GALEX catalogs of UV sources: statistical properties and sample science applications: hot white dwarfs in the Milky Way

We describe the content and properties of UV source catalogs from GALEX’s All-Sky Imaging Survey (AIS, 5σ depth ≈19.9(FUV)/20.8(NUV) mag, in the AB system) and Medium-depth Imaging Survey (MIS, 5σ depth ≈22.6(FUV)/22.7(NUV) mag), constructed by Bianchi L., et al.: Mon. Not. R. Astron. Soc. (2010, in press). The catalogs contain 65.3/12.6 million (AIS/MIS) unique UV sources with photometric error in NUV less than 0.5 mag, over 21?435(AIS)/1579(MIS) square degrees. Matched optical data from GSC-II provide additional B, R, I photometry for the brightest sources, and SDSS provides u g r i z photometry over 7325(AIS)/1103(MIS) square degrees overlap areas. We discuss statistical properties that are relevant for understanding sample selection biases and completeness, in potential science applications of these catalogs. The FUV (1344–1786 Å) and NUV (1771–2831 Å) photometry uniquely enable selection of the hottest stellar objects, in particular hot white dwarfs (WD), which are elusive at optical wavelengths because of their hot temperatures and faint luminosities. From the GALEX-SDSS matched sources we selected ～40?000 Milky Way (MW) stars hotter than about 18?000 K (FUV-NUV?相似文献   

Heavy Metal Accumulation in the Lichen Evernia prunastri Transplanted at Urban, Rural and Industrial Sites in Central Italy

The lichen Evernia prunastri has been employed for biomonitoring the atmospheric deposition of heavy metals at urban, rural and industrial sites in Central Italy. Lichen samples have been collected in a control site 1500 m a. s. l. (Parco Nazionale dAbruzzo, Central Italy) and subsequently transplanted at urban site (Cassino city center), at rural location 7 km away from Cassino (S. Elia Fiumerapido) and at industrial location (Piedimonte S. Germano) surrounding an automobile factory. Once defined the surface of impact relevant to this work, the lichen samples were transplanted at the four cardinal points of each site. Studies of bioaccumulation of Pb, Cd, Cr, Cu and Zn in lichen samples were performed five times at regular intervals between November 2000–December 2001. Microwave digestion of the samples and graphite furnace atomic absorption spectrometry were employed for the heavy metal determinations. Suitable certified reference materials (CRM) were used for validation of the analytical methodology. Results showed the ability of Evernia prunastri to accumulate the heavy metals under study. As expected, the area chosen as control site showed significantly (Friedman test, cluster analysis) lower impact in comparison to the other sites and the rural site showed smaller impact than the urban and the industrial sites.     

Discrete modelling of vertical track–soil coupling for vehicle–track dynamics

This paper presents a coupled lumped mass model (CLM model) for the vertical dynamic coupling of railway track through the soil. The well-known Winkler model and its extensions are analysed and fitted on the result obtained numerically with a finite–infinite element model in order to validate the approach in a preliminary step. A mass–spring–damper system with frequency independent parameters is then proposed for the interaction between the foundations, representing the contact area of the track with the soil. The frequency range of track–soil coupling is typically under 100 Hz. Analytical expressions are derived for calibrating the system model with homogeneous and layered half-spaces. Numerical examples are derived, with emphasis on soil stiffness and layering. The dynamic analysis of a track on various foundation models is compared with a complete track–soil model, showing that the proposed CLM model captures the dynamic interaction of the track with the soil and is reliable to predict the vertical track deflection and the reaction forces acting on the soil surface.     

Free field vibrations caused by high-speed lines: Measurement and time domain simulation

In recent years, the high-speed train (HST) network has developed considerably, unfortunately increasing vibration nuisances in its neighbourhood. This paper aims to present some vibration measurements collected on a Belgian site located between Brussels and Paris/London and travelled by the Thalys and Eurostar high-speed trains, and to compare them with the results obtained by a recently developed model, involving the compound vehicle/track/soil system. Assuming that the soil can be reasonably decoupled from the track, the approach first considers the train/track subsystem. The latter is studied by combining a multibody model of the vehicle with a finite element model of the track, both so far limited to the vertical motion. The ground forces given by this first simulation are then applied on a finite/infinite element model of the soil subsystem, where the infinite elements are placed on the border of the mesh in order to properly represent an unbounded domain. Both simulations are performed in the time domain, offering the opportunity to include non-linearities. The good correspondence between numerical and experimental results shows that the model is reliable for predicting the vibration produced by the high-speed vehicles. Finally, the paper presents some cases showing the importance of including the complete vehicle and the soil layering to the model.     

Discovery of Late Jurassic fossils inside modern sediments at Gorringe Bank (Eastern Atlantic Ocean) and some geological implications.

