Showing papers by "University of Paris published in 1974"
TL;DR: The variational principle states that if a differentiable function F has a finite lower bound (although it need not attain it), then, for every E > 0, there exists some point u( where 11 F'(uJj* < l, i.e., its derivative can be made arbitrarily small as discussed by the authors.
2,105 citations
01 Jan 1974
TL;DR: The finite element method is studied which provides an effective way for numerically solving such problems and an algorithm for computing the approximate solution is given.
Abstract: Publisher Summary This chapter discusses the finite element method for solving the neutron transport equation and spatial discretization. It also discusses the numerical approximation of a problem by a finite element method using triangular or quadrilateral elements and other methods for solving the neutron transport equation. The discrete Galerkin method is equivalent to some implicit Runge-Kutta method. The existence and uniqueness of the approximate solution and an algorithm for computing the approximate solution is given. In the chapter, the finite element method is studied which provides an effective way for numerically solving such problems.
1,050 citations
TL;DR: Further structural simplifications of the active molecule are reported; natural N-acetyl-muramyl-tripeptides have been found active and the smallest adjuvant molecule found is a synthetic N- acetyl muramyl -dipeptide prepared by Sinay et al.
976 citations
TL;DR: In anesthetized cats, effects of midbrain stimulation were studied on evoked activity in dorsal horn lamina 4 and 5 cells and the possible relationship between analgesia and lamina 5 cell inhibition are discussed.
Abstract: Midbrain stimulation in chronically implanted, awake cats in the vicinity of dorsal raphe nucleus evoked profound analgesia to peripherally applied noxious stimuli. Analgesia was not accompanied by other obvious sensory or motor deficits. The peripheral field of analgesia sometimes included the entire body and in other cases was restricted to the hindquarters. Analgesia generally outlasted brain stimulation by no more than 10 sec. Stimulation distant from dorsal raphe led to pronounced motor or emotional effects precluding an adequate test of analgesia. In anesthetized cats, effects of midbrain stimulation were studied on evoked activity in dorsal horn lamina 4 and 5 cells. Stimulation of wide regions of midbrain inhibited pain-evoked activity in most lamina 5 cells without affecting responses of most lamina 4 cells. In some lamina 5 cells, midbrain stimulation inhibited responses to noxious but not innocuous stimuli. The possible role of lamina 5 cells in nociception and the possible relationship between analgesia and lamina 5 cell inhibition are discussed.
401 citations
TL;DR: In this paper, the Euler equation has been considered by several authors including L. Lichtenstein (1925-30), J. Leray (1932-37), M. Wolibner (1938), T. Ebin and J. Marsden [2] have proved the existence of a local solution in the general case.
348 citations
TL;DR: In this article, the consequences of gauge invariance are re-examined in dual models with unit intercept when the dimension of space-time has the maximum value compatible with the absence of ghosts.
290 citations
01 Jan 1974
TL;DR: In this article, a mixed finite element method for the Biharmonic equation is described, in which the approximate solution lies in a finite-dimensional space and the Laplacian Δu of the solution plays a special role.
Abstract: Publisher Summary
This chapter explains a mixed finite element method for the Biharmonic equation One way to avoid the computational difficulty is to use a non-conforming method, in which the approximate solution lies in a finite-dimensional space The other way to avoid the computational difficulty is based on a different variational principle called the standard variational formulation of problem Different variational principle falls into two categories: either the variational principle is explicitly dependent upon a given triangulation of the set Ώ, in which case the method is called hybrid, or otherwise, it is called a mixed method The chapter also discusses an approximate method related to yet another variational principle, in which the Laplacian Δu of the solution plays a special role
220 citations
TL;DR: In this article, a theoretical outline and a body of empirical work relating to the processes of social differentiation and social originality is presented, and a brief account of observations made with regard to groups of children in summer camps, laboratory experiments and the results of surveys in the scientific and artistic communities which fit into the theoretical framework.
Abstract: In this article we have presented a theoretical outline and a body of empirical work relating to the processes of social differentiation and social originality.
If, in a competition, someone else seems to possess a decisive advantage or if mere comparison with this other person constitutes a threat to social identity, there are signs, in given conditions, of a tendency to differentiate oneself from the other, to be different or to do something else, to invent new criteria of being or doing with others or to combine accepted criteria in an original way. In other words, one tends to give proof of originality or, to use a Darwinian metaphor, to occupy ‘vacant places’. Doubtless the strategies described here only apply to certain social systems in which the visibility of the agent is an important social value and in which comparison may pose a threat to that identity. The restoring of identity by way of the search for otherness merits the attention of social psychology.
But originality is not necessarily accepted or not necessarily immediately. Innovation may take time, may necessitate the creation of schismatic groups and the waging of battles for recognition, etc.
We give a brief account of observations made with regard to groups of children in summer camps, laboratory experiments and the results of surveys in the scientific and artistic communities which fit into our theoretical framework. It will not be difficult for the reader to see that this article is a first step in a direction which, in our eyes, holds out a great deal of promise.
