Showing papers by "University of Grenoble published in 1987"

Combined (thalamotomy and stimulation) stereotactic surgery of the VIM thalamic nucleus for bilateral Parkinson disease.

Abstract: Stereotactic thalamotomy of the thalamic nucleus ventralis intermedius (VIM) is routinely used for movement disorders. During this procedure, it has been observed that high-frequency (100 Hz) stimulat

A method for applied ecological studies of fluvial hydrosystems

Abstract: The hydrosystem of the Rhǒne River, France, is considered in 3 dimensions: the upstream-downstream progression, the transversal dimension (main stream, side-arms, marshes, flood plain and their interconnections), and the vertical dimension (relationships between epigean and ground waters). Emphasis is placed on the temporal dimension, which considers changes in the river's dynamics, and on the development of its ecosystems over several centuries. Analyses were performed on different spatial scales; the definitions of functional sectors, functional sets and functional units are based on a combination of geomorphic patterns, fluvial dynamics and ecological processes. Synchronic and diachronic analyses were carried out using functional describers (granulometry and organic content of sediments, floral and faunal communities). These studies deal mainly with the distrubed hydrosystems of regulated rivers. The changes of the ecological successions are focused on after reference to natural models and the reconstitution of ancient human disturbances. Predictive scenarios are proposed to promote ecological management of the alluvial plains in the event of hydroelectric development.

PAC, an Object Oriented Model for Dialog Design

Abstract: PAC is an implementation model that attempts to bridge the gap between the abstract sphere of theoretical models and the practical affairs of building user interfaces. It takes as a basis the vertical decomposition of human-computer interaction into semantic, syntactic and pragmatic layers as promoted by some theoretical models. However, PAC stresses the fact that these notions do not form strict monolithic layers but are distributed across related “chunks”, called interactive objects. For doing so, PAC recursively structures an interactive application in three parts: the Presentation, the Abstraction and the Control. The Presentation defines the the concrete syntax of the application whereas the Abstraction corresponds to the semantics. The Control maintains the mapping and the consistency between the abstract entities and their presentation to the user. The Presentation of an application is in turn decomposed into a set of interactive objects, entities specialized in man-machine communication. As for applications, an interactive object is organized according to the PAC model. PAC has been used for the construction of two interactive applications and is currently applied to the development of a User Interface Management System.

Coalescing of geostrophic vortices

Abstract: Close interactions between pairs of two-dimensional vortices of like sign were investigated in experiments with barotropic vortices and baroclinic vortices. The vortices were generated by sources or sinks in a rotating fluid which, respectively, was homogeneous or contained a two-layer density stratification. For two identical anticyclonic, unstratified vortices there was a critical separation distance beyond which the vortices coalesced to form a single larger anticyclone. The critical distance d*, scaled by the radius R of a core having non-zero relative vorticity, was d*/R = 3.3 ± 0.2. This value is in agreement with results of previous numerical simulations for finite-area vortices in non-rotating flows. The effects on vortex structure of Ekman pumping due to the presence of a rigid boundary caused cyclonic vortices to coalesee from larger distances. Baroclinic vortices in a two-layer stratification were also found to coalesce despite a potential-energy barrier. However, the critical separation distance depended on the internal Rossby radius. When the Rossby radius was large compared with the core radius, vortices coalesced from distances much greater than the critical distance for barotropic vortices. Coalescing of two vortices of equal size and strength led to two symmetric entwined spirals of water, while close interaction of unequal vortices caused the weaker vortex to be wrapped around the outer edge of the stronger. Implications of these results are discussed for ocean eddies and intense atmospheric cyclones.

Variable latencies of noisy signals: Estimation and testing in brain potential data

Abstract: SUMMARY The electric response of the brain related to some event, i.e. stimulus, is usually estimated by repeated stimulation and subsequent averaging of the activity recorded time-locked to the stimulus. The present paper deals with the model that the single responses may have varying latency, i.e. arrival time, after stimulus onset. For estimating the single latencies, a maximum likelihood approach employing iterative Fisher-scoring is developed. Further a statistic for testing on the presence of latency variation is derived. Simulations and real data applications are discussed.

Endosymbiotic origin and codon bias of the nuclear gene for chloroplast glyceraldehyde-3-phosphate dehydrogenase from maize.

