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Functional Spectral Imaging (FSI) models image formation as the recovery of tissue surrogates such as density and stiffness from spectral perturbations of a self-adjoint elliptic operator. Rather than relying on reflectivity or relaxation…

Medical Physics · Physics 2025-10-21 Cesar Mello Fernando Medina da Cunha

This paper discusses a generalization of spectral representations related to convex one-homogeneous regularization functionals, e.g. total variation or $\ell^1$-norms. Those functionals serve as a substitute for a Hilbert space structure…

Numerical Analysis · Mathematics 2015-03-19 Martin Burger , Lina Eckardt , Guy Gilboa , Michael Moeller

In this paper, we study a smoothness regularization method for a varying coefficient model based on sparse and irregularly sampled functional data which is contaminated with some measurement errors. We estimate the one-dimensional…

Methodology · Statistics 2017-11-28 Behdad Mostafaiy

Motivated by distinct walking patterns in real-world free-living gait data, this paper proposes an innovative curve-based sampling scheme for the analysis of functional data characterized by a mixture of covariance structures. Traditional…

Methodology · Statistics 2025-04-10 Yian Yu , Bo Wang , Jian Qing Shi

This note gives a summary of ideas concerning Applied Fourier Analysis, mostly formulated for those who have to give such courses to engineers or mathematicians interested in real life applications. It tries to answer recurrent questions…

Functional Analysis · Mathematics 2024-10-10 Hans G. Feichtinger

The growing use of neuroimaging technologies generates a massive amount of biomedical data that exhibit high dimensionality. Tensor-based analysis of brain imaging data has been proved quite effective in exploiting their multiway nature.…

Numerical Analysis · Computer Science 2016-07-21 Christos Chatzichristos , Eleftherios Kofidis , Giannis Kopsinis , Sergios Theodoridis

Covariance estimation is essential yet underdeveloped for analyzing multivariate functional data. We propose a fast covariance estimation method for multivariate sparse functional data using bivariate penalized splines. The tensor-product…

Methodology · Statistics 2019-06-11 Cai Li , Luo Xiao , Sheng Luo

A new orthogonal decomposition for bivariate probability densities embedded in Bayes Hilbert spaces is derived. It allows one to represent a density into independent and interactive parts, the former being built as the product of revised…

Statistics Theory · Mathematics 2020-12-25 Karel Hron , Jitka Machalová , Alessandra Menafoglio

The spatial random-effects model is flexible in modeling spatial covariance functions, and is computationally efficient for spatial prediction via fixed rank kriging. However, the success of this model depends on an appropriate set of basis…

Methodology · Statistics 2015-04-23 ShengLi Tzeng , Hsin-Cheng Huang

Identifying meaningful signal buried in noise is a problem of interest arising in diverse scenarios of data-driven modeling. We present here a theoretical framework for exploiting intrinsic geometry in data that resists noise corruption,…

Machine Learning · Statistics 2018-01-26 Ishanu Chattopadhyay

Decomposing Electrodermal Activity (EDA) into phasic (short-term, stimulus-linked responses) and tonic (longer-term baseline) components is essential for extracting meaningful emotional and physiological biomarkers. This study presents a…

Signal Processing · Electrical Eng. & Systems 2025-06-10 Charalampos Tsirmpas , Stasinos Konstantopoulos , Dimitris Andrikopoulos , Konstantina Kyriakouli , Panagiotis Fatouros

Formal Concept Analysis (FCA) is a well-established method for data analysis which finds many applications in data mining. Its extension on complex data representation formats brought a wave of new applications to the problems such as gene…

Information Retrieval · Computer Science 2018-09-27 Dmitry Morozov , Mario Lezoche , Hervé Panetto

Active soft bodies can affect their shape through an internal actuation mechanism that induces a deformation. Similar to recent work, this paper utilizes a differentiable, quasi-static, and physics-based simulation layer to optimize for…

Computer Vision and Pattern Recognition · Computer Science 2024-01-29 Lingchen Yang , Byungsoo Kim , Gaspard Zoss , Baran Gözcü , Markus Gross , Barbara Solenthaler

We give an introduction to discrete functional analysis techniques for stationary and transient diffusion equations. We show how these techniques are used to establish the convergence of various numerical schemes without assuming…

Numerical Analysis · Mathematics 2016-02-25 Jerome Droniou

Functional brain imaging through electroencephalography (EEG) relies upon the analysis and interpretation of high-dimensional, spatially organized time series. We propose to represent time-localized frequency domain characterizations of EEG…

The reduced k-particle density matrix of a density matrix on finite-dimensional, fermion Fock space can be defined as the image under the orthogonal projection in the Hilbert-Schmidt geometry onto the space of k-body observables. A proper…

Mathematical Physics · Physics 2019-04-17 Volker Bach , Robert Rauch

Scalar-on-function linear models are commonly used to regress functional predictors on a scalar response. However, functional models are more difficult to estimate and interpret than traditional linear models, and may be unnecessarily…

Methodology · Statistics 2019-06-13 Stephanie T. Chen , Luo Xiao , Ana-Maria Staicu

Response functions of quantum systems, such as electron Green's functions, magnetic, or charge susceptibilities, describe the response of a system to an external perturbation. They are the central objects of interest in field theories and…

Quantum Physics · Physics 2024-02-01 Alexander F. Kemper , Chao Yang , Emanuel Gull

Foundation models have demonstrated remarkable generalization, data efficiency, and robustness properties across various domains. In this paper, we explore the feasibility of foundation models for applications in the control domain. The…

Machine Learning · Computer Science 2024-12-18 Martin Ziegler , Andres Felipe Posada-Moreno , Friedrich Solowjow , Sebastian Trimpe

We give complete and exact descriptions of spaces of ultradifferentiable functions that are closed under composition with either holomorphic or ultradifferentiable functions -- which are two distinct cases. The proof works by considering…

Classical Analysis and ODEs · Mathematics 2017-02-14 Jürgen Pöschel