Coupled fluids model in FRW space-time     

Shynaray Myrzakul  Ratbay Myrzakulov  Lorenzo Sebastiani 《Astrophysics and Space Science》2014,353(2):667-675

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Hydrometeorological controls and erosive response of an extreme alpine debris flow     

Lorenzo Marchi  Marco Cavalli  Marco Sangati  Marco Borga 《水文研究》2009,23(19):2714-2727

On 29 August, 2003, an intense convective storm system affected the Fella River basin, in the eastern Italian Alps, producing rainfall peaks of approximately 390 mm in 12 h. The storm triggered an unusually large debris flow in the ungauged Rio Cucco basin (0·65 km²), with a volume of approximately 78 000 m³. The analysis of the time evolution of the rainstorm over the basin has been based on rainfall estimates from radar observations and data recorded by a raingauge network. Detailed geomorphological field surveys, carried out both before and after the flood of August 2003, and the application of a distributed hydrological model have enabled assessment of flood response, estimation of erosion volumes and sediment supply to the channel network. The accounts of two eyewitnesses have provided useful elements for reconstructing the time evolution and the flow processes involved in the event. Liquid peak discharge estimates cluster around 20 m³ s^?1 km^?2, placing this event on the flood envelope curve for the eastern Italian Alps. The hydrological analysis has shown that the major controls of the flood response were the exceptional cumulated rainfall amount, required to exceed the large initial losses, and the large rainfall intensities at hourly temporal scales, required to generate high flood response at the considered basin scale. Observations on the deposits accumulated on the alluvial fan indicate that, although the dominant flow process was a debris flow, sheetflood also contributed to fan aggradation and fluvial reworking had an important role in winnowing debris‐flow lobes and redistributing sediment on the fan surface. This points out to the large discharge values during the recession phase of the flood, implying an important role for subsurface flow on runoff generation of this extreme flash flood event. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Leaf partitioning of the seagrass Posidonia oceanica between two herbivores: Is Sarpa salpa herbivory underestimated because of Paracentrotus lividus grazing?     

Stefania Pinna  Antonio Pais  Lorenzo Chessa  Nicola Sechi  Giulia Ceccherelli 《Estuarine, Coastal and Shelf Science》2009

In the Mediterranean region, herbivory appears to be a factor controlling the production of the endemic species Posidonia oceanica, which is mainly due to two main macroherbivores: the sea urchin Paracentrotus lividus, and the sparid fish Sarpa salpa. In this context the present study is a contribution in clarifying herbivory on P. oceanica by testing: 1) whether the abundance of grazing marks of the two herbivores is variable across different spatial scales, 2) whether spatial variation of P. lividus grazing marks and its density is consistent, 3) whether there is a dependence of the number of P. lividus grazing marks on its density, 4) whether the grazing of both macroherbivores, P. lividus and S. salpa, involves the entire leaf length, and 5) whether there is a dependence of the number of P. lividus grazing marks on the number of S. salpa grazing bites.  相似文献   

Sulla luminosita’ del cielo e sul contenuto di polveri nell’atmosfera     

Lorenzo Casertano 《Pure and Applied Geophysics》1956,33(1):177-186

Riassunto Si analizzano andamenti sperimentali della luminosità del cielo nelle zone rossa e bleu dello spettro. Dal confronto con diversi andamenti teorici si ottiene la spiegazione per la diversità di comportamento della luminosità nelle due zone considerate, e si riconosce la possibilità che — sotto certe condizioni — è consentito tener conto della sola diffusione primaria. Considerando anche la diffusione non molecolare si indica un metodo per calcolare, dalle misure di luminosità, il valore di un parametro che rappresenta un indice del contenuto di polveri nell’atmosfera. Si discutono alcuni valori trovati in base a misure eseguite all’Osservatorio Vesuviano.

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Summary Experimental outlines of sky brightness in the red and blue fields of spectrum are analized. From comparison with theoretical predictions one desumes the explanation about the different behaviour of brightness in the two considered fields and possibility — under certain conditions — of taking account only primary scattering. Considering also non-molecular scattering a method is shown to deduce, from the measurements of intensities of sky radiation, the value of a parameter representing the content of dust into atmosphere. Some experimental values found in measurements made at the ? Osservatorio Vesuviano ? are discussed.

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Prof.Lorenzo Casertano, Osservatorio Vesuviano,Resina (Napoli)  相似文献   

Some reflections on the fumarolic manifestations of the Los Copahues crater     

Lorenzo Casertano 《Bulletin of Volcanology》1964,27(1):197-215

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The whaling issue: Conservation,confusion, and casuistry     

Phillip J. Clapham  Simon Childerhouse  Nicolas J. Gales  Lorenzo Rojas-Bracho  Michael F. Tillman  Robert L. Brownell Jr. 《Marine Policy》2007

Morishita's “multiple analysis” of the whaling issue [Morishita J. Multiple analysis of the whaling issue: Understanding the dispute by a matrix. Marine Policy 2006;30:802–8] is essentially a restatement of the Government of Japan's whaling policy, which confuses the issue through selective use of data, unsubstantiated facts, and the vilification of opposing perspectives. Here, we deconstruct the major problems with Morishita's article and provide an alternative view of the whaling dispute. For many people in this debate, the issue is not that some whales are not abundant, but that the whaling industry cannot be trusted to regulate itself or to honestly assess the status of potentially exploitable populations. This suspicion has its origin in Japan's poor use of science, its often implausible stock assessments, its insistence that culling is an appropriate way to manage marine mammal populations, and its relatively recent falsification of whaling and fisheries catch data combined with a refusal to accept true transparency in catch and market monitoring. Japanese policy on whaling cannot be viewed in isolation, but is part of a larger framework involving a perceived right to secure unlimited access to global marine resources. Whaling is inextricably tied to the international fisheries agreements on which Japan is strongly dependent; thus, concessions made at the IWC would have potentially serious ramifications in other fora.  相似文献   

