Antibiotic Resistance of Gram Negatives isolates from loggerhead sea turtles (Caretta caretta) in the central Mediterranean Sea     

M. Foti  C. Giacopello  Teresa Bottari  V. Fisichella  D. Rinaldo  C. Mammina 《Marine pollution bulletin》2009,58(9):1363-1366

Previous studies on fish and marine mammals support the hypothesis that marine species harbor antibiotic resistance and therefore may serve as reservoirs for antibiotic-resistance genetic determinants. The aim of this study was to assess the resistance to antimicrobial agents of Gram negative strains isolated from loggerhead sea turtles (Caretta caretta). Oral and cloacal swabs from 19 live-stranded loggerhead sea turtles, with hooks fixed into the gut, were analyzed. The antimicrobial resistance of the isolates to 31 antibiotics was assessed using the disk-diffusion method. Conventional biochemical tests identified Citrobacter spp., Proteus spp., Enterobacter spp., Escherichia spp., Providencia spp., Morganella spp., Pantoea spp., Pseudomonas spp. and Shewanella spp. Highest prevalences of resistance was detected to carbenicillin (100%), cephalothin (92.6%), oxytetracycline (81.3%) and amoxicillin (77.8%). The isolates showing resistance to the widest range of antibiotics were identified as Citrobacter freundii, Proteus vulgaris, Providencia rettgeri and Pseudomonas aeruginosa. In this study, antibiotic resistant bacteria reflect marine contamination by polluted effluents and C. caretta is considered a bioindicator which can be used as a monitor for pollution.  相似文献   

Response time and water origin in a steep nested catchment in the Italian Dolomites          下载免费PDF全文

Daniele Penna  Giulia Zuecco  Stefano Crema  Sebastiano Trevisani  Marco Cavalli  Luisa Pianezzola  Lorenzo Marchi  Marco Borga 《水文研究》2017,31(4):768-782

In this study, we investigate the surface flow time of rise in response to rainfall and snowmelt events at different spatial scales and the main sources originating channel runoff and spring water in a steep nested headwater catchment (Rio Vauz, Italian Dolomites), characterized by a marked elevation gradient. We monitored precipitation at different elevations and measured water stage/streamflow at the outlet of two rocky subcatchments of the same size, representative of the upper part of the catchment dominated by outcropping bedrock, at the outlet of a soil‐mantled and vegetated subcatchment of similar size but different morphology, and at the outlet of the main catchment. Hydrometric data are coupled with stable isotopes and electrical conductivity sampled from different water sources during five years, and used as tracers in end‐member mixing analysis, application of two component mixing models and analysis of the slope of the dual‐isotope regression line. Results reveal that times of rise are slightly shorter for the two rocky subcatchments, particularly for snowmelt and mixed rainfall/snowmelt events, compared to the soil‐mantled catchment and the entire Rio Vauz Catchment. The highly‐variable tracer signature of the different water sources reflects the geomorphological and geological complexity of the study area. The principal end‐members for channel runoff and spring water are identified in rainfall and snowmelt, which are the dominant water sources in the rocky upper part of the study catchment, and soil water and shallow groundwater, which play a relevant role in originating baseflow and spring water in the soil‐mantled and vegetated lower part of the catchment. Particularly, snowmelt contributes up to 64 ± 8% to spring water in the concave upper parts of the catchment and up to 62 ± 11% to channel runoff in the lower part of the catchment. These results offer new experimental evidences on how Dolomitic catchments capture and store rain water and meltwater, releasing it through a complex network of surface and subsurface flow pathways, and allow for the construction of a preliminary conceptual model on water transmission in snowmelt‐dominated catchments featuring marked elevation gradients.  相似文献   

Numerical efficiency assessment of energy dissipators for seismic protection of buildings     

D. Foti  L. Bozzo  F. Lpez-Almansa 《地震工程与结构动力学》1998,27(6):543-556

This paper presents a two-dimensional numerical study on the nonlinear seismic response of buildings equipped with two types of energy dissipators: Constant Friction Slip Braces (CFSB) and Adding Damping and Stiffness (ADAS). Three types of reinforced concrete buildings with 3, 7 and 15 storeys, representatives of the short-medium- and long-period ranges, are considered. Dissipators are placed in steel diagonal braces in all the floors. The sliding threshold (or yielding) forces for each mechanism are selected using two different criteria: (i) they are taken as 50, 75 and 100 per cent of those generated by the equivalent static lateral forces recommended by the UBC-91 for a ductile moment resisting frame and (ii) they are constant in the whole building (this constant value is chosen equal to the maximum forces obtained with the previous criterion). The input consists of ten recorded earthquakes (normalized with respect to their Housner intensity) corresponding to medium and stiff local soil conditions. Average values on the ten registers are given for the maximum horizontal displacement, the base shear, the energy dissipated and the interstorey drift. The possibility of failure in some devices has been numerically simulated to assess the robustness of the system. The obtained results show that both devices are useful to reduce the response compared to the bare frame and that CFSB is more efficient than ADAS; for 7- and 15-storey frames the lateral displacement with CFSB is even smaller than the one for the braced frame (rigid connections instead of dissipators). The conclusions are expected to provide simple design guidelines. © 1998 John Wiley & Sons, Ltd.  相似文献   

