7 research outputs found
Exact controllability for wave equation on general quantum graphs with non-smooth controls
In this paper we study the exact controllability problem for the wave
equation on a finite metric graph with the Kirchhoff-Neumann matching
conditions. Among all vertices and edges we choose certain active vertices and
edges, and give a constructive proof that the wave equation on the graph is
exactly controllable if Neumann controllers are placed at the
active vertices and Dirichlet controllers are placed at the active
edges. The proofs for the shape and velocity controllability are purely
dynamical, while the proof for the exact controllability utilizes both
dynamical and moment method approaches. The control time for this construction
is determined by the chosen orientation and path decomposition of the graph
Recovery of a potential on a quantum star graph from Weyl's matrix
The problem of recovery of a potential on a quantum star graph from Weyl's
matrix given at a finite number of points is considered. A method for its
approximate solution is proposed. It consists in reducing the problem to a
two-spectra inverse Sturm-Liouville problem on each edge with its posterior
solution. The overall approach is based on Neumann series of Bessel functions
(NSBF) representations for solutions of Sturm-Liouville equations, and, in
fact, the solution of the inverse problem on the quantum graph reduces to
dealing with the NSBF coefficients. The NSBF representations admit estimates
for the series remainders which are independent of the real part of the square
root of the spectral parameter. This feature makes them especially useful for
solving direct and inverse problems requiring calculation of solutions on large
intervals in the spectral parameter. Moreover, the first coefficient of the
NSBF representation alone is sufficient for the recovery of the potential. The
knowledge of the Weyl matrix at a set of points allows one to calculate a
number of the NSBF coefficients at the end point of each edge, which leads to
approximation of characteristic functions of two Sturm-Liouville problems and
allows one to compute the Dirichlet-Dirichlet and Neumann-Dirichlet spectra on
each edge. In turn, for solving this two-spectra inverse Sturm-Liouville
problem a system of linear algebraic equations is derived for computing the
first NSBF coefficient and hence for recovering the potential. The proposed
method leads to an efficient numerical algorithm that is illustrated by a
number of numerical tests.Comment: arXiv admin note: substantial text overlap with arXiv:2210.1250
VAS2870 Inhibits Histamine-Induced Calcium Signaling and vWF Secretion in Human Umbilical Vein Endothelial Cells
In this study, we investigated the effects of NAD(P)H oxidase (NOX) inhibitor VAS2870 (3-benzyl-7-(2-benzoxazolyl)thio-1,2,3-triazolo[4,5-d]pyrimidine) on the histamine-induced elevation of free cytoplasmic calcium concentration ([Ca2+]i) and the secretion of von Willebrand factor (vWF) in human umbilical vein endothelial cells (HUVECs) and on relaxation of rat aorta in response to histamine. At 10 μM concentration, VAS2870 suppressed the [Ca2+]i rise induced by histamine. Inhibition was not competitive, with IC50 3.64 and 3.22 μM at 1 and 100 μM concentrations of histamine, respectively. There was no inhibition of [Ca2+]i elevation by VAS2870 in HUVECs in response to the agonist of type 1 protease-activated receptor SFLLRN. VAS2870 attenuated histamine-induced secretion of vWF and did not inhibit basal secretion. VAS2870 did not change the degree of histamine-induced relaxation of rat aortic rings constricted by norepinephrine. We suggest that NOX inhibitors might be used as a tool for preventing thrombosis induced by histamine release from mast cells without affecting vasorelaxation