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Showing papers by "University of Montpellier published in 1981"


Journal ArticleDOI
01 Dec 1981-Nature
TL;DR: In the 1980 joint French-Chinese field expedition in Tibet, the area covered was from the High Himalaya in the south, to the region of Nagqu ∼250 km north of Yangbajain this article.
Abstract: Results are reported from the 1980 joint French–Chinese field expedition in Tibet. The area covered was from the High Himalaya in the south, to the region of Nagqu ∼250 km north of Yangbajain. Ophiolites in the Zangbo valley represent remnants of the crust of an ocean basin which lay adjacent to the Gangdise granodiorite belt in the late Mesozoic. The ophiolites were thrust to the south onto the Cretaceous melange and Triassic flysch but the age of this event is unclear. In the Tertiary, sediments of the Indian margin and the Xigaze basin were folded with steeply dipping cleavage, which indicates some north–south shortening of the crust. However, the Tertiary volcanic sequence on the Lhasa block and further north shows comparatively little folding and thrusting. In the Quaternary, deformation of Tibet was characterized by east–west extension.

273 citations


Journal ArticleDOI
TL;DR: As development progressed, cochlear potentials showed systematic changes in response parameters: the amplitude and threshold sensitivity of both CM and AP increased progressively with age as N1 latency decreased.
Abstract: The development of cochlear function was studied in 81 rat pups by recording the cochlear microphonic (CM) and the compound action potential (AP) from the round window in response to tone bursts and filtered clicks of various frequencies. The first electrophysiological response was the CM which could be obtained from 8- to 9-day-old animals. The AP first appeared at 11-12 days. As development progressed, cochlear potentials showed systematic changes in response parameters: the amplitude and threshold sensitivity of both CM and AP increased progressively with age as N1 latency decreased. All the parameters were within the adult range by the 15th day for the CM and by the 4th week for the AP. The results are discussed in relation to the developmental changes in the middle ear and to the morphological maturation of the organ of Corti.

185 citations


Journal ArticleDOI
TL;DR: The first submersible study of the East Pacific Rise was carried out by the French-American-Mexican project RITA (Rivera-Tamayo) as mentioned in this paper.
Abstract: A submersible study has been conducted in February–March 1978 at the axis of the East Pacific Rise near 21°N. The expedition CYAMEX, the first submersible program to be conducted on the East Pacific Rise, is part of the French-American-Mexican project RITA (Rivera-Tamayo), a 3-year study devoted to detailed geological and geophysical investigations of the East Pacific Rise Crest. On the basis of the 15 dives made by CYANA in the axial area of the Rise, a morphological and tectonic zonation can be established for this moderately-fast spreading center. A narrow, 0.6 to 1.2 km wide zone of extrusion (zone 1), dominated by young lava flows, is flanked by a highly fissured and faulted zone of extension (zone 2) with a width of 1 to 2 km. Further out, zone 3 is dominated by outward tilted blocks bounded by inward-facing fault scarps. Active or recent faults extend up to 12 km from the axis of extrusion of the East Pacific Rise. This represents the first determination from direct field evidence of the width of active tectonism associated with an accreting plate boundary. Massive sulfide deposits, made principally of zinc, copper and iron, were found close to the axis of the Rise. Other signs of the intense hydrothermal activity included the discovery of benthic fauna of gian size similar to that found at the axis of the Galapagos Rift. We emphasize the cyclic character of the volcanicity. The main characteristics of the geology of this segment of the East Pacific Rise can be explained by the thermal structure at depth below this moderately-fast spreading center. The geological observations are compatible with the existence of a shallow magma reservoir centered at the axis of the Rise with a half-width of the order of 10 km.

91 citations


Journal ArticleDOI
TL;DR: The functional correlates of the clear-cut anatomical distinctness between the two magnocellular neurosecretory systems are discussed.
Abstract: The distribution of labelled axonal pathways was studied after unilateral stereotaxic injection of 3H-leucine into either supraoptic (SON) or paraventricular nuclei (PVN). In addition to extrahypothalamic projections of both nuclei, the main efferents appeared to run towards the neurohypophysis, yet with a strikingly different pattern. At the neurohypophysial level, the SO-neurohypophysial tract crossed the inner layers of the median eminence (ME) before scattering in the neural lobe. The PV-neurohypophysial pathway, by contrast, provided an exclusive innervation to the external layer of the whole neurohypophysial organ, including the median eminence, infundibular stalk and neural lobe. The functional correlates of the clear-cut anatomical distinctness between the two magnocellular neurosecretory systems are discussed.

