Radiological characterization of granitoid outcrops and dimension stones of the Variscan Corsica-Sardinia Batholith

This study focuses on the radiological characterization of granitoid outcrops and dimension stones using in situ gamma-ray spectrometry. Extensive measurements were performed on 210 granitoid outcrops of the Corsica-Sardinia Batholith. The large statistical sample allowed us to improve the analysis by considering a log-normal distribution of radioelements and propagating the uncertainties using Monte Carlo method. The activity concentrations of ⁴⁰K, ²²⁶Ra (²³⁸U) and ²³²Th in C-SB area were 1,177 _?304 ⁺⁴⁰⁸ , 60 _?23 ⁺³⁶ and 69 _?25 ⁺³⁸  Bq/kg (at 1σ uncertainty). The median abundance of K, U and Th on the Variscan C-SB was higher than the average values of the upper continental crust and was comparable with Variscan belt. This corresponds to an outdoor absorbed dose rate of 124 _?26 ⁺³³  nGy/h at 1σ uncertainty which is 3σ higher than the population-weighted average absorbed dose rate (60 nGy/h). Seven commercial granites (Rosa Beta, Ghiandone, Giallo San Giacomo, Rosa Cinzia, Grigio Malaga, Bianco Sardo and Grigio Perla) were investigated to characterize their radiological hazard through 147 measurements taken in 73 extractive quarries. All of the commercial granites were categorized as A2 material based on their activity concentration indices, excluding (at the 3σ level) any restriction on their utilization as superficial materials. Rosa Beta, Grigio Malaga, Grigio Perla and Bianco Sardo can also be used as bulk materials as they can be included in the A1 category. In the case of Ghiandone, Giallo San Giacomo and Rosa Cinzia, we are confident of an A1 classification only at the 1σ level.     

The imprint of accretion on the UV spectrum of young stellar objects: an X-Shooter view

The evolution of protoplanetary disks is regulated by its interaction with the central forming star. This interaction happens through accretion of matter from the disk onto the star, and its most significant signatures are the continuum excess in the UV part of the spectrum and the presence of various emission lines. With the VLT/X-Shooter spectrograph, the excess emission in the UV due to accretion can being studied simultaneously with the signatures in the visible and in the near-infrared, giving a simultaneous and complete view of this phenomenon. Here we present some results we obtained using observation and modeling of the UV-excess in young forming stars, which are: (1) the determination of stellar and accretion properties in candidate older accreting young stellar objects and (2) the study of the star-disk interaction in the early stages of planetary system evolution in transitional disk systems.     

Uncertainty in floodplain delineation: expression of flood hazard and risk in a Gulf Coast watershed

This paper investigates the development of flood hazard and flood risk delineations that account for uncertainty as improvements to standard floodplain maps for coastal watersheds. Current regulatory floodplain maps for the Gulf Coastal United States present 1% flood hazards as polygon features developed using deterministic, steady‐state models that do not consider data uncertainty or natural variability of input parameters. Using the techniques presented here, a standard binary deterministic floodplain delineation is replaced with a flood inundation map showing the underlying flood hazard structure. Additionally, the hazard uncertainty is further transformed to show flood risk as a spatially distributed probable flood depth using concepts familiar to practicing engineers and software tools accepted and understood by regulators. A case study of the proposed hazard and risk assessment methodology is presented for a Gulf Coast watershed, which suggests that storm duration and stage boundary conditions are important variable parameters, whereas rainfall distribution, storm movement, and roughness coefficients contribute less variability. The floodplain with uncertainty for this coastal watershed showed the highest variability in the tidally influenced reaches and showed little variability in the inland riverine reaches. Additionally, comparison of flood hazard maps to flood risk maps shows that they are not directly correlated, as areas of high hazard do not always represent high risk. Copyright © 2012 John Wiley & Sons, Ltd.     

Massive star formation in the southern Milky Way

During the past decade we have compiled a large molecular line data base of massive star forming regions in the southern Milky Way. These regions are confined into giant molecular clouds that trace the galactic spiral arms. Their radial distribution has a pronounced peak midway between the Sun and the galactic center, which in the IV quadrant corresponds to the location of the Norma Spiral arm. We study in some detail one of the foremost regions of massive star formation in the Norma arm, using millimeter continuum and line emission maps obtained with the SEST, APEX, and ASTE telescopes. It is a multiple system evolving along a complete GMC core, candidate for future ALMA observations.     

The study of young substellar objects with ALMA

We discuss the potential of ALMA for studying the formation of substellar objects. We first review briefly the various formation mechanisms proposed so far and stress the unique capability of ALMA to detect and study pre-brown dwarf cores and to confirm the core-collapse scenario to the lowest possible masses. We then discuss the properties of disks around substellar objects. We show how it will be possible to detect with ALMA most disks around objects with mass as low as few Jupiter masses, and to resolve spatially their emission in the more favorable cases.     

Modelling of Al impurity in perovskite and ilmenite structures of MgSiO3

A methodology based on the Hartree–Fock theory is used to study pure MgSiO₃ crystals as well as Al doping in perovskite and ilmenite modifications of this mineral. Atomic displacements in the neighbourhood of the defect are obtained for cases when the Al substitutes for either Mg or Si host atoms. The atomic relaxation is due to the changes produced upon the chemical bonding within the defective region and in some occasions obeys the Coulomb electrostatic interaction. Band structure properties are briefly revised for the pure and doped minerals. The occurrence of Al-bound hole polaron is predicted in the ilmenite mineral. The results of output are compared to the available reports on the same subject in both experimental and theoretical fields of the investigation.     

