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Understanding diffusion in microstructures plays a crucial role in many scientific fields, including neuroscience, cancer or energy research. While magnetic resonance (MR) methods are the gold standard for diffusion measurements, spatial…

The diffusion properties of self-propelled particles which move at constant speed and, in addition, reverse their direction of motion repeatedly are investigated. The internal dynamics of particles triggering these reversal processes is…

Biological Physics · Physics 2016-05-30 Robert Großmann , Fernando Peruani , Markus Bär

Propagation of two dimensional pulses in electromagnetically induced tranparency media in the case of perpendicular storing and retrieving pulses has been analyzed. It has been shown that propagation control of the pulses in optically thick…

Quantum Physics · Physics 2009-11-10 Gor Nikoghosyan

Transport in multiphase flow through porous media plays a central role in many biological, geological, and engineered systems. Here, we use numerical simulations of transport in immiscible two-phase flow to investigate dispersion in…

Fluid Dynamics · Physics 2021-11-29 Joachim Mathiesen , Gaute Linga , Marek Misztal , Francois Renard , Tanguy Le Borgne

Radiation dominated accretion disks are likely to be subject to the ``photon bubble'' instability, which may lead to strong density inhomogeneities on scales much shorter than the disk scale height. Such disks -- and magnetized,…

Astrophysics · Physics 2009-11-07 Mateusz Ruszkowski , Mitchell C. Begelman

In order to characterize the mechanisms governing the diffusion of particles in biological scenarios, it is essential to accurately determine their diffusive properties. To do so, we propose a machine learning method to characterize…

Soft Condensed Matter · Physics 2023-11-29 Borja Requena , Sergi Masó , Joan Bertran , Maciej Lewenstein , Carlo Manzo , Gorka Muñoz-Gil

In this work, receiver diversity in advection-dominated diffusion-advection channels is investigated. Strong directed flow fundamentally alters the communication-theoretic properties of molecular communication systems (MC). Specifically,…

Signal Processing · Electrical Eng. & Systems 2026-02-02 Fatih Merdan , Ozgur B. Akan

We study the measurement of transverse diffusion through beam echoes. We revisit earlier observations of echoes in RHIC and apply an updated theoretical model to these measurements. We consider three possible models for the diffusion…

Accelerator Physics · Physics 2017-02-01 Tanaji Sen , Wolfram Fischer

The guiding and transport of energy, for example of electromagnetic waves underpins many technologies that have shaped modern society, ranging from long distance optical fibre telecommunications to on-chip optical processors. Traditionally,…

Diffusion magnetic resonance imaging (dMRI) is a relatively modern technique used to study tissue microstructure in a non-invasive way. Non-Gaussian diffusion representation is related to the restricted diffusion and can provide information…

Signal Processing · Electrical Eng. & Systems 2020-09-17 Tomasz Pieciak , Maryam Afzali , Fabian Bogusz , Aja-Fernández , Derek K. Jones

We present an elementary discussion of the momentum transferred by an electromagnetic wave propagating in a dispersive medium. Our analysis is based on Minkowski's electromagnetic momentum density which have been recently seen to be…

Classical Physics · Physics 2018-01-30 Rodrigo Medina , J. Stephany

The propagation of high-energy cosmic rays through giant molecular clouds constitutes a fundamental process in astronomy and astrophysics. The diffusion of cosmic-rays through these magnetically turbulent environments is often studied…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Marco Fatuzzo , Fulvio Melia , Elizabeth Todd , Fred Adams

Over the past 15 years, several groups have engineered media that are both strongly dispersive and roughly transparent for some finite bandwidth. Relationships and intuitive models that are satisfactory when it is reasonable to neglect…

Optics · Physics 2010-06-01 Douglas H. Bradshaw

A system of degenerate drift-diffusion equations for the electron, hole, and oxygen vacancy densities, coupled to the Poisson equation for the electric potential, is analyzed in a three-dimensional bounded domain with mixed…

Analysis of PDEs · Mathematics 2023-11-29 Ansgar Jüngel , Martin Vetter

We study nanomechanical resonators with frequency fluctuations due to diffusion of absorbed particles. The diffusion depends on the vibration amplitude through inertial effect. We find that, if the diffusion coefficient is sufficiently…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 J. Atalaya , A. Isacsson , M. I. Dykman

Particle sedimentation through porous media is limited by the inability of passive material to overcome surface interactions and a tortuous network of pores. This limits transport, delivery, and effectiveness of chemicals used as reactants,…

Soft Condensed Matter · Physics 2024-07-26 Samuel R. Wilson-Whitford , David Kramer , Jinghui Gao , Maria Chiara Roffin , James F. Gilchrist

Dynamics of a particle diffusing in a confinement can be seen a sequence of bulk-diffusion-mediated hops on the confinement surface. Here, we investigate the surface hopping propagator that describes the position of the diffusing particle…

Statistical Mechanics · Physics 2020-09-23 Denis S. Grebenkov

Denoising diffusion models are a novel class of generative algorithms that achieve state-of-the-art performance across a range of domains, including image generation and text-to-image tasks. Building on this success, diffusion models have…

Machine Learning · Computer Science 2024-03-08 Nic Fishman , Leo Klarner , Valentin De Bortoli , Emile Mathieu , Michael Hutchinson

The propagation of charged particles, including cosmic rays, in a partially ordered magnetic field is characterized by a diffusion tensor whose components depend on the particle's Larmor radius $R_L$ and the degree of order in the magnetic…

High Energy Astrophysical Phenomena · Physics 2016-03-04 A. P. Snodin , A. Shukurov , G. R. Sarson , P. J. Bushby , L. F. S. Rodrigues

We consider a particle that is subject to a constant force and scatters inelastically on a vibrating periodically corrugated floor. At small friction and small radius of the circular scatterers the dynamics is dominated by resonances…

Chaotic Dynamics · Physics 2009-11-10 R. Klages , I. F. Barna , L. Matyas