Concurrent π\pi-vector fields and energy beta-change

The present paper deals with an \emph{intrinsic} investigation of the notion of a concurrent $\pi$-vector field on the pullback bundle of a Finsler manifold $(M,L)$. The effect of the existence of a concurrent $\pi$-vector field on some important special Finsler spaces is studied. An intrinsic investigation of a particular $\beta$-change, namely the energy $\beta$-change ($\widetilde{L}^{2}(x,y)=L^{2}(x,y)+ B^{2}(x,y) with \ B:=g(\bar{\zeta},\bar{\eta})$;$\bar{\zeta} $being a concurrent$\pi$-vector field), is established. The relation between the two Barthel connections$\Gamma$and$\widetilde{\Gamma}$, corresponding to this change, is found. This relation, together with the fact that the Cartan and the Barthel connections have the same horizontal and vertical projectors, enable us to study the energy$\beta$-change of the fundamental linear connection in Finsler geometry: the Cartan connection, the Berwald connection, the Chern connection and the Hashiguchi connection. Moreover, the change of their curvature tensors is concluded. It should be pointed out that the present work is formulated in a prospective modern coordinate-free form.Comment: 27 pages, LaTex file, Some typographical errors corrected, Some formulas simpifie

Detection of Lead in the Carbon-Rich, Very Metal-Poor Star LP625-44: A Strong Constraint on s-Process Nucleosynthesis at Low Metallicity

We report the detection of the Pb I 4057.8A line in the very metal-poor ([Fe/H]=-2.7), carbon-rich star, LP625-44. We determine the abundance of Pb ([Pb/Fe] = 2.65) and 15 other neutron-capture elements. The abundance pattern between Ba and Pb agrees well with a scaled solar system s-process component, while the lighter elements (Sr-Zr) are less abundant than Ba. The enhancement of s-process elements is interpreted as a result of mass transfer in a binary system from a previous AGB companion, an interpretation strongly supported by radial velocity variations of this system. The detection of Pb makes it possible, for the first time, to compare model predictions of s-process nucleosynthesis in AGB stars with observations of elements between Sr and Pb. The Pb abundance is significantly lower than the prediction of recent models (e.g., Gallino et al. 1998), which succeeded in explaining the metallicity dependence of the abundance ratios of light s-elements (Sr-Zr) to heavy ones (Ba-Dy) found in previously observed s-process-enhanced stars. This suggests that one should either (a) reconsider the underlying assumptions concerning the 13C-rich s-processing site (13C-pocket) in the present models, or (b) investigate alternative sites of s-process nucleosynthesis in very metal-poor AGB stars.Comment: 10 pages, 3 figures, Astrophysical Journal Letters, in pres

Generalized β\beta-conformal change and special Finsler spaces

In this paper, we investigate the change of Finslr metrics $$L(x,y) \to\bar{L}(x,y) = f(e^{\sigma(x)}L(x,y),\beta(x,y)),$$ which we refer to as a generalized $\beta$-conformal change. Under this change, we study some special Finsler spaces, namely, quasi C-reducible, semi C-reducible, C-reducible, $C_2$-like, $S_3$-like and $S_4$-like Finsler spaces. We also obtain the transformation of the T-tensor under this change and study some interesting special cases. We then impose a certain condition on the generalized $\beta$-conformal change, which we call the b-condition, and investigate the geometric consequences of such condition. Finally, we give the conditions under which a generalized $\beta$-conformal change is projective and generalize some known results in the literature.Comment: References added, some modifications are performed, LateX file, 24 page

Magnetic resonance spectroscopy of perpendicularly magnetized permalloy multilayer disks

Using a Magnetic Resonance Force Microscope, we compare the ferromagnetic resonance spectra of individual micron-size disks with identical diameter, 1 $m$m, but different layer structures. For a disk composed of a single 43.3 nm thick permalloy (Py) layer, the lowest energy mode in the perpendicular configuration is the uniform precession. The higher energy modes are standing spin-waves confined along the diameter of the disk. For a Cu(30)/Py(100)/Cu(30) nm multilayer structure, it has been interpreted that the lowest energy mode becomes a precession localized at the Cu/Py interfaces. When the multilayer is changed to Py(100)/Cu(10)/Py(10) nm, this localized mode of the thick layer is coupled to the precession of the thin layer

