A convolution approach to X-ray powder line-profile fitting is developed in which the line shape is synthesized from the Cu Ks emission profile, the dimensions of the diffractometer and the physical variables of the specimen. In addition to the integrated intensities and 20 positions of the line profiles, the parameters that may be fitted include the receiving-slit width, the receiving-slit len...

In this paper we present the first BV I CCD photometry of six overlooked old open clusters (Berkeley 44, NGC 6827, Berkeley 52, Berkeley 56, Skiff 1 and Berkeley 5) and derive estimates of their fundamental parameters by using isochrones from the Padova library (Girardi et al. 2000). We found that all the clusters are older than the Hyades, with ages ranging from 0.8 (NGC 6827 and Berkeley 5) t...

Context. Owing to the strong magnetic field and related abnormal surface layers existing in rapidly oscillating Ap (roAp) stars, systematic errors are likely to be present when determining their effective temperatures, which potentially compromises asteroseismic studies of this class of pulsators. Aims. Using the unique angular resolution provided by long-baseline visible interferometry, our go...

Context. Determining the effective temperature of Ap stars, including the roAp stellar pulsators, is a difficult task owing to their strong magnetic field and their related spotted surfaces. It is, however, an important step towards constraining models of their complex atmosphere and testing proposed pulsation excitation mechanisms. Aims. Using the unique angular resolution provided by long-bas...

I describe briefly the Cosmic Microwave Background (hereafter CMB) physics which explains why high accuracy observations of its spatial structure are a unique observational tool both for the determination of the global cosmological parameters and to constrain observationally the physics of the early universe. I also briefly survey the many experiments which have measured the anisotropies of the...

We present mass and radius derivations for a sample of very young, midto late M, low-mass stellar and substellar objects in Upper Scorpius and Taurus. In a previous paper, we determined effective temperatures and surface gravities for these targets, from an analysis of their high-resolution optical spectra and comparisons to the latest synthetic spectra. We now derive extinctions, radii, masses...

In this paper, a multivariate fundamental skew probit (MFSP) model is used to model correlated ordinal responses which are constructed from the multivariate fundamental skew normal (MFSN) distribution originate to the greater flexibility of MFSN. To achieve an appropriate VC structure for reaching reliable statistical inferences, many types of variance covariance (VC) structures are considered ...

This study concentrates on the free pure radial vibrations of hollow spheres made of hypothetically functionally simple power rule graded materials having identical inhomogeneity indexes for both Young’s modulus and the density in an analytical manner. After offering the exact elements of the free vibration coefficient matrices for free-free, free-fixed, and fixed-fixed restraints, a parametric...