University Dellinsubria Sede Of Como

Como, Italy

University Dellinsubria Sede Of Como

Como, Italy

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Roberts G.P.,University of London | Raithatha B.,University of London | Sileo G.,University Dellinsubria Sede Of Como | Pucci S.,Italian National Institute of Geophysics and Volcanology | And 12 more authors.
Geophysical Journal International | Year: 2010

The shallow subsurface structure of the 2009 April 6 Mw 6.3 L'Aquila earthquake surface rupture at Paganica has been investigated with ground penetrating radar to study how the surface rupture relates spatially to previous surface displacements during the Holocene and Pleistocene. The discontinuous surface rupture stepped between en-echelon/parallel faults within the overall fault zone that show clear Holocene/Pleistocene offsets in the top 10 m of the subsurface. Some portions of the fault zone that show clear Holocene offsets were not ruptured in 2009, having been bypassed as the rupture stepped across a relay zone onto a fault across strike. The slip vectors, defined by opening directions across surface cracks, indicate dip-slip normal movement, whose azimuth remained constant between 210° and 228° across the zone where the rupture stepped between faults. We interpret maximum vertical offsets of the base of the Holocene summed across strike to be 4.5 m, which if averaged over 15 kyr, gives a maximum throw-rate of 0.23-0.30 mm yr-1, consistent with throw-rates implied by vertical offsets of a layer whose age we assume to be ~33 ka. This compares with published values of 0.4 mm yr-1 for a minimum slip rate implied by offsets of Middle Pleistocene tephras, and 0.24 mm yr-1 since 24.8 kyr from palaeoseismology. The Paganica Fault, although clearly an important active structure, is not slipping fast enough to accommodate all of the 3-5 mm yr-1 of extension across this sector of the Apennines; other neighbouring range-bounding active normal faults also have a role to play in the seismic hazard. © 2010 The Authors Journal compilation © 2010 RAS.


Re Calegari G.,University Dellinsubria Sede Of Como | Ratcliffe P.G.,University Dellinsubria Sede Of Como | Ratcliffe P.G.,National Institute of Nuclear Physics, Italy
European Physical Journal C | Year: 2014

The asymmetry in the angular distribution of Drell–Yan dilepton pairs in collisions where just one nucleon is transversely polarised has been examined in the literature with a variety of results, differing mainly by factors of 2. We re-evaluate the asymmetry via twist-3 contributions in collinear factorisation. In order to allow complete and in-depth comparison with existing calculations, we supply all calculational details. © 2014, The Author(s).


Donatelli M.,University Dellinsubria Sede Of Como | Serra-Capizzano S.,University Dellinsubria Sede Of Como
Journal of Electrical and Computer Engineering | Year: 2010

This survey paper deals with the use of antireflective boundary conditions for deblurring problems where the issues that we consider are the precision of the reconstruction when the noise is not present, the linear algebra related to these boundary conditions, the iterative and noniterative regularization solvers when the noise is considered, both from the viewpoint of the computational cost and from the viewpoint of the quality of the reconstruction. In the latter case, we consider a reblurring approach that replaces the transposition operation with correlation. For many of the considered items, the anti-reflective algebra coming from the given boundary conditions is the optimal choice. Numerical experiments corroborating the previous statement and a conclusion section end the paper. © 2010 Marco Donatelli and Stefano Serra-Capizzano.


Capizzano S.S.,University Dellinsubria Sede Of Como | Tablino-Possio C.,University of Milan Bicocca
Computers and Mathematics with Applications | Year: 2010

In recent contributions, algebraic multigrid methods have been designed and studied from the viewpoint of spectral complementarity. In this note, we focus our efforts on specific applications and, more precisely, on large linear systems arising from the approximation of the weighted Laplacian with various boundary conditions. We adapt the multigrid idea to this specific setting and we present and critically discuss a wide set of numerical experiments showing the potentiality of the considered approach. © 2010 Elsevier Ltd. All rights reserved.


Donatelli M.,University Dellinsubria Sede Of Como | Serra-Capizzano S.,University Dellinsubria Sede Of Como | Sesana D.,University of Piemonte Orientale
BIT Numerical Mathematics | Year: 2012

Starting from the spectral analysis of g-circulant matrices, we study the convergence of a multigrid method for circulant and Toeplitz matrices with various size reductions. We assume that the size n of the coefficient matrix is divisible by g≥2 such that at the lower level the system is reduced to one of size n/g, by employing g-circulant based projectors. We perform a rigorous two-grid convergence analysis in the circulant case and we extend experimentally the results to the Toeplitz setting, by employing structure preserving projectors. The optimality of the two-grid method and of the multigrid method is proved, when the number θ ∈ ℕ of recursive calls is such that 1 < θ < g. The previous analysis is used also to overcome some pathological cases, in which the generating function has zeros located at "mirror points" and the standard two-grid method with g=2 is not optimal. The numerical experiments show the correctness and applicability of the proposed ideas, both for circulant and Toeplitz matrices. © 2011 Springer Science + Business Media B.V.


