Showing papers by "University of Grenoble published in 1992"

Singular hermitian metrics on positive line bundles

Abstract: The notion of a singular hermitian metric on a holomorphic line bundle is introduced as a tool for the study of various algebraic questions. One of the main interests of such metrics is the corresponding L2 vanishing theorem for Open image in new window cohomology, which gives a useful criterion for the existence of sections. In this context, numerically effective line bundles and line bundles with maximum Kodaira dimension are characterized by means of positivity properties of the curvature in the sense of currents. The coefficients of isolated logarithmic poles of a plurisubharmonic singular metric are shown to have a simple interpretation in terms of the constant e of Seshadri’s ampleness criterion. Finally, we use singular metrics and approximations of the curvature current to prove a new asymptotic estimate for the dimension of cohomology groups with values in high multiples O(kL) of a line bundle L with maximum Kodaira dimension.

Cocycles d'Euler et de Maslov

Abstract: Nous esperons avoir convaincu le lecteur qu'il peut etre utile de considerer la classe de Maslov comme une classe bornee. Dans [Gh], nous avons montre que la classe d'Euler bornee pour un groupe d'homeomorphismes directs du cercle rend compte de la dynamique topologique de ce groupe. Existe-t-il un resultat analogue pour Sp(2n,ℝ)? En d'autres termes, soit Γ un groupe discret et ϱ1, ϱ2 deux representations de Γ dans Sp(2n,ℝ). On suppose que les cocycles ϱ 1 * σ et ϱ 2 * σ definissent la meme classe bornee. Que peut-on en conclure sur ϱ1 et ϱ2? Par ailleurs, l'article [At l] traite aussi d'invariants sur SL(2,ℤ) differents de ceux que nous avons consideres, comme par exemple les fonctionsL de Shimizu. Est-il possible de les faire rentrer naturellement dans notre cadre?

Transplantation et isospectralité. I

Abstract: © Séminaire de Théorie spectrale et géométrie (Chambéry-Grenoble), 1990-1991, tous droits réservés. L’accès aux archives de la revue « Séminaire de Théorie spectrale et géométrie » implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.

Determination of 55-155-155-1in second order QCD from hadronic Z decays

Abstract: Distributions of event shape variables obtained from 120600 hadronicZ decays measured with the DELPHI detector are compared to the predictions of QCD based event generators Values of the strong coupling constant αs are derived as a function of the renormalization scale from a quantitative analysis of eight hadronic distributions The final result, αs(M Z), is based on second order perturbation theory and uses two hadronization corrections, one computed with a parton shower model and the other with a QCD matrix element model

Diabetes mellitus prevalence among dialysed patients in France (UREMIDIAB study).

Abstract: The prevalence of diabetes mellitus among patients treated for end-stage renal failure was studied using a questionnaire mailed to all dialysis units of mainland France in 1989. With a response rate of 80.8%, the study population amounted to 12,903 dialysed patients of whom 884 were declared diabetic (6.9%). In a second phase, the study focused on the diabetic patients treated in the 63 largest units (those with at least four diabetic patients). Seven specially trained physicians completed questionnaires after having interviewed the patients and checked their medical records. All this material was reviewed by the same diabetologist. The conflict of diabetes type declared by both sources of information (the nephrologists and the diabetologist) showed a misclassification rate of 31.2%. Using these new data, the prevalence of type 1 diabetes mellitus was estimated at 1.4% of patients on dialysis therapy in mainland France, and 5.5% for type 2 diabetes mellitus. A north-south declining trend was suggested for type 2 diabetes mellitus. Diabetic nephropathy was the only primary renal diagnosis among 93.9% of type 1 diabetic patients, but only for 36.8% of type 2 diabetic patients. Of the latter, 51.6% had a non-diabetic cause of renal failure. These data show that the proportion of diabetics among patients receiving dialysis, while steadily increasing in France, remains lower than in other countries in Europe and in North America. However, the validity of international comparisons depends on diabetes ascertainment. Heterogeneity in selection of patients and in diabetes type classification by dialysis units may account to a considerable degree for the differences between diabetes mellitus prevalence across countries.