57 citations


Journal ArticleDOI
TL;DR: An association between Est-20.64 and Est-3A alleles was not observed in 19 (1.2%) of the 1599 mosquitoes analyzed, whereas it should have been found in nearly 400 (25%) individuals if the two loci were in equilibrium.
Abstract: Est-2 and Est-3 linkage disequilibrium was investigated in 43 natural populations. An association between Est-2 0.64 and Est-3 A alleles (or its reverse, Est-3 Null and alleles other than Est-2 0.64) was not observed in 19 (1.2%) of the 1599 mosquitoes analyzed, whereas it should have been found in nearly 400 (25%) individuals if the two loci were in equilibrium. This observation is discussed in relation to organophosphate resistance and genetic distance of the two genes.

43 citations


Journal ArticleDOI
TL;DR: It is concluded that mechanical overloading of the heart stimulates the synthesis of cardiac myosin 'isozyme' with a heavy-chain primary structure which is different from that observed in the normal heart of young rat.
Abstract: Heavy chains of myosin rods and subfragment 1 were isolated from normal hearts and from mechanically overloaded hearts of young and older rats. These myosin heavy-chain fragments were cleaved by cyanogen bromide or partially proteolysed by pronase and by chymotrypsin after denaturation with sodium dodecyl sulfate. The peptides, analyzed by electrophoresis on a one-dimensional polyacrylamide slab gel, varied depending on the origin of the cardiac myosin heavy chains. Some bands present in the peptide patterns of the normal heart of young rats were missing from the pattern of greatly hypertrophied hearts and vice versa. We conclude that mechanical overloading of the heart stimulates the synthesis of cardiac myosin ‘isozyme’ with a heavy-chain primary structure which is differen: from that observed in the normal heart of young rat. The patterns from myosin heavy-chain peptides from the hearts of older rats were different from those for peptides from young rat hearts; these results also indicate the presence of a new myosin heavy, chain specific to ageing. No difference was detected between the peptide patterns of heavy chains isolated from hypertrophied hearts of young and older rats, and those isolated from normal hearts of older rats.

37 citations


Journal ArticleDOI
TL;DR: In an attempt at establishing the ultrastructural characteristics of Cajal-Retzius cells defined classically by Golgi methods, neonatal mouse dorso-occipital cortex was prepared for a combined Golgi-EM investigation including 3-D computer reconstructions as discussed by the authors.

33 citations


Journal ArticleDOI
TL;DR: In this article, the antiepileptic drug valproic acid was extracted using solvent demixing, where an excess of some salt such as NaCl is added to a mixture of plasma and acetonitrile.

28 citations


Journal ArticleDOI
TL;DR: In water-deprived rats, the concentration of actin filaments is conspicuously increased along the axons and more clearly in the axonal swellings and endings, where they form a more complex and interconnected network.
Abstract: The ultrastructural organization of actin filaments was studied in the neurohypophysial system of the rat after heavy meromyosin (HMM) labeling. This structural pattern is characterized by (1) a straight arrangement of the filaments parallel to the axonal axis in the proximal nondilated parts of axons, (2) a central location within axonal dilatations, and (3) a higher concentration within axonal endings where the filaments form a complex three-dimensional network. The relationships of the filaments to other axonal structures and organelles was further studied by use of electron microscopic stereoscopy. The actin filaments frequently appear anchored to the axolemma with either polar arrangements of the arrowhead decoration (i) at structurally undifferentiated sites, and (ii) more particularly within perivascular endings, at sites with electron-dense thickenings. In all axonal divisions actin filaments are also found to bind to filamentous material surrounding the microtubules and to various organelles. Within the terminal portions of the axons actin filaments exhibit close relationships to neurosecretory granules and to the numerous smooth microvesicles found in this region. Such preferential relationships are particularly observed both in axon terminals and in pituicytes, with coated vesicles frequently binding actin filaments. In water-deprived rats, the concentration of actin filaments is conspicuously increased along the axons and more clearly in the axonal swellings and endings, where they form a more complex and interconnected network. These data are discussed in the light of a possible involvement of contractile proteins in the mechanisms of axonal transport and terminal release of neurosecretory products.

23 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that if the commutativity of the real algebra A is replaced by the weaker assumption that it is flexible, then A is still finite dimensional, but in this case A has dimension 1, 2, 4 or 8 and is isotopic to R, C, H or C.

