Silicic magma entering a basaltic magma chamber: eruptive dynamics and magma mixing — an example from Salina (Aeolian islands,Southern Tyrrhenian Sea)   总被引：1，自引：0，他引：1  

Natale Calanchi  Rosanna De Rosa  Roberto Mazzuoli  Pierluigi Rossi  Roberto Santacroce  Guido Ventura 《Bulletin of Volcanology》1993,55(7):504-522

The Pollara tuff-ring resulted from two explosive eruptions whose deposits are separated by a paleosol 13 Ka old. The oldest deposits (LPP, about 0.2 km³) consist of three main fall units (A, B, C) deposited from a subplinian column whose height (7–14 km) increased with time from A to C, as a consequence of the increased magma discharge rate during the eruption (1–8x10⁶ kg/s). A highly variable juvenile population characterizes the eruption. Black, dense, highly porphyritic, mafic ejecta (SiO₂=50–55%) almost exclusively form A deposits, whereas grey, mildly vesiculated, mildly porphyritic pumice (SiO₂=56–67%) and white, highly vesiculated, nearly aphyric pumice (SiO₂=66–71%) predominate in B and C respectively. Mafic cumulates are abundant in A, while crystalline lithic ejecta first appear in B and increase upward. The LPP result from the emptying of an unusual and unstable, compositionally zoned, shallow magma chamber in which high density mafic melts capped low density salic ones. Evidence of the existence of a short crystal fractionation series is found in the mafic rocks; the andesitic pumice results from complete blending between rhyolitic and variously fractionated mafic melts (salic component up to 60 wt%), whereas bulk dacitic compositions mainly result from the presence of mafic xenocrysts within rhyolitic glasses. Viscosity and composition-mixing diagrams show that blended liquids formed when the visosities of the two end members had close values. The following model is suggested: 1. A rhyolitic magma rising through the metamorphic basement enterrd a mafic magma chamber whose souter portions were occupied by a highly viscous, mafic crystal mush. 2. Under the pressure of the rhyolitic body the nearly rigid mush was pushed upwards and mafic melts were squeezed against the walls of the chamber, beginning roof fracturing and mingling with silicic melts. 3. When the equilibrium temperature was reached between mafic and silicic melts, blended liquids rapidly formed. 4. When fractures reached the surface, the eruption began by the ejection of the mafic melts and crystal mush (A), followed by the emission of variously mingled and blended magmas (B) and ended by the ejection of nearly unmixed rhyolitic magma (C).  相似文献   

Global Warming and the Summertime Evapotranspiration Regime of the Alpine Region   总被引：1，自引：0，他引：1  

Pierluigi Calanca  Andreas Roesch  Karsten Jasper  Martin Wild 《Climatic change》2006,79(1-2):65-78

Changes of the summer evapotranspiration regime under increased levels of atmospheric greenhouse gases are discussed for three Alpine river basins on the basis of a new set of simulations carried out with a high-resolution hydrological model. The climate change signal was inferred from the output of two simulations with a state-of-the-art global climate model (GCM), a reference run valid for 1961–1990 and a time-slice simulation valid for 2071–2100 under forcing from the A2 IPCC emission scenario. In this particular GCM experiment and with respect to the Alpine region summer temperature was found to increase by 3 to 4 ^∘C, whereas precipitation was found to decrease by 10 to 20%. Global radiation and water vapor pressure deficit were found to increase by about 5% and 2 hPa, respectively. On this background, an overall increase of potential evapotranspiration of about 20% relative to the baseline was predicted by the hydrological model, with important variations between but also within individual basins. The results of the hydrological simulations also revealed a reduction in the evapotranspiration efficiency that depends on altitude. Accordingly, actual evapotranspiration was found to increase at high altitudes and to the south of the Alps, but to decrease in low elevation areas of the northern forelands and in the inner-Alpine domain. Such a differentiation does not appear in the GCM scenario, which predicts an overall increase in evapotranspiration over the Alps. This underlines the importance of detailed simulations for the quantitative assessment of the regional impact of climate change on the hydrological cycle.  相似文献   

