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Showing papers by "Pierre-and-Marie-Curie University published in 1983"


Journal ArticleDOI
TL;DR: In this article, a constrained minimization method was proposed for the case of dimension N = 1 (Necessary and sufficient conditions) for the zero mass case, where N is the number of dimensions in the dimension N.
Abstract: 1. The Main Result; Examples . . . . . . . . . . . . . . . . . . . . . . . 316 2. Necessary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 319 3. The Constrained Minimization Method . . . . . . . . . . . . . . . . . . 323 4. Further Properties of the Solution . . . . . . . . . . . . . . . . . . . . 328 5. The \"Zero Mass\" Case . . . . . . . . . . . . . . . . . . . . . . . . . 332 6. The Case of Dimension N = 1 (Necessary and Sufficient Conditions) . . . . . 335 Appendix. Technical Results . . . . . . . . . . . . . . . . . . . . . . . . 338

2,385 citations



Journal ArticleDOI
01 May 1983-Nature
TL;DR: Pb and Sr isotopic compositions from the Indian Ocean (active ridges, old ocean floor and aseismic ridge samples) confirm the characteristic nature of the mantle record in this region as mentioned in this paper.
Abstract: Pb and Sr isotopic compositions from the Indian Ocean (active ridges, old ocean floor and aseismic ridge samples) confirm the characteristic nature of the mantle record in this region. The results emphasize the importance of mixing processes between the lower mantle (oceanic-island basalt source), and the upper mantle (ridge-basalt source). The isotopic characteristics of the Indian Ocean islands seem to be in agreement with the hypothesis of the reinjection of sediments into the mantle.

601 citations


Journal ArticleDOI
01 Jun 1983-Nature
TL;DR: The mobility of rare-earth elements (REE) and U during hydrothermal alteration of the basalts at spreading centres has long been a matter of concern because of its bearing on the evolution and recycling of the oceanic crust.
Abstract: The mobility of rare-earth elements (REE) and U during hydrothermal alteration of the basalts at spreading centres has long been a matter of concern because of its bearing on the evolution and recycling of the oceanic crust1–6. Previous approaches to this problem have been indirect, through studies on altered dredged basalts or ophiolites. We report here sampling of hydrothermal vent waters from the East Pacific Rise (EPR) at 13° N7,8, which provides the first direct evidence of REE-enriched solutions which, however, leave the budget of these elements in the crust and the ocean rather unmodified. In contrast, uranium, like magnesium, is quantitatively taken up from the seawater during the hydrothermal process.

492 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured the absorption and total scattering coefficients of four phytoplankton species grown in batch cultures and applied the Mie-Lorentz theory applied to polydisperse suspensions.
Abstract: Absorption and total scattering coefficients of four phytoplankton species grown in batch cultures were measured simultaneously. Backscattering coefficients were obtained by using an integrating sphere. These coefficients are transformed into specific coefficients, i.e. related to a unit of concentration in chlorophyll a, and also into dimensionless efficiency factors characteristic of the cells. The specific coefficients differ noticeably from one species to another. Total scattering and backscattering coefficients are clearly depressed near and inside the absorption bands. These minima can be interpreted by combining the theory of anomalous dispersion with Mie-Lorentz theory applied to polydisperse suspensions. The backscattering efficiency (ratio of backscattering to total scattering) of algal cells appears to be very low (typically ~0.1%). These different results must be taken into consideration when interpreting and modeling the optical properties of seawater, particularly ocean color. They also must be considered when modeling photosynthesis, since the variations in the light-harvesting ability of the cells intervene directly in the quantum yield estimate. The optical properties of natural waters depart from those of ideally pure water because of the presence, in variable amounts, of diverse dissolved and particulate substances. From an optical point of view, these can be considered as belonging to four groups: live algal cells; biogenous detritus associated with and deriving from these algae; terrigenous particles and resuspended sediment; and dissolved organic (yellow) substances. Of these, phytoplankton, as the only primary producer in the pelagic environment, is of particular interest. In addition, the algal cells and their debris predominantly determine the optical properties of the water in the open sea, away from land and bottom influence. Depending on the physiological state of the algae and on environmental conditions, primary production is effected through photosynthesis, with a varying yield. Such a yield, estimated on a quan

345 citations


Journal ArticleDOI
TL;DR: The evidence that retardation is a primary disturbance in affective disorders, that it is a core behavioral pattern and not merely a consequence of dysphoric mood is reviewed.

