Articolo in rivista

An adaptative method Volterra-Fredholm integral equations on the half line

In this paper we develop a direct quadrature method for solving Volterra-Fredholm integral equations on an unbounded spatial domain. These problems, when related to some important physical and biological phenomena, are characterized by kernels that present variable peaks along space. The method we…

Large time behavior of signed fractional porous media equations on bounded domains

Following the methodology of Brasco (Adv Math 394:108029, 2022), we study the long-time behavior for the signed fractional porous medium equation in open bounded sets with smooth boundary. Homogeneous exterior Dirichlet boundary conditions are considered. We prove that if the initial datum has…

Spinning particles in twisted gravitational wave spacetimes

Twisted gravitational waves (TGWs) are nonplanar waves with twisted rays that move along a fixed direction in space. We study further the physical characteristics of a recent class of Ricci-flat solutions of general relativity representing TGWs with wave fronts that have negative Gaussian curvature…

Observer-dependent optical properties of stationary axisymmetric spacetimes

The world lines of null particles admit arbitrary parametrizations. In the presence of a family of observers one may introduce along a null world line an extension of the so-called Cattaneo's relative standard time parameter (valid for massive particles) which plays a special role. Another…

Coastline detection from SAR images by level set model

In this paper we present an innovative and automatic procedure which is used to extract the coastline from SAR (Synthetic Aperture Radar) images by the level set model. This model consists in a PDE (Partial Differential Equation) equation governing the evolution of a curve corresponding to the zero…

Diffusione e reazione: dal moto Browniano alla diffusione delle epidemie

I fenomeni di trasporto, e la loro generalizzazione ai casi con reazione, costituiscono un capitolo molto importante della matematica applicata e trovano utilizzo in ambiti molto vari, che vanno dalla diffusione di sostanze inquinanti in atmosfera e in mare, ai processi industriali, alla…

A two-phase two-layer model for transdermal drug delivery and percutaneous absorption

One of the promising frontiers of bioengineering is the controlled release of a therapeutic drug from a vehicle across the skin (transdermal drug delivery). In order to study the complete process, a two-phase mathematical model describing the dynamics of a substance between two coupled media of…

Convergence of solutions for two delays Volterra integral equations in the critical case

In this paper, for the "critical case" with two delays, we establish two relations between any two solutions y(t) and y*(t) for the Volterra integral equation of non-convolution type y(t)=f(t)+\int_{t-\tau}^{t-\delta}k(t,s)g(y(s))ds and a solution z(t) of the first order differential equation \dot…

High biodiversity arises from the analyses of morphometric, biochemical and genetic data in ancient olive trees of South of Italy

Morphometric, biochemical and genetic analyses were conducted on Olea europaea L. of Campania, an area of Southern Italy highly suited to the cultivation of olive trees and the production of extra virgin olive oil (EVOO). We aimed to characterize the distribution of morphological, biochemical and…

Intermittency in the relative separations of tracers and of heavy particles in turbulent flows

Results from direct numerical simulations (DNS) of particle relative dispersion in three-dimensional homogeneous and isotropic turbulence at Reynolds number Re?~300 are presented. We study point-like passive tracers and heavy particles, at Stokes number St=0.6,1 and 5. Particles are emitted from…