Monticelli D.,University Dellinsubria Sede Of Como | Dossi C.,University Dellinsubria Sede Of Como | Castelletti A.,University Dellinsubria Sede Of Como
Analytica Chimica Acta | Year: 2010

The analytical performances of Competitive Ligand Equilibration with Cathodic Stripping Voltammetric detection of the labile fraction (CLE-CSV) were assessed. This speciation method enables the concentration of natural ligand(s) and their conditional stability constants for the complexation of the investigated metal to be determined through thermodynamic considerations. Literature data were discussed and general trends in the precision of the determined parameters identified: ligand concentrations were affected, on average, by a 10% relative percentage standard deviation (RSD%), whereas conditional stability constants showed much lower precision, with an average RSD% of 50%. New experimental data were collected to obtain a complete assessment of accuracy and precision attainable for the determination of strong ligands at the ultra trace level, enabling the whole protocol to be evaluated. Firstly, the side reaction coefficient alpha for the formation of the complex between the added ligand and the investigated metal (αCuL) was determined. The method was subsequently applied to the analysis of solution containing ligand at trace levels (5-50nM) with known complexing characteristics. Copper was used as the model metal ion and ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) as the model ligands. Results evidenced that the CLE-CSV protocol is not affected by systematic errors in the determination of both ligand concentration and the conditional stability constants. Good precision is obtained for ligand concentrations, with an average relative standard deviation (RSD%) of 5%; an average RSD% of 23% was calculated for the conditional stability constants. Including the contribution of the uncertainty in the value of αCuL in the evaluation of the uncertainty in the latter parameter increased the RSD% up to 40%. The CLE-CSV protocol was subsequently applied to the detection of strong ligands in water samples collected in Antarctica: precision was shown to be comparable with literature data. © 2010 Elsevier B.V.


Cinosi A.,Sasol Limited | Cinosi A.,GNR Srl | Andriollo N.,Sasol Limited | Pepponi G.,Fondazione Bruno Kessler | Monticelli D.,University Dellinsubria Sede Of Como
Analytical and Bioanalytical Chemistry | Year: 2011

A total reflection X-ray fluorescence (TXRF) procedure was developed for the determination of metal traces in petrochemical end products or intermediates for surfactant synthesis. The method combines a fast and straightforward sample preparation, i.e. deposition on the sample holder and evaporation of the sample matrix, with an efficient quantification method based on internal standardization (organic gallium standard). The method developed showed detection limits below 0.05 μg g-1 and in most cases below 0.005 μg g-1. Fifteen elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Rh, Sn, Sr, V and Zn) were determined in matrices such as paraffins, n-olefins, linear alkylbenzenes, long-chain alkyl alcohols and esters: typical metal contents were below 1 μg g-1. The results were compared with the reference method ASTM D5708 (test method B) based on inductively coupled plasma optical emission spectroscopy: advantages and drawbacks of the two procedures were critically evaluated. The TXRF method developed showed comparable precision and absence of bias with respect to the reference method. A comparison of the performances of the two methods is presented. © 2010 Springer-Verlag.


Arico A.,University of Cagliari | Donatelli M.,University Dellinsubria Sede Of Como | Nagy J.,Emory University | Serra-Capizzano S.,University Dellinsubria Sede Of Como
Lecture Notes in Electrical Engineering | Year: 2011

Filtering methods are used in signal and image restoration to reconstruct an approximation of a signal or image from degraded measurements. Filtering methods rely on computing a singular value decomposition or a spectral factorization of a large structured matrix. The structure of the matrix depends in part on imposed boundary conditions. Anti-reflective boundary conditions preserve continuity of the image and its (normal) derivative at the boundary, and have been shown to produce superior reconstructions compared to other commonly used boundary conditions, such as periodic, zero and reflective. The purpose of this paper is to analyze the eigenvector structure of matrices that enforce anti-reflective boundary conditions. In particular, a new anti-reflective transform is introduced, and an efficient approach to computing filtered solutions is proposed. Numerical tests illustrate the performance of the discussed methods. © 2011 Springer Science+Business Media B.V.


PubMed | University Dellinsubria Sede Of Como
Type: Journal Article | Journal: Analytica chimica acta | Year: 2010

The analytical performances of Competitive Ligand Equilibration with Cathodic Stripping Voltammetric detection of the labile fraction (CLE-CSV) were assessed. This speciation method enables the concentration of natural ligand(s) and their conditional stability constants for the complexation of the investigated metal to be determined through thermodynamic considerations. Literature data were discussed and general trends in the precision of the determined parameters identified: ligand concentrations were affected, on average, by a 10% relative percentage standard deviation (RSD%), whereas conditional stability constants showed much lower precision, with an average RSD% of 50%. New experimental data were collected to obtain a complete assessment of accuracy and precision attainable for the determination of strong ligands at the ultra trace level, enabling the whole protocol to be evaluated. Firstly, the side reaction coefficient alpha for the formation of the complex between the added ligand and the investigated metal (alpha(CuL)) was determined. The method was subsequently applied to the analysis of solution containing ligand at trace levels (5-50 nM) with known complexing characteristics. Copper was used as the model metal ion and ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) as the model ligands. Results evidenced that the CLE-CSV protocol is not affected by systematic errors in the determination of both ligand concentration and the conditional stability constants. Good precision is obtained for ligand concentrations, with an average relative standard deviation (RSD%) of 5%; an average RSD% of 23% was calculated for the conditional stability constants. Including the contribution of the uncertainty in the value of alpha(CuL) in the evaluation of the uncertainty in the latter parameter increased the RSD% up to 40%. The CLE-CSV protocol was subsequently applied to the detection of strong ligands in water samples collected in Antarctica: precision was shown to be comparable with literature data.

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