239 citations


Book ChapterDOI
01 Jan 1983
TL;DR: A panel of experts appointed to review the problem and make recommendations are presented here as recommendations that have been approved by IUPAC and IUB.
Abstract: Several conventions and notations for polynucleotide conformation have been used by various authors [1–9]. To overcome this confusion, the Joint Commission on Biochemical Nomenclature appointed a panel of experts to review the problem and make recommendations. Their proposals, together with suggestions from the members of JCBN and other scientists, are presented here as recommendations that have been approved by IUPAC and IUB.

165 citations


Journal ArticleDOI
TL;DR: On considere l'equation de Schrodinger suivante: (u t + Δu+uLog|u| 2 = 0 dans R×R N, on donne des resultats sur le comportement asymptotique des solutions as mentioned in this paper.
Abstract: On considere l'equation de Schrodinger suivante: (u t +Δu+uLog|u| 2 =0 dans R×R N . On donne des resultats sur le comportement asymptotique des solutions

155 citations


Journal ArticleDOI
TL;DR: In this paper, a microscopic model for the metal-solution interface is presented, which, for the first time, includes both a nonideal treatment of the metal and a molecular model for solution side.

106 citations


Journal ArticleDOI
TL;DR: In this paper, the non-Abelian Freedman-Townsend gauge tensor model is quantized in large class of covariant gauges using the geometrical reinterpretation of the BRS equations.

104 citations


Journal ArticleDOI
TL;DR: Remarques sur the theorie de Galois des equations differentielles pour les types forts d'un corps algebriquement clos.
Abstract: La communaute mathematique doit etre reconnaissante a Saharon Shelah pour une invention d'une ingenieuse simplicite, celle d'avoir associe a chaque structure M une structure Meq comprenant, outre les elements de M, des “elements imaginaires” qui sont virtuellement presents dans M. La finalite de cette construction est de pourvoir toute formule a parametres dans M, et meme dans Meq, d'un ensemble de definition minimum; tout cela est rappele dans la premiere section du present article.On peut a priori douter de l'utilite d'une construction si innocente, dont la propriete fondamentale est pratiquement evidente; et pourtant elle a ete abondamment montree par son auteur, a qui elle a permis, dans les theoremes de classification des modeles, une decomposition des types en elements simples, qu'on ne voit pas dans M.Cette construction d'un plus petit ensemble de definition pour une formule en rappelle une autre, qui est bien connue des algebristes, celle du corps de definition d'un ideal. Et comme la theorie des corps algebriquement clos de caracteristique donnee elimine les quanteurs, on a le sentiment que l'adjonction d'imaginaires aux modeles de cette theorie est inutile, en un mot qu'elle “elimine les imaginaires”; pour verifier le bien-fonde de ce sentiment, il convient d'abord de preciser ce qu'on entend par la, ce qui est fait dans la deuxieme section.

Journal ArticleDOI
TL;DR: In this paper, the authors consider the response of the metal in the ideally polarisable electrode to charging of the electrode, using a model for the metal surface in contact with the solvent of the electrolyte phase.

Journal ArticleDOI
TL;DR: In this paper, the kinetics of nickel electrocrystallization in strongly acidified chloride electrolytes and in electrolytes containing two additives: 2 butyne 1,4 diol and sodium benzenesulfonate (BS) were investigated.

Journal ArticleDOI
TL;DR: In this article, a quantitative study of the adsorption of diethylether on the three low-index faces (111, 100, and 110) of the gold electrode is presented.

