Signatures of Classical Periodic Orbits on a Smooth Quantum System

Gutzwiller's trace formula and Bogomolny's formula are applied to a non--specific, non--scalable Hamiltonian system, a two--dimensional anharmonic oscillator. These semiclassical theories reproduce well the exact quantal results over a large spatial and energy range.Comment: 12 pages, uuencoded postscript file (1526 kb

Asymptotic and measured large frequency separations

With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available. So-called global oscillation parameters are inferred to characterize the large sets of stars, to perform ensemble asteroseismology, and to derive scaling relations. The mean large separation is such a key parameter. It is therefore crucial to measure it with the highest accuracy. As the conditions of measurement of the large separation do not coincide with its theoretical definition, we revisit the asymptotic expressions used for analysing the observed oscillation spectra. Then, we examine the consequence of the difference between the observed and asymptotic values of the mean large separation. The analysis is focused on radial modes. We use series of radial-mode frequencies to compare the asymptotic and observational values of the large separation. We propose a simple formulation to correct the observed value of the large separation and then derive its asymptotic counterpart. We prove that, apart from glitches due to stellar structure discontinuities, the asymptotic expansion is valid from main-sequence stars to red giants. Our model shows that the asymptotic offset is close to 1/4, as in the theoretical development. High-quality solar-like oscillation spectra derived from precise photometric measurements are definitely better described with the second-order asymptotic expansion. The second-order term is responsible for the curvature observed in the \'echelle diagrams used for analysing the oscillation spectra and this curvature is responsible for the difference between the observed and asymptotic values of the large separation. Taking it into account yields a revision of the scaling relations providing more accurate asteroseismic estimates of the stellar mass and radius.Comment: accepted in A&

The role of temperature in the magnetic irreversibility of type-I Pb superconductors

Evidence of how temperature takes part in the magnetic irreversibility in the intermediate state of a cylinder and various disks of pure type-I superconducting lead is presented. Isothermal measurements of first magnetization curves and magnetic hysteresis cycles are analyzed in a reduced representation that defines an equilibrium state for flux penetration in all the samples and reveals that flux expulsion depends on temperature in the disks but not in the cylinder. The magnetic field at which irreversibility sets in along the descending branch of the hysteresis cycle and the remnant magnetization at zero field are found to decrease with temperature in the disks. The contributions to irreversibility of the geometrical barrier and the energy minima associated to stress defects that act as pinning centers on normal-superconductor interfaces are discussed. The differences observed among the disks are ascribed to the diverse nature of the stress defects in each sample. The pinning barriers are suggested to decrease with the magnetic field to account for these results

Quelques recherches fondamentales sur le virus bovipestique

Les auteurs ont montré à l'aide des techniques d'inhibition des acides nucléiques par les pyrimidines halogénées que le virus bovipestique était un virus à acide ribonucléique. Les inclusions intracytoplasmiques qu'il détermine en cultures cellulaires sont de nature ribonucléoprotéique; elles portent la spécificité antigénique du virus. La replication du virus est uniquement endocytoplasmique, sans participation mitochondriale. La libération s'effectue par bourgeonnement de la surface cellulaire. Tous ces caractères rapprochent le virus bovipestique du groupe des myxovirus, sous-groupe para-influenz

Une hypogammaglobulinémie essentielle des bovins d'Afrique centrale cause d'erreur dans les enquêtes sérologiques

Les auteurs ont rencontré au cours d'enquêtes sérologiques portant sur la peste bovine, la maladie des muqueuses, la rhinotrachéite bovine et l'infection à virus para-influenza-3 des sérums de bovins adultes, vaccinés plusieurs fois contre la peste, n'ayant aucun anticorps décelable in vitro. On peut rattacher le comportement de ces sérums à une hypogammaglobulinémie essentielle évoluant sans troubles apparents. L'importance de cette constatation est soulignée pour les maladies, dont la péripneumonie, où la prophylaxie sanitaire est basée sur la sérologie des bovin

Recherches immunologiques sur la péripneumonie. XI. Un vaccin vivant mixte antibovipestique - antiperipneumonique inoculé en un seul temps. Conception - production - contrôles

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Inducing safer oblique trees without costs

Decision tree induction has been widely studied and applied. In safety applications, such as determining whether a chemical process is safe or whether a person has a medical condition, the cost of misclassification in one of the classes is significantly higher than in the other class. Several authors have tackled this problem by developing cost-sensitive decision tree learning algorithms or have suggested ways of changing the distribution of training examples to bias the decision tree learning process so as to take account of costs. A prerequisite for applying such algorithms is the availability of costs of misclassification. Although this may be possible for some applications, obtaining reasonable estimates of costs of misclassification is not easy in the area of safety. This paper presents a new algorithm for applications where the cost of misclassifications cannot be quantified, although the cost of misclassification in one class is known to be significantly higher than in another class. The algorithm utilizes linear discriminant analysis to identify oblique relationships between continuous attributes and then carries out an appropriate modification to ensure that the resulting tree errs on the side of safety. The algorithm is evaluated with respect to one of the best known cost-sensitive algorithms (ICET), a well-known oblique decision tree algorithm (OC1) and an algorithm that utilizes robust linear programming

Gravitational Radiation Instability in Hot Young Neutron Stars

We show that gravitational radiation drives an instability in hot young rapidly rotating neutron stars. This instability occurs primarily in the l=2 r-mode and will carry away most of the angular momentum of a rapidly rotating star by gravitational radiation. On the timescale needed to cool a young neutron star to about T=10^9 K (about one year) this instability can reduce the rotation rate of a rapidly rotating star to about 0.076\Omega_K, where \Omega_K is the Keplerian angular velocity where mass shedding occurs. In older colder neutron stars this instability is suppressed by viscous effects, allowing older stars to be spun up by accretion to larger angular velocities.Comment: 4 Pages, 2 Figure

Recherches immunologiques sur la péripneumonie. IX - Données nouvelles sur les relations antigéniques de Mycoplasma mycoïdes avec d'autres Mycoplasmataceae

A la première réunion du groupe d'experts sur la péripneumonie bovine (Melbourne, 1960), il avait été proposé une classification sérologique d'un certain nombre de souches d'espèces de la famille des Mycoplasmataceae. Cette classification a été reprise et les protocoles expérimentaux établis de façon plus précise. Les formules antigéniques de 4 espèces de mycoplasmes: - M. mycoïdes - M. caprae - M. laidlawii - M. bovigenitalium représentées par les souches dont nous disposons sont identiques à celles que nous avions déjà proposée

Recherches en vue d'une méthode rapide de diagnostic de la peste bovine

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