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This manuscript is concerned with phase changes of signals transmitted through deforming optical fibres. As a first result, it establishes an exact relation between observable phase changes and the deformation tensor along the fibre. This…

A mutilated model is constructed to approximate the collision term of spin Boltzmann equation that incorporates newly appearing collisional invariants i.e, the total angular momentum. With recourse to degenerate perturbation theory, the…

High Energy Physics - Phenomenology · Physics 2023-01-23 Jin Hu , Zhe Xu

Electron resonant scattering by high-frequency electromagnetic whistler-mode waves has been proposed as a mechanism for solar wind electron scattering and pre-acceleration to energies that enable them to participate in shock drift…

Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short time-scales, such as soon after solar energetic…

Solar and Stellar Astrophysics · Physics 2017-01-18 T. Laitinen , S. Dalla

This paper proposes a data-driven learning framework for identifying governing laws of generalized diffusions with non-gradient components. By combining energy dissipation laws with a physically consistent penalty and first-moment…

Computational Physics · Physics 2025-08-11 Fanze Kong , Chen-Chih Lai , Yubin Lu

In this paper, we develop a model to describe the generalized wave-particle instability in a quasi-neutral plasma. We analyze the quasi-linear diffusion equation for particles by expressing an arbitrary unstable and resonant wave mode as a…

Space Physics · Physics 2020-10-22 Seong-Yeop Jeong , Daniel Verscharen , Robert T. Wicks , Andrew N. Fazakerley

Anomalous diffusion has been investigated in many polymer and biological systems. The analysis of PFG anomalous diffusion relies on the ability to obtain the signal attenuation expression. However, the general analytical PFG signal…

Chemical Physics · Physics 2018-04-27 Guoxing Lin

I present empirical measurements of the rate of relaxation in N-body simulations of stable spherical systems and distinguish two separate types of relaxation: energy diffusion that is largely independent of particle mass, and energy…

Astrophysics of Galaxies · Physics 2015-09-16 J. A. Sellwood

In this paper, we exactly solve, within the grand canonical ensemble, a minimal spin model with the hybrid phase transition. We call the model "diffusion-based" because its hamiltonian can be recovered from a simple dynamic procedure, which…

Statistical Mechanics · Physics 2016-07-13 Agata Fronczak , Piotr Fronczak

We present an enhanced diffusion of nuclear spin polarization in fractional quantum Hall domain phases at $\nu = 2/3$. Resistively-detected NMR mediated by electrically driven domain-wall motion is used as a probe of local nuclear…

Mesoscale and Nanoscale Physics · Physics 2016-05-24 S. Miyamoto , T. Hatano , S. Watanabe , Y. Hirayama

The phase shifts for the higher partial waves in the spin quartet and doublet channel of nd scattering are presented at next-to-leading and next-to-next-to-leading order in an effective field theory in which pions are integrated out. The…

Nuclear Theory · Physics 2017-08-23 F. Gabbiani

We investigate the steady-state spin diffusion for ultracold spin-orbit coupled $^{40}$K gas by the kinetic spin Bloch equation approach both analytically and numerically. Four configurations, i.e., the spin diffusions along two specific…

Quantum Gases · Physics 2015-07-08 T. Yu , M. W. Wu

Topological non-collinear magnetic phases of matter are at the heart of many proposals for future information nanotechnology, with novel device concepts based on ultra-thin films and nanowires. Their operation requires understanding and…

Mesoscale and Nanoscale Physics · Physics 2018-04-20 Flaviano José dos Santos , Manuel dos Santos Dias , Filipe Souza Mendes Guimarães , Juba Bouaziz , Samir Lounis

The classical drift diffusion (DD) model of spin transport treats spin relaxation via an empirical parameter known as the ``spin diffusion length''. According to this model, the ensemble averaged spin of electrons drifting and diffusing in…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Sandipan Pramanik , Supriyo Bandyopadhyay , Marc Cahay

Guiding unconditional diffusion models typically requires either retraining with conditional inputs or per-step gradient computations (e.g., classifier-based guidance), both of which incur substantial computational overhead. We present a…

Machine Learning · Computer Science 2026-02-13 Qingsong Wang , Mikhail Belkin , Yusu Wang

We study nonlinear diffusion problems of the form $u_t=u_{xx}+f(u)$ with free boundaries. Such problems may be used to describe the spreading of a biological or chemical species, with the free boundary representing the expanding front. For…

Analysis of PDEs · Mathematics 2016-08-02 Yihong Du , Bendong Lou

Charge and spin transport in spintronics devices can be described by a spin diffusion equation suitable for modelling scales much larger than the scattering and atomic scales. This work concerns the coarse graining procedure used to compute…

Mesoscale and Nanoscale Physics · Physics 2019-07-02 Vincent Sacksteder

Magnetic resonance microscopy images at cellular resolution (< 10 microns) are limited by diffusion. SNR and spatial resolution suffer from the dephasing of transverse magnetization caused by diffusion of spins in strong gradients. Such…

Diffusion-driven patterns appear on curved surfaces in many settings, initiated by unstable modes of an underlying Laplacian operator. On a flat surface or perfect sphere, the patterns are degenerate, reflecting translational/rotational…

Soft Condensed Matter · Physics 2025-09-09 John R. Frank , Jemal Guven , Mehran Kardar , Leyna Shackleton

The propagation of the transverse-longitudinal acoustic pulses through a strained cubic crystal containing the resonant paramagnetic impurities with effective spin S=1 is investigated. It is supposed that the pulses propagate under…

Pattern Formation and Solitons · Physics 2009-11-11 S. V. Sazonov , N. V. Ustinov