2,358 research outputs found
La lavorazione della lana e dei tessuti fra Padova e Venezia: tracce strutturali e documentarie di età post-antica
Among the studies on wool production and manufacturing in Veneto, there is so far no search relating to archaeological records from the early Middle Ages. Therefore a new topic for discussion may be presented by two underwater discoveries near Fusina (Venice), in the Malamocco-Marghera Canal, dating from the 7th to the 11th century A.D.
Bringing additional elements to corroborate the hypothesis about the wool-textile destination of these archaeological finds, three kinds of indicators are proposed: firstly, the archaeological findings inland near Fusina, confirming attendance from the imperial to the late-antiquity age; secondly, the role of a branch of the river Brenta, called Maior, that was excluded from the Lagoon of Venice only in the 17th century; finally, the manuscript sources from the Middle Ages and the Modern Age are discussed, clearly attesting dying plants and other wool-textile buildings in this land
Effect of symmetry distortions on photoelectron selection rules and spectra of Bi_2Sr_2CaCu_2O_{8+ delta}
We derive photoelectron selection rules along the glide plane in orthorhombic
Bi_2Sr_2CaCu_2O_{8+\delta} (Bi2212). These selection rules explain the reversed
intensity behavior of the shadow and the main band of the material as a natural
consequence of the variating representation of the final state as a function of
k_\parallel. Our one-step simulations strongly support the structural origin of
the shadow band but we also introduce a scenario for detecting
antiferromagnetic signatures in low doping.Comment: AMS-LaTeX, 5 pages, 4 figure
EXITE2 Observation of the SIGMA Source GRS 1227+025
We report the EXITE2 hard X-ray imaging of the sky around 3C273. A 2h
observation on May 8, 1997, shows a 260 mCrab source detected at
in each of two bands (50-70 and 70-93 keV) and located 30'
from 3C273 and consistent in position with the SIGMA source GRS1227+025. The
EXITE2 spectrum is consistent with a power law with photon index 3 and large
low energy absorption, as indicated by the GRANAT/SIGMA results. No source was
detected in more sensitive followup EXITE2 observations in 2000 and 2001 with
3 upper limits of 190 and 65 mCrab, respectively. Comparison with the
flux detected by SIGMA shows the source to be highly variable, suggesting it
may be non-thermal and beamed and thus the first example of a ``type 2''
(absorbed) Blazar. Alternatively it might be (an unprecedented) very highly
absorbed binary system undergoing accretion disk instability outbursts,
possibly either a magnetic CV, or a black hole X-ray nova.Comment: 12 pages, 4 figures, accepted for publication in Ap
The X-ray spectra of Compton-thick Seyfert 2 galaxies as seen by BeppoSAX
Results from BeppoSAX observations of Compton--thick Seyfert 2 galaxies are
summarized and reviewed, and their general properties derived and discussed. In
five out of the seven observed sources, the nucleus is directly visible at high
X-ray energies, where the photons penetrate absorbers with column densities in
the range 1.1-4.3x10^{24} cm-2 (in the other two sources, NGC 1068 and NGC
7674, the nucleus is instead totally obscured at all energies, implying even
larger column densities). In most sources there is unambiguous evidence of a
reflection component from optically thick, cold matter, while in two (or maybe
four) cases there is also evidence of reflection from ionized matter. For the
sources with a measured X-ray luminosity, a comparison with the infrared
luminosity is made; while in two cases (the Circinus galaxy and NGC 4945) the
IR emission appears to be dominated by starburst activity, in the other three
sources (NGC 6240, Mrk 3 and TOL 0109-383) it is likely to be dominated by
reprocessing of the UV and X-ray photons emitted by an AGN.Comment: Accepted for publication in MNRA
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