Journal ArticleDOI
H. Gioanni1, J. Rey1, J. Villalobos1, D. Richard1, A. Dalbera1 
TL;DR: The anatomical and physiological data so far available consistently support the hypothesis of a functional equivalence between the nSS in birds and the nucleus of the optic tract in mammals.
Abstract: In birds, the accessory optic system (AOS) includes two nuclei: the nucleus ectomamillaris (nEM) and the pretectal nucleus superficialis synencephali (nSS) The role of the nSS in the production of a horizontal optokinetic nystagmus (OKN) was studied in the pigeon, by comparing the OKN before and after a unilateral lesion of this nucleus The lesions were performed either by electrolysis or by local application of kainic acid (KA); the KA lesions gave more stable modifications of the OKN than the electrolytic lesions A quantitative analysis of the slow-phase velocity (¯V) of the OKN was carried out on the animals receiving KA lesions (1) Lesion of the nSS provokes the almost total disappearance of the OKN for stimulation of the contralateral eye in the temporo-nasal direction, and a reduction of the OKN for stimulation in the nasotemporal direction Thus, the nSS is essential for the production of the OKN in the temporo-nasal direction, but it also participates in the production of the OKN in the naso-temporal direction (slow-phase direction) (2) The same lesion produces a large increase of the OKN (¯V) when the ipsilateral eye is stimulated in the temporo-nasal direction, and a smaller increase following stimulation in the naso-temporal direction These increases suggest some kind of inhibitory (or disfacilitatory) interactions between the nSS (or the associated system) on one side, and the contralateral optokinetic centers (3) The lesion of one nSS does not provoke a deficit when the stimulation is binocular This result probably reflects the combined effect of both monocular inputs (4) After a pretectal KA injection, a spontaneous nystagmus of the contralateral eye, in the nasotemporal direction, can be seen for several hours The mechanism is still unknown, but it might be rela2ted to a reverse optokinetic after nystagmus (ROKAN)

Journal ArticleDOI
TL;DR: In this paper, a phenomenological-thermodynamical model for the anomalous behavior of the flow of deformable macromolecules is presented, where the structural deformation is characterized by means of a quantity which may be a scalar, a vector or a tensor, and is considered as a so-called internal variable.

Journal ArticleDOI
TL;DR: Two categories of generators, forelimb or anterior locomotion generators (aLGs), and chemosensitive respiration generators (RGs) are both present in this part of the cord, on the one hand; interactions between RGs and pLGs are likely to be achieved via aLGs on the other.
Abstract: In addition to the wellknown fictive locomotion, a fictive respiration can also be obtained in decorticate, unanaesthetized rabbit preparations after curarization and vagotomy.

Journal ArticleDOI
TL;DR: It is concluded that the oxidative metabolism of arachidonic acid is involved in the induction of chromosomal aberrations by PMA in human lymphocytes and the step(s) in the arachIDonic acid cascade responsible for PMA clastogenicity is not yet identified.
Abstract: To gain insight into the mechanism of formation of chromosomal aberrations by the tumor promoter phorbolmyristate acetate (PMA) in human lymphocytes, we investigated the effect of antioxidants and inhibitors of arachidonic acid metabolism. Among the antioxidants bovine erythrocyte CuZn superoxide dismutase, glutathione peroxidase, mannitol (a scavenger of hydroxyl radicals), butylated hydroxytoluene and butylated hydroxyanisole were anticlastogenic while catalase and dimethylfuran (a scavenger of singlet oxygen) were inactive. These results show that the induction of aberrations by PMA occurs via indirect action, i.e. the intermediacy of superoxide and hydroxyl radicals. The following inhibitors of arachidonic acid metabolism were strongly anticlastogenic: the cyclo-oxygenase inhibitors indomethacin and flufenamic acid and the lipoxygenase inhibitor BN1015. Imidazole, nordihydroguaiaretic acid BN 1048 and 5,8,11,14-eicosatetraynoic acid were moderately active. The inhibitor of phospholipase A 2 , fluocinolone acetonide, was also anticlastogenic. We conclude that the oxidative metabolism of arachidonic acid is involved in the induction of chromosomal aberrations by PMA in human lymphocytes. However, because of the limited selectivity of these drugs, it is not yet possible to identify unambiguously the step(s) in the arachidonic acid cascade responsible for PMA clastogenicity.

Journal ArticleDOI
TL;DR: It is proved that every planar graph can be represented by horizontal segments corresponding to vertices and vertical segments correspondingto edges in such a way that no crossing appears.

Journal ArticleDOI
TL;DR: TEM examinations of cross-sectioned Ni electrodeposits grown on oriented substrates show that their structure results of a competition between an epitaxial growth process and a non-epitaxial growing initiated by a substrate independent nucleation as discussed by the authors.

