Theoretical investigation of moir\'e patterns in quantum images

Moir\'e patterns are produced when two periodic structures with different spatial frequencies are superposed. The transmission of the resulting structure gives rise to spatial beatings which are called moir\'e fringes. In classical optics, the interest in moir\'e fringes comes from the fact that the spatial beating given by the frequency difference gives information about details(high spatial frequency) of a given spatial structure. We show that moir\'e fringes can also arise in the spatial distribution of the coincidence count rate of twin photons from the parametric down-conversion, when spatial structures with different frequencies are placed in the path of each one of the twin beams. In other words,we demonstrate how moir\'e fringes can arise from quantum images

Conservation of Orbital Angular Momentum in Stimulated Down-Conversion

We report on an experiment demonstrating the conservation of orbital angular momentum in stimulated down-conversion. The orbital angular momentum is not transferred to the individual beams of the spontaneous down-conversion, but it is conserved when twin photons are taken individually. We observe the conservation law for an individual beam of the down-conversion through cavity-free stimulated emission.Comment: Submitted for publication in Phys. Rev. Let

Moir\'e patterns in quantum images

We observed moir\'e fringes in spatial quantum correlations between twin photons generated by parametric down-conversion. Spatially periodic structures were nonlocally superposed giving rise to beat frequencies typical of moir\'e patterns. This result brings interesting perspectives regarding metrological applications of such a quantum optical setup.Comment: 4 pages, 5 figure

Nearest neighbor embedding with different time delays

A nearest neighbor based selection of time delays for phase space reconstruction is proposed and compared to the standard use of time delayed mutual information. The possibility of using different time delays for consecutive dimensions is considered. A case study of numerically generated solutions of the Lorenz system is used for illustration. The effect of contamination with various levels of additive Gaussian white noise is discussed.Comment: 4 pages, 5 figures, updated to final versio

FLOW CHARACTERIZATION FROM A NACA AIR INTAKE ASSEMBLED IN A CANARD TYPE AIRCRAFT

omputational aerodynamics analyses of a NACA air intake assembled in a canard type aircraft is performed in this work. Semi-empirical calculation through the ESDU (Engineering Science Database Unit) preceded the CFD simulations to define the geometric size of the air intake as well to check its efficiency and drag estimation. The NACA air inlet was considered one of the best options available for implementing in a canard type aircraft since it reduces aerodynamic drag by avoiding protuberances in the fuselage. Numerical studies were performed with the air intake mounted in the aircraft's fuselage at operational flight conditions. These simulations were performed using Reynolds-averaged Navier-Stokes (RANS) and turbulence modeling by using the k-ω SST (Shear-Stress Transport). Data analyses were based on the air inlet efficiency, drag estimation and mainly flow characterization. The numerical results helped to characterize the flow in a canard type aircraft showing that the NACA air intake yielded satisfactory performance with low drag. The approach applied in this work was a partnership with the Brazilian Aircraft Factory (FABE) and Federal University of Uberlândia (UFU) to improve the design of a canard type aircraft. The CFD results have been corroborated by an empirical approach and with some experimental tests performed by the company, pointing towards the reliability of a very efficient design tool for application in industry

DOSE AND TIME DEPENDENCE OF TARGETED AND UNTARGETED EFFECTS AFTER VERY LOW DOSES OF α-PARTICLE IRRADIATION OF HUMAN LUNG CANCER CELLS

Understanding the effects to human health resulting from exposure to low doses of ionizing radiation is a persisting challenge. No one questions the deleterious conse- quences for humans following exposure to high radiation doses; however, in the low dose range, the complex and to some extent unknown cellular responses raise important misgivings about the resulting protective or potentially detrimental effects. Bystander effects are involved in low dose exposures, being characterized by the appearance in unirradiated cells of a cellular damage associated with direct radiation exposure. The purpose of our work was to assess, by using clonogenic and micronuclei assays, the dose and time dependence of the bystander response after cells exposure to very low doses of α-particles and to evaluate its importance in the overall induced damage. The study includes an irradiated cells culture, a medium transfer culture with non-irradiated cells and a culture with irra- diated cells after centrifugation. We observed a non-negligible contribution of the bystander effects in the overall cellular damage. Low-dose hyper-sensitivity was observed for medium transfer and irradiated cells after centrifugation cultures. Delayed and earlier cellular damage were similar in almost all experiments, suggesting an effectiveness of irradiated medium to induce a bystander response soon after irradiation