The one-point PDF of the initial conditions of our local Universe from the IRAS PSC redshift catalogue     

P. Monaco  G. Efstathiou  S. J. Maddox  E. Branchini  C. S. Frenk  R. G. McMahon  S. J. Oliver  M. Rowan-Robinson  W. Saunders  W. J. Sutherland  H. Tadros  S. D. M. White 《Monthly notices of the Royal Astronomical Society》2000,318(3):681-692

The algorithm ztrace of Monaco & Efstathiou is applied to the IRAS PSCz catalogue to reconstruct the initial conditions of our local Universe with a resolution down to ~5  h ¹ Mpc. The one-point probability distribution function (PDF) of the reconstructed initial conditions is consistent with the assumptions that: (i) IRAS galaxies trace mass on scales of ~5  h ¹ Mpc and (ii) the statistics of the primordial density fluctuations are Gaussian. We use simulated PSCz catalogues, constructed from N -body simulations with Gaussian initial conditions, to show that local non-linear bias can cause the recovered initial PDF (assuming no bias) to be non-Gaussian. However, for plausible bias models, the distortions of the recovered PDF would be difficult to detect using the volume finely sampled by the PSCz catalogue. So, for Gaussian initial conditions, a range of bias models remain compatible with our PSCz reconstruction results.  相似文献   

Uplift rates defined by U-series and 14C ages of serpulid-encrusted speleothems from submerged caves near Siracusa,Sicily (Italy)     

Andrea Dutton  Giovanni Scicchitano  Carmelo Monaco  Jolyon M. Desmarchelier  Fabrizio Antonioli  Kurt Lambeck  Tezer M. Esat  L. Keith Fifield  Malcolm T. McCulloch  Graham Mortimer 《Quaternary Geochronology》2009,4(1):2-10

We have established a plausible rate of uplift near Siracusa in southeastern Sicily (Italy) over the last glacial–interglacial cycle using U-series ages of submerged speleothem calcite and ¹⁴C ages of calcite serpulid layers that encrust the speleothems during cave submergence. The precisely determined ages of these sea level benchmarks were compared with expected relative sea level position based on glacio-hydro-isostatic modeling to assess the rate of uplift in this region. When combined with the age of various late Holocene archaeological sites that have been recently described and characterized in terms of their functional position relative to sea level these data collectively define a rate of uplift ≤0.4 mm a^?1 along this portion of the Sicilian coastline. These results are consistent with an age assignment of marine isotope stage (MIS) 5.3 or 5.5 for the Akradina terrace, which in turn places temporal constraints on paleoshorelines above and below this level.  相似文献   

Joint cosmological formation of QSOs and bulge-dominated galaxies     

Pierluigi Monaco  Paolo Salucci  Luigi Danese 《Monthly notices of the Royal Astronomical Society》2000,311(2):279-296

Older and more recent pieces of observational evidence suggest a strong connection between QSOs and galaxies; in particular, the recently discovered correlation between black hole and galactic bulge masses suggests that QSO activity is directly connected to the formation of galactic bulges. The cosmological problem of QSO formation is analysed in the framework of an analytical model for galaxy formation; for the first time a joint comparison with galaxy and QSO observables is performed. In this model it is assumed that the same physical variable that determines galaxy morphology is able to modulate the mass of the black hole responsible for QSO activity. Both halo spin and the occurrence of a major merger are considered as candidates for this role. The predictions of the model are compared with available data for the type-dependent galaxy mass functions, the star formation history of elliptical galaxies, the QSO luminosity function and its evolution (including the obscured objects contributing to the hard-X-ray background), the mass function of dormant black holes and the distribution of black hole-to-bulge mass ratios. A good agreement with observations is obtained if the halo spin modulates the efficiency of black hole formation, and if the galactic haloes at z =0 have shone in an inverted order with respect to the hierarchical one (i.e., stars and black holes in bigger galactic haloes have formed before those in smaller ones). This inversion of hierarchical order for galaxy formation, which reconciles galaxy formation with QSO evolution, is consistent with many pieces of observational evidence.  相似文献   

