A multiwavelength map of the nuclear region of NGC 7582     

Stefano Bianchi  Marco Chiaberge  Enrico Piconcelli  Matteo Guainazzi 《Monthly notices of the Royal Astronomical Society》2007,374(2):697-702

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On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM–Newton     

Matteo Guainazzi  Stefano Bianchi 《Monthly notices of the Royal Astronomical Society》2007,374(4):1290-1302

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Four Classical Methods for Determining Planetary Elliptic Elements: A Comparison     

Alessandra Celletti  Gabriella Pinzari 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):1-52

The discovery of the asteroid Ceres by Piazzi in 1801 motivated the development of a mathematical technique proposed by Gauss, (Theory of the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, 1963) which allows to recover the orbit of a celestial body starting from a minimum of three observations. Here we compare the method proposed by Gauss (Theory of the Motion of the Heavenly Bodies Moving about the Sun in Conic Sections, New York, 1963) with the techniques (based on three observations) developed by Laplace (Collected Works 10, 93–146, 1780) and by Mossotti (Memoria Postuma, 1866). We also consider another method developed by Mossotti (Nuova analisi del problema di determinare le orbite dei corpi celesti, 1816–1818), based on four observations. We provide a theoretical and numerical comparison among the different procedures. As an application, we consider the computation of the orbit of the asteroid Juno.  相似文献   

Estimate of the Transition Value of Librational Invariant Curves     

Alessandra Celletti  Gabriella Della Penna  Claude Froeschlé 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):257-274

We investigate the break-down threshold of librational invariant curves. As a model problem, we consider a variant of a mapping introduced by M. Hénon, which well describes the dynamics of librational motions surrounding a stable invariant point. We verify in concrete examples the applicability of Greene's method, by computing the instability transition values of a sequence of periodic orbits approaching an invariant curve with fixed noble frequency. However, this method requires the knowledge of the location of the periodic orbits within a very good approximation. This task appears to be difficult to realize for a libration regime, due to the different topology of the phase space. To compute the break-down threshold, we tried an alternative method very easy to implement, based on the computation of the fast Lyapunov indicators and frequency analysis. Such technique does not require the knowledge of the periodic orbits, but again, it appears very difficult to have a precision better than Greene's method for the computation of the critical parameter.  相似文献   

Integrated use of biomarkers in the mussel Mytilus galloprovincialis for assessing off-shore gas platforms in the Adriatic Sea: results of a two-year biomonitoring program     

Gomiero A  Da Ros L  Nasci C  Meneghetti F  Spagnolo A  Fabi G 《Marine pollution bulletin》2011,62(11):2483-2495

Despite a large number of gas platforms existing in the Adriatic Sea, which is a semi-enclosed basin characterized by a slow turnover rate and increasing industrial as well as other anthropogenic activities, the effects of these structures on the aquatic ecosystem require further investigation. Since 1998, multidisciplinary studies have been performed by CNR-ISMAR to comply with legislation and to support the development of protocols for the monitoring of offshore activities in the Adriatic Sea. The present study was developed to implement a biomonitoring plan to assess the ecotoxicological effects of the extraction activities of an off-shore gas platform. Biomarkers were evaluated in mussels collected from the platform in relation to physiological stress, DNA damage, cellular damage, oxidative stress and exposure effects. Organic contaminants and trace element bioaccumulation were also assessed in the soft body of the mussels to correlate bioaccumulation of pollutants with biomarker responses. The results indicate an absence of platform-related environmental stress.  相似文献   

Perfluorinated compounds in blood of Caretta caretta from the Mediterranean Sea     

Cristiana Guerranti  Stefania Ancora  Nicola Bianchi  Guido Perra  Emiliano Leonida Fanello  Simonetta Corsolini  Maria Cristina Fossi  Silvano Ettore Focardi 《Marine pollution bulletin》2013

Perfluorinated compounds (PFCs), widely used for their hydro-oil repellent properties, are almost non-degradable in the environment; there is scientific evidence that indicate bioaccumulation. They represent a threat to many organisms, because they are toxic and are endocrine disruptors. Scientific studies have demonstrated the presence of PFCs in blood and liver samples of fish, turtles, birds and mammals of marine ecosystems in different geographical areas. The aim of this study was to determine the distribution of PFOS and PFOA in blood samples of the marine turtle Caretta caretta, using a minimally invasive sampling procedure. 49 blood samples of marine turtle, taken from several Italian marine turtle rescue centers, were analyzed. While PFOA was never detected, measurable concentrations of PFOS were found in 15 blood samples; the values show a range from 1.14 ng/g to 28.51 ng/g (wet wt.). No differences between groups of samples taken from different areas were found.  相似文献   

