Statistical Physics
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The random diffusivity approach for diffusion in heterogeneous systems
(20201216)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 neutralniche model increases with health status and aging
(Plos One, 20201030)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 ... 
Universal spectral features of different classes of random diffusivity processes
(New Journal of Physics, 20200626)Stochastic models based on random diffusivities, such as the diffusing diffusivity approach, are popular concepts for the description of nonGaussian diffusion in heterogeneous media. Studies of these models typically ... 
A generalized Stefan model accounting for system memory and nonlocality
(International Communications in Heat and Mass Transfer, 202005)The Stefan problem, involving the tracking of an evolving phasechange front, is the prototypical example of a moving boundary problem. In basic one dimensional problems it is well known that the front advances as the ... 
A hypothesis about parallelism vs. seriality in dreams
(Front. Psychol., 20191010)The current article discusses the hypothesis about parallelism vs. Seriality in dreams. The process of dream building implies the construction of a complex network of closely interrelated sources. On the other hand, the ... 
Gaussian processes in complex media: new vistas on anomalous diffusion
(Front. Phys., 201909)Normal or Brownian diffusion is historically identified by the linear growth in time of the variance and by a Gaussian shape of the displacement distribution. Processes departing from the at least one of the above conditions ... 
Front Propagation in Random Media
(2019)This PhD thesis deals with the problem of the propagation of fronts under random circumstances. A statistical model to represent the motion of fronts when are evolving in a media characterized by microscopical randomness ... 
Stochastic processes for anomalous diffusion
(2019)Anomalous diffusion is a diffusion process which Mean Square Displacement (MSD) is not a linear funtion of time, what is known as normal diffusion. When the relation is faster than linear, it is called superdiffusion and ... 
Singletrajectory spectral analysis of scaled Brownian motion
(New Journal of Physics, 201906)A standard approach to study timedependent stochastic processes is the power spectral density (PSD), an ensembleaveraged property defined as the Fourier transform of the autocorrelation function of the process in the ... 
Reduced description method in the kinetic theory of Brownian motion with active fluctuations
(Journal of Physics A: Mathematical and Theoretical, 20190901)We develop a microscopic approach to the kinetic theory of manyparticle systems with dissipative and potential interactions in presence of active fluctuations. The approach is based on a generalization of Bogolyubov–Peletminskii ... 
On the propagation of nonlinear transients of temperature and pore pressure in a thin porous boundary layer between two rocks.
(Journal of Hydrology, 2019)The dynamics of transients of fluidrock temperature, pore pressure, pollutants in porous rocks are of vivid interest for fundamental problems in hydrological, volcanic, hydrocarbon systems, deep oil drilling. This can ... 
Restoring property of the MichelsonSivashinsky equation
(Combustion Science and Technology, 2019)In this paper we propose a derivation of the MichelsonSivashinsky (MS) equation that is based on front propagation only, in opposition to the classical derivation based also on the flow field. Hence, the characteristics ... 
Stochastic spatial models in ecology: a statistical physics approach
(Journal of Statistical Physics, 20171121)Ecosystems display a complex spatial organization. Ecologists have long tried to characterize them by looking at how different measures of biodiversity change across spatial scales. Ecological neutral theory has provided ... 
Fractional kinetics in random/complex media
(Handbook of Fractional Calculus with Applications Volume 5 Applications in Physics, Part B, 2019)In this chapter, we consider a randomlyscaled Gaussian process and discuss a number of applications to model fractional diffusion. Actually, this approach can be understood as a Gaussian diffusion in a medium characterized ... 
Fractional Brownian motion in a finite interval: correlations effect depletion or accretion zones of particles near boundaries
(New Journal of Physics, 201902)Fractional Brownian motion (FBM) is a Gaussian stochastic process with stationary, longtime correlated increments and is frequently used to model anomalous diffusion processes. We study numerically FBM confined to a finite ... 
Surrogatebased uncertainty and sensitivity analysis for bacterial invasion in multispecies biofilm modeling
(Communications Nonlinear Sciences and Numerical Simulation, 2019)In this work, we present a probabilistic analysis of a detailed onedimensional biofilm model that explicitly accounts for planktonic bacterial invasion in a multispecies biofilm. The objective is (1) to quantify and ... 
Finiteenergy Lévytype motion through heterogeneous ensemble of Brownian particles
(Journal of Physics A: Mathematical and Theoretical, 20190201)Complex systems are known to display anomalous diffusion, whose signature is a space/time scaling $x \sim t^\delta$ with $\delta \neq 1/2$ in the probability density function (PDF). Anomalous diffusion can emerge jointly ... 
Firespotting generated fires. Part I: The role of atmospheric stability
(Applied Mathematical Modelling, 201902)This is the first part of two papers concerning firespotting generated fires. In this part we deal with the impact of macroscale factors, such as the atmospheric stability, and in the second part we deal with mesoscale ... 
Modeling anomalous heat diffusion: Comparing fractional derivative and nonlinear diffusivity treatments
(International Journal of Thermal Sciences, 201811)In the Fourier heat conduction equation, when the flux definition is expressed as the product of a constant diffusivity and the temperature gradient, the characteristic length scale evolves as the square root of time. ... 
Modeling nonstationarities in highfrequency financial time series
(Physica A: Statistical Mechanics and its Applications, 201901)We study tickbytick financial returns for the FTSE MIB index of the Italian Stock Exchange (Borsa Italiana). We confirm previously detected nonstationarities. Scaling properties reported before for other highfrequency ...