1,024 research outputs found
Analysis of a diffusive effective mass model for nanowires
We propose in this paper to derive and analyze a self-consistent model
describing the diffusive transport in a nanowire. From a physical point of
view, it describes the electron transport in an ultra-scaled confined
structure, taking in account the interactions of charged particles with
phonons. The transport direction is assumed to be large compared to the wire
section and is described by a drift-diffusion equation including effective
quantities computed from a Bloch problem in the crystal lattice. The
electrostatic potential solves a Poisson equation where the particle density
couples on each energy band a two dimensional confinement density with the
monodimensional transport density given by the Boltzmann statistics. On the one
hand, we study the derivation of this Nanowire Drift-Diffusion Poisson model
from a kinetic level description. On the other hand, we present an existence
result for this model in a bounded domain
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 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 , 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
Giant spin-dependent photo-conductivity in GaAsN dilute nitride semiconductor
A theoretical and experimental study of the spin-dependent photoconductivity
in dilute Nitride GaAsN is presented. The non linear transport model we develop
here is based on the rate equations for electrons, holes, deep paramagnetic and
non paramagnetic centers both under CW and pulsed optical excitation. Emphasis
is given to the effect of the competition between paramagnetic centers and non
paramagnetic centers which allows us to reproduce the measured characteristics
of the spin-dependent recombination power dependence. Particular attention is
paid to the role of an external magnetic field in Voigt geometry. The
photoconductivity exhibits a Hanle-type curve whereas the spin polarization of
electrons shows two superimposed Lorentzian curves with different widths,
respectively related to the recombination of free and trapped electrons. The
model is capable of reproducing qualitatively and quantitatively the most
important features of photoluminescence and photocurrent experiments and is
helpful in providing insight on the various mechanisms involved in the electron
spin polarization and filtering in GaAsN semiconductors.Comment: 10 pages, 5 figure
Potentialités androgénétiques du palmier dattier Phoenix dactylifera L. et culture in vitro d'anthères
Genetic potentialities if five male date palm genotypes, and in vitro culture of anthers. The experimental results derived from the study of five date palm (Phoenix dactylifera L.) genotypes indicate that the ability of microspores to divide varies with genotype and culture medium. The highest frequency of microspore division is obtained with the induction medium [Murashige and Skoog (MS 1962) mineral elements, 2,4-dichlorophenoxyacetique (2,4-D), 2-isopentenylaminopurine (2-IP)] containing activated charcoal. The pollinator T106 was considered as the most efficient genotype in our experimentatio
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
Room temperature Giant Spin-dependent Photoconductivity in dilute nitride semiconductors
By combining optical spin injection techniques with transport spectroscopy
tools, we demonstrate a spin-photodetector allowing for the electrical
measurement and active filtering of conduction band electron spin at room
temperature in a non-magnetic GaAsN semiconductor structure. By switching the
polarization of the incident light from linear to circular, we observe a Giant
Spin-dependent Photoconductivity (GSP) reaching up to 40 % without the need of
an external magnetic field. We show that the GSP is due to a very efficient
spin filtering effect of conduction band electrons on Nitrogen-induced Ga
self-interstitial deep paramagnetic centers.Comment: 4 pages, 3 figure
2D Parity Product Code for TSV online fault correction and detection
Through-Silicon-Via (TSV) is one of the most promising technologies to realize 3D Integrated Circuits (3D-ICs).  However, the reliability issues due to the low yield rates and the sensitivity to thermal hotspots and stress issues are preventing TSV-based 3D-ICs from being widely and efficiently used. To enhance the reliability of TSV connections, using error correction code to detect and correct faults automatically has been demonstrated as a viable solution.This paper presents a 2D Parity Product Code (2D-PPC) for TSV fault-tolerance with the ability to correct one fault and detect, at least, two faults.  In an implementation of 64-bit data and 81-bit codeword, 2D-PPC can detect over 71 faults, on average. Its encoder and decoder decrease the overall latency by 38.33% when compared to the Single Error Correction Double Error Detection code.  In addition to the high detection rates, the encoder can detect 100% of its gate failures, and the decoder can detect and correct around 40% of its individual gate failures. The squared 2D-PPC could be extended using orthogonal Latin square to support extra bit correction
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