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Search Results: 1 - 10 of 138763 matches for " K. Bencheikh "
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Nuclear Mean Fields through Selfconsistent Semiclassical Calculations
J. Bartel,K. Bencheikh
Physics , 2002,
Abstract: Semiclassical expansions derived in the framework of the Extended Thomas-Fermi approach for the kinetic energy density tau(r) and the spin-orbit density J(r) as functions of the local density rho(r) are used to determine the central nuclear potentials V_n(r) and V_p(r) of the neutron and proton distribution for effective interactions of the Skyrme type. We demonstrate that the convergence of the resulting semiclassical expansions for these potentials is fast and that they reproduce quite accurately the corresponding Hartree-Fock average fields.
Exact results for the Wigner transform phase space densities of a two-dimensional harmonically confined charged quantum gas subjected to a magnetic field
K. Bencheikh,L. M. Nieto
Physics , 2008, DOI: 10.1103/PhysRevA.78.053614
Abstract: Closed form analytical expressions are obtained for the Wigner transform of the Bloch density matrix and for the Wigner phase space density of a two dimensional harmonically trapped charged quantum gas in a uniform magnetic field of arbitrary strength, at zero and nonzero temperatures. An exact analytic expression is also obtained for the autocorrelation function. The strong magnetic field case, where only few Landau levels are occupied, is also examined, and useful approximate expressions for the spatial and momentum densities are given.
Current reversals in rapidly rotating ultra-cold Fermi gases
K. Bencheikh,S. Medjedel,G. Vignale
Physics , 2014, DOI: 10.1103/PhysRevA.89.063620
Abstract: We study the equilibrium current density profiles of harmonically trapped ultra-cold Fermi gases in quantum Hall-like states that appear when the quasi-two-dimensional trap is set in fast rotation. The density profile of the gas (in the rotating reference frame) consists of incompressible strips of constant quantized density separated by compressible regions in which the density varies. Remarkably, we find that the atomic currents flow in opposite directions in the compressible and incompressible regions -- a prediction that should be amenable to experimental verification.
Gradient corrections to the kinetic energy density functional of a two-dimensional Fermi gas at finite temperature
Brandon P. van Zyl,K. Berkane,K Bencheikh,A. Farrell
Physics , 2010, DOI: 10.1103/PhysRevB.83.195136
Abstract: We examine the leading order semiclassical gradient corrections to the non-interacting kinetic energy density functional of a two dimensional Fermi gas by applying the extended Thomas-Fermi theory at finite temperature. We find a non-zero von Weizs\"acker-like gradient correction, which in the high-temperature limit, goes over to the familiar functional form $(\hbar^2/24m) (\nabla\rho)^2/\rho$. Our work provides a theoretical justification for the inclusion of gradient corrections in applications of density-functional theory to inhomogeneous two-dimensional Fermi systems at any {\em finite} temperature.
Bulk properties of rotating nuclei and the validity of the liquid drop model at finite angular momenta
J. Piperova,D. Samsoen,P. Quentin,K. Bencheikh,J. Bartel,J. Meyer
Physics , 1999, DOI: 10.1016/S0375-9474(99)00159-1
Abstract: Out of self-consistent semi-classical calculations performed within the so-called Extended Thomas-Fermi approach for 212 nuclei at all even angular momentum values I ranging between 0 and 80 \hbar and using the Skyrme SkM* effective force, the I-dependence of associated liquid drop model parameters has been studied. The latter have been obtained trough separate fits of the calculated values of the strong interaction as well as direct and exchange Coulomb energies. The theoretical data basis so obtained, has allowed to make a rough quantitative assessment of the variation with I of the usual volume and surface energy parameters up to spin of \sim 30-40 \hbar. As a result of the combined variation of the surface and Coulomb energies, it has been shown that this I-dependence results in a significant enhancement of the fission stability of very heavy nuclei, balancing thus partially the well-known instability due to centrifugal forces.
Combined Esprit-Rootmusic for DOA-Dod Estimation in Polarimetric Bistatic MIMO Radar
Mohamed Laid Bencheikh;Yide Wang
PIER Letters , 2011,
Abstract: In this paper, we investigate the exploitation of the polarimetric diversity signal properties in a bistatic polarimetric MIMO radar to improve the performance of joint estimation of direction of arrival (DOA) and direction of departure (DOD) of targets using Combined ESPRIT-RootMUSIC technique. Numerical simulations are carried out to illustrate the performance of the proposed approach.
