Showing papers by "University of Grenoble published in 1995"

Bilateral subthalamic nucleus stimulation for severe Parkinson's disease.

Abstract: Subthalamic nucleus (STN) lesions or high-frequency stimulations could improve parkinsonian symptoms in monkeys treated by MPTP. We have applied the procedure of chronic stimulation to the STN in severely disabled parkinsonian patients. This article presents the case of the first patient operated on bilaterally. Bilateral STN stimulation has greatly improved akinesia and rigidity. The benefit was maintained < or = 15 months after surgery. Unilateral stimulation induced motor effects mainly in contralateral limbs. Further studies are needed to evaluate the value of this procedure in the treatment of Parkinson's disease.

Ultrastructural aspects of the acetylation of cellulose

Abstract: An ultrastructural study of the acetylation of cellulose was achieved by subjecting well characterized cellulose samples fromValonia cell wall and tunicin tests to homogeneous and heterogeneous acetylation. The study involved transmission electron microscopy observations on negatively stained microcrystals as well as diffraction contrast images of the cross sections of wall fragments at various stages of the reaction. These observations showed that the acetylation of crystalline cellulose proceeds by a reduction of the diameters of the crystals while their lengths are reduced to a lower extent. These results were corroborated by electron and X-ray diffraction experiments that showed that during the reaction there was a rapid decrease in the intensities of the equatorial diffraction spots of cellulose, whereas those located on the meridian or close to the meridian stayed constant. A model of acetylation of the cellulose crystal is presented. It is based on a non swelling reaction mechanism that affects only the cellulose chains located at the crystal surface. In the case of homogeneous acetylation, the partially acetylated molecules are sucked into the acetylating medium as soon as they are sufficiently soluble. In heterogeneous conditions the cellulose acetate remains insoluble and surrounds the crystalline core of unreacted cellulose.

Computer assisted medical interventions

Abstract: Many medical or surgical interventions can benefit from the use of computers. Through progress of technology and growing consciousness of the possibilities of real clinical improvements with computers, what was in the past the privilege of very few operations (mostly stereotactic neurosurgery) is now entering many surgical specialities. Although many technical issues remain to be solved, there is virtually no limit to the introduction of computers and robots in any surgical speciality. This tendency can take on the most varied forms. At the authors' institute, three golden rules have guided the computer assisted medical interventions (CAMI) project for about ten years: 1) conceive systems for which the clinical value is well defined; 2) develop generic tools that can be applied to many different clinical applications; and 3) provide efficient collaboration between the surgeon and the system through simple interfaces. >

Crystal chemistry of hydrous iron silicate scale deposits at the Salton Sea geothermal field

Abstract: The crystal chemistry of Fe-Si scales deposited from geothermal brines at Salton Sea, California, was studied by powder X-ray diffraction and spectroscopic techniques including infrared, 5VFe M6ssbauer, 27A1 and 29Si nuclear magnetic resonance (NMR), and Fe and Si K-edge extended X-ray absorption fine structure (EXAFS). Scales precipitated at near 250~ from dissolved ferrous iron and silicic acid are composed of hisingerite. This phase is shown to possess the same local structure as nontronite and is a poorly-crystallized precursor of the ferric smectite. A clear distinction can be made at the local scale between hisingerite and 2-line ferrihydrite because, even in their most disordered states, the former possesses a two-dimensional and the latter a three-dimensional anionic framework. At temperature near 100*C Fe-Si scales are a mix of Al-containing opal and hydrous ferrous silicate, whose local structure resembles minnesotaite and greenalite. This hydrous ferrous silicate is very well ordered at the local scale with an average Fe coordination about Fe atoms of 6 +_ 1. The difference in crystallinity between the ferrous and ferric silicate scales was related to variations of growth rates of clay particles precipitated from ferrous and ferric salt solutions. The low crystallinity of the ferric smectite suggests that the oxidation of ferrous iron occurs before polymerization with silica.

Sperm nuclei analysis of a Robertsonian t(14q21q) carrier, by FISH, using three plasmids and two YAC probes

Abstract: The meiotic segregation of chromosomes 14 and 21 was analysed in 1116 spermatozoa from an oligoasthenospermic carrier of a Robsertsonian translocation t(14q21q), and in 16 392 spermatozoa from a control donor, using two-colour fluorescence in situ hybridisation (FISH). Two YAC probes (cloned in yeast artificial chromosomes) specific for regions on the long arms of these chromosomes were co-hybridised. Of the spermatozoa, 12% were unbalanced, resulting from adjacent segregations. Chromosomes X, Y and 1 were also simultaneously detected in 1335 spermatozoa from the same carrier. Whereas gonosomal disomy rates were not significantly different from those of the control donors, disomy 1 were slightly but significantly increased to 0.7%. The diploidy rate was also slightly increased to approximately 1% in the translocation carrier.

