Showing papers by "University of Nice Sophia Antipolis published in 1985"
TL;DR: In this paper, the Stokesian dynamics is used to investigate the rheological behavior of concentrated suspensions in a simple shear flow, and the simulation results suggest that the suspension viscosity becomes infinite at the percolation-like threshold ϕm owing to the formation of an infinite cluster.
Abstract: The newly developed simulation method known as Stokesian dynamics is used to investigate the rheological behaviour of concentrated suspensions. Both the detailed microstructure (e.g. pair-distribution function) and the macroscopic properties are determined for a suspension of identical rigid spherical particles in a simple shear flow. The suspended particles interact through both hydrodynamic and non-hydrodynamic forces. For suspensions with purely hydrodynamic forces, the increase in the suspension viscosity with volume fraction ϕ is shown to be caused by particle clustering. The cluster formation results from the lubrication forces, and the simulations of a monolayer of spheres show a scaling law for the cluster size: lc ∼ [1 − (ϕ/ϕm)½]−1, where ϕm is the maximum volume fraction that can shear homogeneously. The simulation results suggest that the suspension viscosity becomes infinite at the percolation-like threshold ϕm owing to the formation of an infinite cluster. The predicted simulation viscosities are in very good agreement with experiment. A suspension with short-range repulsive interparticle forces is also studied, and is seen to have a non-Newtonian rheology. Normal-stress differences arise owing to the anisotropic local structure created by the interparticle forces. The repulsive forces also reduce particle clustering, and as a result the suspension is shear-thickening.
519 citations
TL;DR: It is reported that c-myc gene is indeed transcribed at a high rate in G0-arrested chinese hamster lung fibroblasts, although the level of mature c- myc mRNA is barely detectable, and these findings support a model of post-transcriptional regulation of c-Myc expression at thelevel of mRNA degradation.
Abstract: There is increasing evidence that at least some of the cellular homologues to retroviral oncogenes (c-onc or proto-oncogenes) are directly linked to the control of cell growth (for a review see ref. 1). Among these, c-myc, the cellular homologue to the avian myelocytomatosis virus (MC29) oncogene, has been shown to express high levels of mRNA during early G0/G1 phase after mitogenic stimulation of T lymphocytes by concanavalin A or of fibroblasts by platelet-derived growth factor (PDGF) or serum. An attractive model proposed for this regulation is that the c-myc gene is strongly repressed in cells arrested in the G0 phase of the cell cycle by a growth factor-sensitive repressor. We have investigated an alternative model of post-transcriptional regulation. This latter model leads to two testable predictions. First, that c-myc mRNA should be unusually unstable, which we have confirmed. And second, that there would be a high level of constitutive expression, a situation opposite to that implied by the repressor model. Here we report that c-myc gene is indeed transcribed at a high rate in G0-arrested chinese hamster lung fibroblasts, although the level of mature c-myc mRNA is barely detectable. The early and dramatic increase in c-myc mRNA levels when these resting cells are stimulated by growth factors is not accompanied by any appreciable change in the transcription rate of c-myc gene. Taken together these findings support a model of post-transcriptional regulation of c-myc expression at the level of mRNA degradation.
261 citations
TL;DR: Restoration of the pHi defect in mutant cells restores the wild‐type phenotype and demonstrates that pHi modulated by growth factor activation of the Na+/H+ antiporter, plays a determinant role in growth control.
228 citations
TL;DR: In this paper, a model for calculating the heat capacity of Al-free silicate melts as a function of temperature and chemical composition was proposed. But the model was not applied to the case of K 2 O-bearing melts, and the available data did not indicate deviations of the heat capacities from an additive function of composition.
134 citations
TL;DR: A genetic approach to the membrane-bound Na + /H + antiporter opens the way to its molecular identification and its role in growth control.
127 citations
TL;DR: It is suggested that AA3 recognizes an antigen (or antigens) which may be involved in a primary biochemical defect in junctional EB, and this antibody may act as a new probe for this potentially lethal mechano‐bullous disease.
Abstract: SUMMARY
AA3 is a novel antibody raised against human amnion, which reacts with the basement membrane of various epithelia of ectodermal origin. We use AA3 to examine the epidermal basement membrane zone in normal skin and different genetically determined types of epidermolysis bullosa (EB), by indirect immunofluorescence. AA3 staining was normal in dystrophic and simplex EB, but was markedly reduced in lesional and non-blistered skin in severe forms of junctional EB. In non-lethal junctional EB, the intensity of staining was variable and appeared to be inversely associated with disease severity, but did not correlate with demonstrable abnormalities of hemidesmosomes. AA3 binding was not reduced in pemphigoid lesions or normal suction blisters. It appeared to localize to the lamina lucida, but with different characteristics compared with antibodies to laminin and bullous pemphigoid antigen. These findings suggest that AA3 recognizes an antigen (or antigens) which may be involved in a primary biochemical defect in junctional EB. Moreover, this antibody may act as a new probe for this potentially lethal mechano-bullous disease.
