The magnetohydrodynamic turbulent cascade in the ecliptic solar wind: Study of Ulysses data   总被引：1，自引：0，他引：1  

Raffaele Marino  Luca Sorriso-Valvo  Pierluigi Veltri  Roberto Bruno 《Planetary and Space Science》2011,59(7):592-597

The occurrence of a nonlinear turbulent energy cascade in solar wind plasma has been recently established through the observation of an exact law from spacecraft measurements. The main results obtained in the fast, polar wind measured by Ulysses spacecraft are reviewed here. In particular, the turbulent cascade is seen as the mean to provide the energy necessary for the local heating in the non-adiabatic expansion of the solar wind. The importance of the density fluctuations in enhancing the turbulent energy transport is also evidenced. The ecliptic wind data measured by Ulysses are studied here in the same framework. This has been done by separating fast and slow streams, in order to avoid mixing of different physical conditions. The results further support the need for separate analysis of the two types of wind.  相似文献   

Natural and historical variability in fluvial processes,beaver activity,and climate in the Greater Yellowstone Ecosystem     

Lyman Persico  Grant Meyer 《地球表面变化过程与地形》2013,38(7):728-750

Two centuries of human activities in the Greater Yellowstone Ecosystem (GYE) have strongly influenced beaver activity on small streams, raising questions about the suitability of the historical (Euro‐American) period for establishing stream reference conditions. We used beaver‐pond deposits as proxy records of beaver occupation to compare historical beaver activity to that throughout the Holocene. Forty‐nine carbon‐14 (¹⁴C) ages on beaver‐pond deposits from Grand Teton National Park indicate that beaver activity was episodic, where multi‐century periods lacking dated beaver‐pond deposits have similar timing to those previously documented in Yellowstone National Park. These gaps in the sequence of dated deposits coincide with episodes of severe, prolonged drought, e.g. within the Medieval Climatic Anomaly 1000–600 cal yr bp , when small streams likely became ephemeral. In contrast, many beaver‐pond deposits date to 500–100 cal yr bp , corresponding to the colder, effectively wetter Little Ice Age. Abundant historical beaver activity in the early 1900s is coincident with a climate cooler and wetter than present and more abundant willow and aspen, but also regulation of beaver trapping and the removal of wolves (the beaver's main predator), all favorable for expanded beaver populations. Reduced beaver populations after the 1920s, particularly in the northern Yellowstone winter range, are in part a response to elk overbrowsing of willow and aspen that later stemmed from wolf extirpation. Beaver populations on small streams were also impacted by low streamflows during severe droughts in the 1930s and late 1980s to present. Thus, both abundant beaver in the 1920s and reduced beaver activity at present reflect the combined influence of management practices and climate, and underscore the limitations of the early historical period for defining reference conditions. The Holocene record of beaver activity prior to Euro‐American activities provides a better indication of the natural range of variability in beaver‐influenced small stream systems of the GYE. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Risk Assessment of Aquifer Salinization in a Large‐Scale Coastal Irrigation Scheme,Italy          下载免费PDF全文

Daniele Zaccaria  Giuseppe Passarella  Daniela D'Agostino  Raffaele Giordano  Samuel Sandoval Solis 《洁净——土壤、空气、水》2016,44(4):371-382

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Bayesian Cloud Analysis: efficient structural fragility assessment using linear regression   总被引：1，自引：1，他引：0  

Fatemeh Jalayer  Raffaele De Risi  Gaetano Manfredi 《Bulletin of Earthquake Engineering》2015,13(4):1183-1203

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Bearing capacity of pile groups under vertical eccentric load     

Di Laora  Raffaele  de Sanctis  Luca  Aversa  Stefano 《Acta Geotechnica》2019,14(1):193-205

The paper deals with the problem of the bearing capacity of pile groups under vertical eccentric load. Widespread practice is to consider the achievement of the axial capacity on the outermost pile as the ultimate limit state of the pile group. However, this approach neglects the ductility of the foundation system and may be thereby overconservative. With the aim of proposing an alternative and more rational approach, a novel formulation for interaction diagrams based on theorems of limit analysis is presented and discussed. The methodology is applicable to the general case of groups of unevenly distributed, dissimilar piles. Piles’ connections to the pile cap are modeled as either hinges or rigid-plastic internal fixities. An application example to a slender structure is also provided, showing that the proposed approach can lead to significant advantages over the traditional design.