Meiotic segregation in males heterozygote for reciprocal translocations: analysis of sperm nuclei by two and three colour fluorescence in situ hybridization.

Abstract: The meiotic segregation of chromosomes was analysed in three reciprocal translocation carriers, using FISH on interphase spermatozoa. The segregation pattern was first studied in 27,844 spermatozoa fr

Meiotic segregation of the X and Y chromosomes and chromosome 1 analyzed by three-color FISH in human interphase spermatozoa

Abstract: Meiotic segregation of the X and Y chromosomes and chromosome 1 was analyzed by three-color fluorescence in situ hybridization (FISH) in 94,575 human interphase spermatozoa from four control subjects.

Système générateur minimal, diviseurs essentiels et $G$-désingularisations de variétés toriques

Abstract: We give a geometric interpretation of the minimal generating system of the semi-group defined by a rational polyhedral cone in any dimension, via a natural bijection with the set of essential divisors of equivariant desingularizations of the toric variety associated to the cone. We prove, for varieties of dimension three, the existence of a desingularization associated to a regular fan whose edges contain the elements of the minimal generating system, its uniqueness for canonical toric varieties of index at least two, and the uniqueness in general up to flops. We give an example of non-existence of such desingularizations in dimension four. Introduction. L'etude des varietes algebriques munies de Γaction d'un tore, entreprise par Demazure [5] en introduisant les eventails et developpee ensuite par beaucoup d'autres pour les varietes singulieres, repose sur un dictionnaire entre des objets geometriques et combinatoires. Nous poursuivons cette etude avec une interpretation geometrique du systeme generateur minimal G du semi-groupe defϊni par un cone polyedral rationnel σ: il existe une bijection naturelle entre G et les diviseurs essentiels des desingularisations equivariantes de la variete torique Vσ associee a σ sur un corps k, en dimension quelconque (theoreme 1.10). En dimension trois on demontre, en utilisant la theorie de Mori, que les diviseurs essentiels equivariants correspondant aux elements de G sont aussi essentiels pour toute desingularisation de Vσ, non necessairement equivariante (theoreme 2.5). On appelle G-desingularisation de Vσ une desingularisation equivariante definie par une subdivision de σ en un eventail dont les aretes portent les elements de G (G-subdivision reguliere), i.e. telle que tout diviseur exceptionnel soit essentiel. On demontre, en dimension trois, Γexistence des G-desingularisations par une methode constructive a partir d'un modele terminal minimal (theoreme 2.9), une caracterisation des G-subdivisions regulieres par la minimalite de leur volume (proposition 2.12), et le fait que toute G-desingularisation domine un modele terminal minimal (theoreme 2.22). Ce dernier resultat et Γunicite de la G-desingularisation d'une variete torique canonique d'indice > 1 (theoreme 2.23) impliquent Γunicite en general Mots-clέs: Varietes toriques, diviseurs essentiels, desingularisations, theorie de Mori, systemes generateurs de semi-groupes. 1991 Mathematics Subject Classification. Primary 14E15; Secondary 14L30, 14J30. 126 c. BOUVIER ET G. GONZALEZ-SPRINBERG a flops pres (corollaire 2.24). En dimension supέrieure ou egale a quatre, il n'existe pas necessairement des G-desingularisations de varietes toriques, comme le montre le contre-exemple 3.1. Une partie de ces resultats a ete annoncee dans [1]. Dans le premier paragraphe on fait des rappels, on donne les definitions sur les eventails et les varietes toriques utilises dans la suite et on demontre Γinterpretation geometrique du systeme generateur minimal. La deuxieme partie porte sur les resultats pour les varietes toriques en dimension trois: les diviseurs essentiels, Γexistence et la construction des G-desingularisations, ainsi que les proprietes d'unicite. Le dernier paragraphe est un exemple d'une variete torique terminale d'indice un de dimension quatre qui n'admet pas de G-desingularisation. Nous remercions Monique Lejeune-Jalabert et Michel Brion pour des discussions fructueuses, Arlette Guttin-Lombard pour la grande qualite de frappe dont elle est coutumiere. Le deuxieme auteur remercie Γinvitation de JAMS a Ohnuma et du Tokyo Institute of Technology pour un sejour en Aoύt 1993 pendant lequel il a pu faire avancer la redaction de cet article. Les editeurs nous signalent Γexistence de recoupements entre certains resultats de cet article et de Γarticle \"An algorithmic desingularization of 3-dimensional toric varieties\" de Stefano Aguzzoli et Daniele Mundici a paraϊtre dans cette revue. (The editor's note: It appeared in Tόhoku Math. J. 46, No. 4 (1994), 557-572.) 1. Rappels et definitions. Interpretation geometrique du systeme generateur minimal. Soit d un en tier positif, N un Z-module libre de rang d et M=Homz(JV, Z) son dual. Les β-espaces vectoriels N(x)z Q et M(χ)z Q sont notes respectivement NQ et MQ. Un cone dans NQ est toujours suppose convexe et polyedral: pour un tel cone σ, il existe un en tier s et des points vh \\«1=0 oun2 = 0} des elements irreductibles du semi-groupe <τn7V\\{0}. PROPOSITION 1.2. Lensemble Gσ engendre le semi-groupe σn7V\\{0} et il est contenu dans tout systeme generateur de σn7V\\{0}. En particulier, Gσ estfini. G-DESINGULARISATIONS DE VARIETES TORIQUES 127 DEMONSTRATION. Le cone σ etant fortement convexe, il existe un element m de M tel que σ soit contenu dans le demi-espace m~{Q) de NQ et tel que Γintersection de σ avec Γhyperplan m\" 1 ^) soit la face {0} de σ. Un element non nul x de σnN est alors somme d'au plus m(x) elements de σnN\\{0}. Soit * = Σf= 1 n{ une ecriture de x comme somme d'elements de σnΛf\\{0} avec p maximal. Alors les nh l<ί

