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In compressed sensing (CS) MRI, model-based methods are pivotal to achieving accurate reconstruction. One of the main challenges in model-based methods is finding an effective prior to describe the statistical distribution of the target…

Image and Video Processing · Electrical Eng. & Systems 2025-10-21 Tao Hong , Zhaoyi Xu , Se Young Chun , Luis Hernandez-Garcia , Jeffrey A. Fessler

In this paper we characterize quasi-contraction, stable and convergent weighted conditional type (WCT) operators on $L^p(\mu)$. Indeed we provide equivalent conditions for quasi-contraction WCT operators. Also, we prove that convergence,…

Functional Analysis · Mathematics 2024-06-13 Y. Estaremi , Z. Huang

We report the findings of new exact analytical solutions to the cosmological fluid equations, namely for the case where the initial conditions are perturbatively close to a spherical top-hat profile. To do so we enable a fluid description…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-28 Cornelius Rampf

Using small deformations of the total energy, as introduced in [31], we establish that damped second order gradient systems $$u^{\prime\prime}(t)+\gamma u^\prime(t)+\nabla G(u(t))=0,$$may be viewed as quasi-gradient systems. In order to…

Analysis of PDEs · Mathematics 2019-04-22 Mohamed Ali Jendoubi , Pascal Bégout , Jérôme Bolte , Mohamed Jendoubi

We consider a damped/driven cubic NLS equation on a torus under the limit when first the amplitude of solutions goes to zero and then the period of the torus goes to infinity. We suggest another proof of the kinetic approximation for the…

Mathematical Physics · Physics 2025-06-05 Andrey Dymov

In the context of finite tensor products of Hilbert spaces, we prove that similarity of a tensor product of operator semigroups to a contraction semigroup is equivalent to the corresponding similarity for each factor, after an appropriate…

Functional Analysis · Mathematics 2025-09-04 J. Oliva-Maza , Y. Tomilov

Deep neural networks (DNNs) have witnessed great successes in semantic segmentation, which requires a large number of labeled data for training. We present a novel learning framework called Uncertainty guided Cross-head Co-training (UCC)…

Computer Vision and Pattern Recognition · Computer Science 2023-02-24 Jiashuo Fan , Bin Gao , Huan Jin , Lihui Jiang

The quasi-SU(3) symmetry, as found in shell model calculations, refers to the dominance of the single particle plus quadrupole-quadrupole terms in the Hamiltonian used to describe well deformed nuclei, and to the subspace relevant in its…

Nuclear Theory · Physics 2007-05-23 C. E. Vargas , J. G. Hirsch , J. P. Draayer

We introduce the notion of almost representations of Lie algebras and quantum tori, and establish an Ulam-stability type phenomenon: every irreducible almost representation is close to a genuine irreducible representation. As an…

Mathematical Physics · Physics 2022-02-01 Louis Ioos , David Kazhdan , Leonid Polterovich

Motivated by recent applications to entropy theory in dynamical systems, we generalise notions introduced by Matthews and define weakly weighted and componentwisely weakly weighted (generalised) quasi-metrics. We then systematise and extend…

Information Theory · Computer Science 2022-12-19 Ilaria Castellano , Anna Giordano Bruno , Nicolò Zava

We establish quaternionic contact (qc) versions of the so called Almost Schur Lemma, which give estimations of the qc scalar curvature on a compact qc manifold to be a constant in terms of the norm of the $[-1]$-component and the norm of…

Differential Geometry · Mathematics 2022-04-12 Stefan Ivanov , Alexander Petkov

We study mappings on sub-Riemannian manifolds which are quasi-regular with respect to the Carnot-Caratheodory distances and discuss several related notions. On H-type Carnot groups, quasiregular mappings have been introduced earlier using…

Metric Geometry · Mathematics 2016-06-21 Katrin Fassler , Anton Lukyanenko , Kirsi Peltonen

The combination of a large superconducting gap, low transition temperature, and quasi two-dimensionality in strongly underdoped high temperature superconductors severely constrains the behavior of the ab-plane superfluid density \rho with…

Superconductivity · Physics 2007-05-23 Igor F. Herbut , Matthew J. Case

We provide a commentary on Teichm{\"u}ller's paper "Extremale quasikonforme Abbildungen und quadratische Differentiale" (Extremal quasiconformal mappings of closed oriented Riemann surfaces), Abh. Preuss. Akad. Wiss., Math.-Naturw. Kl.…

Geometric Topology · Mathematics 2015-11-05 Athanase Papadopoulos , Vincent Alberge , Weixu Su

We study the almost sure convergence of randomly truncated stochastic algorithms. We present a new convergence theorem which extends the already known results by making vanish the classical condition on the noise terms. The aim of this work…

Probability · Mathematics 2009-06-29 Jérôme Lelong

We introduce a notion of quasiconvexity for continuous functions $f$ defined on the vector bundle of linear maps between the tangent spaces of a smooth Riemannian manifold $(M,g)$ and $\mathbb{R}^m$, naturally generalizing the classical…

Analysis of PDEs · Mathematics 2026-04-21 Aurora Corbisiero , Chiara Leone , Carlo Mantegazza

The convex closure of entropy vectors for quasi-uniform random vectors is the same as the closure of the entropy region. Thus, quasi-uniform random vectors constitute an important class of random vectors for characterizing the entropy…

Information Theory · Computer Science 2022-06-07 Satyajit Thakor , Dauood Saleem

In this paper, we construct a new class of modules for the Schr\"{o}dinger algebra $\mS$, called quasi-Whittaker module. Different from \cite{[ZC]}, the quasi-Whittaker module is not induced by the Borel subalgebra of the Schr\"{o}dinger…

Representation Theory · Mathematics 2013-11-21 Yan-an Cai , Yongsheng Cheng , Ran Shen

We develop a non-perturbative method to derive the probability distribution $P(\delta_R)$ of the density contrast within spherical cells in the quasi-linear regime. Indeed, since this corresponds to a rare-event limit a steepest-descent…

Astrophysics · Physics 2009-11-06 P. Valageas

Symmetric function theory is a key ingredient in the Schubert calculus of Grassmannians. Quasisymmetric functions are analogues that are similarly central to algebraic combinatorics, but for which the associated geometry is poorly…

Combinatorics · Mathematics 2023-05-03 Oliver Pechenik , Matthew Satriano