85 citations
TL;DR: Along the Mediterranean coasts of France, Cymodocea nodosa (Ucria) Ascherson occupies wide expanses between depths of 0.5 m and 18 m, and shows dimorphism, with rapid growth during April-May, and very much slower growth from October-March.
84 citations
TL;DR: In the parameter space of a fluid subject to triple convection, there is a critical hypersurface on which three growth rates of linear theory vanish and all the rest are distinctly negative as mentioned in this paper.
Abstract: In the parameter space of a fluid subject to triple convection, there is a critical hypersurface on which three growth rates of linear theory vanish and all the rest are distinctly negative. When parameter values are chosen to place the system very near to this polycritical condition, the temporal behavior of the system may be complicated and even chaotic. This remark, based on rather general considerations (Arneodo et al., 1984), is here illustrated by an example from GFD (Arneodo et al., 1982): two-dimensional Boussinesq thermohaline convection (or semi-convection) in a planeparallel layer rotating about a vertical axis and subject to mathematically convenient boundary conditions. The treatment is made in terms that show why the results may apply to many fluid dynamical systems or indeed to other kinds of triply unstable systems and, using both amplitude equations and mappings, we discuss the chaos that can arise.
82 citations
TL;DR: One of the primary inactivating cleavages of neurotensin by rat brain synaptic membranes occurs at the Arg8‐Arg9 peptide bond, leading to the formation of NT1‐8 and NT9‐13, and the role of a postproline dipeptidyl‐aminopeptidase is established in the secondary processing of NT 9‐13 formation.
Abstract: One of the primary inactivating cleavages of neurotensin (NT) by rat brain synaptic membranes occurs at the Arg8-Arg9 peptide bond, leading to the formation of NT1-8 and NT9-13. The involvement at this site of a recently purified metalloendopeptidase was demonstrated by the use of its specific inhibitor, N-[1(R,S)-carboxy-2-phenylethyl]-alanylalanylphenylalanine-p-amino -benzoate, which exerts an inhibition on NT1-8 formation with an IC50 (0.6 microM) close to its Ki for the purified metalloendopeptidase (1.94 microM). Furthermore, we established the role of a postproline dipeptidyl-aminopeptidase in the secondary processing of NT9-13 formation.
80 citations
73 citations
TL;DR: Results indicate that a slow component of skeletal muscle contraction is related to the inward Ca2+ current flowing through dihydropyridine sensitive voltage-dependent Ca2 + channels.
TL;DR: In this paper, the authors study the preturbulent transitions for the Couette-Taylor flows via bifurcation theory in the presence of symmetry and show that the linearized stability analysis leads to multiple eigenvalues for the most simple flows.
Abstract: We study the preturbulent transitions for the Couette-Taylor flows via bifurcation theory in the presence of symmetry. The difficulty is that the linearized stability analysis leads to multiple eigenvalues for the most simple flows. Only a consideration of the symmetry-group action on the critical eigenvectors allows us to derive and to solve the bifurcation equations. We recover through this analysis the different patterns which are observed in experiments as the Reynolds number is increased: Steady Taylor vortices and bifurcation of either wavy, or twisted vortices from the Taylor vortex flow in the case of co-rotating cylinders; spiral vortices in the case of (strongly) counterrotating cylinders, and ribbon-cells, which have not yet been observed in experiments. Then we show that, under natural assumptions on the loss of stability of these oscillatory flows, the next bifurcation leads to quasi-periodic flows without frequency locking, whose different patterns are studied.
TL;DR: In this article, it was proved that the stochastic normal form of a general system undergoing a Hopf bifurcation contains new types of terms which did not appear in the deterministic normal form.
TL;DR: In this article, the isothermal compressibility of six silicate/aluminosilicate minerals (Mg 2 SiO 4, MgSiO 3, CaMgSi 2 O 6, Mg 3 Al 2 Si 3 O 12, NaAlSi2 O 6, NaSiO 6, NAlSi 3 O 8 ) and availble thermodynamic data was calculated for pressures ranging from 0.001 to 150 kbar.