Acute administration of levodopa-benserazide and tolcapone, a COMT inhibitor, in Parkinson's disease

Abstract: Tolcapone, a catechol-O-methyltransferase inhibitor, can interfere with the metabolism of levodopa and dopamine and could prolong the motor effect induced by levodopa in parkinsonian patients. To test this hypothesis, we studied the motor effect induced by three acute administrations of a dose of le

Strange baryon production in z-hadronic decays

Abstract: A study of the production of strange octet and decuplet baryons in hadronic decays of the Z recorded by the DELPHI detector at LEP is presented. This includes the first measurement of the∑± average multiplicity. The total and differential cross sections, the event topology and the baryon-antibaryon correlations are compared with current hadronization models.

Production characteristics of K0 and light meson resonances in hadronic decays of the Z0

Abstract: An analysis of inclusive production of K0 and the meson resonances K*±(892), ρ0(770),f0(975) andf2(1270) in hadronic decays of the Z0 is presented, based on about 973,000 multihadronic events collected by the DELPHI detector at LEP during 1991 and 1992. Overall multiplicities have been determined as 1.962±0.060 K0 mesons, 0.712±0.067 K*±(892) and 1.21±0.15ρ0(770) per hadronic Z0 decay. The average multiplicities off0(975) for scaled momentum,xp, in the range 0.05≤xp≤0.6 and off2(1270) for 0.05≤xp≤1.0 are 0.098±0.016 and 0.170±0.043 respectively. Thef0(975) and ρ0(770)xp-spectra have similar shapes. Thef2(1270)/ρ0(770) ratio increases withxp. The average multiplicities and the differential cross sections are compared with the JETSET Parton Shower model. The model with default parameters fails to reproduce the experimental K0 momentum spectrum at low momentum, describes the K*±(892) and ρ0(770)xp-spectrum shapes, but significantly overestimates their production rates.

A study of radiative muon-pair events at Z0 energies and limits on an additional Z′ gauge beson

Abstract: An analysis is reported on the channele+e−→μ+μ−(nγ), n=1,2..., using data taken with the DELPHI detector at LEP from 1990 to 1992. Differential cross sections of the radiative photons as a function of photon energy and of the angle between the photon and the muon are presented. No significant deviations from expectations are observed. The data are also used to extract the muon-pair cross section and asymmetry below the Z0 peak by using those events with relatively hard initial state radiative photon(s). The measured cross section and asymmetry show no significant deviation from the Standard Model expectations. These results together with the DELPHI cross section and asymmetry measurements at the LEP energies from the 1990 to 1992 running periods are used to determine limits on the Z0-Z′ gauge boson mixing angle θZ′ and on the Z′ mass. There is no indication of the existence of a Z′; the limits obtained on the mixing angle substantially improve upon existing limits. The 95% confidence level allowed ranges of θZ′ in various models are: $$\begin{gathered} - 0.0070 \leqslant \theta _{Z'} \leqslant 0.0078,E_6 (\chi )\bmod el, \hfill \\ - 0.0075 \leqslant \theta _{Z'} \leqslant 0.0095,E_6 (\psi )\bmod el, \hfill \\ - 0.029 \leqslant \theta _{Z'} \leqslant 0.029,E_6 (\eta )\bmod el, \hfill \\ - 0.0068 \leqslant \theta _{Z'} \leqslant 0.0082,L - R(1.)\bmod el, \hfill \\ - 0.0057 \leqslant \theta _{Z'} \leqslant 0.0077,L - R(\sqrt 2 )\bmod el. \hfill \\ \end{gathered} $$