194 citations
TL;DR: In this article, the authors show that resonance Raman scattering and hot luminescence are two distinct physical processes, although they are always simultaneously present and can interfere with each other.
Abstract: Using density-matrix formalism which takes into account relaxation more correctly, we show that resonance Raman scattering and hot luminescence are two distinct physical processes, although they are always simultaneously present and can interfere with each other. The transient response of the two processes are, however, different.
169 citations
TL;DR: This chapter provides an overview of the quantum–mechanical work done in conformation of amino acid residues of proteins with the double objective of comparing the results with those of the previous empirical computations and with the constantly and rapidly increasing amount of experimental data.
Abstract: Publisher Summary This chapter provides an overview of the quantum–mechanical work done in conformation of amino acid residues of proteins with the double objective of comparing the results with those of the previous empirical computations and with the constantly and rapidly increasing amount of experimental data. The most extensive applications have been in the field of proteins and their constituents, which exhibit the most significant conformational problems in biochemistry. The conformational properties of amino acid residues and polypeptides may be classified into three categories corresponding broadly to successive stages of development and refinement, and include—(1) empirical computations in the hard sphere approximation, (2) empirical computations in the partitioned potential energy approximation, and (3) quantum–mechanical computations. The best procedure, which allows the determination of the individual molecular orbitals, is the self-consistent field method. In the great majority of theoretical studies—whether empirical or quantum–mechanical—on the conformational properties of polypeptides, proteins, and their constituents the peptide bond has been considered as planar and trans; however, new developments in a number of directions have increased the interest of taking into consideration the possible nonplanarity of the peptide bonds.
164 citations
01 Mar 1974
TL;DR: The simplest fragment tested — the disaccharide tetrapeptide (I) — increases circulating antibodies to ovalbumin and induces a delayed hypersensitivity toward this antigen, indicating the immunoadjuvant activity of soluble cell wall peptidoglycans is a property of the monomeric unit and is not restricted to acid fast bacteria.
TL;DR: In this article, the free energy of dense fluids with permanent dipoles is computed through the Monte Carlo method with two types of intermolecular interaction: Stockmayer potential and hard-sphere potential with an added dipolar interaction.
Abstract: The free energy of dense fluids with permanent dipoles is computed through the Monte Carlo method with two types of intermolecular interaction: Stockmayer potential and hard-sphere potential with an added dipolar interaction. A comparison is made with the Pade representation recently proposed by Stell which is shown to be good. In the case of hard spheres with permanent dipoles we propose another equally successful perturbation theory, which is based on a partial resummation of the mixed perturbation theory first introduced by Lebowitz, Stell, and Baer. This perturbation theory is then applied to the general case of an interaction composed of a spherically symmetric two-body potential with permanent dipoles.
TL;DR: Comparison of experimental results with theoretical results derived from various postulated mechanisms, supports a “ping-pong” mechanism, involving the intermediate participation of a fructosyl-enzyme in the mechanism of action of levansucrase of Bacillus subtilis.
Abstract: The mechanism of action of levansucrase of Bacillus subtilis was investigated by initial velocity measurements of reactions catalyzed by this enzyme and initial velocity of isotopic exchange at equilibrium. Comparison of experimental results with theoretical results derived from various postulated mechanisms, supports a “ping-pong” mechanism, involving the intermediate participation of a fructosyl-enzyme. Rate constants for each step of this sequential mechanism were estimated.
TL;DR: It seems that the first fifteen days of life constitutes a critical or sensitive period during which the stimulation received by young worker from the cocoons has a powerful influence on the behaviour which it will later manifest as an adult.
Abstract: Young worker ants of the species Formica polyctena separated from the mother-colony on the day of hatching and reared in groups of 250 to 300 individuals will accept and care for the cocoons of a different species, even of a different genus (Formica sanguinea, F. pratensis, Camponotus vagus, and Lasius niger). If such a group of young workers has been in contact, during the first fifteen days of life, with cocoons of one or another of these species (and in the absence of cocoons of their own species) only cocoons of this same species are subsequently accepted and tended. Cocoons of their own species are not recognised as such but treated as food. Worker F. polyctena which have matured in the presence of cocoons of their own species devour those belonging to strange species. When cocoons are totally absent from their early environment the workers turn out to be incapable of tending the cocoon of any species, including their own kind. It thus appears that the first fifteen days of life constitutes a critical or sensitive period during which the stimulation received by young worker from the cocoons has a powerful influence on the behaviour which it will later manifest as an adult. This stimulation appears, indeed, to be an indispensible element in ontogenesis of the behaviour of caring for the cocoons. In the majority of the experimental colonies the "familiar" cocoons are still recognised after a six months period of hibernation, in the absence of all cocoons. It seems that the characteristics of this phenomenon, and those of a sensitive period and memorization in particular, are essentially those of Imprinting as described in various Vertebrates. An unusual aspect of the phenomenon however, which is related to the social structure existing among ants, is provided by the fact that the efficiency of the imprinting is increased by the presence of a queen amidst the cocoons during the sensitive period.