PAssive COastal TOMography: an Innovative Approach for the Remote Monitoring of Sea Temperature     

Enrico De  Marinis  Paola Picco  Alessandro Crise  Otello Gasparini  Stefano Salon 《Marine Ecology》2002,23(S1):122-137

Abstract. This paper describes a new Ocean Acoustic Tomography (OAT) methodology - a passive tomography - presently in an advanced development phase. This technique has been developed for long-term, extensive, remote monitoring of the seawater temperature spatial distribution, which is estimated from the received noise emitted from ships of opportunity. To test the passive tomographic processor under controlled conditions, the components of the naval noise from different kinds of vessels was analysed and realistic naval noise was simulated. The feasibility of the proposed methodology was confirmed by test-runs on semi-synthetic data; its capability to resolve temperature profiles will be better assessed with the use of real acoustic and environmental data collected during the INTIMATE00 experiment performed in October 2000 in the Atlantic Ocean off the Portuguese coast. An analysis of the space and time variability of the Empirical Orthogonal Function (EOF) decomposition of the sound speed (SSP) in the Mediterranean Sea has been carried out to identify areas where acoustic tomography can be successfully applied. Results from simulations in the South Adriatic Sea, which was identified as a region with a high sound speed variability associated with the seasonal cycle and with the main oceanographic processes, are reported.  相似文献   

A Model to Study the Bias on Q Estimates Obtained by Applying the Rise Time Method to Earthquake Data     

S. de Lorenzo 《Pure and Applied Geophysics》1998,153(2-4):419-438

—Among Q-estimation methods a simple linear technique consists of the evaluation of the increasing rise time of body waves with the increase of their travel time. This method, known as the rise time method, was theoretically justified for an impulsive source time function (Dirac delta function). Wu and Lees (1996), throughout finite difference calculations, showed that, when considering finite source time functions, characterized by a cut-off frequency around 20 Hz, the rise time method can be satisfactorily applied to invert earthquake data.¶In order to establish the applicability of the rise time method to an arbitrary earthquake source we analytically solved the problem of the propagation, throughout an anelastic medium, of a signal generated by a finite dimensions seismic source the shear dislocation fault of Brune (1970). Analyzing theoretical rise time vs. travel-time curves, we were able to distinguish two different corner frequency ranges in which the trend is different. When corner frequency is below 10 Hz the discrepancies with the rise time method increase with a decrease of the corner frequency. When corner frequency is above 10 Hz no meaningful differences are observed.¶The application of the model to a synthetic data set, based on the sources-receivers configuration of the 15 November 1995 Border Town, Nevada, earthquake sequence, shows that a significant bias affects Q estimates obtained with the rise time method, for seismic events characterized by a Brune corner frequency less than 5 Hz.  相似文献   

Geology and geochemistry of high-grade, volcanic rock-hosted, mercury mineralisation in the Nuevo Entredicho deposit, Almadén district, Spain     

Michel Jébrak  Pablo L. Higueras  Éric Marcoux  Saturnino Lorenzo 《Mineralium Deposita》2002,37(5):421-432

The Nuevo Entredicho deposit contains the richest concentration of mercury in the Almadén district, locally grading as much as 45% Hg. This ore deposit is hosted within an alkaline, conically shaped diatreme, about 150 m in diameter, which was subsequently filled with phreatomagmatic breccias. The diatreme cuts an Ordovician to Silurian clastic sedimentary rock sequence that is intercalated with basaltic sills. Structural analysis reveals a complex tectonic history with three main phases of Hercynian deformation. Mineralisation occurs as cinnabar replacements in volcanic tuffs and breccias and as recrystallised veins in tensions cracks associated with pyrophyllite and hydrothermal pyrite, which is strongly enriched in Cu, Pb and Hg. Lead isotopes in pyrite are characterised by high ²⁰⁷Pb/²⁰⁴Pb ratios (15.70-15.75), suggesting a contribution of ancient upper continental crust remobilised by Silurian-Devonian volcanism, with no mantle involvement. Sulphur isotopes of epigenetic cinnabar and pyrite range from +10.3 to +10.8‰ and from +10.6 to +11.9‰ respectively, suggesting a uniform sulphur source or a constant mixing ratio in the ore fluids. These isotopic compositions differ from those measured in the syngenetic deposits of the Almadén district; they suggest a higher temperature of ore formation of about 300 °C, and a genesis related to a distinct hydrothermal flow path at the Nuevo Entredicho deposit. Deposition of anomalously high-grade mercury ore at Nuevo Entredicho is related to a combination of (1) an abundance of black shale that provided sulphur and increasingly reducing conditions with high sulphide/sulphate ratios, (2) explosive Silurian-Devonian mafic magmatism that provided an initial source of mercury, (3) tectonic activity that lead to structurally favourable sites for ore deposition, and (4) replacement of secondary, carbonate-rich volcanic rocks.  相似文献   

Transtensional shear zones controlling volcanic eruptions: the Middle Pleistocene Mt Amiata volcano (inner Northern Apennines,Italy)     

Andrea Brogi  Domenico Liotta  Marco Meccheri  Lorenzo Fabbrini 《地学学报》2010,22(2):137-146

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