842 research outputs found
Spectral theory for linearized p-Laplace equations
No full textWe continue and completely set up the spectral theory initiated in Castorina et al. [D. Castorina, P. Esposito, B. Sciunzi, Degenerate elliptic equations with singular nonlinearities, Calc. Var. Partial Differential Equations, 34 (2009), 279–306] for the linearized operator arising from Δ_p u+f(u)=0. We establish existence and variational characterization of all the eigenvalues, and by a weak Harnack inequality
we deduce Hölder continuity for the corresponding eigenfunctions, this regularity being sharp. The Morse index of a positive solution can be now defined in the classical way,
and we will illustrate some qualitative consequences one should expect to deduce from
such information. In particular, we show that zero Morse index (or more generally, nondegenerate)
solutions on the annulus are radial
Prime riflessioni in merito alle nuove eccezioni relative agli appalti e le concessioni tra enti nell’ambito del settore pubblico, alla luce della vecchia giurisprudenza sull’in house
No full textRelazione nell'ambito della conferenza dal titolo Integrazione europea, servizi pubblici e diritti fondamentali.The article reproduces the speech at the seminar on the topic "European Integration, public services and fundamental rights", during which the Author has expressed some preliminary thoughts on the innovations introduced on the in-house requirements set by the new European Directives on public procurements. The seminar was organized by the Jean Monnet Chair of Prof. Emilio Castorina, which is focused on “public services, fundamental rights and European constitutionalism”, and took place in Catania, at the Department of Law (Villa Cerami) January 31, 2014
Fe isotopic ratios in selected groundwater samples from the Ravenna and Friuli coastal plains, NE Italy and significance for the environment
No full textHigh Fe concentrations (from 1.34 to 12.72 mg/L) were measured by Pezzetta et al.(2011) in groundwater samples from the Lower Friulan Plain near the north Adriatic seacoast. The research has unveiled a positive correlation between Fe concentrations and groundwater salinization (0.9–19679 mg/L Cl) and a particularly wide range of d56Fe (from –5.3 to +2.15‰ relative to IRMM-14 international standard, Castorina et al., 2013), compared with literature data. Furthermore, a positive correlation between d56Fe and Fe concentrations has been found. The present study has investigated the relationship of Fe isotopic ratios to Fe and chloride concentrations in groundwater samples from the Ravenna Plain near the north Adriatic seacoast aimed at comparing the results with those obtained from the Friulan Plain area. Therefore, the following characteristics have been recognized: a) Ravenna groundwater displays a smaller isotopic range (d56Fe from –2.6 to 0‰) than
Friulan groundwater, b) unlike the positive correlation in Friulan groundwater, no correlation exists between d56 Fe and Fe concentrations (<0.02–3.13 mg/L) in Ravenna
groundwater, c) there is a positive correlation between
d56Fe and pH in Ravenna groundwater while there are negative or nil correlations in Friulian groundwater, and d) there is a negative correlation between d56Fe and chloride concentrations(55–16,800 mg/L) in Ravenna groundwater, while there are positive or nil correlations in Friulian groundwater. These different characteristics of groundwater from the two
coastal Plains likely reflect different processes taking place in the two sites despite the broadly similar environments. The particularly isotopic lighter Fe compositions of most of groundwater samples from the Friulan Plain have been explained by isotopic fractionation during repeated cycling of Fe precipitation. This multi-staged process apparently does not significantly operate in the Ravenna Plain, where groundwater
generally contains much lower Fe concentrations, suggesting that redox conditions arecomparatively less exasperated. The low Fe concentrations may also explain the lack of any correlation with d56Fe as well as the positive correlation between d56Fe and pH in groundwater from the Ravenna Plain. Lastly, the negative correlation between d56Fe and Cl in Ravenna groundwater indicates that with increasing salinization, there is likely precipitation of 56 Fe-rich ferrihydrite, thus leaving groundwater 56Fe-poor. In contrast, in lower-salinity waters, probably biologically-mediated reduction of Fe(III) to Fe(II) in the
56 Fe-rich ferrihydrite present in sediments, can release 56
Fe-rich Fe(II) to groundwater, that thus acquires the 56
Fe-rich signature. Lastly, as the Friulan Plain was significantly disseminated of Fe wastes from smelter plants in the past, the more positive d56Fe values measured in those groundwater samples were explained by waste leaching (Castorina et al., 2013). As Fe industrial pollution does not occur in the Ravenna Plain, where however, isotopic values nearing those positive of the Friulan Plain, have also been measured, this may render the above explanation not fully plausible, suggesting that the more positive d56Fe measured in the Friulan Plain can be due mainly to more extreme natural causes.