20 citations


Journal ArticleDOI
TL;DR: Blinded female rats underwent additional midbrain raphe lesions, in order to explore the role of the raphe in the organization of endogenous circadian rhythms for ACTH, corticosterone (B) and motor activity (MA).

Journal ArticleDOI
TL;DR: In this article, the authors show the span of results which can be obtained by modeling a system's behavior by stochastic processes and demonstrate practical rules for employing Markov and semi-Markov models.
Abstract: This paper shows the span of results which can be obtained by modeling a system's behavior by stochastic processes and demonstrates practical rules for employing Markov and semi-Markov models. The introduction summarizes several methods for reliability analysis and gives the advantages and drawbacks of four methods: Markov processes, semi-Markov processes, supplementary variables, the method of stages. The remainder deals with reliability and availability modeling of a 2-unit redundant computer system. There are a) two types of maintenance: corrective (c. m.) and preventive (p. m.), and b) two system parameters: coverage, and an increased failure rate when one unit is under repair or inspection. Approximate expressions for reliability, mean time to failure, and asymptotic availability show the effects of the system parameters as well as of the shapes of the Cdf's of the times related to maintenance actions. For c.m., Markov modeling is a good approximation. For p.m., Markov modeling is a rough approximation; one can go to semi-Markov models or to the method of stages. Lastly, an approximate expression is given for the mean inspection interval which maximizes reliability and availability for p.m.


Journal ArticleDOI
TL;DR: In this article, sections of immature (postnatal day 5) mouse cerebral cortex were examined for several cell-type specific immunological markers, such as Glial Fibrillary acidic (GFA) protein or vimentin were detected in astrocytic cell processes.

Journal ArticleDOI
TL;DR: In this paper, an infra-red transmitting chalcogenide glass-ceramic nucleated by germanium selenide (GeSe2) was used to obtain a fracture toughness of 0.848 MN m−3/2, sag point of 530°C and satisfactory infra red transmission.
Abstract: The aim of this study was to produce an infra-red transmitting chalcogenide glass-ceramic nucleated by an appropriate nucleant. In order to crystallize chalcogenide glasses in a controlled manner a preliminary series of experiments, in which the metals of group IVB of the periodic table of elements were used as nucleants, showed that zirconium is an effective additive. Studies of glass compositionsxZrSe2-(100−x) [As0.1Ge0.3Se0.6] indicated that for values ofx 0.25 and 0.50 mol%, glass-ceramics with high thermomechanical properties were produced. By heat treating at 400° C for 15 h, the glass As0.1Ge0.3Se0.6 with 0.25 mol% ZrSe2 was transformed into a glass-ceramic with a fracture toughness of 0.848 MN m−3/2, a sag point of 530° C and satisfactory infra-red transmission. X-ray diffraction analysis revealed that the precipitated crystal phase was germanium selenide (GeSe2). The parasite absorption band with a maximum around 800cm−1 generally present in the infra-red spectra was eliminated by adding 0.1 wt% metallic zirconium. The infra-red transmision and thermomechanical properties for glass-ceramics of compositions with 0.50 mol% ZrSe2 were poorer than for those with 0.25 mol% ZrSe2, for the same heat treatment condtions. The kinetics and activation energies of crystallization were studied by means of electron microscopy. The mechanism of controlled crystallization proceeds by the precipitation of crystalline GeSe2 on the ZrSe2 nuclei formed by heat treatment of the initial chalcogenide glass supersaturated in ZrSe2.

Journal ArticleDOI
01 Jan 1981
TL;DR: In this article, the formation of liaison Si-O-Ti dans les gels de SiO2 -TiO2 and SiO 2 -P2 O5 is investigated.
Abstract: L'analyse structurale des gels et des verres des systemes SiO2 — TiO2 et SiO2 — P2 O5 a ete effectuee par spectroscopie Infra rouge et Raman. On a pu mettre en evidence la formation de liaison Si-O-Ti dans les gels de SiO2 — TiO2 . Cette liaison est caracterisee par une bande IR situee a 950 cm— 1 . Dans le cas des verres du systeme SiO2 — P2 O5 la spectroscopie Raman montre une bande d'absorption a 1140 cm— 1 caracteristique de la liaison Si — O — P. L'eau de structure des verres est analysee par spectroscopie IR en transmission. Il apparait que dans les verres SiO2 — P2 O5 les groupes hydroxyles se fixent preferentiellement sur l'atome de phosphore.