Algorithmic approach for the asymptotic behavior of a system of parabolic quasi-variational inequalities
M. A. Bencheikh Le Hocine,M. Haiour
Applied Mathematical Sciences , 2013,
Abstract: In this paper we evaluate the variation in $L^{infty }$ -norm between $%u_{h}^{i}left( T,xright) ;~i=1,...,J~$ the discrete solution calculated atthe moment $T$ and $u_{infty }^{i}$; the asymptotic continuous solution ofthe system of parabolic quasi-variational inequalities with noncoerciveoperators. The proof uses an algorithmic approach and the system of ellipticquasi-variational inequalities results.
Occurrence of Salmonella in Chicken Carcasses and Giblets in Meknes-Morocco
Chaiba Abdellah,Rhazi Filali Fouzia,Chahlaoui Abdelkader,Soulaymani Bencheikh Rachida
Pakistan Journal of Nutrition , 2008,
Abstract: A study was conducted to estimate the occurrence and distribution of Salmonella in raw chicken meat and giblets (liver and gizzard) on the Moroccan market. From November 2005 to November 2006, a total of 576 samples were collected from retailers. Of these, 144 samples were from popular market, 144 from artisanal slaughterhouses, 144 from poulterers` shops and 144 from a supermarket at Meknes (centre-south Morocco). Of the total 576 samples examined, Salmonella was detected in 57 (9.90%) of the samples analyzed. Among the chicken samples examined high proportion of gizzard (13.88 %), liver (11.11 %), leg (8.33 %) and breast (6.25 %) were contaminated with Salmonella. In summary 30 (20.83 %) of the popular market samples, 24 (16.66 %) of the traditional slaughterhouses samples and 3 (2.08%) of the poulterers` shops were positive for one or more Salmonella. Out of the total 57 Salmonella isolates, 4 different serotypes were identified of which S. Typhimurium (40.35%) was the most frequent followed by S. Newport (26.31%). S. Montevideo (17.54 %) and S. Heidelberg (15.78 %). Results of the present study indicated that there was a high level of Salmonella contamination of chicken meat and giblets in popular market and artisanal slaughterhouses, which could be considered as one of the major potential source of human salmonellosis in Morocco.
Assessing the Number of Clusters From a Mixture of Von Mises-Fisher
Wafia Parr Bouberima,Mohamed Nadif,Yamina Khemal Bencheikh
Lecture Notes in Engineering and Computer Science , 2010,
Abstract:
Epidemiological profile of snakebites in Morocco
Arfaoui, A;Hmimou, R;Ouammi, L;Soulaymani, A;Mokhtari, A;Chafiq, F;Soulaymani-Bencheikh, R;
Journal of Venomous Animals and Toxins including Tropical Diseases , 2009, DOI: 10.1590/S1678-91992009000400005
Abstract: the present work aims to find the epidemiological profile of snakebites in morocco through a retrospective study of 1,423 snakebite cases that occurred between 1992 and 2007. data were obtained from medical charts of envenomation at the poison control and pharmacovigilance center of morocco. results revealed that 86% of the snakebites had occurred in rural areas and that males were significantly more affected than females at a sex ratio of 23:20. furthermore, 35% of the bites happened during the summer, with a peak of 215 cases in june (15.1%). we also discovered that 67.3% of the patients were bitten during the day. the age group that comprised the most agriculturally active persons, from 20 to 44 years old, was the most affected by snakebites (551 cases). in terms of evolution, patients who were at least 60 years of age (8.89%) as well as those who were less than 10 years old (7.50%) presented higher mortality. according to clinical severity grades, the data revealed a 70% predominance of grade 2 cases (430). deaths had occurred only in patients with grades 3 and 4. furthermore, grade 4 patients presented 100% mortality whereas grade 3 registered 10.7%. the distribution of snakebites according to administrative regions in morocco showed a predominance of the souss-massa-daraa region both in terms of frequency (32%) and mortality (72.1%). our study clearly displayed the severity and extent of the snakebite problem in the country, thus revealing that public health authorities should give more attention to this serious situation.
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