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We study mass fluxes in aggregation models where mass transfer to large scales by aggregation occurs alongside desorption or fragmentation. Two models are considered. (1) A system of diffusing, aggregating particles with influx and outflux…

Statistical Mechanics · Physics 2009-11-13 Colm Connaughton , R. Rajesh , Oleg Zaboronski

Einstein's kinetic theory of the Brownian motion, based upon light water molecules continuously bombarding a heavy pollen, provided an explanation of diffusion from the Newtonian mechanics. Since the discovery of quantum mechanics it has…

Mathematical Physics · Physics 2010-09-07 Laszlo Erdos

In this work, we investigate the effects of chirality, accounting for translational diffusion, on active Brownian particles in two and three dimensions. Despite the inherent complexity in solving the Fokker-Planck equation, we demonstrate a…

Statistical Mechanics · Physics 2025-09-04 Anweshika Pattanayak , Amir Shee , Debasish Chaudhuri , Abhishek Chaudhuri

A system of interacting Brownian particles subject to short-range repulsive potentials is considered. A continuum description in the form of a nonlinear diffusion equation is derived systematically in the dilute limit using the method of…

Statistical Mechanics · Physics 2017-10-12 Maria Bruna , S. Jonathan Chapman , Martin Robinson

The Bloch equations, which describe spin precession and relaxation in external magnetic fields, can be generalized to include the evolution of polarization tensors of various ranks in arbitrary multipole fields. The derivation of these…

Quantum Physics · Physics 2015-10-23 Hans-Juergen Stoeckmann , Dirk Dubbers

Diffusion tensor coefficients play a central role in describing cosmic-ray transport in various astrophysical environments permeated with magnetic fields, which are usually modeled as a fluctuating field on top of a mean field. In this…

High Energy Astrophysical Phenomena · Physics 2024-07-09 O. Deligny

The problem of anomalous diffusion in momentum space is considered for plasma-like systems on the basis of a new collision integral, which is appropriate for consideration of the probability transition function (PTF) with long tails in…

Statistical Mechanics · Physics 2015-05-18 S. A. Trigger , W. Ebeling , G. J. F. van Heijst , P. P. J. M. Schram , I. M. Sokolov

Nuclear magnetic resonance (NMR) is a widely used nondestructive method to study random motion of spin-bearing particles in different systems. In the long-time limit the theoretical description of the NMR experiments is well developed and…

Statistical Mechanics · Physics 2018-03-06 Vladimir Lisy , Jana Tothova

\hspace{2mm} Diffusion-weighted magnetic resonance imaging (dMRI) of the brain offers unique capabilities including noninvasive probing of tissue microstructure and structural connectivity. It is widely used for clinical assessment of…

Image and Video Processing · Electrical Eng. & Systems 2025-12-30 Davood Karimi , Simon K. Warfield

This study introduces a novel approach for image reconstruction based on a diffusion model conditioned on the native data domain. Our method is applied to multi-coil MRI and quantitative MRI reconstruction, leveraging the domain-conditioned…

Machine Learning · Computer Science 2023-09-06 Wanyu Bian , Albert Jang , Fang Liu

A method based on the Fast Fourier Transform is proposed to obtain the dispersion relation of acoustic waves in heterogeneous periodic media with arbitrary microstructures. The microstructure is explicitly considered using a voxelized…

Materials Science · Physics 2021-06-24 J. Segurado , R. A. Lebensohn

It is common for dispersion curves of damped periodic materials to be based on real frequencies versus complex wavenumbers or, conversely, real wavenumbers versus complex frequencies. The former condition corresponds to harmonic wave motion…

Materials Science · Physics 2016-04-26 Michael J. Frazier , Mahmoud I. Hussein

We introduce a model of self-propelled particles carrying out a Brownian motion with a diffusion coefficient which depends on the local density of particles within a certain finite radius. Numerical simulations show that in a range of…

Statistical Mechanics · Physics 2009-11-11 Cristobal Lopez

An effort has been made to solve the Cauchy problem of the Navier-Stokes equations in the whole space by two methods. It is proved that the sum of the three vorticity components is a time-invariant in fluid motion. It has been proved that,…

Fluid Dynamics · Physics 2014-09-18 F. Lam

In two prior papers of this series, it was proposed that a wavefunction model of a heavy particle and a collection of light particles might generate ``Brownian-Motion-Like" trajectories as well as diffusive motion (displacement proportional…

Quantum Physics · Physics 2025-09-16 Leonardo De Carlo , W. David Wick

Particles transported in fluid flows, such as cells, polymers, or nanorods, are rarely spherical. In this study, we numerically and theoretically investigate the dispersion of an initially localized patch of passive elongated Brownian…

Fluid Dynamics · Physics 2021-09-15 Ajay Harishankar Kumar , Stuart J. Thomson , Thomas R. Powers , Daniel M. Harris

The evolution of a closed two-dimensional surface driven by both mean curvature flow and a reaction--diffusion process on the surface is formulated into a system, which couples the velocity law not only to the surface partial differential…

Numerical Analysis · Mathematics 2020-08-18 Balázs Kovács , Buyang Li , Christian Lubich

Various astrophysical studies have motivated the investigation of the transport of high energy particles in magnetic turbulence, either in the source or en route to the observation sites. For strong turbulence and large rigidity, the…

High Energy Astrophysical Phenomena · Physics 2011-07-08 I. Plotnikov , G. Pelletier , M. Lemoine

The standard Bloch oscillation normally refers to the oscillatory tunneling dynamics of quantum particles in a periodic lattice plus a linear gradient. In this work we theoretically investigate the generalized form of the Bloch oscillation…

Atomic Physics · Physics 2019-11-13 Qian-Ru Zhu , Shou-Long Chen , Shao-Jun Li , Xue-Ting Fang , Lushuai Cao , Zhong-Kun Hu

The analytical theory of diffusive cosmic ray acceleration at parallel stationary shock waves with magnetostatic turbulence is generalized to arbitrary shock speeds $V_s=\beta_1c$, including in particular relativistic speeds. This is…

High Energy Astrophysical Phenomena · Physics 2015-08-19 Reinhard Schlickeiser