Results 111 to 120 of about 4,674,369 (143)

The Clinical Spectrum of Essential Hypertension

Archives of Internal Medicine, 1974
The majority of hypertensive patients fall into the borderline and mild groups. A smaller percentage of the hypertensive population falls into the groups with persistent elevations in diastolic blood pressure of 105 mm Hg or higher. However, they are a most important group because treatment has been effective in reducing their high risk of developing ...
openaire   +2 more sources

On the Essential Spectrum of Quantum Graphs

Integral Equations and Operator Theory, 2017
This paper studies the spectral theory of Schrödinger operators which are defined on a metric graph, embedded in \(\mathbb{R}^n\), which has a periodic structure in the sense that it is invariant under translations defined by of a subgroup of \(\mathbb{R}^n\) isomorphic to \(\mathbb{Z}^m\) (i.e. a lattice).
openaire   +2 more sources

Spectrum of a Model Operator in the Perturbation Theory of the Essential Spectrum

Theoretical and Mathematical Physics, 2005
zbMATH Open Web Interface contents unavailable due to conflicting licenses.
Yodgorov, G. R., Muminov, M. E.
openaire   +1 more source

On the Essential Spectrum of a Differentially Rotating Star

ZAMM, 1999
The authors study the essential spectrum of a family \(L_{k,0}\) (\(k\in {\mathbb Z}\)) of mixed order partial differential operators which arise after separation of variables in the linearised Euler equation. Such an equation could be a model for natural oscillation of a differentially rotating stars.
Faierman, M., Lifschitz, A., Mennicken, R., Möller, M.   +3 more
openaire   +2 more sources

On the Linear Essential Spectrum Operator

2018
This paper presents: Let A be a unital \(C^{*}\)-algebra of real rank zero and B be a unital semisimple complex Banach algebra. We characterize linear maps from A onto B that compress different essential spectral sets such as the (left, right) essential spectrum, the semi-Fredholm spectrum, and the Weyl spectrum.
openaire   +2 more sources

The Essential Spectrum of Some Matrix Operators

Mathematische Nachrichten, 1994
From authors' introduction: We consider operators \(L_0\) defined by a \(2\times 2\) block operator matrix \[ L_0= \left(\begin{matrix} A & B\\ C & D\end{matrix}\right),\tag{\(*\)} \] where the entries are in general unbounded operators, \(A\) acting in a Banach space \(X_1\), \(D\) acting in a Banach space \(X_2\), and \(B\), \(C\) acting between ...
Atkinson, F. V., Langer, H., Mennicken, R., Shkalikov, A. A.   +3 more
openaire   +2 more sources

Remarks on Bifurcation from the Essential Spectrum

1999
In this note we prove the existence of two families of solutions bifurcating from the essential spectrum for problem (1) below. We use a new perturbation method recently developed (see [1], [2], [3]).
BADIALE, Marino, AMBROSETTI A.
openaire   +2 more sources

On the Unboundedness of the Essential Spectrum

American Journal of Mathematics, 1952
openaire   +2 more sources

Essential Spectrum of Upper Triangular Operator Matrices

Annals of Functional Analysis, 2020
Junjie Huang, Xiufeng Wu
exaly  

Essential Spectrum

1978
Paul Richard Halmos, Viakalathur Shankar Sunder   +1 more
openaire   +1 more source