An effective mass theorem for the bidimensional electron gas in a strong magnetic field

We study the limiting behavior of a singularly perturbed Schr\"odinger-Poisson system describing a 3-dimensional electron gas strongly confined in the vicinity of a plane $(x,y)$ and subject to a strong uniform magnetic field in the plane of the gas. The coupled effects of the confinement and of the magnetic field induce fast oscillations in time that need to be averaged out. We obtain at the limit a system of 2-dimensional Schr\"odinger equations in the plane $(x,y)$, coupled through an effective selfconsistent electrical potential. In the direction perpendicular to the magnetic field, the electron mass is modified by the field, as the result of an averaging of the cyclotron motion. The main tools of the analysis are the adaptation of the second order long-time averaging theory of ODEs to our PDEs context, and the use of a Sobolev scale adapted to the confinement operator

Anisotropic thermal magnetoresistance for an active control of radiative heat transfer

We predict a huge anisotropic thermal magnetoresistance (ATMR) in the near-field radiative heat transfer between magneto-optical particles when the direction of an external magnetic field is changed with respect to the heat current direction. We illustrate this effect with the case of two InSb spherical particles where we find that the ATMR amplitude can reach values of up to 800% for a magnetic field of 5 T, which is many orders of magnitude larger than its spintronic analogue in electronic devices. This thermomagnetic effect could find broad applications in the fields of ultrafast thermal management as well as magnetic and thermal remote sensing.Comment: 6 pages, 4 figure

Could Alfa fibers substitute glass fibers in composite materials?

In the present work polyester resin composites with Alfa fibers in the form of pulp were prepared and their properties were compared with those of polyester resin reinforced with glass fibers, the latter composites being widely used for structural applications. The composites were prepared using two manufacturing processes, namely hand lay-up and vacuum molding, to assess the influence of the process on the composites properties. Firstly, the tensile properties for the two composites were evaluated. The composites thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis. Finally, the morphology of a glass fiber composite (GFC) and Alfa pulp composite (APC) was analyzed by scanning electron microscopy, to characterize the composites surface and cross-sections.The authors would like to thank CTC (Centre technique de la Chimie) for their valuable help during mechanical testing. The company Solutions Composites, especially Mr.Adel Hammami is gratefully acknowledged for financial and material support. The authors also wish to thank the members of the Department of Polymer Engineering University of Minho, Guimarães, Portugal for their valuable cooperation. This research work is carried out as part of a mobidocPhD, a program financed by the European Union within Pasri Projet. M.C Paiva acknowledges the Portuguese Foundation for Science and Technology (FCT) and the European program FEDER/COMPETE for the financial support through project PEst-C/CTM/ LA0025/2013 (LA 25-2015-2017)

About A Rare Cause Of Primary Hyperparathyroidism

Introduction: Primary hyperparathyroïdism is observed in 35 to 44 subjects/ 100000 persons. The increased production of parathyroid hormones is secondary to primary glandular modifications consisting mainly in adenomas. The authors report a clear-cell hyperplasia causing primary hyperparathyroidism. Observation: We report the case of a 25-year-old man who was admitted to explore pathologic fractures of the left arm and a malignant hypercalcaemia. Complementary laboratory tests revealed primary hyperparathyroidism. A multiple endocrine neoplasia was excluded by radiologic examinations. Cervical ultra-sound examination revealed 2 parathyroid adenomas and per-operative exploration showed 3 « adenomas ». Microscopic examination of the 4 parathyroid glands specimen concluded to a clear cell hyperplasia. Conclusion: Clear cell hyperplasia is a benign cause of primary hyperparathyroidism. The diagnosis is based upon histologic findings and examination of the 4 glands

Bayesian Signal Subspace Estimation with Compound Gaussian Sources

International audienceIn this paper, we consider the problem of low dimensional signal subspace estimation in a Bayesian con- text. We focus on compound Gaussian signals embedded in white Gaussian noise, which is a realistic modeling for various array processing applications. Following the Bayesian framework, we derive two algorithms to compute the maximum a posteriori (MAP) estimator and the so-called minimum mean square distance (MMSD) estimator, which minimizes the average natural distance between the true range space of interest and its estimate. Such approaches have shown their interests for signal subspace esti- mation in the small sample support and/or low signal to noise ratio contexts. As a byproduct, we also introduce a generalized version of the complex Bingham Langevin distribution in order to model the prior on the subspace orthonormal basis. Finally, numerical simulations illustrate the performance of the proposed algorithms

Signal subspace change detection in structured covariance matrices

International audienceTesting common properties between covariance matricesis a relevant approach in a plethora of applications. In thispaper, we derive a new statistical test in the context of structuredcovariance matrices. Specifically, we consider low rank signalcomponent plus white Gaussian noise structure. Our aim is totest the equality of the principal subspace, i.e., subspace spannedby the principal eigenvectors of a group of covariance matrices. Adecision statistic is derived using the generalized likelihood ratiotest. As the formulation of the proposed test implies a non-trivialoptimization problem, we derive an appropriate majorizationminimizationalgorithm. Finally, numerical simulations illustratethe properties of the newly proposed detector compared to thestate of the art

First documented presence of Galeocerdo cuvier (Péron & Lesueur, 1822) (ELASMOBRANCHII, CARCHARHINIDAE) in the Mediterranean basin (Libyan waters)

One male and one female specimen of tiger shark, Galeocerdo cuvier (Peron & Lesueur, 1822), were accidentally caught by a drifting longline for swordfish in the south Mediterranean (Libyan waters). This finding confirms beyond any doubt that the tiger shark may be encountered in the waters of the Mediterranean Sea. Although records of this species has previously been reported, the information is partial or dubious, due to the lack of a description of the individuals found or the uncertain provenance of preserved material. Our finding confirms the record of this species in the southern part of the Mediterranean basin. Images, as well as morphometrics and information on stomach contents are given. Based on the size of the individuals, it is considered that the two specimens were born recently, presumably inside the Mediterranean Sea and likely close to the area where the individuals were found

Birefringence in nonlinear anisotropic dielectric media

Light propagation is investigated in the context of local anisotropic nonlinear dielectric media at rest with the dielectric coefficients $\epsilon^\mu{}_\nu = \epsilon^\mu{}_\nu (\vec{E},\vec{B})$ and constant $\mu$, in the limit of geometrical optics. Birefringence was examined and the general conditions for its occurrence were presented. A toy model is exhibited, in which uniaxial birefringent media with nonlinear dielectric properties could be driven by external fields in such way that birefringence may be artificially controlled. The effective geometry interpretation is also addressed.Comment: 5 pages, 1 figur

Simulation of resonant tunneling heterostructures: numerical comparison of a complete Schr{ö}dinger-Poisson system and a reduced nonlinear model

Two different models are compared for the simulation of the transverse electronic transport through an heterostructure: a $1D$ self-consistent Schr{ö}dinger-Poisson model with a numerically heavy treatment of resonant states and a reduced model derived from an accurate asymptotic nonlinear analysis. After checking the agreement at the qualitative and quantitative level on quite well understood bifurcation diagrams, the reduced model is used to tune double well configurations for which nonlinearly interacting resonant states actually occur in the complete self-consistent model