Abstract: The nuclei of plant cells harbor genes for two types of glyceraldehyde-3-phosphate dehydrogenases (GAPDH) displaying a sequence divergence corresponding to the prokaryote/eukaryote separation. This strongly supports the endosymbiotic theory of chloroplast evolution and in particular the gene transfer hypothesis suggesting that the gene for the chloroplast enzyme, initially located in the genome of the endosymbiotic chloroplast progenitor, was transferred during the course of evolution into the nuclear genome of the endosymbiotic host. Codon usage in the gene for chloroplast GAPDH of maize is radically different from that employed by present-day chloroplasts and from that of the cytosolic (glycolytic) enzyme from the same cell. This reveals the presence of subcellular selective pressures which appear to be involved in the optimization of gene expression in the economically important graminaceous monocots.

Introduction to the Invariant Formulation of Anisotropic Constitutive Equations

Abstract: The aim of this Chapter is to present some elementary notion for non-specialists in the invariant formulation of anisotropic constitutive equations. Much of this Chapter is taken from [1].

Nombres de Lelong généralisés, théorèmes d'intégralité et d'analyticité

Abstract: Let X be a Stein space and T a closed positive current on X . Given any continuous plurisubharmonic exhaustion function φ on X , a generalized Lelong number ν(T, φ) is introduced, using Monge-Ampère operators defined by Bedford and Taylor. It is shown that the number ν(T, φ) depends only on the behaviour of the function φ near its poles. As a consequence, we derive a very simple proof of Thie’s theorem on the integrality of classical Lelong numbers for analytic subsets, as well as a generalized version of Siu’s theorem on the analyticity of the level sets associated to Lelong numbers.

Physics and Chemistry of Interstellar Polycyclic Aromatic Molecules

Abstract: The properties and the behaviour of polycyclic aromatic molecules (PAH, mainly hydrocarbons with 20–100 carbon atoms) are discussed in different interstellar environments. Their charge is regulated by the same mechanisms as that of interstellar grains. However, it is mainly limited in practice to a single elementary charge, positive or negative; several states of charge very often coexist. In molecular clouds their large polarizability and photodetachment are important in determining their charge. In dense clouds they can play an important role in the ionization by bearing a significant fraction of the negative charge and as a sink for molecular and especially atomic positive ions. Their temperature is not well defined when their internal energy Ei is small, because the low density of energy levels prevents an efficient energy redistribution; however, the latter is achieved when Ei >2 0.1 eV. They remain in their ground vibrational level most of the time between high temperature spikes following absorption of UV or visible photons, ion recombination or other reactions with gas. particles. The rate of photolysis of different atoms is estimated by the theory of molecular reactions and their lifetime in interstellar radiation fields is evaluated. Direct photolysis of H atoms can be important. Their periphery is probably often not completely saturated by H atoms; they therefore can contain radical sites, and possibly hetero-atoms and non hexagonal cycles. Physisorption on the lattice surface is probably unimportant; chemisorption there and hence of sticking of gas particles is uncertain. The main reactions with the gas are accretion of atoms on peripheral radical sites, and reactions with positive ions. C+ can lead both to condensation or to sputtering. The generation, growth and destruction mechanisms are discussed. PAH’s with less than ∿ 20 carbon atoms are photolysed by UV radiation. Larger ones are mainly destroyed in shocks and in the hot gas on time scales of about a few 108 years comparable to those of grains. One possible generation mechanism is by cleavage of carbon grains from grain-grain collisions in moderate shocks. The possibility of synthesis from small carbon molecules is also discussed. Growth by accretion of gas particles, mainly C+, can be relatively fast, if condensation is more important than sputtering in C+ reactions. Accretion onto grains in molecular clouds is slowed by the negative charges; it proceeds at a rate comparable to that of grain coagulation. Desorption of accreted PAH’s is probably efficient in moderate shocks.

Coherent baroclinic eddies on a sloping bottom

Abstract: A coherent and stable baroclinic eddy in a rotating fluid was produced on a sloping bottom by releasing a dome of salt water into the ambient fresh water. A strong cyclonic vortex is produced above the heavy dome. The entire eddy system moves ‘north-westward’ (with the up-slope direction designated ‘north’) as a ‘Taylor column’. The eddy system displays long lifetimes, but it is shown that a theory of isolated systems cannot account for the experimental observations. Instead, it is demonstrated that the vortex flow above the lens is along the lines of constant depth, producing a net pressure force on the lens, which approximately balances the buoyancy force. When Ekman friction is also included, it accounts for the northward motion of the dome.

Chromosome analysis of spermatozoa from a male heterozygous for a 13;14 Robertsonian translocation

Abstract: Cytogenetic analysis of 78 spermatozoa from a man heterozygous for a t(13;14) Robertsonian translocation was performed. R banding was applied for chromosomal identification. Incidence of normal and balanced complements were respectively 50% and 41.3%. Six unbalanced complements (7.7%) were observed, resulting from adjacent segregation. Although alternate segregation is the most common mode of distribution, the possibility of producing unbalanced zygotes exists. The frequency of abnormalities unrelated to the translocation was 16.5% including 12.8% hypohaploidy, 2.5% hyperhaploidy, and 1.2% of structural aberrations. An excess of t(13;14) X complements was observed (24 with X versus 14 with Y). This may result from the close association between trivalent (13;14) and X chromosome observed in the pachytene spermatocyte nucleus.

