Showing papers by "University of Paris published in 1971"

Galilei Group and Galilean Invariance

Abstract: Publisher Summary Galileo Galilei explicitly introduced the principle of relativity in physics. He was the first one to recognize the existence of inertial transformations, connecting various frames of reference in which the laws of physics take the same form. Starting with the recognition that the Galilean transformation laws were but an approximation to the more exact Lorentz formulas, one could distinguish the abstract principle of relativity from its concrete expressions, as various possible theories of relativity. At the same time, one could begin to see the basic role played by the relevant theory of relativity in structuring a given physical theory—Galilean relativity for classical mechanics, Einstein relativity for “relativistic” mechanics, and electromagnetism. Applications of the Galilei group are described for classical physics and for quantum physics. A “super-Galilei group” has been defined in relation to non-relativistic cosmology. This is a sixteen-parameter group acting on the five-dimensional manifold of space-time and gravitational potential.

Raman Study of Liquids. I. Theory of the Raman Spectra of Diatomic Molecules in Inert Solutions

Abstract: A theory is proposed to explain the Raman spectra of inert solutions of diatomic molecules; this theory can also be considered as an approximate theory of Raman spectra of pure liquids The theory is a stochastic-type theory related to similar theories of infrared and NMR spectra The vapor-solution band shifts are shown to depend on the difference between the solvent-solute interaction energies of the two vibrational states involved in the transition The analysis of the band profiles is made separately for the isotropic and anisotropic components, respectively, of a Raman spectrum The former spectrum is produced by vibrational relaxation mechanisms alone; the bands are all asymmetric although, in certain cases, the asymmetric perturbation is small enough to be neglected The latter spectrum is produced by both vibrational and reorientational relaxation mechanisms The theory predicts the existence of a continuous sequence of band forms comprising, among others, the profile with an $O\ensuremath{-}Q\ensuremath{-}S\ensuremath{-}$ type structure, the Lorentzian profile, the Gaussian profile, the Voigt profile, and several sorts of asymmetric profiles The resulting Raman spectrum appears as a superposition, with appropriate coefficients, of an isotropic and anisotropic spectrum A procedure is indicated permitting a separate study of vibrational and reorientational relaxation effects

Mechanism of the Electrocrystallization of Nickel and Cobalt in Acidic Solution

Abstract: This mechanism is studied by means of the analysis of the polarization characteristic and of the cathodic impedance. The results, obtained from an acidic solution of the Watts type, strongly support the hypothesis that the cathodic reaction occurs in several steps probably involving an adion . In the case of nickel, the results can be accounted for by a mechanism implying two successive transfer reactions in which acts as an intermediate compound and not as a catalyst. The presence in the electrolyte of either sodium benzenesulfonate or 2‐butyne 1,4‐diol (two inhibitors commonly used for the electrocrystallization of nickel) specifically modifies the kinetic parameters of transfer reactions and diminishes the capacity of the electrochemical double‐layer. This capacity is defined thanks to a least‐squares analysis of the cathodic impedance.

The H2S+ radical ion

Abstract: The emission spectrum between 4000 and 5000 A obtained by Horani, Leach and Rostas by controlled energy electron excitation of H2S is shown to belong to H2S+. The decrease and subsequent increase of the bending vibrational intervals in the A 2 A 1 state of H2S+ and D2S+ indicates a barrier to linearity of approximately 4600 cm-1. A preliminary rotational analysis of the spectrum leads to the following molecular parameters for the ground state: r 0″ = 1·358 A, valence angle 92° 54′. A detailed comparison of the optical and photoelectron spectra has been made and selection rules for the photoelectron spectra are presented. It is shown that in order to understand the vibronic patterns of both types of spectra it is necessary to consider in detail Renner-Teller vibronic interaction. A barrier to linearity in the 2 A 1 state of H2S+ alone is insufficient to account for the interesting change in the spectrum of the 2 A 1-1 A 1 transition at energies corresponding to the potential maximum.

On the reverse transition of a turbulent flow under the action of buoyancy forces

Abstract: Experiments were conducted in an ascending laminar flow through a vertical pipe under combined free and forced convection at constant heat flux through the wall.Mean velocity and temperature profiles were measured with a hot-wire probe. This velocity profile which is deformed by the buoyancy forces, enabled us to compute the reduced acceleration parameter. The profiles obtained showed that the value of the parameter at which reverse transition takes place is approximately the same as that found in isothermal boundary-layer flow. By measuring the autocorrelation function of the velocity after the reverse transition it was shown that the flow in the boundary layer becomes laminar as well as fluctuating and that it oscillates with a predominating period.

Reproductive biology and embryonic development of eledone cirrosa cephalopoda octopoda

Abstract: Analyses of bottom trawl samples and feeding experiments in the laboratory revealed a reproduction period ranging from late March to early August in Eledone cirrosa of the Catalonian Sea (Western Mediterranean). The embryonic development, studies for the first time on eggs laid in the laboratory, shows no basic difference from that of other Octopodidae. The newly hatched animals are planktonic; morphologically, this feature is expressed by a relatively small arm-length.