TL;DR: Results confirm previously reported studies indicating that CLL is a monoclonal proliferative disease and demonstrate that the CLL lymphocyte surface membrane bears, on the average, only 10% of the L chain determinants present on the normal lymphocyte.
TL;DR: The survival of the rho(+) factor and of Drug(R) mitochondrial genetic markers after exposure to ethidium bromide has been studied and hypotheses on the mechanism of petite mutation discussed.
Abstract: The survival of the ρ+ factor and of DrugR mitochondrial genetic markers after exposure to ethidium bromide has been studied. A technique allowing the determination of DrugR genetic markers among a great number of both grande and petite colonies has been developed. The results have been analyzed by the target theory. The survival of the ρ+ factor is always less than the survival of any DrugR genetic marker. The survivals of CR and ER are similar to each other, while that of OR is greater than that of the other two DrugR markers. All possible combinations of DrugR markers have been found among the ρ- petite cells induced, while the only type found among the grande colonies is the preexisting one. The loss of the CR and ER genetic markers was found to be the most frequently concomitant, while the correlation between the loss of the OR marker and the other two DrugR markers is less strong. Similar results have been obtained after U.V. irradiation. Interpretations concerning the structure of the yeast mitochondrial genome are given and hypotheses on the mechanism of petite mutation discussed.
TL;DR: The reaction mechanism of “Koelle's thiocholine method” and "Karnovsky's ferricyanide method" for the localization of acetylcholinesterase activity have been studied and some modifications for these two methods have been proposed.
Abstract: The reaction mechanism of “Koelle's thiocholine method” and “Karnovsky's ferricyanide method” for the localization of acetylcholinesterase activity have been studied. Some modifications for these two methods have been proposed.
TL;DR: In this paper, the Roy equations are applied to ππ phenomenology and the complete set of amplitudes consistent with these experiments and with the theoretical constraints of analyticity, crossing and unitarity are presented.
TL;DR: In this article, the elastic electromagnetic and weak form factors for nucleons, π and K mesons were studied and the experimental data as well as theoretical approaches were reviewed for these form factors.
TL;DR: In this article, the results of Mossbauer measurements on disordered b.c. and Fe-Co alloys are presented and it is shown that in these alloys the frequently used phenomenological expression H Fe = a μ Fe + b μ gives a very poor description because of the tendency of short-range ordering.
TL;DR: In this paper, the vibrational relaxation of n -H 2 has been studied in the interval 500 −40°K and the results show a marked departure from the high temperature Landau-Teller behaviour: the deexcitation rate becomes approximately constant for the lowest investigated temperatures.
TL;DR: In this paper, the Hartree-Fock model was used for the series CH4 to PbH4 within the spherically symmetric one-centre expansion approximation.
TL;DR: Mutants requiring threonine plus methionine (or homoserine), or threonines plus methIONine plus diaminopimelate (or HomoserineplusdiminopIMelate) have been isolated from strains possessing only one of the three isofunctional aspartokinases, and their mapping is described.
Abstract: Mutants requiring threonine plus methionine (or homoserine), or threonine plus methionine plus diaminopimelate (or homoserine plus diaminopimelate) have been isolated from strains possessing only one of the three isofunctional aspartokinases. They have been classified in several groups according to their enzymatic defects. Their mapping is described. Several regions of the chromosome are concerned: thrA (aspartokinase I-homoserine dehydrogenase I) is mapped in the same region as thrB and thrC (0 min). lysC (aspartokinase III) is mapped at 80 min, far from the other genes coding for diaminopimelate synthesis. metLM (aspartokinase II-homoserine dehydrogenase II) lies at 78 min closely linked to metB, metJ, and metF.
TL;DR: Differential games with stopping times are introduced in this paper, and the behavior of the value is studied as the coefficient of the diffusion matrix goes to zero, where the upper value satisfies a variational inequality of the first order.
TL;DR: In this paper, the energy loss spectra in the first series transition metals (Ti, V, Cr, Mn, Fe, Co, Ni) have been obtained by transmission of 35 keV electrons through thin films in the spectral range 2 to 120 eV.
Abstract: Energy loss spectra in the first series transition metals (Ti, V, Cr, Mn, Fe, Co, Ni) have been performed by transmission of 35 keV electrons through thin films (200 to 400 A) in the spectral range 2 to 120 eV. Experimental data processing enables to distinguish between single scattering volume losses and surface losses. Characteristic functions, such as the energy loss function, the complex dielectric constant, and the optical absorption coefficient are computed and compared with results obtained by different methods.
Ces spectres de pertes d'energie des metaux de transition de la premiere serie (Ti, V, Cr, Mn, Fe, Co, Ni) ont ete obtenus par transmission d'electrons rapides (35 keV) a travers des couches minces (200 a 400 A) sur un intervalle d'energie important (2 a 120 eV). L'analyse numerique des donnees permet de distinguer les pertes par diffusion unique en volume des pertes de surface. Certaines grandeurs caracteristiques de l'echantillon comme la fonction perte d'energie, la constante dielectrique complexe et le coefficient de photo-absorption en sont deduites et comparees avec des resultats obtenus par des methodes differentes.