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We demonstrate the experimental determination of the diffusion propagator using magnetic resonance (MR) techniques. To this end, a recently introduced method was implemented on a benchtop MR scanner and incorporated into profiling and…

Materials Science · Physics 2021-07-01 Alfredo Miguel Ordinola Santisteban , Evren Özarslan

We introduce the notion of Bartlett spectral measure for isometrically invariant random measures on proper metric commutative spaces. When the underlying Gelfand pair corresponds to a higher-rank, connected, simple matrix Lie group with…

Probability · Mathematics 2025-03-04 Michael Björklund , Mattias Byléhn

In brain imaging, the image acquisition and processing processes themselves are likely to introduce noise to the images. It is therefore imperative to reduce the noise while preserving the geometric details of the anatomical structures for…

Numerical Analysis · Mathematics 2022-01-04 Moo K. Chung

We discuss the distribution of various estimators for extracting the diffusion constant of single Brownian trajectories obtained by fitting the squared displacement of the trajectory. The analysis of the problem can be framed in terms of…

Statistical Mechanics · Physics 2015-05-28 Denis Boyer , David S. Dean

We consider the inverse problem of determining different type of information about a diffusion process, described by ordinary or fractional diffusion equations stated on a bounded domain, like the density of the medium or the velocity field…

Analysis of PDEs · Mathematics 2019-07-05 Yavar Kian , Zhiyuan Li , Yikan Liu , Masahiro Yamamoto

We present Manifold Diffusion Fields (MDF), an approach that unlocks learning of diffusion models of data in general non-Euclidean geometries. Leveraging insights from spectral geometry analysis, we define an intrinsic coordinate system on…

Machine Learning · Computer Science 2024-01-23 Ahmed A. Elhag , Yuyang Wang , Joshua M. Susskind , Miguel Angel Bautista

Diffusive transport properties of a quantum Brownian particle moving in a tilted spatially periodic potential and strongly interacting with a thermostat are explored. Apart from the average stationary velocity, we foremost investigate the…

Statistical Mechanics · Physics 2009-11-11 L. Machura , M. Kostur , P. Talkner , J. Luczka , P. Hänggi

Denoising diffusion models, a class of generative models, have garnered immense interest lately in various deep-learning problems. A diffusion probabilistic model defines a forward diffusion stage where the input data is gradually perturbed…

Image and Video Processing · Electrical Eng. & Systems 2023-06-06 Amirhossein Kazerouni , Ehsan Khodapanah Aghdam , Moein Heidari , Reza Azad , Mohsen Fayyaz , Ilker Hacihaliloglu , Dorit Merhof

We analyze the time reversed dynamics of generative diffusion models. If the exact empirical score function is used in a regime of large dimension and exponentially large number of samples, these models are known to undergo transitions…

Statistics Theory · Mathematics 2025-11-17 Anand Jerry George , Rodrigo Veiga , Nicolas Macris

We study boundary values of holomorphic functions in translation-invariant distribution spaces of type $\mathcal{D}'_{E'_{\ast}}$. New edge of the wedge theorems are obtained. The results are then applied to represent…

Functional Analysis · Mathematics 2015-07-28 Pavel Dimovski , Stevan Pilipovic , Jasson Vindas

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

This work deals with an inverse boundary value problem arising from the equation of heat conduction. We reconstruct small perturbations of the (isotropic) heat conductivity distribution from partial (on accessible part of the boundary)…

Analysis of PDEs · Mathematics 2016-02-10 Aymen Jbalia , Abdessatar Khelifi

We show that for ultracontractive irreducible Dirichlet metric measure spaces, the Dirichlet spectrum is discrete for a restriction to any connected open set without any assumption on regularity of the boundary. The main applications…

Probability · Mathematics 2024-10-30 Marco Carfagnini , Maria Gordina , Alexander Teplyaev

Let $(X,d,\mu)$ be a $RCD^\ast(K, N)$ space with $K\in \mathbb{R}$ and $N\in [1,\infty]$. For $N\in [1,\infty)$, we derive the upper and lower bounds of the heat kernel on $(X,d,\mu)$ by applying the parabolic Harnack inequality and the…

Metric Geometry · Mathematics 2015-12-02 Renjin Jiang , Huaiqian Li , Huichun Zhang

Computational neuroimaging involves analyzing brain images or signals to provide mechanistic insights and predictive tools for human cognition and behavior. While diffusion models have shown stability and high-quality generation in natural…

Computer Vision and Pattern Recognition · Computer Science 2025-02-11 Haokai Zhao , Haowei Lou , Lina Yao , Wei Peng , Ehsan Adeli , Kilian M Pohl , Yu Zhang

This paper concerns the mathematical analyses of the diffusion model in machine learning. The drift term of the backward sampling process is represented as a conditional expectation involving the data distribution and the forward diffusion.…

Machine Learning · Computer Science 2024-12-11 Yubin Lu , Zhongjian Wang , Guillaume Bal

We introduce a new approach for estimating the invariant density of a multidimensional diffusion when dealing with high-frequency observations blurred by independent noises. We consider the intermediate regime, where observations occur at…

Statistics Theory · Mathematics 2024-04-19 Raphaël Maillet , Grégoire Szymanski

We consider a processor sharing queue where the number of jobs served at any time is limited to $K$, with the excess jobs waiting in a buffer. We use random counting measures on the positive axis to model this system. The limit of this…

Probability · Mathematics 2012-07-02 Jiheng Zhang , J. G. Dai , Bert Zwart

We introduce a computational framework to statistically infer thermophysical properties of any given wall from in-situ measurements of air temperature and surface heat fluxes. The proposed framework uses these measurements, within a…

Applications · Statistics 2018-08-16 Lia De Simon , Marco Iglesias , Benjamin Jones , Christopher Wood

We consider the problem of estimating the density of observations taking values in classical or nonclassical spaces such as manifolds and more general metric spaces. Our setting is quite general but also sufficiently rich in allowing the…

Probability · Mathematics 2019-02-12 G. Cleanthous , A. Georgiadis , G. Kerkyacharian , P. Petrushev , D. Picard
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