During a recent expedition at the Gorringe Bank (eastern Atlantic, 150 miles SW off Portugal), one of the rare sites in the ocean where mantle rocks crop out at very shallow depths (? 30 m), the Gettysburg and Ormonde seamounts, the two summits on the Gorringe Bank, were surveyed in detail. At Gettysburg seamount, within the modern bioclastic material, which is continually produced on the summit and exported to deep water, several examples of Mesozoic cephalopods were found. These fossils, reworked ‘in situ’, gave an age spanning from Kimmeridgian–Tithonian to Hauterivian (145–155 Ma) and recall some condensed Jurassic sequences of the Thetyan region compatible with shallow water (< 200 m). The serendipitous discovery of such ancient faunas within modern sediments suggests that Gorringe Bank was a seamount at the early opening of the Atlantic Ocean and requires us to reassess the age of rifting along the Iberian margin and the importance of vertical tectonics for non‐volcanic, mantle‐rooted seamounts.     

Late Cretaceous, synorogenic, low-angle normal faulting along the Schlinig fault (Switzerland, Italy, Austria) and its significance for the tectonics of the Eastern Alps

The Schlinig fault at the western border of theÖtztal nappe (Eastern Alps), previously interpreted as a west-directed thrust, actually represents a Late Cretaceous, top-SE to -ESE normal fault, as indicated by sense-of-shear criteria found within cataclasites and greenschist-facies mylonites. Normal faulting postdated and offset an earlier, Cretaceous-age, west-directed thrust at the base of theÖtztal nappe. Shape fabric and crystallographic preferred orientation in completely recrystallized quartz layers in a mylonite from the Schlinig fault record a combination of (1) top-east-southeast simple shear during Late Cretaceous normal faulting, and (2) later north-northeast-directed shortening during the Early Tertiary, also recorded by open folds on the outcrop and map scale. Offset of the basal thrust of theÖtztal nappe across the Schlinig fault indicates a normal displacement of 17 km. The fault was initiated with a dip angle of 10° to 15° (low-angle normal fault). Domino-style extension of the competent Late Triassic Hauptdolomit in the footwall was kinematically linked to normal faulting.

The Schlinig fault belongs to a system of east- to southeast-dipping normal faults which accommodated severe stretching of the Alpine orogen during the Late Cretaceous. The slip direction of extensional faults often parallels the direction of earlier thrusting (top-W to top-NW), only the slip sense is reversed and the normal faults are slightly steeper than the thrusts. In the western Austroalpine nappes, extension started at about 80 Ma and was coeval with subduction of Piemont-Ligurian oceanic lithosphere and continental fragments farther west. The extensional episode led to the formation of Austroalpine Gosau basins with fluviatile to deep-marine sediments. West-directed rollback of an east-dipping Piemont-Ligurian subduction zone is proposed to have caused this stretching in the upper plate.     

Geological and hydrogeological reconstruction of the main aquifers of the Maltese islands

Hydrogeology Journal - Geological and hydrogeological conceptualizations of the five main aquifers of Malta were performed by means of characterization of the groundwater bodies’ geometries...     

Relationships between seep-carbonates,mud volcanism and basin geometry in the Late Miocene of the northern Apennines of Italy: the Montardone mélange

The Montardone mélange (Mm) is a chaotic, block-in-matrix unit outcropping in the Montebaranzone syncline in the northern Apennines. The Mm occurs in the uppermost part of the Termina Fm, the Middle–Late Miocene interval of a succession deposited in a wedge-top slope basin (Epiligurian succession). The Mm is closely associated with bodies of authigenic carbonates, characterized by negative values of δ¹³C (from ?18.22 to ?39.05 ‰ PDB) and chemosynthetic benthic fauna (lucinid and vesicomyid bivalves). In this paper, we propose that the Mm is a mud volcano originated by the post-depositional reactivation and rising of a stratigraphically lower mud-rich mass transport body (Canossa–Val Tiepido sedimentary mélange or olistostrome) triggered by fluid overpressure. We base our conclusion on (1) the Mm pierces the entire Termina Fm and older Epiligurian units and represents the direct continuation of the underlying Canossa–Val Tiepido mélange; (2) the geometry and facies distribution of the Montebaranzone sandstone body, which are compatible with a confined basin controlled by the rising of the Mm; (3) the systematic presence of large-scale (lateral extension 300–400 m) seep-carbonates associated with the mélange, suggesting a persistent gas-enriched fluid vent from the ascending overpressured mud; (4) blocks and clasts sourced from the Mm, hosted by the authigenic carbonates, conveyed by ascending mud and gas-enriched fluids. The Mm represents one of the few fossil examples of reactivation of a basin-scale sedimentary mélange (olistostrome); a three-stage model showing mechanisms of Mm raising is proposed.