Macro‐ and meso‐scale structural criteria for identifying pre‐thrusting normal faults within foreland fold‐and‐thrust belts: Insights from the Central‐Northern Apennines (Italy)          下载免费PDF全文

Fernando Calamita  Alessandra Di Domenica  Paolo Pace 《地学学报》2018,30(1):50-62

Reliable macro‐ and meso‐scale structural criteria for identifying pre‐thrusting normal faults within inversion‐dominated foreland thrust belts are here reappraised by showing field cases from the Central‐Northern Apennines of Italy. Field‐based analyses of relative chronologies among the structures allow determination of the timing of pre‐thrusting normal faulting, the positive inversion of the faults and their post‐thrusting reactivation when absolute chronostratigraphic constraints are lacking. The correct identification of pre‐thrusting normal faults allows recognition of shortcut and reactivation anticlines, and these have important implications for the definition of the thrust‐belt structural style and for the estimation of post‐orogenic extension.  相似文献   

Editorial     

Alessandra Celletti  Frank Schulz 《Celestial Mechanics and Dynamical Astronomy》2018,130(1):1

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High‐P tectono‐metamorphic evolution of mylonites from the Variscan basement of the Northern Apennines,Italy          下载免费PDF全文

Deborah Lo Pò  Roberto Braga  Hans‐Joachim Massonne  Giancarlo Molli  Alessandra Montanini  Giuseppe M. Bargossi 《Journal of Metamorphic Geology》2018,36(1):23-39

Strain localization within shear zones may partially erase the rock fabric and the metamorphic assemblage(s) that had developed before the mylonitic event. In poly‐deformed basements, the loss of information on pre‐kinematic phases of mylonites hinders large‐scale correlations based on tectono‐metamorphic data. In this study, devoted to a relict unit of Variscan basement reworked within the nappe stack of the Northern Apennines (Italy), we investigate the possibility to reconstruct a complete pressure (P)–temperature (T)–deformation (D) path of mylonitic micaschist and amphibolite by integrating microstructural analysis, mineral chemistry and thermodynamic modelling. The micaschist is characterized by a mylonitic fabric with fine‐grained K‐white mica and chlorite enveloping mica‐fishes, quartz, and garnet pseudomorphs. Potassic white mica shows Mg‐rich cores and Mg‐poor rims. The amphibolite contains green amphibole+plagioclase+garnet+quartz+ilmenite defining S₁ with a superposed mylonitic fabric localized in decimetre‐ to centimetre‐scale shear zones. Garnet is surrounded by an amphibole+plagioclase corona. Phase diagram calculations provide P–T constraints that are linked to the reconstructed metamorphic‐deformational stages. For the first time an early high‐P stage at >11 kbar and 510°C was constrained, followed by a temperature peak at 550–590°C and 9–10 kbar and a retrograde stage (<475°C, <7 kbar), during which ductile shear zones developed. The inferred clockwise P–T–D path was most likely related to crustal thickening by continent‐continent collision during the Variscan orogeny. A comparison of this P–T–D path with those of other Variscan basement occurrences in the Northern Apennines revealed significant differences. Conversely, a correlation between the tectono‐metamorphic evolution of the Variscan basement at Cerreto pass, NE Sardinia and Ligurian Alps was established.  相似文献   

NGC 3147: a 'true' type 2 Seyfert galaxy without the broad-line region     

S. Bianchi  A. Corral  F. Panessa  X. Barcons  G. Matt  L. Bassani  F. J. Carrera  E. Jiménez-Bailón 《Monthly notices of the Royal Astronomical Society》2008,385(1):195-199

We report on simultaneous optical and X-ray observations of the Seyfert galaxy, NGC 3147. The XMM–Newton spectrum shows that the source is unabsorbed in the X-rays  ( N _H < 5 × 10²⁰ cm⁻²)  . On the other hand, no broad lines are present in the optical spectrum. The origin of this optical/X-rays misclassification (with respect to the Unification Model) cannot be attributed to variability, since the observations in the two bands are simultaneous. Moreover, a Compton-thick nature of the object can be rejected on the basis of the low-equivalent width of the iron Kα line (≃130 eV) and the large ratio between the 2–10 keV and the [O  iii ] fluxes. It seems therefore inescapable to conclude that NGC 3147 intrinsically lacks the Broad-Line Region, making it the first 'true' type 2 Seyfert galaxy.  相似文献