Effective Hamiltonian for the D'Alembert Planetary Model Near a Spin/Orbit Resonance     

Luca Biasco  Luigi Chierchia 《Celestial Mechanics and Dynamical Astronomy》2002,83(1-4):223-237

The D'Alembert model for the spin/orbit problem in celestial mechanics is considered. Using a Hamiltonian formalism, it is shown that in a small neighborhood of a p:q spin/orbit resonance with (p,q) different from (1,1) and (2,1) the 'effective' D'Alembert Hamiltonian is a completely integrable system with phase space foliated by maximal invariant curves; instead, in a small neighborhood of a p:q spin/orbit resonance with (p,q) equal to (1,1) or (2,1) the 'effective' D'Alembert Hamiltonian has a phase portrait similar to that of the standard pendulum (elliptic and hyperbolic equilibria, separatrices, invariant curves of different homotopy). A fast averaging with respect to the 'mean anomaly' is also performed (by means of Nekhoroshev techniques) showing that, up to exponentially small terms, the resonant D'Alembert Hamiltonian is described by a two-degrees-of-freedom, properly degenerate Hamiltonian having the lowest order terms corresponding to the 'effective' Hamiltonian mentioned above.  相似文献   

Response of the bacterial community to in situ bioremediation of organic-rich sediments   总被引：8，自引：0，他引：8  

Vezzulli L  Pruzzo C  Fabiano M 《Marine pollution bulletin》2004,49(9-10):740-751

A field trial experiment was carried out to assess the potential of bioremediation for mobilisation of carbon in organic-rich sediments. Both bioaugmentation (bio-fixed microorganisms) and biostimulation (oxygen release compounds--ORC) protocols have been tested and the response of the bacterial community has been described to assess the baseline for bioremediation potential. Multifactorial ANOVA revealed that bioaugmentation protocol had an effect in stimulate mobilisation processes and significantly enhanced extra-cellular enzymatic activity rates. In contrast biostimulation treatment did not have an effect on mobilisation rates but contributed to enhance bacterial efficiency through a maximization of the bacterial production:enzymatic activity ratio. Average calculation of net mobilised carbon showed that 23% increase of mobilised pool was accounted for bioaugmentation in summer. Although biostimulation accounted for a smaller increase in mobilised carbon (<10%), the use of ORC resulted in an increased mineralisation and net carbon loss via respiration. Based on our results, a conceptual model for application of bioremediation to face the problem of sediment eutrophication is discussed.  相似文献   

Geochemical and O-isotope constraints on the evolution of lithospheric mantle in the Ross Sea rift area (Antarctica)     

Cristina?PerinelliEmail author  Pietro?Armienti  Luigi?Dallai 《Contributions to Mineralogy and Petrology》2006,151(3):245-266

Peridotite xenoliths found in Cenozoic alkali basalts of northern Victoria Land, Antarctica, vary from fertile spinel-lherzolite to harzburgite. They often contain glass-bearing pockets formed after primary pyroxenes and spinel. Few samples are composite and consist of depleted spinel lherzolite crosscut by amphibole veins and/or lherzolite in contact with poikilitic wehrlite. Peridotite xenoliths are characterized by negative Al₂O₃–Mg# and TiO₂–Mg# covariations of clino- and orthopyroxenes, low to intermediate HREE concentrations in clinopyroxene, negative Cr–Al trend in spinel, suggesting variable degrees of partial melting. Metasomatic overprint is evidenced by trace element enrichment in clinopyroxene and sporadic increase of Ti–Fe_tot. Preferential Nb, Zr, Sr enrichments in clinopyroxene associated with high Ti–Fe_tot contents constrain the metasomatic agent to be an alkaline basic melt. In composite xenoliths, clinopyroxene REE contents increase next to the veins suggesting metasomatic diffusion of incompatible element. Oxygen isotope data indicate disequilibrium conditions among clinopyroxene, olivine and orthopyroxene. The highest δ¹⁸O values are observed in minerals of the amphibole-bearing xenolith. The δ¹⁸O_cpx correlations with clinopyroxene modal abundance and geochemical parameters (e.g. Mg# and Cr#) suggest a possible influence of partial melting on oxygen isotope composition. Thermobarometric estimates define a geotherm of 80°C/GPa for the refractory lithosphere of NVL, in a pressure range between 1 and 2.5 GPa. Clinopyroxene microlites of melt pockets provide P–T data close to the anhydrous peridotite solidus and confirm that they originated from heating and decompression during transport in the host magma. All these geothermometric data constrain the mantle potential temperature to values of 1250–1350°C, consistent with the occurrence of mantle decompressional melting in a transtensive tectonic regime for the Ross Sea region.  相似文献   

Global change and relative sea level rise at Venice: what impact in term of flooding     

Laura Carbognin  Pietro Teatini  Alberto Tomasin  Luigi Tosi 《Climate Dynamics》2010,35(6):1039-1047