Journal ArticleDOI
01 Jan 1983-Nature
TL;DR: In this article, a multiple tilted "packs of cards" model was proposed for normal faults in which rotational deformation within the major blocks is accommodated by normal faulting on previously formed tension fractures, thus defining smaller blocks of second and third generation.
Abstract: A characteristic pattern of normal faults that we have studied in several regions illustrates successive geometries relating to increasing amounts of extension from 10–50% (Gulf of Suez, Egypt) to 50–100% (Western Gulf of California, Mexico) up to 200% (Southern Basin and Range, USA). Tension fractures formed at an early stage of extension have an essential role. The resulting structure is described as a multiple tilted "packs of cards" model in which rotational deformation within the major blocks is accommodated by normal faulting on previously formed tension fractures, thus defining smaller blocks of second and third generation.

Journal ArticleDOI
TL;DR: In this paper, mixed-valence vanadium pentoxide gels have been obtained by polymerization of vanadic acid and they exhibit semiconducting properties which arise from electron hopping between VIV and Vv ions.
Abstract: Mixed-valence vanadium pentoxide gels have been obtained by polymerization of vanadic acid. They exhibit semiconducting properties which arise from electron hopping between VIV and Vv ions. Such gels can easily be deposited onto a substrate, giving layers of high electrical conductivity (σ =0.l Ω−1 cm−1 at 300 K). Their electrical properties can be described by the small-polaron model, and the main parameters have been determined by conductivity measurements, E.S.B. and optical spectroscopy. The optical and thermal activation energies are found to be E opt = 0.87 eV and Eth = 0.17eV. The transfer integral J = 0 05 eV is quite small, and the electron–phonon coupling parameter γ = 14 is rather high. The structural disorder of this amorphous semiconductor was estimated from electrical and E.S.R. experiments. It leads to a localization of the charge carriers.

Journal ArticleDOI
TL;DR: Comparison of the two yeast r1-introns with equivalent introns of N. crassa and A. nidulans mitochondria reveals that introns with very similar RNA secondary structures can accommodate different types of ORFs.
Abstract: We have screened numerous different yeast species for the presence of sequences homologous to the intron of the mitochondrial 21S rRNA gene of Saccharomyces cerevisiae (intron r1) and found them in all Kluyveromyces species, some of the Saccharomyces species and none of the other yeasts tested. We have determined the nucleotide sequence of the r1-intron in K. thermotolerans and compared it with that of S. cerevisiae. The two introns are inserted at the same position within the 21S rRNA gene. They contain homologous internal open reading frames (ORFs) initiated at the same AUG codon which can be aligned over their entire length. Several silent multi-substitutions indicate that these intronic ORFs represent selectively conserved functional genes. Other intron segments, on the contrary, reveal short blocks of extensive homology separated by non-homologous stretches and/or additions-deletions. Comparison of our two yeast r1-introns with equivalent introns of N. crassa and A. nidulans mitochondria reveals that introns with very similar RNA secondary structures can accommodate different types of ORFs.

Journal ArticleDOI
TL;DR: In this article, the authors measured the Brillouin scattering from the liquid under hydrostatic pressure up to 30 GPa, and derived Elastic moduli derived from the frequency shifts with bulk modulus values obtained from compressibility data.
Abstract: Brillouin scattering from ${\mathrm{H}}_{2}$O under hydrostatic pressures up to 30 GPa is reported. Sound velocities in the liquid region agree with previous ultrasonic measurements and discontinuities are observed at the liquid---ice VI and ice VI---ice VII phase transitions. Elastic moduli derived from the frequency shifts are compared with bulk modulus values obtained from compressibility data.

Journal ArticleDOI
01 Jan 1983-Nature
TL;DR: A review of modern radiometric dates for the Precambrian-Cambrian boundary is presented in this article, which is consistent with a considerably younger age for the boundary than previously accepted.
Abstract: Although the base of the Phanerozoic is an important date in the history of life and of the Earth's crust, few conclusive data have been available to estimate the numerical age of this boundary Accurate and reliable modern data now exist, however, and those relevant modern radiometric dates are summarized in this review and are shown to be consistent with a considerably younger age for the Precambrian–Cambrian boundary than previously accepted

Journal ArticleDOI
TL;DR: The spatial and temporal distribution of extracellular matrix was studied during pre- and perinatal ontogenesis of normal and reeler mutant mice to suggest that the major components are glycosaminoglycans and their possible role in relation to afferent axon targeting is discussed.

