Porto Oscillation Code (POSC)

The Porto Oscillation Code (POSC) has been developed in 1995 and improved over the years, with the main goal of calculating linear adiabatic oscillations for models of solar-type stars. It has also been used to estimate the frequencies and eigenfunctions of stars from the pre-main sequence up to the sub-giant phase, having a mass between 0.8 and 4 solar masses. The code solves the linearised perturbation equations of adiabatic pulsations for an equilibrium model using a second order numerical integration method. The possibility of using Richardson extrapolation is implemented. Several options for the surface boundary condition can be used. In this work we briefly review the key ingredients of the calculations, namely the equations, the numerical scheme and the output.Comment: Accepted for publication in Astrophysics and Space Science

Split-sideband spectroscopy in slowly modulated optomechanics

Optomechanical coupling between the motion of a mechanical oscillator and a cavity represents a new arena for experimental investigation of quantum effects on the mesoscopic and macroscopic scale.The motional sidebands of the output of a cavity offer ultra-sensitive probes of the dynamics. We introduce a scheme whereby these sidebands split asymmetrically and show how they may be used as experimental diagnostics and signatures of quantum noise limited dynamics. We show split-sidebands with controllable asymmetry occur by simultaneously modulating the light-mechanical coupling $g$ and $\omega_M$ - slowly and out of-phase. Such modulations are generic but already occur in optically trapped set-ups where the equilibrium point of the oscillator is varied cyclically. We analyse recently observed, but overlooked, experimental split-sideband asymmetries; although not yet in the quantum regime, the data suggests that split sideband structures are easily accessible to future experiments

Cavity cooling a single charged nanoparticle

The development of laser cooling coupled with the ability to trap atoms and ions in electromagnetic fields, has revolutionised atomic and optical physics, leading to the development of atomic clocks, high-resolution spectroscopy and applications in quantum simulation and processing. However, complex systems, such as large molecules and nanoparticles, lack the simple internal resonances required for laser cooling. Here we report on a hybrid scheme that uses the external resonance of an optical cavity, combined with radio frequency (RF) fields, to trap and cool a single charged nanoparticle. An RF Paul trap allows confinement in vacuum, avoiding instabilities that arise from optical fields alone, and crucially actively participates in the cooling process. This system offers great promise for cooling and trapping a wide range of complex charged particles with applications in precision force sensing, mass spectrometry, exploration of quantum mechanics at large mass scales and the possibility of creating large quantum superpositions.Comment: 8 pages, 5 figures Updated version includes additional references, new title, and supplementary information include

The magnitude of the variation in glycemia: a new parameter for risk assessment in acute coronary syndrome?

INTRODUCTION AND OBJECTIVES: The aim was to evaluate the relationship between the magnitude of the variation in the level of glycemia during hospitalization and in-hospital and long-term mortality and postdischarge endpoints in two groups of patients with acute coronary syndrome: those with and those without a previous diagnosis of diabetes. METHODS: The study included 1210 patients admitted for acute coronary syndrome between May 2004 and July 2007. The study population was divided in two subgroups: patients with a previous diagnosis of diabetes (n=386) and nondiabetics (n=824). Each subgroup was further divided into four smaller groups according to the quartile of glycemia variation: diabetics (Q1: or=164 mg/dl) and nondiabetics (Q1: or=60 mg/dl). Patients were followed up for an average of 18 months after the occurrence of the acute coronary syndrome. RESULTS: In diabetic patients, there was no relationship between the magnitude of the glycemia variation and in-hospital or postdischarge endpoints. In nondiabetics, no significant difference was observed in in-hospital mortality or morbidity, but statistically significant clinical differences were found during follow-up. Multivariate regression analysis showed that Q4 versus Q1, age >or=70 years, and previous antiplatelet or angiotensin-converting enzyme inhibitor therapy were independent predictors of postdischarge endpoints in the nondiabetic group. CONCLUSIONS: In nondiabetic acute coronary syndrome patients, the magnitude of the variation in glycemia observed during hospitalization was a strong independent predictor of postdischarge clinical endpoints

Comparisons for Esta-Task3: Cles and Cesam

We present the results of comparing three different implementations of the microscopic diffusion process in the stellar evolution codes CESAM and CLES. For each of these implementations we computed models of 1.0, 1.2 and 1.3 M$_{\odot}$. We analyse the differences in their internal structure at three selected evolutionary stages, as well as the variations of helium abundance and depth of the stellar convective envelope. The origin of these differences and their effects on the seismic properties of the models are also considered.Comment: 10 pages, 8 figures, Joint HELAS and CoRoT/ESTA Workshop on Solar/Stellar Models and Seismic Analysis Tools, Novembre, Porto 2007 To be published in EAS Publications Serie

Combinations of Nitrogen and Sulphur for Signal Grass Yield

Signal grass (Brachiaria decumbens) is grown in Brazilian pastures, and the increase in forage yield of such pastures is achieved by fertilization. Nitrogen (N) is the nutrient mostly demanded for increasing grass productivity, and its utilization creates a demand for other nutrients, such as sulphur (S). These two nutrients are well related in plant metabolism, but the S nutrition of signal grass must be better understood. The use of a fractional factorial makes possible the study of several rates of these two nutrients, that combined with the response surface methodology allows anyone to find out the responses to these rates combinations. The objective of this research was to obtain the responses in dry matter yield of plant tops and roots of signal grass grown under N and S combinations

Optical doping and damage formation in AIN by Eu implantation

AlN films grown on sapphire were implanted with 300 keV Eu ions to fluences from 3×1014 to 1.4×1017 atoms/cm2 in two different geometries: “channeled” along the c-axis and “random” with a 10° angle between the ion beam and the surface normal. A detailed study of implantation damage accumulation is presented. Strong ion channeling effects are observed leading to significantly decreased damage levels for the channeled implantation within the entire fluence range. For random implantation, a buried amorphous layer is formed at the highest fluences. Red Eu-related photoluminescence at room temperature is observed in all samples with highest intensities for low damage samples (low fluence and channeled implantation) after annealing. Implantation damage, once formed, is shown to be stable up to very high temperatures.FCT - POCI/FIS/57550/2004FCT - PTDC/FIS/66262/2006FCT - PTDC/CTM/100756/200