Experimental investigation on sea ripple evolution over sloping beaches     

Carmelo Petrotta  Carla Faraci  Pietro Scandura  Enrico Foti 《Ocean Dynamics》2018,68(9):1221-1237

This paper reports on a wave flume experimental campaign carried out to investigate the appearance, the growth and the migration of small scale bedforms on a sloping sandy bed due to both regular and random waves. A Vectrino Profiler along with a structured light approach were used for velocity and morphodynamic measurements at two positions, one located above the horizontal bed, and the other one above the sloping beach. The velocity was computed by phase averaging the velocity measurements. Several velocity profiles were analyzed, identifying an offshore-directed steady current that extends from few centimeters above the bottom for all the analyzed water column. Ripple geometry was measured by a structured light approach and compared with that predicted by several models to shed light on the effects induced by the sloping beach on the shape and asymmetry. Along the sloping beach, the ripples appeared strongly asymmetric with the onshore half wavelengths smaller than the offshore ones. Finally, ripple geometry and migration triggered by regular waves were compared with those generated by random waves with comparable flow orbital amplitude showing a good agreement.  相似文献   

Comment on “Effect of surface wave inversion non-uniqueness on 1D seismic ground response analysis” by Roy et al.     

Alberto Pettiti  Sebastiano Foti  Cesare Comina 《Natural Hazards》2015,75(1):975-981

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Seismic characterization of shallow bedrock sites with multimodal Monte Carlo inversion of surface wave data     

Paolo Bergamo  Cesare Comina  Sebastiano Foti  Margherita Maraschini 《Soil Dynamics and Earthquake Engineering》2011

Sites with a limited overburden over a stiff basement are of particular relevance for seismic site response. The characterization of such stratigraphies by means of surface wave methods poses some difficulties in interpretation. Indeed the presence of sharp seismic contrasts between the sediments and the shallow bedrock is likely to cause a relevance of higher modes in the surface wave apparent dispersion curve, which must be properly taken into account in order to provide reliable results. In this study a Monte Carlo algorithm based on a multimodal misfit function has been used for the inversion of experimental dispersion curves. Case histories related to the characterization of stations of the Italian accelerometric network are reported. Spectral ratios and amplification functions associated to each site are moreover evaluated to provide an independent benchmark test. The results show the robustness of the inversion method in such non-trivial conditions and the possibility of getting an estimate of uncertainty related to solution non-uniqueness.  相似文献   

Surface wave surveys for seismic site characterization of accelerometric stations in ITACA     

S. Foti  S. Parolai  P. Bergamo  G. Di Giulio  M. Maraschini  G. Milana  M. Picozzi  R. Puglia 《Bulletin of Earthquake Engineering》2011,9(6):1797-1820

This paper reports on site characterization for a set of accelerometric stations of the RAN (Italian accelerometric network) with specific attention to the shear wave velocity profile. The latter is indeed of primary importance for the usability of the accelerometric database. Surface wave analysis has been chosen as the primary investigation method since it offers the possibility of reaching the required accuracy with reasonable costs. A range of different techniques, both of the active-source and passive-source types, has been adopted to cope with the objectives of the characterization in relation to specific geological settings. Quality assessment of experimental data has been implemented to check the consistency of the measurements also with respect to the fundamental hypotheses of the method. Strategies to improve the reliability and robustness of the surface wave data inversion were exploited in order to mitigate problems arising from solution non-uniqueness and influence of higher modes in the propagation. Comparisons with independent borehole tests, available at some specific sites, confirm the reliability of the results. Although the research program covered only a subset of the network, the obtained results show the importance of specific experimental investigations aimed at estimating the shear wave velocity profile. Indeed the results lead to a re-classification of several sites with respect to the preliminary classification based on surface geology. Within this context, four selected case histories are reported in the present paper.  相似文献   

