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We demonstrate that continuous time random walks in which successive waiting times are correlated by Gaussian statistics lead to anomalous diffusion with mean squared displacement <r^2(t)>~t^{2/3}. Long-ranged correlations of the waiting…

Statistical Mechanics · Physics 2015-05-14 Vincent Tejedor , Ralf Metzler

We consider a classic two-state switching diffusion model from a single-particle tracking perspective. The mean and the variance of the time-averaged mean square displacement (TAMSD) are computed exactly. When the measurement time (i.e.,…

Statistical Mechanics · Physics 2019-11-05 Denis S. Grebenkov

Local diffusion coefficients in disordered systems such as spin glass systems and living cells are highly heterogeneous and may change over time. Such a time-dependent and spatially heterogeneous environment results in irreproducibility of…

Statistical Mechanics · Physics 2016-12-21 Takuma Akimoto , Eiji Yamamoto

We define and study in detail \emph{utraslow scaled Brownian motion (USBM)\/} characterised by a time dependent diffusion coefficient of the form $D(t)\simeq 1/t$. For unconfined motion the mean squared displacement (MSD) of USBM exhibits…

Statistical Mechanics · Physics 2015-03-30 Anna Bodrova , Aleksei V. Chechkin , Andrey G. Cherstvy , Ralf Metzler

Anomalous diffusion has been widely observed by single particle tracking microscopy in complex systems such as biological cells. The resulting time series are usually evaluated in terms of time averages. Often anomalous diffusion is…

Statistical Mechanics · Physics 2017-09-13 Stas Burov , Jae-Hyung Jeon , Ralf Metzler , Eli Barkai

We study the ergodic properties of superdiffusive, spatiotemporally coupled Levy walk processes. For trajectories of finite duration, we reveal a distinct scatter of the scaling exponents of the time averaged mean squared displacement…

Statistical Mechanics · Physics 2015-06-11 Aljaz Godec , Ralf Metzler

There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here, a novel method to elucidate the fluctuating diffusivity from trajectory data is developed. The time-averaged…

Statistical Mechanics · Physics 2017-10-25 Tomoshige Miyaguchi

Local diffusion coefficients in disordered materials such as living cells are highly heterogeneous. Quenched disorder is utilized substantially to study such complex systems, whereas its analytical treatment is difficult to handle. We…

Statistical Mechanics · Physics 2016-11-02 Takuma Akimoto , Eli Barkai , Keiji Saito

Standard continuous time random walk (CTRW) models are renewal processes in the sense that at each jump a new, independent pair of jump length and waiting time are chosen. Globally, anomalous diffusion emerges through action of the…

Statistical Mechanics · Physics 2015-06-17 Johannes HP Schulz , Aleksei V Chechkin , Ralf Metzler

The three-dimensional (3D) Fick's diffusion equation and fractional diffusion equation are solved for different reflecting boundaries. We use the continuous time random walk model (CTRW) to investigate the time averaged mean square…

Soft Condensed Matter · Physics 2017-09-25 Shanlin Qin , Yong He

Logarithmic aging phenomena are prevalent in various systems, including electronic materials and biological structures. This study utilizes a generalized continuous time random walk (CTRW) framework to investigate the mechanisms behind the…

Statistical Mechanics · Physics 2024-09-24 Chunyan Li , Haiwen Liu , X. C. Xie

In this article, we generalize the recent Discrete Time Random Walk (DTRW) algorithm, which was introduced for the computation of probability densities of fractional diffusion. Although it has the same computational complexity and shares…

Computational Physics · Physics 2018-08-20 Gurtek Gill , Peter Straka

Many theoretical treatments of transport in heterogeneous Darcy flows consider advection only. When local-scale dispersion is neglected, flux-weighting persists over time; mean Lagrangian and Eulerian flow velocity distributions relate…

Fluid Dynamics · Physics 2024-07-25 Lian Zhou , Scott K. Hansen

Brownian yet non-Gaussian diffusion has recently been observed in numerous biological and active matter system. The cause of the non-Gaussian distribution have been elaborately studied in the idea of a superstatistical dynamics or a…

Statistical Mechanics · Physics 2021-06-02 Xudong Wang , Yao Chen

In a recent work we introduced a semi-Markovian discrete-time generalization of the telegraph process. We referred this random walk to as squirrel random walk (SRW). The SRW is a discrete-time random walk on the one-dimensional infinite…

Probability · Mathematics 2023-01-18 Thomas M. Michelitsch , Federico Polito , Alejandro P. Riascos

The L\'evy walk model is a stochastic framework of enhanced diffusion with many applications in physics and biology. Here we investigate the time averaged mean squared displacement $\bar{\delta^2}$ often used to analyze single particle…

Statistical Mechanics · Physics 2014-06-03 Daniela Froemberg , Eli Barkai

We study the joint action of the non-Poisson renewal events (NPR) yielding Continuous Time Random Walk (CTRW) with index alpha < 1 and two different generators of Hurst coefficient H not equal to 0.5, one generating fractional Brownian…

Statistical Mechanics · Physics 2016-08-03 Elvis Geneston , Rohisha Tuladhar , M. T. Beig , Mauro Bologna , Paolo Grigolini

Continuous time random walk (CTRW) subdiffusion along with the associated fractional Fokker-Planck equation (FFPE) is traditionally based on the premise of random clock with divergent mean period. This work considers an alternative CTRW and…

Statistical Mechanics · Physics 2014-09-24 Igor Goychuk

Intermittent stochastic processes appear in a wide field, such as chemistry, biology, ecology, and computer science. This paper builds up the theory of intermittent continuous time random walk (CTRW) and L\'{e}vy walk, in which the…

Statistical Mechanics · Physics 2020-03-20 Tian Zhou , Pengbo Xu , Weihua Deng

Although time-dependent random media with short range correlations lead to (possibly biased) normal tracer diffusion, anomalous fluctuations occur away from the most probable direction. This was pointed out recently in 1D lattice random…

Disordered Systems and Neural Networks · Physics 2017-07-19 Pierre Le Doussal , Thimothée Thiery