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This paper proposes to address the issue of complexity reduction for the numerical simulation of multiscale media in a quasi-periodic setting. We consider a stationary elliptic diffusion equation defined on a domain $D$ such that…

Numerical Analysis · Mathematics 2019-09-11 Quentin Ayoul-Guilmard , Anthony Nouy , Christophe Binetruy

We consider the notion of the matrix (tensor) distribution of a measurable function of several variables. On the one hand, it is an invariant of this function with respect to a certain group of transformations of variables; on the other…

Dynamical Systems · Mathematics 2023-11-03 A. Vershik

Fueled by the expressive power of deep neural networks, normalizing flows have achieved spectacular success in generative modeling, or learning to draw new samples from a distribution given a finite dataset of training samples. Normalizing…

Machine Learning · Computer Science 2023-05-05 Yuehaw Khoo , Michael Lindsey , Hongli Zhao

Diffusion magnetic resonance has been employed for determining the distribution of net displacements (ensemble average propagator), moments and correlations of net displacements, and the steady-state distribution of magnetized particles.…

Materials Science · Physics 2021-05-04 Evren Özarslan

Efficient probability density estimation is a core challenge in statistical machine learning. Tensor-based probabilistic graph methods address interpretability and stability concerns encountered in neural network approaches. However, a…

Machine Learning · Computer Science 2023-12-14 Ruituo Wu , Jiani Liu , Ce Zhu , Anh-Huy Phan , Ivan V. Oseledets , Yipeng Liu

Three-dimensional random tensor models are a natural generalization of the celebrated matrix models. The associated tensor graphs, or 3D maps, can be classified with respect to a particular integer or half-integer, the degree of the…

Combinatorics · Mathematics 2015-05-07 Eric Fusy , Adrian Tanasa

Diffusion magnetic resonance imaging (dMRI) is an emerging medical technique used for describing water diffusion in an organic tissue. Typically, rank-2 tensors quantify this diffusion. From this quantification, it is possible to calculate…

Computer Vision and Pattern Recognition · Computer Science 2016-06-28 Hernan Dario Vargas Cardona , Mauricio A. Alvarez , Alvaro A. Orozco

We propose Microscopic Propagator Imaging (MPI) as a novel method to retrieve the indices of the microscopic propagator which is the probability density function of water displacements due to diffusion within the nervous tissue…

Neurons and Cognition · Quantitative Biology 2025-03-03 Tommaso Zajac , Gloria Menegaz , Marco Pizzolato

Elliptically symmetric distributions are widely used in portfolio modeling, as well as in signal processing applications for modeling impulsive background noises. Of particular interest are algorithms for covariance estimation and subspace…

Statistics Theory · Mathematics 2016-12-01 Christophe Culan , Claude Adnet

Magnetic Resonance Elastography (MRE) can characterize biomechanical properties of soft tissue for disease diagnosis and treatment planning. However, complicated wavefields acquired from MRE coupled with noise pose challenges for accurate…

Image and Video Processing · Electrical Eng. & Systems 2023-04-05 Shengyuan Ma , Runke Wang , Suhao Qiu , Ruokun Li , Qi Yue , Qingfang Sun , Liang Chen , Fuhua Yan , Guang-Zhong Yang , Yuan Feng

This paper proposes famillies of multimatricvariate and multimatrix variate distributions based on elliptically contoured laws in the context of real normed division algebras. The work allows to answer the following inference problems about…

Statistics Theory · Mathematics 2024-05-14 José A. Díaz-García , Francisco J. Caro-Lopera

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 study modeling and inference with the Elliptical Gamma Distribution (EGD). We consider maximum likelihood (ML) estimation for EGD scatter matrices, a task for which we develop new fixed-point algorithms. Our algorithms are efficient and…

Computation · Statistics 2018-06-04 Reshad Hosseini , Suvrit Sra , Lucas Theis , Matthias Bethge

Multilayer networks have become increasingly ubiquitous across diverse scientific fields, ranging from social sciences and biology to economics and international relations. Despite their broad applications, the inferential theory for…

Methodology · Statistics 2026-02-24 Zhaozhe Liu , Gongjun Xu , Haoran Zhang

This work is motivated by multimodality breast cancer imaging data, which is quite challenging in that the signals of discrete tumor-associated microvesicles (TMVs) are randomly distributed with heterogeneous patterns. This imposes a…

Machine Learning · Statistics 2019-03-22 Xiwei Tang , Xuan Bi , Annie Qu

Models of diffusion MRI within a voxel are useful for making inferences about the properties of the tissue and inferring fiber orientation distribution used by tractography algorithms. A useful model must fit the data accurately. However,…

Quantitative Methods · Quantitative Biology 2017-02-08 Ariel Rokem , Jason D. Yeatman , Franco Pestilli , Kendrick N. Kay , Aviv Mezer , Stefan van der Walt , Brian A. Wandell

We propose estimating the scale parameter (mean of the eigenvalues) of the scatter matrix of an unspecified elliptically symmetric distribution using weights obtained by solving Tyler's M-estimator of the scatter matrix. The proposed…

Methodology · Statistics 2023-05-09 Esa Ollila , Daniel P. Palomar , Frederic Pascal

Ultra-low-field (ULF) MRI is emerging as an alternative modality to high-field (HF) MRI due to its lower cost, minimal siting requirements, portability, and enhanced accessibility factors that enable large-scale deployment. Although ULF-MRI…

Recently, a non-iterative multi-frequency subspace migration imaging algorithm was developed based on an asymptotic expansion formula for thin, curve-like electromagnetic inclusions and the structure of singular vectors in the Multi-Static…

Mathematical Physics · Physics 2013-12-30 Won-Kwang Park

The behavior of a 2-D model of an extended hemielliptic silicon lens of a size typical for THz applications is accurately studied for the case of a plane E-wave illumination. The full-wave analysis of the scattering problem is based on the…