Lava trees and tree molds (“cannon stones”) of Mt. Etna     

Pietro?Carveni  Giuliana?MeleEmail author  Santo?Benfatto  Sebastiano?Imposa  Maria?Salleo Puntillo 《Bulletin of Volcanology》2011,73(6):633-638

Unique volcanic structures, known in the literature as “lava trees” and “tree molds”, have formed at several sites on Mt. Etna volcano (northeastern Sicily, Italy). They form when a fluid lava flow runs over a tree, wraps around it and, while the wood burns off, solidifies forming a hollow cast of the tree. The inhabitants of the Etna area call these formations “pietre cannone” (“cannon stones”) because of their cylindrical shape. The first documentation of lava trees is from Hawaii, but the first eye-witnessed accounts of their formation are, to our knowledge, from Etna’s 1865 eruption. Although many of the literature examples of lava trees and tree molds formed in pahoehoe, many of those reported in this work formed in a’a. The sites where we have found the lava tree molds are located within the territory of the Etna Regional Park; most occur next to walking trails and have a high potential for geotourism.  相似文献   

Turbulence-induced steady streaming in an oscillating boundary layer: On the reliability of turbulence closure models     

Luca Cavallaro  Pietro Scandura  Enrico Foti 《Coastal Engineering》2011

The accuracy of several closure models of the Reynolds-Averaged Navier–Stokes Equations in predicting the characteristics of an oscillating turbulent wall boundary layer is analyzed. The analysis involves four low Reynolds number k − ε models and a k − ω model and it is carried out by comparing the model results both with experimental data and with data obtained by a Direct Numerical Simulation (DNS) of the Navier–Stokes equations. The boundary layer is generated by a spatially constant time-oscillating pressure gradient given by the sum of two harmonic components characterized by angular frequencies Ω^∗ and 2Ω^∗ respectively, which generates a steady streaming because of the asymmetry of turbulence intensity during the cycle. Thus the results are relevant to the boundary layer at the bottom of nonlinear sea waves. The attention is therefore focused on the accuracy of the models in reproducing the period averaged profiles of the hydrodynamic characteristics of the steady streaming. The instantaneous quantities, such as time development of the wall shear stress, profiles of the streamwise velocity, Reynolds stresses and turbulent kinetic energy are also considered and analyzed. The results shows that a model can be judged better or worse than other models depending on the specific flow characteristic under investigation. However, an approach has been adopted which allowed to rank the models according to their accuracy in predicting the values of the hydrodynamic quantities involved in the present study.  相似文献   

Application of a GIS-aided method for the assessment of volcaniclastic soil sliding susceptibility to sample areas of Campania (Southern Italy)   总被引：2，自引：1，他引：1  

Sebastiano Perriello Zampelli  Eliana Bellucci Sessa  Marco Cavallaro 《Natural Hazards》2012,61(1):155-168

A significant part of Campania is extensively covered by volcaniclastic soils, deriving from the alteration of airfall-sedimented formations of layered ashes and pumices that were ejected by Campi Flegrei and Mt. Somma–Vesuvius during explosive eruptions. Where such soils cover steep slopes cut in carbonate bedrock, landforms depend essentially on the morpho-evolution of such slopes prior to the deposition of the volcaniclastic soils, because these are generally present only as thin veneers, up to a few meters of total thickness. Historical records and local literature testify that, in this part of Campania, landslides that originate on carbonate slopes covered by such soils and terminate at their foot or at gully outlets are frequent, following critical rainfall events. Such landslides can be classified as complex, occurring initially as debris slides, but rapidly evolving into debris avalanches and/or debris flows. The localization of the initial sliding areas (i.e. “sources”) on the slopes depends on both the spatial distribution of characters of the soil cover and the spatial distribution of the triggering rainfall events. It therefore appears reasonable to separate the two aspects of the problem and focus on the former one, in order to attempt an assessment of soil sliding susceptibility in the event of landslide-triggering rainfall. In this paper, some results of the application of a method aimed at such an assessment are presented. The method, called SLIDE (from SLiding Initiation areas DEtection), is based on the concept that, for a spatially homogeneous soil cover and a spatially homogeneous landslide-triggering rainfall sequence, different values of threshold slope gradient for limit equilibrium conditions exist, depending on morphological characters of the soil cover, such as its continuity and planform curvature. The method is based on the assessment of (1) soil cover presence, (2) discontinuities within soil cover, (3) slope gradients and curvature, by means of good resolution DEMs. It has been applied to sample carbonate slopes of Campania, where landslides originated either repeatedly or recently. Results are encouraging, and a soil sliding susceptibility map of a large area, based on a simplified version of method, is also presented.  相似文献