Inter- and intraobserver variation in the interpretation of electromyographic tests

Abstract: This study was undertaken with the aim of evaluating inter- and intraobserver variation on the pathophysiological interpretation of individual electromyographic (EMG) tests on muscles and nerve segments. Seven physicians from 6 European EMG laboratories independently interpreted 81 EMG studies comprising 735 muscle tests and 726 tests on nerve segments. Pathophysiological conclusions were inferred from findings of these tests without considering clinical information. For most combinations of findings, both the inter- and intraobserver variations on the interpretation were low, suggesting that common criteria for pathophysiological interpretations were used and that these were used consistently. For some combinations of findings, however, there was disagreement on whether these indicated specific or unspecific pathophysiological changes. In particular disagreement on whether findings indicated demyelination may be of clinical significance. A large part of the intraobserver variation may be explained by a change towards more cautious interpretations during the study for most of the physicians. It is concluded that there is a need to seek for consensus on the pathophysiological interpretation of individual findings and for incentives to ensure consistency in interpretations. The fact that experienced physicians changed their ways to interpret findings during the study suggests that agreement may be improved globally.

Muscle GSH-Px activity after prolonged exercise, training, and selenium supplementation

Abstract: A double-blind study of the effects of supplementing with selenium vs. placebo on the physiological responses to acute and chronic exercise was conducted in 24 healthy, nonsmoking males, mean age 22.9 +/- 2.1 yr, randomly divided into two groups of 12 (Pla/Sel). After a controlled period in the absence of training, all subjects were put on an individualized endurance training program with the same rules of progression and overload (3 sessions/wk x 10 wk). Supplementation, either real (240 micrograms of organic selenium/d in Sel group) or imaginary (Pla group) was administered during the same period. In each of the conditions Pre- and Post- (training +/- sel supplementation), muscle, plasma, and systemic parameters were determined before (BF) and after (AF) acute exercise, involving the repetition of muscle work cycles separated by 5-min recovery periods, combining 20 min at 65% and a maximal duration of 100% VO2 max of running on a treadmill, leading the subjects to exhaustion between 2 h 40 min and 3 h 30 min. Changes in parameters as a function of three independent variables: 1. Acute exercise (E); 2. Chronic exercise (T); and 3. Selenium supplementing (S) were tested with ANOVA and the Student's t-test on paired series. Among the variables examined, muscle glutathione peroxidase (GPx) presented a remarkable behavior.(ABSTRACT TRUNCATED AT 250 WORDS)

Variation in performance of the EMG examination at six European laboratories.

Abstract: The quality of the EMG examination might be improved by standardization. However, knowledge about interlaboratory differences in the performance of the EMG examination is a prerequisite for standardization. The aim of this study was to describe differences in EMG techniques used and number of muscles and nerves examined per patient at 6 European EMG laboratories. The EMG results of 595 patients were prospectively sampled. The average number of muscles examined per patient in different disorders varied from laboratory to laboratory, for example from 3.0 to 10.8 muscles in anterior horn cell disorders and from 2.0 to 5.5 muscles in myopathies. The average number of muscles examined by quantitative EMG varied from 0 to 4.3 in anterior horn cell disorders and from 0.0 to 4.5 in myopathies. Also the average number of nerve segments examined per patient varied from laboratory to laboratory for example from 2.7 to 17.7 for motor segments and from 3.1 to 9.0 for sensory segments in polyneuropathies. The laboratories that used needle electrodes for nerve conduction studies and quantitative analysis of individual motor unit potentials examined a smaller number of muscles and nerves than laboratories using surface electrodes for nerve conduction studies and qualitative EMG studies. The results of this study may have impact on guidelines and examination protocols as well as on quality assurance.

In-vitro decondensation of human spermatozoa for fluorescence in-situ hybridization.

Abstract: In order to enhance the efficiency of fluorescence in-situ hybridization (FISH) on human interphase spermatozoa, a simple method for partial decondensation of human spermatozoa chromatin is described. The spermatozoa were washed once in 0.01 M Tris and decondensed using 10 mM dithiothreitol in 0.05 M Tris for 10-50 min, before being spread onto clean slides. Sperm samples were observed every 10 min under a phase-contrast microscope in order to modify the duration of the decondensation process. Using several centromeric or YAC probes in multicolour FISH, high hybridization rates were obtained.