References
1. E. Pezzetta, A. Lutman, I. Martinuzzi, C. Viola, G. Bernardis and V. Fuccaro, Iron concentrations in selected groundwater samples from the lower Friulian Plain, northeast Italy: Importance of salinity. Environ. Earth Sci., 62, pp. 377–391, 2011.
2. F. Castorina, R. Petrini, A. Galic, F.F. Slejko, U. Aviani, E. Pezzetta and G. Cavazzini, The fate of iron in waters from a coastal environment impacted by metallurgical industry in northern Italy: Hydrochemistry and Fe-isotopes. Applied Geochemistry, 2013 (in press)
Small-scale heterogeneity in calc-alkaline granitoids: an example from leucogranites and granodiorites of the Budduso’ intrusion (NE Sardinia, Italy)
No full textRare earth elements, yttrium, and the isotopic composition of Sr and Nd for assessing the origin of the Quaternary travertines from Acquasanta Terme (Marche, central Italy)
No full textSome constraints to the isochron method by an iterative least-squares approach: application to the Budduso’ leucogranites (NE Sardinia, Italy)
No full textEarly Pliocene 87Sr/86Sr isotopic record from DSDP Site 132 (Tyrrhenian Sea)
No full text87Sr/ 86Sr measurements were carried out on planktonic foraminiferal shell samples collected in the Early Pliocene succession of DSDP Site 132 (Tyrrhenian Sea, Western Mediterranean). The measured ratios range between 0.708980 and 0.709023, showing moderate fluctuations and a maximum variation of 0.000043 that falls within the uncertainty range of the Sr isotope measurements (± 0.000022) and suggests relatively constant ratios throughout this succession.
The Mediterranean seawater 87Sr/ 86Sr ratios measured in a sample collected 55 cm above the Miocene / Pliocene Boundary and dated to 5.31 ± 0.01 Ma, are consistent with those measured in coeval oceanic successions, confirming the open marine depositional environment revealed by foraminiferal assemblages.
The measured ratios are consistent with those collected in the Lower Pliocene deep sea sequence at Hole 654A (about 70 km NW from DSDP Site 132) and these are also comparable with other data from coeval oceanic and on land successions, taking into account the uncertainty of the Sr isotope measurements.
The occurrence of relatively constant ratios throughout this succession, as previously shown in other coeval deep sea sequences of the Mediterranean and if verified in other successions, may hamper precise age determinations of the Early Pliocene marine carbonate in this basin
Biased Nd-model ages in highly evolved granites: an example from the Budduso’ intrusion (NE Sardinia, Italy)
No full textNd-model ages calculated with respect to a depleted mantle source (T(DM)) have been widely applied to granitoids in order to date events of mantle-crust differentiation, often referred as "crustal residence ages". The basic assumption for a Nd-model age to represent a crustal residence age is that intracrustal processes such as interactions with fluids, partial melting and fractional crystallization cause little or no fractionation of the Sm - Nd pair. The present study reports on the geochemistry and Sm - Nd isotopes of leucogranites from the Budduso' intrusion, belonging to the Hercynian orogeny in Northern Sardinia (Italy). It is shown that fractionation of a LREE-rich mineral phase as allanite causes a significant variation of the Sm/Nd ratio in the residual melt, thus inducing biased Nd-model ages which have no direct meaning of crustal residence ages
Il Plain English - colonialismo linguistico o linguicidio?
No full textAtti a cura di G. Agresti e F. Rosat
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