Representations for Isotropic and Anisotropic Non-Polynomial Tensor Functions

Abstract: Material symmetries of a continuum impose definite restrictions on the form of constitutive relations. The restrictions are specified in the representations of isotropic and anisotropic tensor functions and indi­cate the type and the number of independent variables involved in a cons­titutive relation. Thus, in a properly written constitutive equation, the material symmetries are automatically verified.

The United Nations Convention against Torture and other Cruel, Inhuman or Degrading Treatment or Punishment

Abstract: General Introduction On 16 and 17 November 2004 the United Nations Committee against Torture met in Geneva to examine Argentina’s fourth periodic report (CAT/C/55/Add.7) on the implementation of the Convention against Torture and Other Cruel, Inhuman or Degrading Treatment or Punishment by the State of Argentina, at its 622 nd and 625 th meetings. Conclusions and recommendations were subsequently adopted by the Committee (CAT/C/CR/33/1).

Relations between the plastid gene dosage and the levels of 16S rRNA and rbcL gene transcripts during amyloplast to chloroplast change in mixotrophic spinach cell suspensions.

Abstract: Spinach cell suspension cultures maintained in photomixotrophic conditions exhibit plastids which undergo cyclic morphological transformations along a growth cycle. Ultrastructural studies show that the green chloroplasts present at the initial stage differentiate into amyloplasts during the subsequent log phase and then return to chloroplasts in stationary phase. The changes of the levels of plastid DNA (pt DNA) per cell have been determined along the growth cycle, as a percentage of total DNA by hybridization of definite amounts of total DNA to a radioactive probe of cloned pt DNA. The number of pt DNA copies have been estimated to 1125 per cell at the maximum of amyloplast development and to 5940 copies per cell at the maximum of chloroplast differentiation. Hybridizations of defined amounts of total cellular RNA to labelled probes of the 16S rDNA and of the rbcL gene allowed estimations of the variations of the corresponding cellular RNA pools. These variations are well correlated with the changes of the ptDNA cellular levels. These results show that the ptDNA gene dosage plays a central role in the regulation of the plastid transcript levels in this system.

In vitro transcription initiation of the rDNA operon of spinach chloroplast by a highly purified soluble homologous RNA polymerase

Abstract: Two promoters, Pl and P2, have been identified upstream of the structural gene for the 16S rRNA in spinach chloroplasts (Lescure et al. 1985). A highly purified soluble spinach chloroplast RNA polymerase is shown to initiate correctly in vitro the transcription of the ribosomal DNA operon of spinach chloroplasts at the PI promoter. The P2 promoter is used only by the E. coli RNA polymerase either in vivo or in vitro. However, the P1 promoter is used at a higher frequency than the P2 promoter by the heterologous system. Both promoters appear to be used more efficiently if the DNA template is in a supercoiled form. The P2 promoter is not used in vivo in chloroplasts even if the processing of RNAs is blocked by using lincomycin.

An orthogonal systolic array for the algebraic path problem

Abstract: This paper is devoted to the design of an orthogonal systolic array ofn(n+1) elementary processors which can solve any instance of the Algebraic Path Problem within only 5n−2 time steps, and is compared with the 7n−2 time steps of the hexagonal systolic array of Rote [8].

The Association Isoflurane-verapamil Causes Regional Left-ventricular Dyssynchrony in the Dog

Abstract: In ten dogs anesthetized with 1% inspired isoflurane, the effect of low-dose verapamil on global and regional myocardial function was studied. The administration of verapamil resulted in no change in heart rate or blood pressure, but left ventricular stroke work, peak power, LV dP/dt max, and aortic blood acceleration were significantly reduced, while coronary blood flow remained unchanged. End-diastolic length increased in territory supplied by both left anterior descending (LAD) and left circumflex (LC) artery, but a significant decrease in systolic shortening occurred in the LAD segment only. Dyssynchrony of wall motion, characterized by post-systolic shortening, accompanied in three animals by a small amount of systolic lengthening, appeared with the administration of verapamil and was more pronounced in the LAD segment. Such patterns of wall motion have usually been attributed to myocardial ischemia. In the absence of significant reduction in coronary blood flow, and in the presence of a delay in onset of shortening and lengthening, these patterns of wall motion are more likely to reflect dyssynchrony of regional function than ischemia.