Modelling ecosystem functions and properties at different time and spatial scales in shallow coastal lagoons: An application of the LOICZ biogeochemical model     

Gianmarco Giordani  Martina Austoni  José M. Zaldívar  Dennis P. Swaney  Pierluigi Viaroli 《Estuarine, Coastal and Shelf Science》2008

The Land-Ocean Interactions in the Coastal Zone (LOICZ) biogeochemical model (LBM) was applied at different temporal and spatial scales in 17 Italian lagoons of the LaguNet network (http://www.dsa.unipr.it/lagunet). A series of alternative assumptions taking into account benthic vegetation and sedimentary fluxes were introduced and compared with the classical LBM approach at various time scales. The reliability of the LBM application to the seventeen Italian lagoons was tested by comparison to a pool of shallow coastal systems from the global LOICZ database with comparable depths and sizes. The nutrient loads of the Italian sites can be considered relatively low, particularly for dissolved inorganic phosphorus (DIP). Although the median values of estimated internal transformations (source-sink) of both dissolved inorganic phosphorous and nitrogen at the LaguNet sites were comparable with the selected LOICZ sites, the positive and negative extreme values were one order of magnitude lower. Overall, the LBM applications to the Italian sites gave good quality budgets for shallow systems subjected to relatively low nutrient inputs and with a wide range of primary producer communities, including seagrass, macroalgae and phytoplankton. Furthermore, stoichiometry of Carbon:Nitrogen:Phosphorous for the different primary producer groups allowed the integration of previous studies by identifying a series of relationships between nutrient loads and ecosystem functions.  相似文献   

A modeling language to support the interoperability of global navigation satellite systems     

Daniele Gianni  Joachim Fuchs  Pierluigi De Simone  Marco Lisi 《GPS Solutions》2013,17(2):175-198

The availability of multiple Global Navigation Satellite Systems (GNSS) will offer the opportunity to provide seamless navigation services and improved positioning performance. However, before this opportunity can be exploited, a number of issues need to be solved to ensure the compatibility and interoperability of existing GNSS. In particular, the GNSS interoperability can be technically defined as the capability of receivers to compute their global position using two or more GNSS signals. This capability can be more effectively achieved if Signal-In-Space interface specifications are available in a consistent, unambiguous, and possibly standard format, which can support engineers to design interoperable receivers. We aim to support the design of interoperable receivers with the introduction of the Interface Communication Modeling Language (ICML), a graphical language for the formal specification of Signal-In-Space interfaces. The ICML language enables receiver engineers to specify these interfaces at different levels of abstraction, such as analog signal or binary data. In addition, the ICML language also supports the specification of conversion routines between adjacent levels, for the representation of the dynamic aspects—e.g., convolution and encryption processes—of the interface specification. As such, the ICML language proposes an alternative format to textual-based interface specifications and can possibly integrate with the ongoing trend of the Model-based Systems Engineering approaches. We present the structure of the framework implementing the language and an example ICML-based specification for a simplified and reduced version of the Galileo Freely Accessible Navigation (F/NAV) message. The language metamodel is also attached for technical reference. An important caveat: no endorsement is made for the use of the ICML language for the official Galileo Signal-In-Space interface specification.  相似文献   

The characterization of extraordinary extreme events (EEEs) for the assessment of design rainfall depths with high return periods     

Anna Pelosi  Pierluigi Furcolo  Fabio Rossi  Paolo Villani 《水文研究》2020,34(11):2543-2559

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Soil Budget,Net Export,and Potential Sinks of Nitrogen in the Lower Oglio River Watershed (Northern Italy)     