Journal ArticleDOI
TL;DR: The D'Entrecasteaux Zone (Southwest Pacific) is an arched submarine horst-and graben structure, which extends from the northern end of the New Caledonia ridge to the western border of the new Hebrides island arc.

Journal ArticleDOI
TL;DR: The absolute energy of the Lyman $\ensuremath{\alpha}$ lines of hydrogenlike ions has been measured and the value of the Lamb shift of argon evaluated for the first time as mentioned in this paper.
Abstract: The x-ray transitions ($n=2\ensuremath{\rightarrow}n=1$) emitted by fast hydrogenlike and heliumlike argon ions have been studied. The absolute energy of the Lyman $\ensuremath{\alpha}$ lines of hydrogenlike ions has been measured and the value of the ($1s$) Lamb shift of argon evaluated for the first time. The $^{3}P_{1,2}$ and $^{1}P_{1}$ transitions of heliumlike argon have also been studied at very high precision and their energies compared to multiconfiguration Dirac-Fock calculations. The energies of Lyman $\ensuremath{\alpha}$ lines are of 3323.2\ifmmode\pm\else\textpm\fi{}0.5 eV ($\mathrm{Ly}{\ensuremath{\alpha}}_{1}$) and 3318.1\ifmmode\pm\else\textpm\fi{}0.5 eV ($\mathrm{Ly}{\ensuremath{\alpha}}_{2}$), and those of $n=2\ensuremath{\rightarrow}n=1$ transitions for heliumlike argon are of 3123.6\ifmmode\pm\else\textpm\fi{}0.25 eV ($^{3}P_{1}$), 3126.4\ifmmode\pm\else\textpm\fi{}0.4 eV ($^{3}P_{2}$), and 3139.6\ifmmode\pm\else\textpm\fi{}0.25 eV ($^{1}P_{1}$).

Journal ArticleDOI
TL;DR: Efferents originating from the rat medial prefrontal cortex and projecting to diencephalic and mesencephalic structures were analyzed electrophysiologically and it was estimated that a large proportion of the prefrontal cells which project to a given subcortical structure also innervate one or two other sub cortical areas.
Abstract: Efferents originating from the rat medial prefrontal cortex and projecting to diencephalic and mesencephalic structures were analyzed electrophysiologically. The antidromic activation technique was used in order to identify cortical neurons which innervate the medio-dorsal nucleus of the thalamus (MD), lateral habenula, ventro-medial mesencephalic tegmentum (VMT), substantia nigra (SN), superior colliculus (SC) and central gray (CG). Corresponding cortical neurons, found mainly in layers V and VI, were distributed in the rostro-caudal extension of the medial prefrontal cortex. Their conduction velocities were relatively slow and ranged between 0.4 and 5.5 m/s. The reciprocal collision test allowed us to determine whether a given cortical neuron innervated only one structure or whether it sent axon collaterals to other subcortical areas. Twelve patterns of axonal branching were established: MD-VMT, MD-SN, MD-SC, VMT-SN, VMT-SC, VMT-CG, SN-SC, habenula-VMT, habenula-CG, MD-SN-SC, VMT-SN-SC and VMT-habenula-CG. Finally, it was estimated that a large proportion of the prefrontal cells which project to a given subcortical structure also innervate one or two other subcortical areas. Results are discussed in the light of anatomical data and their functional significance.

Journal ArticleDOI
TL;DR: In this article, a method of determining the form of the hypothetical gravitational Lagrangianf(R) replacing the Einsteinian LagrangiansR in order to avoid the singularity in cosmological solutions is discussed.
Abstract: We discuss a method of determining the form of the hypothetical gravitational Lagrangianf(R) replacing the Einsteinian LagrangianR in order to avoid the singularity in cosmological solutions. Instead of supposing some form off(R) and then trying to solve the generalized Einstein equations, we treatf(R) as an unknown function while inserting the cosmological solution coinciding with Friedmann solution everywhere except for the singularity, which is replaced by a regular minimum of the scale factora (t) (a regular maximum of curvature). Then we findf(R) by numerical integration. The Lagrangians thus obtained for different cases (k=0, ± 1, and with the equation of state corresponding to pure radiation) have some common properties, among which ¦f(R)¦ < ¦R¦ (concavity), and the absence of asymptotes.