We present new empirical and theoretical calibrations of two photometric metallicity indices based on Walraven photometry. The empirical calibration relies on a sample of 48 Cepheids for which iron ...abundances based on high resolution spectra are available in the literature. They cover a broad range in metal abundance (-0.5 < Fe/H < +0.5) and the intrinsic accuracy of the Metallicity Index Color (MIC) relations is better than 0.2 dex. The theoretical calibration relies on a homogeneous set of scaled-solar evolutionary tracks for intermediate-mass stars and on pulsation predictions concerning the topology of the instability strip. The metal content of the adopted evolutionary tracks ranges from Z=0.001 to Z=0.03 and the intrinsic accuracy of the MIC relations is better than 0.1 dex.
Astrophys.J. 623 (2005) 860-865 We present three different optical and near-infrared (NIR) data sets for
evolved stars in the Galactic Globular Cluster Omega Cen The comparison between
observations ...and homogeneous sets of stellar isochrones and Zero-Age Horizontal
Branches provides two reasonable fits. Both of them suggest that the so-called
anomalous branch has a metal-intermediate chemical composition (-1.1 < Fe/H <
-0.8) and is located ~500 pc beyond the bulk of Omega Cen stars. These findings
are mainly supported by the shape of the subgiant branch in four different
color-magnitude diagrams (CMDs). The most plausible fit requires a higher
reddening, E(B-V)=0.155 vs. 0.12, and suggests that the anomalous branch is
coeval, within empirical and theoretical uncertainties, to the bulk of Omega
Cen stellar populations. This result is supported by the identification of a
sample of faint horizontal branch stars that might be connected with the
anomalous branch. Circumstantial empirical evidence seems to suggest that the
stars in this branch form a clump of stars located beyond the cluster.
We report on two X-ray observations of the transient source XTE J0421+560
performed by BeppoSAX, and on a series of observations performed by the 0.7m
Teramo-Normale Telescope. Outburst peak ...occurrence time and duration depend on
photon energy: the outburst peak is achieved first in the X-ray band, then in
the optical and finally in the radio. An exponential decay law fits well the
X-ray data except in the TOO2 0.5-1.0 keV band, where erratic time variability
is detected. During TOO1 the e-folding time scale decreases with energy up to ~
20 keV, when it achieves a saturation; during TOO2 it decreases up to ~ 2 keV
and then increases. This change is correlated with a spectral change,
characterized by the onset of a soft (< 2 keV) component in TOO2 (Orr et al.
1998). This component might originate from the relativistic jets, while the
hard component is more likely associated to processes occurring in the
circumstellar matter and/or near the compact object. Optical observations show
that the object appears intrinsically red even during the outburst. The nature
of the compact object is discussed.
We present three different optical and near-infrared (NIR) data sets for evolved stars in the Galactic Globular Cluster Omega Cen The comparison between observations and homogeneous sets of stellar ...isochrones and Zero-Age Horizontal Branches provides two reasonable fits. Both of them suggest that the so-called anomalous branch has a metal-intermediate chemical composition (-1.1 < Fe/H < -0.8) and is located ~500 pc beyond the bulk of Omega Cen stars. These findings are mainly supported by the shape of the subgiant branch in four different color-magnitude diagrams (CMDs). The most plausible fit requires a higher reddening, E(B-V)=0.155 vs. 0.12, and suggests that the anomalous branch is coeval, within empirical and theoretical uncertainties, to the bulk of Omega Cen stellar populations. This result is supported by the identification of a sample of faint horizontal branch stars that might be connected with the anomalous branch. Circumstantial empirical evidence seems to suggest that the stars in this branch form a clump of stars located beyond the cluster.
We report on two X-ray observations of the transient source XTE J0421+560 performed by BeppoSAX, and on a series of observations performed by the 0.7m Teramo-Normale Telescope. Outburst peak ...occurrence time and duration depend on photon energy: the outburst peak is achieved first in the X-ray band, then in the optical and finally in the radio. An exponential decay law fits well the X-ray data except in the TOO2 0.5-1.0 keV band, where erratic time variability is detected. During TOO1 the e-folding time scale decreases with energy up to ~ 20 keV, when it achieves a saturation; during TOO2 it decreases up to ~ 2 keV and then increases. This change is correlated with a spectral change, characterized by the onset of a soft (< 2 keV) component in TOO2 (Orr et al. 1998). This component might originate from the relativistic jets, while the hard component is more likely associated to processes occurring in the circumstellar matter and/or near the compact object. Optical observations show that the object appears intrinsically red even during the outburst. The nature of the compact object is discussed.
16 patients with Kaposi's Sarcoma were examined with in vitro tests for cellular immunity and with determination of antibody titres to Cytomegalovirus. It was stated that the Cytomegalovirus ...antibodies were related with new viral infections favoured by the immunosuppression.
9 patients with Kaposi's sarcoma, not treated with immunosuppressant drugs, were studied. In the Kaposi's disseminated form an impaired function of T mediated immunity (Leukocytes migration ...inhibition for PHA and PPD and skin test for DNCB) was found. The number of T lymphocytes (E rosettes) was normal. In the Kaposi's initial form with multiple dermal plaques and nodules, these alterations of cellular immunity were absent. In 4 patients elevated titles of Cytomegalovirus antibodies were found. The occurrence of an impairment of cellular immunity only in the serious and disseminated Kaposi's form is emphasized by the Authors.