TL;DR: It is suggested that cyclic GMP is a second messenger of neurotensin in neuroblastoma clone N1E115, and that the cyclic AMP concentration only decreased by 20-30%.
01 Oct 1985
TL;DR: In the age of the increase of information and of changes in the ways we know as to how knowledge is presently acquired, the continually growing spread of what is called the "paranormal" presents a problem in which the overall education implications cannot be fully appreciated.
Abstract: In the age of the increase of information and of changes in the ways we know as to how knowledge is presently acquired, the continually growing spread of what is called the ‘paranormal’, presents a problem in which the overall education implications cannot be fully appreciated. The proponents of the ‘paranormal’ indeed make knowledge seem mystifying. In particular, the result of this is a conception of the world in which numerous phenomena escape, without remedy, the understanding and therefore, the grasp of the majority of individuals. The best therapy against the harmful distortion caused by the kinds of thinking which mislead us into this sort of ordering of the world (which ends up demoralizing the individual) is to develop the ‘zetetique’, that is, to develop critical evaluation. This development, in which the educational system is the basic essential element, must rely upon practical means of inquiry, for which, to come full circle, the paranormal may offer a foundation from which to start. It is th...
TL;DR: In this paper, the authors provided explicit expressions for the partial derivatives of the associated energy functional with respect to the coordinates xil, 1 ⩽ l l n, of each of the variable nodes Mi, i = 1,…, p.
TL;DR: In this paper, the authors presented a method of producing an efficient and controlled ionization of the TCNQ molecules in pure molecular microcrystals, according to whether the ionization is complete or incomplete.
TL;DR: The results further characterize the ‘immortalized’ state induced by plt and myc as one in which the cells maintain a normal growth control in many respects but can be further acted upon to produce a neoplastic progeny.
Abstract: Focus formation in rat fibroblasts exposed to a tumour promoter after transfer of polyoma plt and myc oncogenes
TL;DR: The results suggest that both the dihydropyridine and phenylalkylamine receptors on the cardiac Ca2+-channel can exist in interconvertible high and low affinity states in vitro, and that the proportion of receptors in each affinity state can be altered by the absence or presence of divalent cations.
TL;DR: The observation of small epithelial islands near the apical surface of the retained tooth supports the theory that the tumor originates from Malassez's rests.
TL;DR: In this article, the authors synthesized new fluorinated surfactants (anionic, cationic or amphoteric) with an hydroxyl on Cα to the perfluoroalkyl chain.
TL;DR: In this article, the magnetization and 1.15 μm wavelength Faraday rotation of YIG with 0.06 single crystals have been measured for two directions of the applied magnetic field (H [111] and H [110]) up to 50 kOe.
Abstract: The magnetization and 1.15 μm wavelength Faraday rotation of Ce x Y 3-x Fe 5 O 12 (Ce x = YIG) with x = 0.06 single crystals have been measured. For two directions of the applied magnetic field (H [111] and H [110]) up to 50 kOe, the isothermal magnetization curves are identical to that of pure YIG between 4.2 and 300 K. On the other hand, the Faraday rotation (F.R.) in a maximum field of 20 kOe parallel to the [111] direction is always negative (with respect to the positive FR of YIG) and strongly enhanced when the temperature is lowered from 300 to 77 K. These interesting magnetooptical properties are associated to the presence of Ce3+ions in the samples.
TL;DR: In this article, the binding of human lipoproteins to cultured mouse Ob17 preadipose and adipose cells was studied, using labeled VLDL, LDL and apoprotein E-free HDL.
TL;DR: In this article, an experimental fiber-spinning device has been built in order to study the draw-resonance phenomenon in nearly isothermal conditions The influence of the output rate, of the take-up speed and of the spinning length was studied for four different polyesters.
Abstract: An experimental fiber-spinning device has been built in order to study the draw-resonance phenomenon in nearly isothermal conditions The influence of the output rate, of the take-up speed and of the spinning length was studied for four different polyesters The experimental results are in accordance with non-isothermal and viscoelastic computations
TL;DR: In this article, Heisenberg-like inequalities are derived from commutator identities, linking the quadratic dispersion in momentum to several functions of the position variable (or conversely).
TL;DR: In this paper, mutant clones of Ob17 preadipose cells resistant to the cytotoxic action of ouabain have been isolated and their ability to grow in serum-supplemented medium containing ⩾3 mM ouABain is consistent with the decreased OUABain sensitivity of K + transport observed in one of these clones (Ob17-OR11).