Available energy and energy balance closure at four coniferous forest sites across Europe

The available energy (AE), driving the turbulent fluxes of sensible heat and latent heat at the earth surface, was estimated at four partly complex coniferous forest sites across Europe (Tharandt, Germany; Ritten/Renon, Italy; Wetzstein, Germany; Norunda, Sweden). Existing data of net radiation were used as well as storage change rates calculated from temperature and humidity measurements to finally calculate the AE of all forest sites with uncertainty bounds. Data of the advection experiments MORE II (Tharandt) and ADVEX (Renon, Wetzstein, Norunda) served as the main basis. On-site data for referencing and cross-checking of the available energy were limited. Applied cross checks for net radiation (modelling, referencing to nearby stations and ratio of net radiation to global radiation) did not reveal relevant uncertainties. Heat storage of sensible heat J _H, latent heat J _E, heat storage of biomass J _veg and heat storage due to photosynthesis J _C were of minor importance during day but of some importance during night, where J _veg turned out to be the most important one. Comparisons of calculated storage terms (J _E, J _H) at different towers of one site showed good agreement indicating that storage change calculated at a single point is representative for the whole canopy at sites with moderate heterogeneity. The uncertainty in AE was assessed on the basis of literature values and the results of the applied cross checks for net radiation. The absolute mean uncertainty of AE was estimated to be between 41 and 52 W m^?2 (10–11 W m^?2 for the sum of the storage terms J and soil heat flux G) during mid-day (approximately 12% of AE). At night, the absolute mean uncertainty of AE varied from 20 to about 30 W m^?2 (approximately 6 W m^?2 for J plus G) resulting in large relative uncertainties as AE itself is small. An inspection of the energy balance showed an improvement of closure when storage terms were included and that the imbalance cannot be attributed to the uncertainties in AE alone.     

Effects of Thermal Stability and Incoming Boundary-Layer Flow Characteristics on Wind-Turbine Wakes: A Wind-Tunnel Study

Wind-tunnel experiments were carried out to study turbulence statistics in the wake of a model wind turbine placed in a boundary-layer flow under both neutral and stably stratified conditions. High-resolution velocity and temperature measurements, obtained using a customized triple wire (cross-wire and cold wire) anemometer, were used to characterize the mean velocity, turbulence intensity, turbulent fluxes, and spectra at different locations in the wake. The effect of the wake on the turbulence statistics is found to extend as far as 20 rotor diameters downwind of the turbine. The velocity deficit has a nearly axisymmetric shape, which can be approximated by a Gaussian distribution and a power-law decay with distance. This decay in the near-wake region is found to be faster in the stable case. Turbulence intensity distribution is clearly non-axisymmetric due to the non-uniform distribution of the incoming velocity in the boundary layer. In the neutral case, the maximum turbulence intensity is located above the hub height, around the rotor tip location and at a distance of about 4–5.5 rotor diameters, which are common separations between wind turbines in wind farms. The enhancement of turbulence intensity is associated with strong shear and turbulent kinetic energy production in that region. In the stable case, the stronger shear in the incoming flow leads to a slightly stronger and larger region of enhanced turbulence intensity, which extends between 3 and 6 rotor diameters downwind of the turbine location. Power spectra of the streamwise and vertical velocities show a strong signature of the turbine blade tip vortices at the top tip height up to a distance of about 1–2 rotor diameters. This spectral signature is stronger in the vertical velocity component. At longer downwind distances, tip vortices are not evident and the von Kármán formulation agrees well with the measured velocity spectra.     

Tetrapods from the Upper Cretaceous (Turonian–Maastrichtian) Bauru Group of Brazil: a reappraisal

An updated, annotated list of all tetrapods from the Adamantina, Uberaba and Marília formations (Bauru Group), which constitute some of the best studied Upper Cretaceous units in Brazil, is presented. Tetrapod diversity in the Bauru Group is remarkable, including an admixture of typically austral Gondwanan taxa (e.g., abelisaurids, notosuchians) and boreal Gondwanan forms (e.g., carcharodontosaurids). Of note is the absence of Laurasian taxa in the upper portion of the Bauru Group. With the exception of some turtles, an anuran, mesoeucrocodylians and one titanosaur, most taxa from the Bauru Group are based on fragmentary and isolated bones, and as such many specimens can be identified only to a higher taxonomic level. Fishes, turtles, anurans, mesoeucrocodylians, dinosaurs, birds and mammals from the Adamantina and Marília formations resemble the latest Late Cretaceous vertebrate faunas from southern South America, except for the absence of ornithischian dinosaurs.     

Genetic evolution of Permo-Triassic volcaniclastic sequences at Uspallata, Mendoza Precordillera, Argentina

Permo-Triassic volcanic rocks of the Choiyoi Group crop out at Quebrada de Santa Elena and del Telégrafo, Mendoza Precordillera, Argentina. In this area, six volcanic events were generated through three volcanic stages that include collapse of voluminous Plinian columns associated to caldera pressurization and depressurization, emplacement of sub-volcanic bodies and dikes connected to depressurization of the magmatic chamber and establishment of resurgent domes and lava associated to caldera collapse events.

Petrologic and geochemical data indicate increasing acidification toward younger events varying from dacitic to rhyodacitic and rhyolitic rocks. The lithofacial organization allows correlating with the Lower to Upper Permian Horcajo Formation described in the Valle del Río de los Patos, San Juan province. Geochemical data suggests subduction-related arc magmatism in an extensional condition during Lower to Upper Permian.