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We study the inductive biases of diffusion models with a conditioning-variable, which have seen widespread application as both text-conditioned generative image models and observation-conditioned continuous control policies. We observe that…

Machine Learning · Computer Science 2025-12-23 Daniel Pfrommer , Zehao Dou , Christopher Scarvelis , Max Simchowitz , Ali Jadbabaie

A new solution to the mono-dimensional diffusion equation for time-variable first kind boundary condition is presented where the time-variable function at the surface is derived proposing a surface saturation model. This solution may be…

Materials Science · Physics 2022-12-08 Guglielmo Macrelli

We introduce a methodology for performing parameter inference in high-dimensional, non-linear diffusion processes. We illustrate its applicability for obtaining insights into the evolution of and relationships between species, including…

Machine Learning · Statistics 2024-11-15 Nicklas Boserup , Gefan Yang , Michael Lind Severinsen , Christy Anna Hipsley , Stefan Sommer

How many times a diffusing molecule can permeate across a membrane or be adsorbed on a substrate? We employ the encounter-based approach to find the statistics of adsorption or permeation events for molecular diffusion in a general…

Chemical Physics · Physics 2025-07-15 Denis S. Grebenkov

This thesis is devoted to the application of random matrix theory to the study of random surfaces, both discrete and continuous; special emphasis is placed on surface boundaries and the associated boundary conditions in this formalism. In…

Mathematical Physics · Physics 2016-03-04 Benjamin Niedner

The paper addresses the single-file diffusion in the presence of an absorbing boundary. The emphasis is on an interplay between the hard-core interparticle interaction and the absorption process. The resulting dynamics exhibits several…

Statistical Mechanics · Physics 2014-02-26 Artem Ryabov , Petr Chvosta

We present equivalent conditions and asymptotic models for the diffraction problem of elastic and acoustic waves in a solid medium surrounded by a thin layer of fluid medium. Due to the thinness of the layer with respect to the wavelength,…

Numerical Analysis · Mathematics 2022-05-16 Victor Péron

A cross-diffusion system describing ion transport through biological membranes or nanopores in a bounded domain with mixed Dirichlet-Neumann boundary conditions is analyzed. The ion concentrations solve strongly coupled diffusion equations…

Analysis of PDEs · Mathematics 2017-06-23 Anita Gerstenmayer , Ansgar Jüngel

The main objective of this paper is analysis of the initial-boundary value problems for the linear time-fractional diffusion equations with a uniformly elliptic spatial differential operator of the second order and the Caputo type…

Analysis of PDEs · Mathematics 2023-04-18 Yuri Luchko , Masahiro Yamamoto

In the present work, we propose a new parameterization for the concentration flux using fractional derivatives. The fractional order differential equation in the longitudinal and vertical directions is used to obtain the concentration…

Atmospheric and Oceanic Physics · Physics 2018-12-26 A. G. Goulart , M. J. Lazo , J. M. S. Suarez

This paper deals with an inverse source problem for the $1$D time-fractional diffusion equation by using boundary measurement. The conditional stability in identification of the unknown source term is proved on the basis of the Fourier…

Analysis of PDEs · Mathematics 2016-08-25 Zhiyuan Li

In this note, we discuss a poorly known alternative boundary condition to the usual Neumann or `stress-free' boundary condition typically used to weaken boundary layers when diffusion is present but very small. These `diffusion-free'…

Fluid Dynamics · Physics 2024-06-19 Yufeng Lin , Rich Kerswell

We consider the classical problem of particle diffusion in $d$-dimensional radially-symmetric systems with absorbing boundaries. A key quantity to characterise such diffusive transport is the evolution of the proportion of particles…

Computational Physics · Physics 2022-09-07 Elliot J. Carr

Consider ``stochastic differential equations" driven by fractional Brownian motion with Hurst parameter H (1/4 <H< 1). Their solutions are sometimes called fractional diffusion processes. The main purpose of this paper is conditioning these…

Probability · Mathematics 2025-12-02 Yuzuru Inahama

We present strongly stable semi-discrete finite difference approximations to the quarter space problem (x>0, t>0) for the first order in time, second order in space wave equation with a shift term. We consider space-like (pure outflow) and…

General Relativity and Quantum Cosmology · Physics 2024-07-11 Gioel Calabrese , Carsten Gundlach

We discuss a class of diffusion-type partial differential equations on a bounded interval and discuss the possibility of replacing the boundary conditions by certain linear conditions on the moments of order 0 (the total mass) and of…

Analysis of PDEs · Mathematics 2018-12-21 Delio Mugnolo , Serge Nicaise

We consider a reaction-diffusion equation on a 3D thin porous media of thickness $\varepsilon$ which is perforated by periodically distributed cylinders of size $\varepsilon$. On the boundary of the cylinders we prescribe a dynamical…

Analysis of PDEs · Mathematics 2025-12-18 María Anguiano

Data scarcity is a fundamental barrier in Electrical Impedance Tomography (EIT), as undersampled Dirichlet-to-Neumann (DtN) measurements can substantially degrade conductivity reconstructions. We address this bottleneck by completing…

Numerical Analysis · Mathematics 2026-02-10 Ke Chen , Haizhao Yang , Chugang Yi

In this paper we examine boundary effects in a fractional chemotactic equation derived from a kinetic transport model describing cell movement in response to chemical gradients (chemotaxis). Specifically, we analyze reflecting boundary…

Analysis of PDEs · Mathematics 2025-06-05 Gissell Estrada-Rodriguez , Heiko Gimperlein

The near membrane layer is defined as a region where the concentration of the substance transported across the membrane drops $k$ times. The time evolution of such a layer is studied experimentally by means of the laser interferometric…

Condensed Matter · Physics 2007-05-23 Kazimierz Dworecki , Tadeusz Kosztolowicz , Slawomir Wasik , Stanislaw Mrowczynski