Duality for symmetric second rank tensors. II. The linearized gravitational field

The construction of dual theories for linearized gravity in four dimensions is considered. Our approach is based on the parent Lagrangian method previously developed for the massive spin-two case, but now considered for the zero mass case. This leads to a dual theory described in terms of a rank two symmetric tensor, analogous to the usual gravitational field, and an auxiliary antisymmetric field. This theory has an enlarged gauge symmetry, but with an adequate partial gauge fixing it can be reduced to a gauge symmetry similar to the standard one of linearized gravitation. We present examples illustrating the general procedure and the physical interpretation of the dual fields. The zero mass case of the massive theory dual to the massive spin-two theory is also examined, but we show that it only contains a spin-zero excitation.Comment: 20 pages, no figure

Parameter analysis of brake squeal using finite element method

International audienceBrake Squeal is a friction induced instability phenomenon known to be one of the most annoying noise for drivers. This paper focuses on the mode coupling aspect of brake squeal by means of a multi parametric analysis. The study is based on a Finite Element model of the whole brake corner. A complex eigenvalue analysis is undertaken, with a modal projection technique, to detect the stable and unstable modes. Following this process, the brake stability is assessed as a function of the friction coefficient. The results highlight accurately the modecoupling phenomenon also referred to as coalescence. Then, the emphasis is put on the disc Young modulus variability by launching a numerical design of experiment. Finally, the brake robustness is displayed as functions of the friction coefficient and of the disc Young modulus.Le crissement de frein est un phénomène d'instabilité vibratoire induit par le frotte-ment, connu comme l'un des bruits les plus gênants pour le conducteur. Cet article se focalise, grâce à une analyse multiparamétrique, sur la coalescence de modes lors du crissement. L'étude se base sur un modèle éléments finis du système de freinage complet. Une analyse aux valeurs propres complexes est réalisée, avec une technique de projection modale, afin de déterminer quels sont les modes stables et instables. Une étude paramétrique permet de déterminer la stabilité du système en fonction de la valeur du coefficient de frottement. Les résultats décrivent avec précision le phénomène de coalescence. Enfin, un plan d'expérience est lancé afin d'évaluer l'influence du frottement et du module d'Young du disque sur la stabilité du système

N-terminal amino acid sequences of the major outer membrane proteins from a Neisseria meningitidis group B strain isolated in Brazil

The four dominant outer membrane proteins (46, 38, 33 and 28 kDa) were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in a semi-purified preparation of vesicle membranes of a Neisseria meningitidis (N44/89, B:4:P1.15:P5.5,7) strain isolated in Brazil. The N-terminal amino acid sequence for the 46 kDa and 28 kDa proteins matched that reported by others for class 1 and 5 proteins respectively, whereas the sequence (25 amino acids) for the 38 kDa (class 3) protein was similar to class 1 meningococcal proteins. The sequence for the 33 kDa (class 4) was unique and not homologous to any known protein

A Local Pair Natural Orbital-Based Multireference Mukherjee’s Coupled Cluster Method

This paper reports the development of a local variant of Mukherjee’s state-specific multireference coupled cluster method based on the pair natural orbital approach (LPNO-MkCC). The current implementation is restricted to single and double excitations. The performance of the LPNO-MkCCSD method was tested on calculations of naphthyne isomers, tetramethyleneethane, and β-carotene molecules. The results show that 99.7–99.8% of correlation energy was recovered with respect to the MkCC method based on canonical orbitals. Moreover, the errors of relative energies between different isomers or along a potential energy curve (with respect to the canonical method) are below 0.4 kcal/mol, safely within the chemical accuracy. The computational efficiency of our implementation of LPNO-MkCCSD in the ORCA program allows calculation of the β-carotene molecule (96 atoms and 1984 basis functions) on a single CPU core