Journal ArticleDOI
TL;DR: The topographical variations in fiber size in the cochlear nerve of cat were quantitatively studied by electron microscopy and there are significant differences in fiber diameter with regard to their length for fibers derived from the apical turn.
Abstract: The topographical variations in fiber size in the cochlear nerve of cat were quantitatively studied by electron microscopy. Measurements of fiber size as they appeared at the outlet of the spiral lamina show that fibers originating from the basal part of the cochlea are larger than those from the apex. When the diameter of apical fibers and their axoplasms at two different levels are compared, a significant variation in size is observed. As they appear in the internal acoustic meatus the apical fibers are larger at the level of the nerve trunk compared with the same fibers near the ganglion cell bodies. There are significant differences in fiber diameter with regard to their length for fibers derived from the apical turn. These results are compared with previous findings.

Journal ArticleDOI
TL;DR: In neural lobes of Sprague-Dawley rats fixed with glutaraldehyde but without osmication, toluidine blue staining of semi-thin sections revealed two clear axon types: type I, highly stained, and type II, slightly stained.

Journal ArticleDOI
TL;DR: The parameters of the Mossbauer spectra, namely isomer shift, quadrupole splitting and linewidth were obtained before and after crystallization of glass samples of composition xSn0.5Se0.1Ge0.3Se 0.6 with x = 5 ∼ 30 mol as discussed by the authors.
Abstract: The parameters of Mossbauer spectra, namely isomer shift, quadrupole splitting and linewidth were obtained before and after crystallization of glass samples of composition xSn0.5Se0.5 (100x) (As0.1Ge0.3Se0.6) with x = 5 ∼ 30 mol.%. It is demonstrated that the higher the crystallinity, the more the isomer shift decreases, this is probably due to the variation of average SnSe bond length. An electric field imbalance in the Sn nucleus caused by distortion of (Sn Se6) octahedra in glasses showed a greater quadrupole splitting as compared with glass-ceramics of the same tin content.

Journal ArticleDOI
TL;DR: In this paper, the authors introduce a forme quadratique liee a la trace d'une extension algebrique finie, dont 1'invariant d'Arf est lie a un invariant introduit par E. Berlekamp.
Abstract: Soit K une extension algebrique finie de la trace permet d'associer a K une forme bilineaire symetrique sur K a valeurs rationnelles dont le discriminant est le discriminant du corps K. En tant que forme bilineaire, elle a ete etudiee par plusieurs auteurs ([3], [7], [11]). Dans cet article, nous retrouvons dans un cadre plus general, certains resultats etablis par ces auteurs et nous nous interessons plus particulierement au cas de la caracteristique 2; en effet, formes bilineaires symetriques et formes quadratiques different alors legerement. Nous introduisons done une forme quadratique liee a la trace d'une extension algebrique finie, dont 1'invariant d'Arf est lie a un invariant introduit par E. Berlekamp ([1]). Nous signalons aussi le cas des algebres centrales simples et de leur trace reduite.

Journal ArticleDOI
TL;DR: The 1H NMR spectra of a number of new derivatives of benzobicyclo[3.1]heptene were examined and interpreted by using a single set of coupling constants as mentioned in this paper.
Abstract: The 1H NMR spectra of a number of new derivatives of benzobicyclo[3.1.1]heptene were examined and interpreted by using a single set of coupling constants. All the compounds belonging to this system are in a γ-shaped configuration. Surprisingly, two different proton-proton spin-spin coupling constants (4J=5.5 to 6 Hz and 8.5 Hz) were obtained for the cyclobutane ring.

Journal ArticleDOI
01 Jul 1981-Steroids
TL;DR: It was found that testosterone stimulated CBG production in ducks without altering thyroxine levels.


Book ChapterDOI
01 Jan 1981
TL;DR: Die ambulante parenterale Ernahrung ist eine besondere Art der intravenosen ErnahRung, deren Realisierung dank technischer Fortschritte auf dem Gebiet der Infusionssysteme and neuer Konzeptionen der Nahrlosungen moglich wurde.
Abstract: Die ambulante parenterale Ernahrung ist eine besondere Art der intravenosen Ernahrung, deren Realisierung dank technischer Fortschritte auf dem Gebiet der Infusionssysteme und neuer Konzeptionen der Nahrlosungen moglich wurde [7]. Die Ziele der ambulanten parenteralen Ernahrung sind der Neuaufbau substantieller Bestandteile des Organismus, das Vermeiden einer exzessiven Fettsynthese und die Erhaltung des physiologischen Ernahrungszustands. So wird es moglich, durch Rehabilitation des muskulo-ossaren Systems den optimalen Ernahrungszustand zu erhalten.