Production of strange b-baryons decaying into xi-/+-l-/+ pairs at lep

Abstract: An excess of events containing, in a jet, a samesign Ξ∓−l∓ pair as compared to those with an oppositesign Ξ∓−l± pair has been observed in an analysis of 1.7 million hadronic Z0 decays collected by the DELPHI detector at LEP between 1991 and 1993 inclusive. The probability for this signal to come from non B-baryon decays is less than 5×10−4. The measured production fraction corresponds to: per lepton species, averaged for electrons and muons and assuming that the two channels have an equal contribution. Semileptonic decays of Λb baryons can account for less than 10% of these events and the major part of the signal has to originate from Ξb semileptonic decays. Using the subsample of these events where the Ξ∓ trajectory has been measured in the Vertex Detector, the lifetime of B-baryons producing a Ξ∓ in their semileptonic decay final state is found to be: $$\tau (B - baryon \to \Xi ^ - \ell ^ - X) = 1.5_{ - 0.4}^{ + 0.7} \pm 0.3ps.$$

Lifetime of Charged and Neutral B Hadrons using Event Topology

Abstract: The lifetimes of charged and neutral B hadrons have been measured using data collected by the DELPHI experiment at LEP between 1991 and 1993. B hadrons are tagged as jets with a secondary vertex and the charge of the B candidate is taken to be the sum of the charges of the particles in the secondary vertex. Approximately 1,434,000 multihadronic Z0 decays yielded 1817 B hadron candidates. The B purity was estimated to be around 99.1±0.3%, and 83% (70%) of the events measured as neutral (charged) came from neutral (charged) B's. The mean lifetimes of charged and neutral B hadrons were found to be 1.72±0.08 (stat.) ±0.06 (syst.) ps and 1.58±0.11 (stat.)±0.09 (syst.) ps respectively. The ratio of their lifertimes, τcharged/τneutral, was 1.09−0.10+0.11 (stat.)±0.08 (syst.). By making assumptions about the Bs0 and Λb0 states, the B+ and B0 meson lifetimes were determined to be τB+ = 1.72 ± 0.08 (stat.) ±0.06 (syst.) ps and τB+ = 1.63 ± 0.14 (stat.)±0.13 (syst.) ps and the ratio of their lifetimes was:

Denotational Semantics for an Active Rule Execution Model

Abstract: In the last few years, many active database models have been proposed. Some of them have been implemented as research prototypes. The use and study of these prototypes shows that it is difficult to get a clear idea of the proposed approaches and to compare them. More generally there are some unquestionable difficulties in understanding, reasoning about and teaching behavior of active database systems. We think there is a need for formal descriptions of the semantics of such systems in order to describe and to understand them with less ambiguities, to compare them and to come up with some progress in defining standard concepts and functionalities for active databases.

B* production in Z decays

Abstract: The decayB*→Bγ has been observed with the DELPHI detector at LEP, where theB* meson is produced inZ boson decays. The combination of inclusively reconstructedB mesons with well-measured converted photons yields a measurement of the flavour-averagedB*-B mass difference of 45.5±0.3 (stat.) ±0.8 (syst.) MeV/c2. 95% confidence level upper limits at 6 MeV/c2 are placed on both the isospin (i.e.B+-B0) and theBs-Bud splitting of the mass difference. The production ratio ofB* toB mesons inZ decays is measured to be 0.72±0.03 (stat.) ±0.06 (syst.). Limits on the production cross-section of other hypothetical excitedB hadron states decaying radiatively are established. The differentialB* cross section has been measured to be in good agreement with the averageb fragmentation, yielding an average fractionalB* energy of 〈xE〉=0.695±0.009 (stat.) ±0.013 (syst.). From the decay angular distribution the relative contribution of longitudinalB* polarisation states is measured to be σL/(σL + σT) = 0.32 ± 0.04 (stat.) ±0.03 (syst.).

In-vitro decondensation of human spermatozoa for fluorescence in-situ hybridization

Abstract: In order to enhance the efficiency of fluorescence in-situ hybridization (FISH) on human interphase spermatozoa, a simple method for partial decondensation of human spermatozoa chromatin is described. The spermatozoa were washed once in 0.01 M Tris and decondensed using 10 mM dithiothreitol in 0.05 M Tris for 10-50 min, before being spread onto clean slides. Sperm samples were observed every 10 min under a phase-contrast microscope in order to modify the duration of the decondensation process. Using several centromeric or YAC probes in multicolour FISH, high hybridization rates were obtained.