Elisa Soana  Erica Racchetti  Alex Laini  Marco Bartoli  Pierluigi Viaroli 《洁净——土壤、空气、水》2011,39(11):956-965

A nitrogen mass balance, realized for the lower Oglio River basin (Po River Plain, northern Italy), suggested an elevated impact of agricultural activities in this watershed. Livestock manure, synthetic fertilizers, biological fixation, atmospheric deposition, and wastewater sludge contributed 51, 34, 12, 2, and 1% of total N (TN) input, respectively (basin average 450 kg N ha^?1 arable land (AL) year^?1, overall input 100 115 t N year^?1). Crop uptake, ammonia volatilization and denitrification in soils contributed 65, 21, and 14%, respectively, of TN output (basin average 270 kg N ha^?1 AL year^?1, overall output 60 060 t N year^?1). N inputs exceeded outputs by 40 056 t N year^?1, resulting in a basin average surplus of about 180 kg N ha^?1 AL year^?1. About 34% of the N surplus was exported annually from the basin while the remaining amount (about 26 800 t N year^?1) underwent other unaccounted for processes within the watershed. The relevance of nitrogen removal via denitrification in aquatic compartments within the watershed was evaluated. Denitrification in the secondary drainage network can represent a relevant nitrogen sink due to great linear extension (over 12 500 km), with estimated nitrogen loss up to 8500 t N year^?1. Denitrification in the riverbed and in perifluvial wetlands have the potential to remove only a small fraction of the nitrogen surplus (<3%). Evidence suggests the relevance of groundwater as a site of nitrogen accumulation.  相似文献   

Evaluation of cell lysis procedures and use of a micro fluidic system for an automated DNA-based cell identification in interplanetary missions     

J.A. Hall  E. Felnagle  M. Fries  S. Spearing  L. Monaco  A Steele   《Planetary and Space Science》2006,54(15):1600-1611

A Modular Assay System for Solar System Exploration (MASSE) is being developed to include sample handling, pre-treatment, separation and analysis of biological target compounds by both DNA and protein microarrays. To better design sensitive and accurate initial upstream sample handling of the MASSE instrument, experiments investigating the sensitivity and potential extraction bias of commercially available DNA extraction kits between classes of environmentally relevant prokaryotes such as gram-negative bacteria (Escherichia coli), gram-positive bacteria (Bacillus megatarium), and Archaea (Haloarcula marismortui) were performed. For extractions of both planktonic cultures and spiked Mars simulated regolith, FTA^® paper demonstrated the highest sensitivity, with detection as low as 1×10¹ cells and 3.3×10² cells, respectively. In addition to the highest sensitivity, custom modified application of FTA^® paper extraction protocol is the simplest in terms of incorporation into MASSE and displayed little bias in sensitivity with respect to prokaryotic cell type. The implementation of FTA paper for environmental microbiology investigations appears to be a viable and effective option potentially negating the need for other pre-concentration steps such as filtration and negating concerns regarding extraction efficiency of cells. In addition to investigations on useful technology for upstream sample handling in MASSE, we have also evaluated the potential for μTAS to be employed in the MASSE instrument by employing proprietary lab-on-a-chip development technology to investigate the potential for microfluidic cell lysis of different prokaryotic cells employing both chemical and biological lysis agents. Real-time bright-field microscopy and quantitative PMT detection indicated that that gram positive, gram negative and archaeal cells were effectively lyzed in a few seconds using the microfluidic chip protocol developed. This included employing a lysis buffer with components including lysozyme, Protease, Proteinase K, Tween-20 and TritonX-100. The effectiveness of antibiotics and other chemical lysis agents were also screened and demonstrated partial effectiveness on all three cell types. This work demonstrates a step wise approach to evaluating the efficacy and sensitivity of commercial macro-scale technology and state-of-the-art developmental microfluidic technology under consideration for incorporation into the remotely operated MASSE instrument currently under development at the Carnegie Institution of Washington.  相似文献