Results 71 to 80 of about 8,503 (184)
Finite extensions of Bessel sequences
, 2014 The paper studies finite extensions of Bessel sequences in infinite-dimensional Hilbert spaces. We provide a characterization of Bessel sequences that can be extended to frames by adding finitely many vectors.
Bakić, Damir, Berić, Tomislav
core +1 more source
Mathematical Methods in the Applied Sciences, Volume 49, Issue 4, Page 3353-3384, 15 March 2026.ABSTRACT The article examines a boundary‐value problem in a bounded domain Ωε$$ {\Omega}_{\varepsilon } $$ consisting of perforated and imperforate regions, with Neumann conditions prescribed at the boundaries of the perforations. Assuming the porous medium has symmetric, periodic structure with a small period ε$$ \varepsilon $$, we analyze the limit ...
Taras Melnyk
wiley +1 more source
Semiclassical inequalities for Dirichlet and Neumann Laplacians on convex domains
Communications on Pure and Applied Mathematics, Volume 79, Issue 3, Page 762-822, March 2026.Abstract We are interested in inequalities that bound the Riesz means of the eigenvalues of the Dirichlet and Neumann Laplacians in terms of their semiclassical counterpart. We show that the classical inequalities of Berezin–Li–Yau and Kröger, valid for Riesz exponents γ≥1$\gamma \ge 1$, extend to certain values γ<1$\gamma <1$, provided the underlying ...
Rupert L. Frank, Simon Larson
wiley +1 more source
Combining Riesz bases in $\mathbb R^d$
Revista Matemática Iberoamericana, 2016 We prove that every finite union of rectangles with edges parallel to the axes in \mathbb R^d admits a Riesz basis of exponentials.
Gady Kozma, Shahaf Nitzan
openaire +1 more source
Generalized quasi‐geostrophic equation in critical Lorentz–Besov spaces, based on maximal regularity
Mathematische Nachrichten, Volume 299, Issue 3, Page 637-660, March 2026.Abstract We consider the quasi‐geostrophic equation with its principal part (−Δ)α${(-\mathrm{\Delta})^{\alpha}}$ for α>1/2$\alpha >1/2$ in Rn$\mathbb {R}^n$ with n≥2$n \ge 2$. We show that for every initial data θ0∈Ḃr,q1−2α+nr$\theta _0 \in \dot{B}^{1-2\alpha + \frac{n}{r}}_{r, q}$ with 1
Hideo Kozono +2 more
wiley +1 more source
ON COMPLETE RIESZ–FISCHER SEQUENCES IN A HILBERT SPACE
Проблемы анализаWe prove that if {𝑓_𝑛}^\infty_{n=1} is a complete Riesz–Fischer sequence in a separable Hilbert space 𝐻, then 𝑇 :={𝑓 \in 𝐻 : \Sum ...
Elias Zikkos
doaj +1 more source
Abstract and Applied Analysis, 2011 This paper is concerned with analyzing the mathematical properties, such as the regularity and stability of nonstationary biorthogonal wavelet systems based on exponential B-splines.
Yeon Ju Lee, Jungho Yoon
doaj +1 more source
Riesz Bases of Root Vectors of Indefinite Sturm-Liouville problems with eigenparameter dependent boundary conditions, I [PDF]
, 2007 We consider a regular indefinite Sturm-Liouville problem with two self-adjoint boundary conditions, one being affinely dependent on the eigenparameter.
Binding, Paul, Ćurgus, Branko
core +5 more sources
Pigment Cell &Melanoma Research, Volume 39, Issue 2, March 2026.Pigment‐associated cellular features, such as melanin levels and organelles, can be quantified in live cells with label‐free multimodal imaging. Quantitative phase imaging (cyan) measures cell mass, scattering (yellow) reports organelle content, including melanosomes, and absorbance imaging (magenta) captures pigment such as melanin.
Rebecca G. Zitnay +8 more
wiley +1 more source
Ibn Al-Haitham Journal for Pure and Applied Sciences, 2017 The aim of this paper is prove a theorem on the Riesz mean of expansions with respect to Riesz bases, which extends the previous results of Loi and Tahir on the Schrodinger operator to the operator of 4-th order.
M. B. Tahir, A. A. Aswhad
doaj