Myringoplasty in children: Retrospective analysis of 60 cases

Myringoplasty or type 1 tympanoplasty aims the restoration of the anatomic integrity of the tympanic membrane; it's a very common surgery in otology. The objective was to evaluate the anatomic and functional results of this surgery in children using the retro-auricular approach. Sixty young patients with diagnosis of simple tympanic perforation were evaluated; these patients underwent myringoplasty by a retro-auricular approach (underlay technique) between November 2010 and May 2013. It's a retrospective evaluation of the anatomic and functional results of theses myringoplasties. Mean age at surgery was 8, 5 years old, cartilage was used as graft in our entire patient, closure of perforation was successful in 48 cases (80%), and audiometric results showed functional improvement in 27 (45%) patients, no significant change was noted in the remaining patients. The results of myringoplasty in children seem worse than those in adults. However, a large study with a long follow up is warranted in order to come to definitive conclusions

Analysis of TerraSAR-X data and their sensitivity to soil surface parameters over bare agricultural fields

International audienceCette recherche a pour objectif de mettre en évidence la contribution des capteurs haute résolution pour une meilleure caractérisation de la surface du sol et pour analyser les effets de la polarisation et de l'angle d'incidence radar. L'objectif de cet article est d'analyser la sensibilité des données haute résolution Terrassar-X sur des sols sans couverture végétale et d'étudier la variabilité spatiale. Les relations entre le coefficient de rétrodiffusion et les paramètres du sol seront étudiés grâce aux images (TerraSAR, Ikonos, SPOT) ainsi que grâce aux mesures de terrain recueillies pendant plusieurs campagnes de terrain en hiver et printemps 2008-2009. Ce travail a été mené sur le bassin de l'Orgeval (France). / Our research aims to show the contribution of high resolution spatial sensors for a better characterization of soil surface, and to analyze polarization effects and radar incidence angle. The objective of this paper is to analyze the sensitivity of very high resolution TerraSAR-X radar data taken over bare soils, and to study the spatial variability. The relationship between backscattering coefficient and soil's parameters (moisture, surface roughness, and texture) will be examined by means of satellite images (TerraSAR, Ikonos, SPOT), as well as ground truth measurements, recorded during several field campaigns in the winter and spring of 2008 and 2009. This study is carried out on Orgeval catchment (France)

Lorentz-violating vs ghost gravitons: the example of Weyl gravity

We show that the ghost degrees of freedom of Einstein gravity with a Weyl term can be eliminated by a simple mechanism that invokes local Lorentz symmetry breaking. We demonstrate how the mechanism works in a cosmological setting. The presence of the Weyl term forces a redefinition of the quantum vacuum state of the tensor perturbations. As a consequence the amplitude of their spectrum blows up when the Lorentz-violating scale becomes comparable to the Hubble radius. Such a behaviour is in sharp contrast to what happens in standard Weyl gravity where the gravitational ghosts smoothly damp out the spectrum of primordial gravitational waves.Comment: 14 pages, 3 figures, REVTeX 4.

On Finslerized Absolute Parallelism spaces

The aim of the present paper is to construct and investigate a Finsler structure within the framework of a Generalized Absolute Parallelism space (GAP-space). The Finsler structure is obtained from the vector fields forming the parallelization of the GAP-space. The resulting space, which we refer to as a Finslerized Parallelizable space, combines within its geometric structure the simplicity of GAP-geometry and the richness of Finsler geometry, hence is potentially more suitable for applications and especially for describing physical phenomena. A study of the geometry of the two structures and their interrelation is carried out. Five connections are introduced and their torsion and curvature tensors derived. Some special Finslerized Parallelizable spaces are singled out. One of the main reasons to introduce this new space is that both Absolute Parallelism and Finsler geometries have proved effective in the formulation of physical theories, so it is worthy to try to build a more general geometric structure that would share the benefits of both geometries.Comment: Some references added and others removed, PACS2010, Typos corrected, Amendemrnts and revisions performe