Relative sea level rise (RSLR) due to climate change and geodynamics represents the main threat for the survival of Venice, emerging today only 90 cm above the Northern Adriatic mean sea level (msl). The 25 cm RSLR occurred over the 20th century, consisting of about 12 cm of land subsidence and 13 cm of sea level rise, has increased the flood frequency by more than seven times with severe damages to the urban heritage. Reasonable forecasts of the RSLR expected to the century end must be investigated to assess the suitability of the Mo.S.E. project planned for the city safeguarding, i.e., the closure of the lagoon inlets by mobile barriers. Here we consider three RSLR scenarios as resulting from the past sea level rise recorded in the Northern Adriatic Sea, the IPCC mid-range A1B scenario, and the expected land subsidence. Available sea level measurements show that more than 5 decades are required to compute a meaningful eustatic trend, due to pseudo-cyclic 7–8 year long fluctuations. The period from 1890 to 2007 is characterized by an average rate of 0.12 ± 0.01 cm/year. We demonstrate that linear regression is the most suitable model to represent the eustatic process over these 117 year. Concerning subsidence, at present Venice is sinking due to natural causes at 0.05 cm/year. The RSLR is expected to range between 17 and 53 cm by 2100, and its repercussions in terms of flooding frequency are associated here to each scenario. In particular, the frequency of tides higher than 110 cm, i.e., the value above which the gates would close the lagoon to the sea, will increase from the nowadays 4 times per year to a range between 20 and 250. These projections provide a large spread of possible conditions concerning the survival of Venice, from a moderate nuisance to an intolerable aggression. Hence, complementary solutions to Mo.S.E. may well be investigated.  相似文献   

Theoretical Derivation of a Peak Particle Velocity–Distance Law for the Prediction of Vibrations from Blasting     

Luigi Sambuelli 《Rock Mechanics and Rock Engineering》2009,42(3):547-556

I would like to suggest a theoretical justification for the mathematical structure of some laws for predicting the maximum particle velocity vibration from blasting operations in the light of some basic notions of elastic and anelastic wave theory. Within this point of view, in dimensionally correct expressions, the terms pertaining to the rock, to the blast and to the seismic wave become evident and recognisable. A law is presented that can be used to forecast the maximum particle velocity on the basis of some blast design and rock parameters. Four tests of the proposed law performed with real data sets seem to confirm fairly well its reliability.  相似文献   

AVES: A high performance computer cluster array for the INTEGRAL satellite scientific data analysis     

Memmo Federici  Bruno Luigi Martino  Pietro Ubertini 《Experimental Astronomy》2012,34(1):105-121

In this paper we describe a new computing system array, designed, built and now used at the Space Astrophysics and Planetary Institute (IAPS) in Rome, Italy, for the INTEGRAL Space Observatory scientific data analysis. This new system has become necessary in order to reduce the processing time of the INTEGRAL data accumulated during the more than 9 years of in-orbit operation. In order to fulfill the scientific data analysis requirements with a moderately limited investment the starting approach has been to use a ??cluster?? array of commercial quad-CPU computers, featuring the extremely large scientific and calibration data archive on line.  相似文献   

Geological and geophysical investigation of Kamil crater,Egypt     

Stefano Urbini  Iacopo Nicolosi  Antonio Zeoli  Sami El Khrepy  Ahmed Lethy  Mahfooz Hafez  Mohamed El Gabry  Ahmed El Barkooky  Aly Barakat  Mahomoud GOMAA  Ali M. Radwan  Mohamed El Sharkawi  Massimo D’orazio  Luigi Folco 《Meteoritics & planetary science》2012,47(11):1842-1868

Abstract– We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small‐scale hypervelocity impact craters. It is an exceptionally well‐preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth‐to‐diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45°. Newly identified asymmetries, including the off‐center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well‐preserved craters. Geomagnetic data reveal no buried individual impactor masses >100 kg and suggest that the total mass of the buried shrapnel >100 g is approximately 1050–1700 kg. Based on this mass value plus that of shrapnel >10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.  相似文献   

Chondritic micrometeorites from the Transantarctic Mountains     

Matthias Van GINNEKEN  Luigi FOLCO  Carole CORDIER  Pierre ROCHETTE 《Meteoritics & planetary science》2012,47(2):228-247

Abstract– On the basis of morphological and petrographic characteristics, eight “giant” unmelted micrometeorites in the 300–1100 μm size range were selected from the Transantarctic Mountain micrometeorite collection, Victoria Land, Antarctica. Mineralogical and geochemical data obtained by means of scanning electron microscopy, electron probe microanalyses, and synchrotron X‐ray diffraction allow their classification as chondritic micrometeorites. The large size of the micrometeorites increases considerably the amount of mineralogical and geochemical information compared to micrometeorites in smaller size fractions, therefore allowing a better definition of their parent material. A large variety of material is observed: five micrometeorites are related to unequilibrated and equilibrated ordinary chondrite, one to CV chondrite, one to CM chondrite, and one to CI chondrite parent materials. Besides reporting the first occurrence of a CV‐like micrometeorite, our study shows that the abundance of chondritic material supports observations from recent studies on cosmic spherules that a large part of the micrometeorite flux in this size range is of asteroidal origin.  相似文献   

Gentrification as space domestication. The High Line Art case     

Pier Luigi Sacco  Maria Tartari  Guido Ferilli  Giorgio Tavano Blessi 《Urban geography》2019,40(4):529-554

In this paper, we critically examine the role of artistic locational choices and practices in the context of gentrification processes in urban renewal contexts. We characterize gentrification as a form of domestication of space, and explore the extent to which artistic choices and practices relate to such process with reference to the deontological dilemma of legitimization within the art system vs. responsible empowerment of vulnerable local constituencies. We illustrate our argument with an analysis of the High Line Art project, and show how this can be considered as a textbook example of art-driven space domestication leading to brutal forms of gentrification. We comment on the threat that this provides to the social credibility of artistic practices as an agency of responsible social change.  相似文献   

Una semplice dimostrazione del teorema di bjerknes sulle circolazioni atmosferiche     

Prof. Dr. Luigi Castoldi 《Pure and Applied Geophysics》1950,18(1):160-161

Riassunto Si fa uso di una formula di derivazione di un integrale di superficie per dimostrare un teorema meteorologico diV. Bjerknes.

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Summary Use is made of a differentiation's formula for surface integrals in showing aV. Bjerknes' meteorological theorem.

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