Global microscopic calculations of ground-state spin and parity for odd-mass nuclei

Systematic calculations of ground-state spin and parity of odd-mass nuclei have been performed within the Hartree--Fock--BCS (HFBCS) approach and the Finite-Range Droplet Model for nuclei for which experimental data are available. The unpaired nucleon has been treated perturbatively, and axial and left-right reflection symmetries have been assumed. As for the HFBCS approach, three different Skyrme forces have been used in the particle-hole channel, whereas the particle-particle matrix elements have been approximated by a seniority force. The calculations have been done for the 621 nuclei for which the Nubase 2003 data set give assignments of spin and parity with strong arguments. The agreement of both spin and parity in the self-consistent model reaches about 80% for spherical nuclei, and about 40% for well-deformed nuclei regardless of the Skyrme force used. As for the macroscopic-microscopic approach, the agreement for spherical nuclei is about 90% and about 40% for well-deformed nuclei, with different sets of spherical and deformed nuclei found in each model.Comment: 5 pages, 4 figures (three in color), 1 table, to be submitted to Physical Review

Lattice energy-momentum tensor with Symanzik improved actions

We define the energy-momentum tensor on lattice for the $\lambda \phi^4$ and for the nonlinear $\sigma$-model Symanzik tree-improved actions, using Ward identities or an explicit matching procedure. The resulting operators give the correct one loop scale anomaly, and in the case of the sigma model they can have applications in Monte Carlo simulations.Comment: Self extracting archive fil

Charon's radius and density from the combined data sets of the 2005 July 11 occultation

The 2005 July 11 C313.2 stellar occultation by Charon was observed by three separate research groups, including our own, at observatories throughout South America. Here, the published timings from the three data sets have been combined to more accurately determine the mean radius of Charon: 606.0 +/- 1.5 km. Our analysis indicates that a slight oblateness in the body (0.006 +/- 0.003) best matches the data, with a confidence level of 86%. The oblateness has a pole position angle of 71.4 deg +/- 10.4 deg and is consistent with Charon's pole position angle of 67 deg. Charon's mean radius corresponds to a bulk density of 1.63 +/- 0.07 g/cm3, which is significantly less than Pluto's (1.92 +/- 0.12 g/cm3). This density differential favors an impact formation scenario for the system in which at least one of the impactors was differentiated. Finally, unexplained differences between chord timings measured at Cerro Pachon and the rest of the data set could be indicative of a depression as deep as 7 km on Charon's limb.Comment: 25 pages including 4 tables and 2 figures. Submitted to the Astronomical Journal on 2006 Feb 0

Vacuum Polarization Effects in the Lorentz and PCT Violating Electrodynamics

In this work we report new results concerning the question of dynamical mass generation in the Lorentz and PCT violating quantum electrodynamics. A one loop calculation for the vacuum polarization tensor is presented. The electron propagator, "dressed" by a Lorentz breaking extra term in the fermion Lagrangian density, is approximated by its first order: this scheme is shown to break gauge invariance. Then we rather consider a full calculation to second order in the Lorentz breaking parameter: we recover gauge invariance and use the Schwinger-Dyson equation to discuss the full photon propagator. This allows a discussion on a possible photon mass shift as well as measurable, observable physical consequences, such as the Lamb-shift.Comment: Latex file, 19 pages, no figures, includes PACS number

Einstein-Weyl structures and Bianchi metrics

We analyse in a systematic way the (non-)compact four dimensional Einstein-Weyl spaces equipped with a Bianchi metric. We show that Einstein-Weyl structures with a Class A Bianchi metric have a conformal scalar curvature of constant sign on the manifold. Moreover, we prove that most of them are conformally Einstein or conformally K\"ahler ; in the non-exact Einstein-Weyl case with a Bianchi metric of the type $VII_0, VIII$ or $IX$, we show that the distance may be taken in a diagonal form and we obtain its explicit 4-parameters expression. This extends our previous analysis, limited to the diagonal, K\"ahler Bianchi $IX$ case.Comment: Latex file, 12 pages, a minor modification, accepted for publication in Class. Quant. Gra

Progressive ataxia with oculo-palatal tremor and optic atrophy

The final publication is available at Springer via doi: 10.​1007/​s00415-013-7136-

Aggressive Emerging Pathovars of Xanthomonas arboricola Represent Widespread Epidemic Clones Distinct from Poorly Pathogenic Strains, as Revealed by Multilocus Sequence Typing

Deep and comprehensive knowledge of the genetic structure of pathogenic species is the cornerstone on which the design of precise molecular diagnostic tools is built. Xanthomonas arboricola is divided into pathovars, some of which are classified as quarantine organisms in many countries and are responsible for diseases on nut and stone fruit trees that have emerged worldwide. Recent taxonomic studies of the genus Xanthomonas showed that strains isolated from other hosts should be classified in X. arboricola, extending the host range of the species. To investigate the genetic structure of X. arboricola and the genetic relationships between highly pathogenic strains and strains apparently not relevant to plant health, we conducted multilocus sequence analyses on a collection of strains representative of the known diversity of the species. Most of the pathovars were clustered in separate monophyletic groups. The pathovars pruni, corylina, and juglandis, responsible for pandemics in specific hosts, were highly phylogenetically related and clustered in three distinct clonal complexes. In contrast, strains with no or uncertain pathogenicity were represented by numerous unrelated singletons scattered in the phylogenic tree. Depending on the pathovar, intra- and interspecies recombination played contrasting roles in generating nucleotide polymorphism. This work provides a population genetics framework for molecular epidemiological surveys of emerging plant pathogens within X. arboricola. Based on our results, we propose to reclassify three former pathovars of Xanthomonas campestris as X. arboricola pv. arracaciae comb. nov., X. arboricola pv. guizotiae comb. nov., and X. arboricola pv. zantedeschiae comb. nov. An emended description of X. arboricola Vauterin et al. 1995 is provided