or cells. Neurotensin is rapidly degraded by primary cultured neurons. The sites of primary inactivating cleavages are the Pro7-Arg8, Arg8-Arg9, and Pro10-Tyr11 bonds. Proline endopeptidase is totally responsible for the cleavage at the Pro7-Arg8 bond and contributes to the hydrolysis mainly at the Pro10-Tyr11 site. However, the latter breakdown is also generated by a neurotensin-degrading neutral metallopeptidase. The cleavage at the Arg8-Arg9 bond is due to a peptidase that can be specifically inhibited by N-[1 (R, S)-carboxy-2-phenylethyl]-alanyl-alanyl-phenylalanyl-p-aminobenzoate. The secondary processing occurring on neurotensin degradation products are: (1) a bestatin-sensitive aminopeptidasic conversion of neurotensin, 11-13 to free Tyr11, and (2) a rapid cleavage of neurotensin8-13 by proline endopeptidase. A model for the inactivation of neurotensin in primary cultured neurons is proposed and compared to that previously described for purified rat brain synaptic membranes.
TL;DR: In this article, the authors demonstrate the possibility of obtaining high quality proton-exchanged (PE) lithium niobate guides by performing the exchange at high temperatures (300°C) in benzoic acid diluted with lithium benzoate.
Abstract: In this paper we demonstrate the possibility of obtaining high-quality proton-exchanged (PE) lithium niobate guides by performing the exchange at high temperatures (300°C) in benzoic acid diluted with lithium benzoate. Rutherford backscattering studies suggest that the higher exchange temperatures avoid the production of niobium dislocations, and, IR absorption measurements suggest that the use of lithium benzoate diluted melts prevents the creation of interstitial hydrogen.
TL;DR: Seeds of Cymodocea nodosa (Ucria) Aschers.
TL;DR: The authors propose resolution numerique par une methode de differences finies en particulier aux structures complexes des ecoulements tridimensionnels dans des cylindres horizontaux.
Abstract: Resolution numerique par une methode de differences finies. On s'interesse en particulier aux structures complexes des ecoulements tridimensionnels dans des cylindres horizontaux
TL;DR: In this article, the competition between external and internal length scales is studied theoretically on a two-dimensional amplitude evolution model of a fluid layer heated from below, and a spatially-periodic excitation is applied to the stress-free, isothermal boundaries at a wavenumber close to the critical wavenumbers for the onset of the instability.
TL;DR: La discussion porte sur the signification ecologique de the bioturbation sur les sediments lagonaires.
Abstract: Quelques aspects de la biologie de Callichirus armatus A. Milne Edwards, 1870, un crustace fouisseur du groupe des callianasses, ont ete etudies pour la premiere fois. La distribution, les densites de peuplement, l'activite de creusement et la bioturbation dues a C. armatus ont ete etudiees dans differents lagons de Polynesie francaise. Des donnees preliminaires sur le cycle sexuel et les mues ont pu etre obtenues. La discussion porte sur la signification ecologique de la bioturbation sur les sediments lagonaires.
TL;DR: For stationary signals disturbed by white noise, an approach based upon a modified least-squares method leads to a good unbiased estimator of the parameters.
Abstract: Recent approaches to the modeling of nonstationary signals by means of AR or ARMA models use a representation with time-varying parameters. The time-varying parameters are assumed to be linear combinations of a set of basis time functions so that the model is specified by constant parameters. For stationary signals disturbed by white noise, an approach based upon a modified least-squares method leads to a good unbiased estimator of the parameters. In this correspondence, a similar algorithm deriving the unbiased parameters for nonstationary signals in white noise is given. The experimental results show the good performance of the proposed estimator.
TL;DR: In this paper, the authors studied the unfoldings of 0(2)-equivariant vector fields whose linearization has two pairs of purely imaginary eigenvalues, and they used isotropy subgroup techniques to classify the types of solutions which occur.
