360 degree domain wall generation in the soft layer of magnetic tunnel junctions

High spatial resolution X-ray photo-emission electron microscopy technique has been used to study the influence of the dipolar coupling taking place between the NiFe and the Co ferromagnetic electrodes of micron sized, elliptical shaped magnetic tunnel junctions. The chemical selectivity of this technique allows to observe independently the magnetic domain structure in each ferromagnetic electrode. The combination of this powerful imaging technique with micromagnetic simulations allows to evidence that a 360 degree domain wall can be stabilized in the NiFe soft layer. In this letter, we discuss the origin and the formation conditions of those 360 degree domain walls evidenced experimentally and numerically

Artificial Kagome Arrays of Nanomagnets: A Frozen Dipolar Spin Ice

Magnetic frustration effects in artificial kagome arrays of nanomagnets are investigated using x-ray photoemission electron microscopy and Monte Carlo simulations. Spin configurations of demagnetized networks reveal unambiguous signatures of long range, dipolar interaction between the nanomagnets. As soon as the system enters the spin ice manifold, the kagome dipolar spin ice model captures the observed physics, while the short range kagome spin ice model fails.Comment: 4 pages, 4 figures, 1 tabl

Optimization of cw sodium laser guide star efficiency

Context: Sodium laser guide stars (LGS) are about to enter a new range of laser powers. Previous theoretical and numerical methods are inadequate for accurate computations of the return flux and hence for the design of the next-generation LGS systems. Aims: We numerically optimize the cw (continuous wave) laser format, in particular the light polarization and spectrum. Methods: Using Bloch equations, we simulate the mesospheric sodium atoms, including Doppler broadening, saturation, collisional relaxation, Larmor precession, and recoil, taking into account all 24 sodium hyperfine states and on the order of 100 velocity groups. Results: LGS return flux is limited by "three evils": Larmor precession due to the geomagnetic field, atomic recoil due to radiation pressure, and transition saturation. We study their impacts and show that the return flux can be boosted by repumping (simultaneous excitation of the sodium D2a and D2b lines with 10-20% of the laser power in the latter). Conclusions: We strongly recommend the use of circularly polarized lasers and repumping. As a rule of thumb, the bandwidth of laser radiation in MHz (at each line) should approximately equal the launched laser power in Watts divided by six, assuming a diffraction-limited spot size.Comment: 15 pages, 12 figures, to be published in Astronomy & Astrophysics, AA/2009/1310

The correlation of RNase A enzymatic activity with the changes in the distance between Nepsilon2-His12 and N delta1-His119 upon addition of stabilizing and destabilizing salts.

The effect of stabilizing and destabilizing salts on the catalytic behavior of ribonuclease A (RNase A) was investigated at pH 7.5 and 25 degrees C, using spectrophotometric, viscometric and molecular dynamic methods. The changes in the distance between N(epsilon2) of His(12) and N(delta1) of His(119) at the catalytic center of RNase A upon the addition of sodium sulfate, sodium hydrogen sulfate and sodium thiocyanate were evaluated by molecular dynamic methods. The compactness and expansion in terms of Stokes radius of RNase A upon the addition of sulfate ions as kosmotropic salts, and thiocyanate ion as a chaotropic salt, were estimated by viscometric measurements. Enzyme activity was measured using cytidine 2', 3'-cyclic monophosphate as a substrate. The results from the measurements of distances between N(epsilon2) of His(12) and N(delta1) of His(119) and Stokes radius suggest (i) that the presence of sulfate ions decreases the distance between the catalytic His residues and increases the globular compactness, and (ii) that there is an expansion of the enzyme surface as well as elongation of the catalytic center in the presence of thiocyanate ion. These findings are in agreement with activity measurements

Analytical Models Synthesis of Power Electronic Converters

In this paper we proposes a synthesis of different mathematical models of power electronic converters based on Thevenin/Norton equivalent circuits. Those models, composed by impedances and harmonic noise sources, are helpful to predict the conducted ElectroMagnetic Interferences (EMI) generated by converters connected to the electrical network. Moreover, the extracted impedances are determining for sizing EMC filters. The proposed analytical model is tested with PSpice simulations and validated by experimental measurements, from DC frequency until 30MHz

Thrombose de la veine ovarienne au post-partum, révélée par un syndrome appendiculaire: à propos d’un cas

Une patiente de 27 ans a présenté à J13 du post partum, suite à un accouchement eutocique non compliqué et sans anamnèse infectieuse, une douleur en fosse iliaque droite évoluant dans un contexte fébrile. Devant une suspicion clinique et biologique d'appendicite, nous avons réalisé une échographie abdominopelvienne qui était normale. Le complément par scanner abdominale, a objectivé une thrombose de la veine ovarienne (TVO) à droite remontant jusqu'à la veine cave inférieure. Le traitement médical était basé essentiellement sur les anticoagulants. L'évolution était favorable

Prise en charge du Cancer de la Vulve

Le cancer de la vulve est relativement rare. Son étiopathogénie est actuellement mieux élucidée. Sa prise en charge, essentiellement chirurgicale, a évolué vers une approche conservatrice grâce aux résections limitées et à la lymphadénectomie sélective qui a permis de réduire considérablement la morbidité et les séquelles chirurgicales sans pour autant altérer le pronostic. La prise en charge du cancer de la vulve doit être multidisciplinaire incluant une chirurgie minimale invasive dans les stades précoces et une radio-chimiothérapie : préopératoires dans les stades localement avancés, en adjuvant en cas de facteurs de risque de rechute et en palliatif dans les formes inopérables. La prévention repose sur le traitement des lésions précancéreuses et la vaccination anti HPV

BALANCED SCORECARD : ENJEUX DE L’I NFORMATION ENTRE CONSTAT ET PRATIQUE DE LA PERFORMANCE

La performance des entreprises est au coeur des préoccupations de plusieurs chercheurs et professionnels en gestion. Depuis plusieurs années, ils étudient les différents liens entre des variables contextuelles comme la stratégie, la structure ou encore l’incertitude perçue de l’environnement et l’effet combiné de ces facteurs sur la performance de l’entreprise. Il s’agit en fait, d’un système de mesure de la performance permettant aux responsables a tous les niveaux un autocontrôle de leurs activités par la déclination de la stratégie en termes opérationnels, mettre l’organisation en adéquation avec la stratégie, transformer la stratégie en un processus continue,… on parle du tableau de bord. Ce travail s’inscrit dans une démarche constructiviste de conception et de mise en œuvre de Balanced Scorecard. En fait ce dernier est l’un des outils les plus utilisés pour l’évaluation des performances au sein des entreprises. Toutefois, sa conception, par les contrôleurs de gestion, pose souvent des difficultés en termes de systèmes d’information adéquats afin de mieux répondre aux attentes et besoins de ses différents utilisateurs