Strong quantum correlations in four wave mixing in 85^{85}Rb vapor

We study quantum intensity correlations produced using four-wave mixing in a room-temperature rubidium vapor cell. An extensive study of the effect of the various parameters allows us to observe very large amounts of non classical correlations.Comment: 8 pages and 8 figures; work presented at the SPIE Photonics Europe conference (Brussels, 2010

Oxidative Stress in Cancer

Contingent upon concentration, reactive oxygen species (ROS) influence cancer evolution in apparently contradictory ways, either initiating/stimulating tumorigenesis and supporting transformation/proliferation of cancer cells or causing cell death. To accommodate high ROS levels, tumor cells modify sulfur-based metabolism, NADPH generation, and the activity of antioxidant transcription factors. During initiation, genetic changes enable cell survival under high ROS levels by activating antioxidant transcription factors or increasing NADPH via the pentose phosphate pathway (PPP). During progression and metastasis, tumor cells adapt to oxidative stress by increasing NADPH in various ways, including activation of AMPK, the PPP, and reductive glutamine and folate metabolism

Diffusion microbienne par aérosol lors du détartrage ultrasonique: étude descriptive.

The aim of this study was to evaluate the bacterial spreading by using ultrasonic scaler and air-polisher. During ultrasonic scaling, bacterial spray is important near patient's mouth (30 cm), principally without good aspiration devices. In this case, clear spreading is observed at 2 m from the patient. Air-polishing compared to ultrasonic scaling produces larger microorganisms pollution

Laser Dynamics

Bridging the gap between laser physics and applied mathematics, this book offers a new perspective on laser dynamics. Combining fresh treatments of classic problems with up-to-date research, asymptotic techniques appropriate for nonlinear dynamical systems are shown to offer a powerful alternative to numerical simulations. The combined analytical and experimental description of dynamical instabilities provides a clear derivation of physical formulae and an evaluation of their significance. Starting with the observation of different time scales of an operating laser, the book develops approximation techniques to systematically explore their effects. Laser dynamical regimes are introduced at different levels of complexity, from standard turn-on experiments to stiff, chaotic, spontaneous or driven pulsations. Particular attention is given to quantitative comparisons between experiments and theory. The book broadens the range of analytical tools available to laser physicists and provides applied mathematicians with problems of practical interest, making it invaluable for graduate students and researchers.SCOPUS: bk.binfo:eu-repo/semantics/published

Genetic evaluation of calving ease for Walloon Holstein dairy cattle.

Calving complications have an incidence on the economic profitability of dairy herds. In the Walloon Region of Belgium, calving ease data recording is being done on voluntary basis since 2000. This allows now the implementation of a genetic evaluation of Holstein dairy cattle addressing the need of dairy breeders to select bulls in order to reduce frequency of calving problems. Calving ease scores were analyzed using univariate animal linear models, which were fitted with the genetic correlation between direct and maternal additive genetic effects either estimated or constrained to zero. Variance components and related genetic parameters were estimated from a dataset including 33,155 calving records. Included in the models were fixed season effects, fixed herd effects and fixed sex of calf*age of dam classes*group of calvings interaction effects, random herd*year of calving effects, random maternal permanent environment effects, and random animal direct and maternal additive genetic effects. For both models, direct and maternal heritabilities for calving ease were about 8% and about 2%, respectively. Genetic correlation between direct and maternal additive effects was found to be non-significantly different from zero. So, an animal linear model with genetic correlation between direct and maternal effects constrained to zero was adopted for the routine genetic evaluation of calving ease for Walloon Holstein dairy cattle. This model was validated by Interbull in January 2013 and, since April 2013, the Walloon Region of Belgium has officially participated to the international MACE evaluation for calving traits

Delayed pulse dynamics in single mode class B lasers

info:eu-repo/semantics/publishe

Laser Nd + : YVO4 (dynamique et conduite optimale)

Ce travail s'inscrit dans le cadre général de l'étude de la dynamique des lasers de classe B. Trois aspects sont abordés concernant respectivement la génération d'impulsions de forme arbitraire, la validation de modèles de lasers existants et la mise en évidence d'effets "cliquet" dans la dynamique de ces lasers. Une première partie présente deux méthodes mises au point pour la génération d'impulsions de forme arbitraire (triangle, gaussienne, impulsion à deux bosses) en dépit de la propension du laser à fournir des impulsions "sécante-hyperbolique". Dans les deux cas un Algorithme Génétique (AG) détermine les paramètres du signal de conduite optimal. Si pour la première méthode ce signal est construit à partir de fonctions élémentaires, pour la seconde il résulte d'une interpolation entre points de collocation fixés par l'AG. Les outils développés (couplage captures rapides/traitements en temps réel par AG) ont été mis à profit pour étudier la validité des différents modèles décrivant la dynamique des lasers de classe B fonctionnant en régime monomode ou bi-raie. L'AG est alors utilisé pour comparer l'évolution temporelle de l'intensité émise par le laser à celle calculée à partir du modèle. Ils permettent ainsi d'identifier le modèle le mieux adapté et de déterminer ses paramètres. La bonne connaissance que nous avons de la dynamique de notre laser nous a incité à effectuer une étude détaillée d'effets étonnants induits par une modulation temporelle asymétrique du pompage. Les expériences réalisées constituent la première mise en évidence sur un laser d'un effet "cliquets" similaire à celui proposé par Feynman pour extraire de l'énergie d'un mouvement erratique.LILLE1-BU (590092102) / SudocSudocFranceF

Comment on "Formation of repetitively nanosecond spatial solitons in a saturable absorber Q-switched laser"

1 pageIn their recent letter..

Stabilizing or destabilizing lasers by continuous delayed feedback

The equations for a class B laser with loss modulation and delayed feedback have been analysed. By using asymptotic methods, an amplitude equation is determined which describes the first period doubling bifurcation. From this equation, it is shown that the feedback may stabilize an initially unstable periodic solution by shifting the period doubling bifurcation point. However, we also show that the feedback may destabilize an initially stable periodic solution for different values of the parameters. Our results are substantiated by a numerical study of the laser equations and by new experiments on a CO 2 laser.SCOPUS: ar.jinfo:eu-repo/semantics/publishe