Study of final state photons in hadronic Z0 decay and limits on new phenomena

Abstract: The differential cross section for final state radiation from primary quarks is obtained from a study of isolated energetic photons produced in the reactione+e−→Z0→hadrons+γ, as measured in the DELPHI detector at the CERN LEP collider. When combined with the measurement of the total hadronic width of theZ0, the observed rate determines the electroweak coupling constants of up and down type quarks, i.e., $$v_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern- ulldelimiterspace} 3}}^2 + a_{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern- ulldelimiterspace} 3}}^2 = 1.13 \pm 0.29 and v_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern- ulldelimiterspace} 3}}^2 + a_{{2 \mathord{\left/ {\vphantom {2 3}} \right. \kern- ulldelimiterspace} 3}}^2 = 1.65 \pm 043.$$ No evidence is seen for additional photon production from anomalous decays of theZ0 or from decays of new particles. This measurement leads to upper limits on the production cross section times branching fraction of (a) the Higgs boson in the reactione+e−→Z0→H +γ,H→hadrons, (b) an excited quark,q*→q+γ, and (c) the contribution of an anomalous decay of theZ0 into a photon and hadrons. These limits, all at the 95% confidence level, vary from 3 to 10pb as the mass of the intermediate state (H,q* orZ*) varies from 10 GeV/c2 to 80 GeV/c2.

Sonochemistry of epoxyalkylhalides in the presence of a zinc–copper couple

Abstract: Under sonication in aqueous ethanol, a zinc–copper couple induces the conjugated addition of epoxyalkyl groups to electron deficient alkenes in synthetically useful yields, provided that the two reducible functionalities are sufficiently far apart; 3,4-epoxyalkylhalides have been found to form cyclopropane adducts.

Measurement of the partial width of the Z0 into b anti-b final states using their semileptonic decays

Abstract: The spectra of prompt electrons and muons from the semi-leptonic decays of heavy hadrons produced inZ 0 decays have been used to measure the coupling of theZ 0 tob quarks weighted by theB hadrons mean semi-leptonic branching fraction, giving a value: $$BR_{sl}^b *{{\Gamma _{b\bar b} } \mathord{\left/ {\vphantom {{\Gamma _{b\bar b} } {\Gamma _H }}} \right. \kern- ulldelimiterspace} {\Gamma _H }} = 0.0221 \pm 0.0015$$ . The data has also been used to measure the value of the fragmentation parameter, defined in the context of the LUND PS Model, version 7.2, giving: $$\varepsilon (b) = \left( {8\begin{array}{*{20}c} { + 5} \\ { - 3} \\ \end{array} \pm 2} \right)10^{ - 3} $$ . The corresponding value of the mean fraction of the beam energy taken by aB hadron in the fragmentation of ab quark is: $$\overline {X_E^b } = 0.69\begin{array}{*{20}c} { + 0.02} \\ { - 0.03} \\ \end{array} \pm 0.01$$ . If the values of $$\Gamma _{b\bar b} $$ andΓ H are taken from the Standard Model, the following value is obtained for the mean semi-leptonic braching fraction ofB hadrons: BR sl =(10.1±0.7)%. Taking the value of $${{\Gamma _{b\bar b} } \mathord{\left/ {\vphantom {{\Gamma _{b\bar b} } {\Gamma _{\rm H} }}} \right. \kern- ulldelimiterspace} {\Gamma _{\rm H} }}$$ from an independent analysis of DELPHI data based on the use of the boosted sphericity product, a value: BR sl =(10.1±1.3)% is obtained.

Echographic and Doppler screening of the forearm arteries in professional volleyball players.

Abstract: We evaluated nine professional volleyball players by clinical, echographic, and Doppler technique examina tion of the forearm and digital arteries to determine vascular damage caused by repeated trauma. The re sults of these tests showed that one-third of the sub jects had vascular lesions in the right hand; only one of these was symptomatic. This suggests that noninva sive screening should be recommended and included in the regular medical check-ups of professional ath letes in whom repeated trauma to the hand is likely, such as volleyball players.

Beyond Principal Component Analysis: A Trilinear Decomposition Model and Least Squares Estimation.

Abstract: The paper derives sufficient conditions for the consistency and asymptotic normality of the least squares estimator of a trilinear decomposition model for multiway data analysis.

Muscle bioenergetics in skiers: studies using NMR spectroscopy.

