Statistical Physics
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Wiener-Hopf Integral Equations in Mean First-passage Time Problems for Continuous-time Random Walks
Dahlenburg, M.
; Pagnini, G. (2023)
We study the mean first-passage time (MFPT) for asymmetric continuous time random walks in continuous space characterised by finite mean waiting times and jump amplitudes with both finite average and finite variance. We ... -
Exact calculation of the mean first-passage time of continuous-time random walks by nonhomogeneous Wiener-Hopf integral equations
Dahlenburg, M.; Pagnini, G. (2022-12-23)
We study the mean first-passage time (MFPT) for asymmetric continuous-time random walks in continuous-space characterised by waiting-times with finite mean and by jump-sizes with both finite mean and finite variance. In ... -
Anomalous diffusion originated by two Markovian hopping-trap mechanisms
Vitali, S.; Paradisi, P.; Pagnini, G. (2022)
We show through intensive simulations that the paradigmatic features of anomalous diffusion are indeed the features of a (continuous-time) random walk driven by two different Markovian hopping-trap mechanisms. If $p ... -
A high-resolution fuel type mapping procedure based on satellite imagery and neural networks: Updating fuel maps for wildfire simulators
López-De-Castro, M.; Prieto-Herráez, D.; Asensio-Sevilla, M.I.; Pagnini, G. (2022)
A major limitation in the simulation of forest fires involves the proper characterization of the surface vegetation over the study area, based on land cover maps. Unfortunately, these maps may be outdated, with areas where ... -
Fire-spotting generated fires. Part II: The role of flame geometry and slope
Egorova, V.; Trucchia, A.; Pagnini, G. (2022)
This is the second part of a series of two papers concerning fire-spotting generated fires. While, in the first part, we focus on the impact of macro-scale factors on the growth of the burning area by considering the ... -
The tempered space-fractional Cattaneo equation
Beghin, L.; Garra, R.; Mainardi, F.; Pagnini, G. (2022)
We consider the time-fractional Cattaneo equation involving the tempered Caputo space-fractional derivative. There is an increasing interest in the recent literature for the applications of the fractional-type Cattaneo ... -
The Fokker–Planck equation of the superstatistical fractional Brownian motion with application to passive tracers inside cytoplasm
Runfola, C.; Vitali, S.; Pagnini, G. (2022)
By collecting from literature data experimental evidence of anomalous diffusion of passive tracers inside cytoplasm, and in particular of subdiffusion of mRNA molecules inside live Escherichia coli cells, we obtain the ... -
Wildfire Spreading: a new application of the Beta distribution
(2022)This dissertation is in the mathematical physics area, more specifically, applications in the statistics field. The thesis, under the supervision of Dr. Gianni Pagnini, was carried out at the BCAM - Basque Centre for ... -
Beta Distribution in Wildfire Spreading
(2022)This paper is the result of research work carried out in collaboration with the Statistical Physics team of the Basque Center for Applied Mathematics in Bilbao, supervised by Dr. Gianni Pagnini. Main subject is PROPAGATOR, ... -
Statistical Characterization of Wildfire Dynamics: Studying the Relation Between Burned Area and Head of the Fire
(2022-06-06)We show that the probability density function (PDF) of an area enclosed by a random perimeter is driven by the PDF of the integration bounds and the mean value of the perimeter function. With reference to wildfires, if the ... -
Fractional Diffusion and Medium Heterogeneity: The Case of the Continuos Time Random Walk
Sposini, V.; Vitali, S.; Paradisi, P.; Pagnini, G. (2021-07-24)
In this contribution we show that fractional diffusion emerges from a simple Markovian Gaussian random walk when the medium displays a power-law heterogeneity. Within the framework of the continuous time random walk, the ... -
Stochastic Properties of Colliding Hard Spheres in a Non-equilibrium Thermal Bath
Bazzani, A.; Vitali, S.; Montanari, C.; Monti, M.; Rambaldi, S.; Castellani, G. (2021-07-24)
We consider the problem of describing the dynamics of a test particle moving in a thermal bath using the stochastic differential equations. We briefly recall the stochastic approach to the Brownian based on the statistical ... -
Stochastic resetting by a random amplitude
Dahlenburg, M.; Chechkin, A. V.; Schumer, R.; Metzler, R. (2021-05-18)
Stochastic resetting, a diffusive process whose amplitude is reset to the origin at random times, is a vividly studied strategy to optimize encounter dynamics, e.g., in chemical reactions. Here we generalize the resetting ... -
Exact distributions of the maximum and range of random diffusivity processes
(2021-02-09)We study the extremal properties of a stochastic process $x_t$ defined by the Langevin equation ${\dot {x}}_{t}=\sqrt{2{D}_{t}}\enspace {\xi }_{t}$, in which $\xi_t$ is a Gaussian white noise with zero mean and $D_t$ is a ... -
Surrogate based Global Sensitivity Analysis of ADM1-based Anaerobic Digestion Model
(2021)In order to calibrate the model parameters, Sensitivity Analysis routines are mandatory to rank the parameters by their relevance and fix to nominal values the least influential factors. Despite the high number of works ... -
Study of Wound Healing Dynamics by Single Pseudo-Particle Tracking in Phase Contrast Images Acquired in Time-Lapse
Scheda, R.; Vitali, S.; Giampieri, E.; Pagnini, G.; Zironi, I. (2021-03)
Cellular contacts modify the way cells migrate in a cohesive group with respect to a free single cell. The resulting motion is persistent and correlated, with cells’ velocities self-aligning in time. The presence of a dense ... -
SHOULD I STAY OR SHOULD I GO? ZERO-SIZE JUMPS IN RANDOM WALKS FOR LÉVY FLIGHTS
Pagnini, G.; Vitali, S. (2021-02)
We study Markovian continuous-time random walk models for Lévy flights and we show an example in which the convergence to stable densities is not guaranteed when jumps follow a bi-modal power-law distribution that is equal ... -
Exact first-passage time distributions for three random diffusivity models
(2021-01-04)We study the extremal properties of a stochastic process $x_t$ defined by a Langevin equation $\dot{x}= \sqrt{2D_o V (B_t )} \xi_t$, where $\xi$ is a Gaussian white noise with zero mean, $D_0$ is a constant scale factor, ... -
The random diffusivity approach for diffusion in heterogeneous systems
(2020-12-16)The two hallmark features of Brownian motion are the linear growth $\langle x^2(t) \rangle = 2 D d t$ of the mean squared displacement (MSD) with diffusion coefficient $D$ in $d$ spatial dimensions, and the Gaussian ... -
Gut microbiota ecology: Biodiversity estimated from hybrid neutral-niche model increases with health status and aging
Sala, C.; Giampieri, E.; Vitali, S.; Garagnani, P.; Remondini, D.; Bazzani, A.; Franceschi, C.; Castellani, G. (2020-10-30)
In this work we propose an index to estimate the gut microbiota biodiversity using a modeling approach with the aim of describing its relationship with health and aging. The gut microbiota, a complex ecosystem that links ...
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