Structure and transcription of the 5S rRNA gene from spinach chloroplasts.

Abstract: The nucleotide sequence of the spinach chloroplast 5S rRNA gene and its flanking regions has been determined. A prokaryotic type promoter is to be found upstream of the 5S rRNA gene. Northern blot experiments with selected gene probes show that the 5S gene is co-transcribed with the other ribosomal genes of the operon. This result is confirmed by 5′ S1 mapping of in vivo RNAs synthesised in chloroplasts or in an E. coli strain harboring a mutlicopy plasmid containing the 5S rRNA gene and its flanking regions. In vitro transcription experiments show that initiation of transcription does not occur at the level of the putative 5S rRNA gene promoter. Therefore, we conclude that the 5S rRNA is synthesized only be co-transcription of its gene with the other ribosomal genes of the operon. 3′ S1 nuclease mapping in the spacer region between the 4.5S and the 5S rRNA genes reveals a set of protected fragments located in an A.T rich region downstream of a very stable hairpin and immediately upstream of the putative 5S promoter. This result is interpreted by the presence of preterminated transcripts or processing sites in this region.

Correction to “An equivalence between relational database dependencies and a fragment of propositional logic”

Abstract: According to the definition of satisfaction of Boolean dependencies, Theorem 15 is not true for Boolean dependencies with negation. (A positive Boolean dependency is built using the Boolean connectives c, c, and n; a general Boolean dependency (with negation) may use also the Boolean connective ¬.) Actually, the definition of satisfaction is not meaningful for Boolean dependencies with negation, since many are never satisfied. We show how the definition of satisfaction should be changed in order to make Boolean dependencies with negation meaningful and correct the error.We associate with each relation r a set a(r) of truth assignments, as follows. For each pair of distinct tuples of r, the set a(r) contains the truth assignment that maps an attribute A to true if the two tuples are equal on A, and to false if the two tuples have different values for A. A Boolean dependency s is satisfied by a relation r if s (i.e., the corresponding Boolean formula) satisfies every truth assignment of a(r).The original definition given in the paper is equivalent to having a(r) also include the truth assignment that is generated by pairs in which both tuples are really the same tuple of r, that is, to having a(r) also always include the truth assignment t mapping all attributes to true. Under that definition, however, many Boolean dependencies with negation are never satisfied and, hence, are meaningless. More precisely, according to the original definition, a Boolean dependency is satisfied by

On the effects of a midocean ridge on the general circulation: numerical simulations with an eddy-resolved ocean model

Abstract: High resolution ocean general circulation model experiments were carried out to investigate the effects of a midocean ridge on the eddy field and the mean circulation on the basin scale. A quasigeostrphic two-layer model was used. Long term statistics were computed for a detailed comparison with the flat bottom case. An eddy-driven anticyclonic gyre, locked over the topography, appears as a new feature of the deep circulation pattern. The eddy energy radiation in both layers is strongly constrained by the topography. Insofar as surface currents are concerned, the ridge acts, to a limited extent, as a new western boundary for the eastern basin.

Immunofluorescent localization of collagen types I, III and IV, fibronectin, laminin, and basement membrane proteoglycan in developing mouse skin.

Abstract: The distribution of various extracellular matrix components was studied in frozen sections of embryonic (14–18 days) and early postnatal (birth and 4 days post parturn) dorsal mouse skin using monospecific antibodies and indirect immunofluorescence. Basement membrane zone components — type IV collagen, laminin and heparan sulphate proteoglycan — were found to be uniformly and unchangingly distributed along the dermal-epidermal junction. In contrast, the distribution of interstitial matrix components — types I and III collagen, and fibronectin — was heterogeneous and varied with the stages of hair development. Collagens became sparse and were eventually completely removed from the prospective dermal papilla and from a one-cell-thick sheath of dermal cells around hair buds. They remained absent from the dermal papilla throughout hair organogenesis. Fibronectin was always present around dermal papilla cells and was particularly abundant along the dermal-epidermal junction of hair rudiments, as well as underneath hair buds. In contrast, in interfollicular skin, collagens accumulated in increasing density, while fibronectin became progressively sparser. It thus appears that interstitial collagens and fibronectin are distributed in a manner which is related to hair morphogenesis. In morphogenetically active regions, collagen density is low, while that of fibronectin is high. Conversely, in histologically stabilized zones, collagen is abundant and fibronectin is sparse. This microheterogeneous distribution of interstitial collagens and of fibronectin might thus constitute part of the morphogenetic message that the dermis is known to transmit to the epidermis during the development of skin and of cutaneous appendages.