Results 11 to 20 of about 141 (138)

Study of the asymptotic eigenvalue distribution and trace formula of a second order operator-differential equation

open access: yesBoundary Value Problems, 2011
The purpose of writing this article is to show some spectral properties of the Bessel operator equation, with spectral parameter-dependent boundary condition.
Aslanova Nigar
doaj   +2 more sources

Resolvent estimates for 2-dimensional perturbations of plane Couette flow

open access: yesElectronic Journal of Differential Equations, 2002
We present results concerning resolvent estimates for the linear operator associated with the system of differential equations governing 2 dimensional perturbations of plane Couette flow.
Pablo Braz e Silva
doaj   +1 more source

Simple study designs in ecology produce inaccurate estimates of biodiversity responses

open access: yesJournal of Applied Ecology, Volume 56, Issue 12, Page 2742-2754, December 2019., 2019
We suggest that more investment in more robust designs is needed in ecology since inferences from simpler designs, even with large sample sizes may be misleading. Facilitating this requires longer‐term funding and stronger research–practice partnerships. We also propose ‘accuracy weights’ and demonstrate how they can weight studies in three recent meta‐
Alec P. Christie   +6 more
wiley   +1 more source

Existence conditions for periodic solutions of second-order neutral delay differential equations with piecewise constant arguments

open access: yesOpen Mathematics, 2020
In this paper, we describe a method to solve the problem of finding periodic solutions for second-order neutral delay-differential equations with piecewise constant arguments of the form x″(t) + px″(t − 1) = qx([t]) + f(t), where [⋅] denotes the greatest
I. Muminov Mukhiddin, H. M. Murid Ali
doaj   +1 more source

Spectrum and Analytic Functional Calculus for Clifford Operators via Stem Functions

open access: yesConcrete Operators, 2021
The main purpose of this work is the construction of an analytic functional calculus for Clifford operators, which are operators acting on certain modules over Clifford algebras.
Vasilescu Florian-Horia
doaj   +1 more source

Study of the property (bz) using local spectral theory methods

open access: yesArab Journal of Basic and Applied Sciences, 2023
For a bounded linear operator, by local spectral theory methods, we study the property [Formula: see text] which means that the difference of the approximate point spectrum with the upper semi-Fredholm spectrum coincides with the set of all finite-range ...
Elvis Aponte, Jose Soto, Ennis Rosas
doaj   +1 more source

Gap localization of TE‐modes by arbitrarily weak defects

open access: yesJournal of the London Mathematical Society, Volume 95, Issue 3, Page 942-962, June 2017., 2017
Abstract This paper considers the propagation of TE‐modes in photonic crystal waveguides. The waveguide is created by introducing a linear defect into a periodic background medium. Both the periodic background problem and the perturbed problem are modelled by a divergence type equation.
B. M. Brown   +4 more
wiley   +1 more source

Spectral properties of the Klein‐Gordon s‐wave equation with spectral parameter‐dependent boundary condition

open access: yesInternational Journal of Mathematics and Mathematical Sciences, Volume 2004, Issue 27, Page 1437-1445, 2004., 2004
We investigate the spectrum of the differential operator Lλ defined by the Klein‐Gordon s‐wave equation y″ + (λ − q(x)) 2y = 0, x ∈ ℝ+ = [0, ∞), subject to the spectral parameter‐dependent boundary condition y′(0) − (aλ + b)y(0) = 0 in the space L2(ℝ+), where a ≠ ±i, b are complex constants, q is a complex‐valued function.
Gülen Başcanbaz-Tunca
wiley   +1 more source

On unbounded commuting Jacobi operators and some related issues

open access: yesConcrete Operators, 2019
We consider the situations, when two unbounded operators generated by infinite Jacobi matrices, are self-adjoint and commute. It is found that if two Jacobi matrices formally commute, then two corresponding operators are either self-adjoint and commute ...
Osipov Andrey
doaj   +1 more source

Scattering properties of Sturm-Liouville equations with sign-alternating weight and transmission condition at turning point

open access: yesOpen Mathematics, 2023
In this article, we focus on the scattering analysis of Sturm-Liouville type singular operator including an impulsive condition and turning point. In the classical literature, there are plenty of papers considering the positive values of the weight ...
Çoşkun Nimet, Görgülü Merve
doaj   +1 more source

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