Abstract: Sedentary human subjects (n = 6) and two homogeneous groups of athletes, trained for down-hill skiing (n = 5) and cross-country skiing (n = 7), were subjected to cardiorespiratory testing and to evaluation of the bioenergetics of calf muscles by means of Phosphorus Nuclear Magnetic Resonance Spectroscopy. The exercise consisted of successive plantar flexions performed at graded fractions of the maximal voluntary contraction force. It appears from this study that the decrease in phosphocreatine level induced by exercise at 80% of maximal voluntary contraction, was smaller in the muscles of athletes who trained for cross-country skiing, than in the muscles of down-hill skiers and control subjects. Intracellular acidosis was virtually absent in cross-country athletes. The rate of restitution of phosphocreatine, after the exercise, was higher in both groups of skiers, compared to sedentary subjects. The maximal oxygen consumption and the maximal alactic power were higher in athletes than in sedentary subjects. NMR data and mechanical measurements are used in consideration with functional systemic indexes to characterize the capabilities of skiers.

Anti-Epstein-Barr virus-nuclear antigen-1, -2A and -2B antibodies in rheumatoid arthritis patients and their relatives.

Abstract: We have examined serum antibodies to Epstein-Barr virus Nuclear Antigen (EBNA)-1,-2A and-2B, in addition to antibodies to viral capsid antigen and early antigen in 100 rheumatoid arthritis patients and 50 of their relatives. Using indirect immunofluorescence on transfected cells and Western-blot technique, we have found increased frequency and litres of antibodies to EBNA-2B in patients and, to a lesser degree, in their family members, whereas other anti-Epstein-Barr virus antibodies appeared to be similar to controls. Cross-inhibition experiments were carried out and show that antibodies to EBNA-2A are distinct from those to-2B, and vice verse.

Neutron yields and angular distributions produced in antiproton annihilation at rest in uranium

Abstract: Measurements of neutron yields and their angular distributions in coincidence with fission fragments produced in antiproton annihilation at rest in a natural uranium target have been carried out Low Energy Antiproton Ring (LEAR) at CERN. A total of 16.3\ifmmode\pm\else\textpm\fi{}0.9 neutrons per annihilation have been found, distributed among direct knockout (27%), evaporation (21%), and fission (52%) processes. Angular distributions show that neutrons below approximately 5 MeV result entirely from moving fission fragments, and above approximately 12 MeV entirely from the excited, prescission nucleus. An estimate of the angular momentum of the excited fission fragment gives \ensuremath{\sim}13\ensuremath{\Elzxh}. We are able to account for all baryons produced in annihilation, including neutrons from this experiment and light charged nuclei found in another LEAR experiment, to within 4.5\ifmmode\pm\else\textpm\fi{}2.5 of the initial 237 units in the initial state.

Three decades of HDLs. II. Conlan through Verilog

Abstract: For pt.1 see ibid., June 1992. Current hardware description languages (HDLs) benefit from the efforts of designers of VHDLs in the mid-1970s through the late 1980s. The developers of four HDLs discuss their motivations and their views of how their work relates to the present very-high-speed integrated circuit HDLs (VHDLs). The languages discussed are Conlan, ADLIB/SABLE, Zeus, and Verilog. >

Suppression of chaos by periodic oscillations in a model for cyclic AMP signalling in Dictyostelium cells.

Abstract: We investigate how the introduction of cells oscillating periodically affects the behaviour of a suspension ofDictyostelium discoideum amoebae undergoing chaotic oscillations of cyclic AMP. The analysis of a model indicates that a tiny proportion of periodic cells suffices to transform chaos into periodic oscillations in such suspensions. A similar result is obtained by forcing the aperiodic oscillations by a small-amplitude, periodic input of cyclic AMP. The results provide an explanation for the observation of regular oscillations in suspensions of a putatively chaotic mutant ofDictyostelium discoideum 12. More generally, the results show how chaos in biological systems may disappear through the coupling with periodic oscillations.

Approximate distribution of parameter estimators for first‐order autoregressive models

Abstract: Formulae for the exact bias and mean square error for the least squares for forward-backward least squares estimators are obtained based on the explicit expressions for the moment-generating and characteristic functions of quadratic form in the first-order autoregressive process Asymptotic expressions for their cumulants and the maximum likelihood estimator are given Approximations of the distributions of the above estimators are proposed based on the Ornstein-Ulenbeck process A simple computational procedure for the exact distribution is developed, and some numerical comparisons are given which support the overall good accuracy of the approximation and confirm that the maximum likelihood estimator performs better than the others

Integrated Tools for Object Oriented Persistent Application Development

Abstract: This paper presents the main characteristics of an integrated environment for object oriented, persistent application development. We first discuss the rationale of our approach and give our analysis of current database systems or persistent languages. Using such systems or languages is still a very difficult task because persistent application development combines the complexity of database schema design together with a software engineering problem.