Abstract: In this paper we study the unfoldings of 0(2)-equivariant vector fields whose linearization has two pairs of purely imaginary eigenvalues. Such singularities may be expected to occur at isolated points in a centre manifold reduction of two-parameter systems with full circular symmetry. This situation differs from the corresponding non-symmetric system in that generically the eigenvalues may be either simple or double. The case when both eigenvalues are simple is similar to the Takens codimension-two singularity. Our interest lies in the cases where one or both of the purely imaginary eigenvalues are double; these cases lead to 6- and 8-dimensional centre manifolds, respectively. We use isotropy subgroup techniques to classify the types of solutions which occur. These include periodic solutions and 2-, 3-, and 4-dimensional invariant tori.
20 Aug 1986
TL;DR: In this article, it is shown that there is a strong experimental correlation between a good seeing and a low wind speed at the tropopause level, which is known to be beneficial for high angular resolution and speckle interferometry.
Abstract: In order to be efficient, new astronomical methods, like high angular resolution and speckle interferometry require subarc second seeing conditions and long speckle boiling time. It is now well known that there is a close relationship between the seeing and the integrated vertical profile of atmospheric turbulence, from the focus plane of the telescope up to the stratosphere. The measurement of the spread function of a star image does not tell anything about the respective contributions of the inside of the dome, the boundary layer and the free atmosphere. Disturbances coming from the first two slabs can be avoided by : removing the heat sources, cooling the floor, building the observatory above the inversion layer, simulating the site in a wind tunnel... But there is no a priori knowledge about the free atmosphere turbulence. In the literature, such profiles are too scarce and sparse to foresee a clima-tology. In this paper, it will be shown that there is a strong experimental correlation between a good seeing and a low wind speed at the tropopause level. The study rely on already published sesonal variations of the seeing in La Silla, Chile, and Hawaii, and on atlas of climatology of the atmospheric circulation at 200 millibars level. It seems that subarc second seeing conditions require tropopause wind speeds lower than 20ms-1. A quick look at the wind behavior let us hope very good image quality above sites located in the northern part of Chile, near Peru. A fortunate consequence of our assumption is that slow tropopause wind selected sites will likely have a long speckle time life.
TL;DR: A perifusion system, with which the rate of enzyme inactivation is minimal and systematic, has been devised and used and the data show that the secretion of a pool of pre-existing lipoprotein lipase molecules is followed by the release of newly synthesized enzyme molecules.
TL;DR: Genetic and biochemical evidence is presented establishing that the Na + –H + antiporter is a major pH i -regulating system in fibroblasts, that growth factors activate the antiporter by increasing its pH i sensitivity, and that growth factor-induced cytoplasmic alkalinization is essential for reinitiation of DNA synthesis and growth at neutral and acidic pH o .
Abstract: Publisher Summary This chapter presents genetic and biochemical evidence establishing that the Na + –H + antiporter is a major pH i -regulating system in fibroblasts, that growth factors activate the antiporter by increasing its pH i sensitivity, and that growth factor-induced cytoplasmic alkalinization is essential for reinitiation of DNA synthesis and growth at neutral and acidic pH o . In addition, the chapter presents specific selection procedures that have led to the isolation of three classes of mutants of Na + –H + antiport system: (1) mutants partially or totally defective, (2) mutants with altered Na + or amiloride binding sites, and (3) mutants overproducing the antiporter. The first advances in genetics of Na + –H + antiport system offered new approach to analyze the physiology of pH i -regulating system in fibroblasts, the role of pH i in growth control, and the identification of Na + –H + antiport at a molecular level. Na + –H + antiporter is a major pH i -regulating system in fibroblasts. In the presence of HCO − 3 , the operation of a 4-acetamide-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS)-sensitive and Na + -dependent Cl −- -HCO − 3 antiporter is a good substitute for Na + -H + exchange in pH, regulation. Growth factor-induced cytoplasmic alkalinization is triggered by activation of the Na + –H + antiporter. Growth factor activation results from an increased affinity of the system for internal H + . pH i exerts a control on the rate of cell entry into S phase. α-thrombin, a potent activator of polyphosphoinositide breakdown in CCL39 cells, activates as serum growth factors and phorbol esters, the Na + –H + antiporter by increasing its affinity for internal H + . The molecular identification of the antiporter molecule(s) should demonstrate if the change in pH i sensitivity reflects different states of kinase C-dependent phosphorylation.
