806 research outputs found
The Wide-Angle Outflow of the Lensed z = 1.51 AGN HS 0810+2554
We present results from X-ray observations of the gravitationally lensed z =
1.51 AGN HS 0810+2554 performed with the Chandra X-ray Observatory and
XMM-Newton. Blueshifted absorption lines are detected in both observations at
rest-frame energies ranging between ~1-12 keV at > 99% confidence. The inferred
velocities of the outflowing components range between ~0.1c and ~0.4c. A strong
emission line at ~6.8 keV accompanied by a significant absorption line at ~7.8
keV is also detected in the Chandra observation. The presence of these lines is
a characteristic feature of a P-Cygni profile supporting the presence of an
expanding outflowing highly ionized iron absorber in this quasar. Modeling of
the P-Cygni profile constrains the covering factor of the wind to be > 0.6,
assuming disk shielding. A disk-reflection component is detected in the
XMM-Newton observation accompanied by blueshifted absorption lines. The
XMM-Newton observation constrains the inclination angle to be < 45 degrees at
90% confidence, assuming the hard excess is due to blurred reflection from the
accretion disk. The detection of an ultrafast and wide-angle wind in an AGN
with intrinsic narrow absorption lines (NALs) would suggest that quasar winds
may couple efficiently with the intergalactic medium and provide significant
feedback if ubiquitous in all NAL and BAL quasars. We estimate the mass-outflow
rate of the absorbers to lie in the range of 1.5 and 3.4 Msolar/yr for the two
observations. We find the fraction of kinetic to electromagnetic luminosity
released by HS 0810+2554 is large (epsilon = 9 (-6,+8)) suggesting that
magnetic driving is likely a significant contributor to the acceleration of
this outflow.Comment: 27 pages, 13 figures, Accepted for publication in Ap
A deep look at the inner regions of the mini-BAL QSO PG 1126-041 with XMM-Newton
A long XMM-Newton observation of the mini-BAL QSO PG 1126-041 allowed us to
detect a highly ionized phase of X-ray absorbing gas outflowing at v~15000
km/s. Physical implications are briefly discussed.Comment: 2 pages, 2 figures. Proceedings of "X.ray Astronomy 2009", Bologna
09/7-11/2009, AIP Conference Series, Eds. A. Comastri, M. Cappi, L. Angelin
Grotta Romanelli (Southern Italy, Apulia). Legacies and issues in excavating a key site for the Pleistocene of the Mediterranean
Grotta Romanelli, located on the Adriatic coast of southern Apulia (Italy), is considered a key site for the Mediterranean Pleistocene for its archaeological and palaeontological contents. The site, discovered in 1874, was re-evaluated only in 1900, when P. E. Stasi realised that it contained the first evidence of the Palaeolithic in Italy. Starting in 1914, G. A. Blanc led a pioneering excavation campaign, for the first-time using scientific methods applied to systematic palaeontological and stratigraphical studies. Blanc proposed a stratigraphic framework for the cave. Different dating methods (C-14 and U/Th) were used to temporally constrain the deposits. The extensive studies of the cave and its contents were mostly published in journals with limited distribution and access, until the end of the 1970s, when the site became forgotten. In 2015, with the permission of the authorities, a new excavation campaign began, led by a team from Sapienza University of Rome in collaboration with IGAG CNR and other research institutions. The research team had to deal with the consequences of more than 40 years of inactivity in the field and the combined effect of erosion and legal, as well as illegal, excavations. In this paper, we provide a database of all the information published during the first 70 years of excavations and highlight the outstanding problems and contradictions between the chronological and geomorphological evidence, the features of the faunal assemblages and the limestone artefacts
Interaction of Cd(II) and Ni(II) terpyridine complexes with model polynucleotides: a multidisciplinary approach
Two metal complexes of 2,2′:6′,2″-terpyridine (terpy), i.e. Cd(terpy)Cl2 and Ni(terpy)Cl2·3H2O, have been prepared and extensively characterized. The interaction of Cd(terpy)Cl2 with synthetic DNA models, poly(dA-dT)·poly(dA-dT) (polyAT) and poly(dG-dC)·poly(dG-dC) (polyGC), has been studied by CD, fluorescence and UV-vis electronic absorption spectroscopy at several metal/polynucleotide-phosphate ratios and for different NaCl concentrations. All the experimental results indicate an intercalative mechanism of interaction. The optimized geometry of the cadmium complex intercalated between the sixth and seventh base pairs of (AT) and (GC) dodecanucleotide duplexes, obtained by quantum mechanics/molecular mechanics (QM/MM) calculations, lends support to the proposed mechanism. The calculated models provide some additional structural details of the intercalation complex at the molecular level. To evidence the influence of the charge and geometry of the metal complex on the mechanism of interaction with polynucleotides, the nickel complex-polyAT system has been studied to some extent by means of CD and UV-vis spectroscopy, and by thermal melting experiments. The results suggest that the octahedral complex cation [Ni(terpy)(H2O)2Cl]+ interacts with polyAT by partial intercalation assisted by electrostatic interaction with the negative charges of the backbone phosphate groups
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