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The meromictic alpine Lake Cadagno: Orographical and biogeochemical description     

Claudio Del Don  Kurt W. Hanselmann  Raffaele Peduzzi  Reinhard Bachofen 《Aquatic Sciences - Research Across Boundaries》2001,63(1):70-90

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Biomass composition and methods for the determination of metabolic reserve polymers in phototrophic sulfur bacteria     

Claudio Del Don  Kurt W. Hanselmann  Raffaele Peduzzi  Reinhard Bachofen 《Aquatic Sciences - Research Across Boundaries》1994,56(1):1-15

To study nutrient fluxes within aquatic ecosystems, the synthesis of biomass and of various storage polymers has been analysed in samples from a meromictic alpine lake. Methods are described for the quantitative determination of whole cell biomass, glycogen, polyhydroxyalkanoates (PHA) and sulfur. Methods were adapted to conditions present in natural environments and tested with samples from blooms of Chromatiaceae and with corresponding laboratory cultures. Dried bacterioplankton-biomass has been analyzed for sulfur, glycogen and polyhydroxyalkanoates, and after complete oxidation for SO ₄ ^2- , NO ₃ ^- and HPO ₄ ^2- . The average elemental composition of biomass from phototrophic sulfur bacteria, depleted of sulfur and carbon storage compounds, was C₃₈₀H₅₈₀O₁₅₃N₆₇P₃S_2.5M, where M stands for the content of the remaining minor elements. C, H, O, N, P and S accounted for 86.7% of the total dry mass. Storage sulfur in natural populations was equivalent to 2.5% to 13.5% of the dry mass; its content varied by 80% within a diurnal cycle. Glycogen contents fluctuated by approximately 50%; they accounted for 7.5% to 15.2% of the dry cell mass. The total content of reserve materials per cell never exceeded 30% of the dry mass. PHA had not been found in appreciable amounts in cells harvested from the natural lake habitat. Under certain conditions in the laboratoryChromatium okenii could be induced, however, to produce polyhydroxyalkanoates. Sulfur, glycogen and PHA contents of 33, 26 and 11%, respectively, were achieved under laboratory-culture conditions. Cells with up to 60% of their dry mass consisting of reserve materials can be obtained under selected laboratory conditions.  相似文献   

Comparaison au moyen de la lysotypie entre souches d'Aeromonas de pisciculture et souches isolées de l'homme     

Par Raffaele Peduzzi  Antonella Demarta 《Aquatic Sciences - Research Across Boundaries》1986,48(2):161-170

The spreading of bacteria of the genusAeromonas in intensive fish rearing tanks was analyzed during one year. Lysotyping has established epidemiologic correlations between the strains ofAeromonas isolated from the aquatic environment and those of clinical (human) origin.

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Dédié à Wolfgang Geiger  相似文献   

Tomographic inversion of local earthquake data from the Gioia Tauro basin (south-western Calabria, Italy)   总被引：1，自引：0，他引：1  

R. Raffaele  H. Langer  S. Gresta  F. Moia 《Geophysical Journal International》2006,165(1):167-179

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A strategy for the determination of the dielectric permittivity of a lossy soil exploiting GPR surface measurements and a cooperative target     

Francesco Soldovieri  Giancarlo Prisco  Raffaele Persico   《Journal of Applied Geophysics》2009,67(4):288-295

In this paper we deal with an indirect measure of the dielectric permittivity of the soil starting from GPR surface data collected on a buried “cooperative” target, meant as an object buried on purpose and whose extent is known a-priori. This target is exploited in order to achieve, from its image obtained from a suitable GPR data processing, an indirect measure of the dielectric permittivity of the embedding soil. GPR data processing is based on a linear microwave tomographic approach funded on the Born Approximation. Using this Born approach on two-dimensional inversion tests, we investigate the effect of the soil's electrical conductivity and permittivity on this indirect measure and demonstrate that the electrical field scattered by a spot-like buried object permits an accurate estimation of the soil permittivity even when no information of the soil conductivity is available.  相似文献