TL;DR: The results are in favor of a localization of lipoprotein lipase in adipose cells as being typical of that of a secretory protein and underline the absence oflipoproteinlipase in the cell cytoplasm.
TL;DR: In this paper, partially degraded (hydroxypropyl)cellulose methanolysates were acetylated in an acetic anhydride/dioxane mixture with a perchloric acid catalyst, yielding (acetoxypropyl)-celluloses (APC) samples with an unit ester content per anhydroglucose unit of three.
Abstract: Partially degraded (hydroxypropyl)cellulose methanolysates were acetylated in an acetic anhydride/dioxane mixture with a perchloric acid catalyst, yielding (acetoxypropyl)cellulose (APC) samples with an unit ester content per anhydroglucose unit of three. Eight APC samples of molar masses from 10,000 to 1.8 × 105 g/mol were prepared. On heating, all the samples displayed biphasic behavior prior to isotropization. The isotropization temperature of the samples increased rapidly with molar mass, attaining a limiting value of 174°C. The substitution of hydroxyl groups of HPC by acetyl groups lowered the limiting value. Lyotropic mesophases of APC in dimethyl acetamide (DMAc) showed isotropization temperatures that increase nonlinearly with increasing APC concentration. For chains with contour lengths exceeding 72 nm, the critical concentration for mesophase formation, 0, does not depend on the chain length. However, for short chains the 0 value increases rapidly with decreasing chain length. The cholesteric reflection wavelength, λ0, of a thermotropic APC sample of low molar mass is greater than that of a higher molar mass sample at a given temperature and increases with increasing temperature for all samples. Partially acetylated (hydroxypropyl)cellulose displays reflection colors at lower temperatures than the fully acetylated APC.
TL;DR: In this paper, the synthesis and properties of four peroxo Ti(IV) complexes of pyrazine- and pyridinedicarboxylic acids, were reported.
TL;DR: The fundamental research reviewed may be followed by the discovery of molecular receptor defects in clinical syndromes of insulin resistance.
Abstract: The recent characterization of the human insulin receptor structure and its intrinsic tyrosine kinase activity represent major advances in our understanding of the mechanism of insulin action. It is reasonable to think that the insulin-induced autophosphorylation and activation of its receptor kinase represent an important event in the action of insulin on cell metabolism and growth. The fundamental research reviewed may be followed by the discovery of molecular receptor defects in clinical syndromes of insulin resistance.
TL;DR: In this article, a collective coordinate method is used to study theoretically and numerically the stability and the dynamics of a sine-Gordon soliton trapped in a confining potential, and a remarkably simple approximated solution is found and checked by numerical simulations.
Abstract: A collective-coordinate method is used to study theoretically and numerically the stability and the dynamics of a sine-Gordon soliton trapped in a confining potential. The example of a harmonic well is emphasized. A remarkably simple approximated solution is found and checked by numerical simulations. The perturbed soliton is stable up to high (relativistic) energies and its profile has the following kinklike dependence on space and time: U(x,t)=4 ${\mathrm{tan}}^{\mathrm{\ensuremath{-}}1}$exp[( 1+(1/4)V(y) / [1-(y'${)}^{2}$] ${)}^{1/2}$[x-y(t)]] , where V(y) is the potential energy of the particlelike kink at x=y(t). When an external driving force is present, resonances are pointed out and their nonlinear nature is stressed.