9,228 research outputs found
Wellbeing in Workers during COVID-19 Pandemic: The Mediating Role of Self-Compassion in the Relationship between Personal Resources and Exhaustion
Is it time for an endovascular first approach for ruptured thoracoabdominal aortic aneurysms?
A self-consistent test of Comptonization models using a long BeppoSAX observation of NGC 5548
We test accurate models of Comptonization spectra over the high quality data
of the BeppoSAX long look at NGC 5548. The data are well represented by a plane
parallel corona with an inclination angle of 30, a soft photon
temperature of 5 eV and a hot plasma temperature and optical depth of 360 keV and 0.1, respectively. If energy balance
applies, such values suggest that a more ``photon-starved'' geometry (e.g. a
hemispheric region) is necessary. The spectral softening detected during a
flare, appears to be associated to a decrease of the heating-to-cooling ratio,
indicating a geometric and/or energetic modification of the disk plus corona
system. The hot plasma temperature derived with the models above is
significantly higher than that obtained fitting the same data with a power law
plus high energy cut off model for the continuum. This is due to the fact that
in anisotropic geometries Comptonization spectra show "intrinsic" curvature
which moves the fitted high energy cut-off to higher energies.Comment: 4 pages, 2 figures, to appear in the proceedings of the conference
"X-ray Astronomy '99", Bologna, Italy, September 199
WARP: a WIMP double phase Argon detector
The WARP programme for dark matter search with a double phase argon detector
is presented. In such a detector both excitation and ionization produced by an
impinging particle are evaluated by the contemporary measurement of primary
scintillation and secondary (proportional) light signal, this latter being
produced by extracting and accelerating ionization electrons in the gas phase.
The proposed technique, verified on a 2.3 liters prototype, could be used to
efficiently discriminate nuclear recoils, induced by WIMP's interactions, and
measure their energy spectrum. An overview of the 2.3 liters results and of the
proposed 100 liters detector is shown.Comment: Proceeding for IDM200
Hard X-ray emission from the galaxy cluster A2256
After the positive detection by BeppoSAX of hard X-ray radiation up to ~80
keV in the Coma cluster spectrum, we present evidence for nonthermal emission
from A2256 in excess of thermal emission at a 4.6sigma confidence level. In
addition to this power law component, a second nonthermal component already
detected by ASCA could be present in the X-ray spectrum of the cluster, not
surprisingly given the complex radio morphology of the cluster central region.
The spectral index of the hard tail detected by the PDS onboard BeppoSAX is
marginally consistent with that expected by the inverse Compton model. A value
of ~0.05 microG is derived for the intracluster magnetic field of the extended
radio emission in the northern regions of the cluster, while a higher value of
\~0.5 microG could be present in the central radio halo, likely related to the
hard tail detected by ASCA.Comment: 10 pages, 2 figures. To appear in ApJ
O-105. Follow-up of 100 children, aged 1 and 2 years, born after intracytoplasmic sperm injection
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