Multiple forms of duck-egg white lysozyme. Primary structure of two duck lysozymes.

Abstract: Lysozyme was purified from pooled samples of Peking, Kaki and “wild-type” duck eggwhites by gel filtration and ion-exchange chromatography on Amberlite CG-50. Two different lysozymes were found, called in relation with previous studies, duck-lysozyme II and ducklysozyme III. The enzymes were shown to be pure by several criteria. The complete primary structures of the two duck lysozymes were established. The reduced and alkylated enzymes were subjected to digestion with trypsin. The structures of all the tryptic peptides were established. For both lysozymes, alignment of the tryptic peptides into a single chain containing 129 amino acids was determined from basic overlap peptides obtained by digestion of the enzyme with chymotrypsin. Six replacements were noted between the two duck lysozymes. Further comparisons were achieved with hen egg-white and other lysozymes; the possibility of the existence of multiple alleles at one lysozyme locus is suggested for explaining the presence of multiple duck lysozymes.

Quantum mechanical study of the conformational and electronic properties of acetylcholine and its agonists muscarine and nicotine.

Abstract: The conformational and electronic properties of acetylcholine, muscarine, and nicotine have been investigated by the quantum mechanical method of perturbative configuration interaction using localized orbitals. The results obtained in the field of preferred conformations, in particular in the case of acetylcholine, are in satisfactory agreement with experimental observations based on X-ray data. The distribution of the net electronic charges indicates, among other conclusions, the nearly neutral character of the quaternary nitrogen, the distribution of a large fraction (70-80%) of the formal positive charge of this nitrogen on the surrounding alkyl groups, producing a large cationic globe, and the near equivalence of the net total negative charges on the 2 oxygen atoms of acetylcholine. Altogether, the results do not favor a primordial role played by changes of conformation in the interactions of acetylcholine with different cholinergic nerve receptors, although some such changes may occur because of the appreciable flexibility of this molecule. They point rather to the importance in this respect of the electronic characteristics of the molecule. Thus, the involvement of the cationic globe in interactions with all cholinergic nerve receptors and that of the carbonyl and ester oxygens of acetylcholine in interactions with the nicotinic and muscarinic receptors, respectively, seems plausible.

Vecteurs totalisateurs d'une algèbre de von Neumann

Abstract: We prove that the set of cyclic vectors for a von Neumann algebra in a Hilbert spaceH is aGδ set, which is empty or dense. We obtain some corollaries, for instance: if (A1,A2 ...) is a sequence of von Neumann algebras inH, and if eachAn has a cyclic vector and a separating vector, then there exists a vector inH which is cyclic and separating for eachAn. For algebras of local observables, we improve the known results connecting the infinite type of the algebras and the existence of cyclic and separating vectors.

Analytical-band centrifugation of an active enzyme-substrate complex. 2. Determination of active units of various enzymes.

Abstract: Through the use of the analytical active-enzyme-centrifugation method we have been able to measure the sedimentation coefficients of enzymes which have not yet been obtained in highly purified preparations: aspartate-semialdehyde dehydrogenase from Escherichia coli and from yeast and lactate dehydrogenase from rabbit muscle. We have also been able to determine unambigously the polymerization state of the fully active unit of β-galatosidase from E. coli, alcohol dehydrogenase from yeast as well as the polymerization state of the fully active unit of two enzymes which undergo an association-dissociation concentration-dependent reaction, glucose-6-phosphate dehydrogenase from yeast and glutamate dehydrogenase from beef liver (for this last enzyme the active-enzyme-centrifugation method has been applied with NAD, NADH, NADP and NADPH as coenzymes and also for its alanine dehydrogenase activity).

Passive immunotherapy of leukemia and other cancer.

Abstract: Publisher Summary Several experimental systems are used to study the possibilities of passive immunotherapy. In many studies, tumor cells are grafted and differ from the host by histocompatibility antigens. This chapter considers only those instances where the malignant cells are syngenic with the host so that rejection phenomena are caused by the presence of leukemia- or tumor-associated antigens. Aiding the natural defense of an organism in the rejection of a malignant disease by injecting circulating antibodies directed against the transformed cells is a simple idea that has led to numerous experiments and clinical trials. The presence in the primary host of circulating antibodies directed against tumor-associated antigens is demonstrated in animals. In the very special case of Burkitt's lymphoma, the presence of considerable amounts of circulating antibodies having cytotoxic activity in vitro against the lymphoma cells may be related to the occurrence of spontaneous regression in the disease. In tumor induced by the murine sarcoma viruses, it is shown that the injection of antiserum directed against the virus can reduce the number of takes and the growth rate of the tumors.