4,610 research outputs found
Position-dependent-mass; Cylindrical coordinates, separability, exact solvability, and PT-symmetry
The kinetic energy operator with position-dependent-mass in cylindrical
coordinates is obtained. The separability of the corresponding Schr\"odinger
equation is discussed within radial cylindrical mass settings. Azimuthal
symmetry is assumed and spectral signatures of various z-dependent interaction
potentials (Hermitian and non-Hermitian PT-symmetric) are reported.Comment: 16 page
The neonatal splice variant of Nav1.5 potentiates in vitro invasive behaviour of MDA-MB-231 human breast cancer cells
Upregulation of functional voltage-gated Na+ channels (VGSCs) occurs in metastatic human breast cancer (BCa) in vitro and in vivo. The present study aimed to ascertain the specific involvement of the 'neonatal' splice variant of Nav1.5 (nNav1.5), thought to be predominant, in the VGSC-dependent invasive behaviour of MDA-MB-231 cells. Functional activity of nNav1.5 was suppressed by two different methods targeting nNav1.5: (i) small interfering RNA (siRNA), and (ii) a polyclonal antibody (NESO-pAb); effects upon migration and invasion were determined. nNav1.5 mRNA, protein and signalling were measured using real-time PCR, Western blotting, and patch clamp recording, respectively. Treatment with the siRNA rapidly reduced (by similar to 90%) the level of nNav1.5 (but not adult Nav1.5) mRNA, but the protein reduction was much smaller (similar to 30%), even after 13 days. Nevertheless, the siRNA reduced peak VGSC current density by 33%, and significantly increased the cells' sensitivity to nanomolar tetrodotoxin (TTX). Importantly, the siRNA suppressed in vitro migration by 43%, and eliminated the normally inhibitory effect of TTX. Migrated MDA-MB-231 cells expressed more nNav1.5 protein at the plasma membrane than non-migrated cells. Furthermore, NESO-pAb reduced migration by up to 42%, in a dose-dependent manner. NESO-pAb also reduced Matrigel invasion without affecting proliferation. TTX had no effect on cells already treated with NESO-pAb. It was concluded that nNav1.5 is primarily responsible for the VGSC-dependent enhancement of invasive behaviour in MDA-MB-231 cells. Accordingly, targeting nNav1.5 expression/activity may be useful in clinical management of metastatic BCa
Nerve growth factor enhances voltage-gated Na+ channel activity and transwell migration in Mat-LyLu rat prostate cancer cell line
The highly dynamic nature of voltage-gated Na+ channel (VGSC) expression and its controlling mechanism(s) are not well understood. In this study, we investigated the possible involvement of nerve growth factor (NGF) in regulating VGSC activity in the strongly metastatic Mat-LyLu cell model of rat prostate cancer (PCa). NGF increased peak VGSC current density in a time- and dose-dependent manner. NGF also shifted voltage to peak and the half-activation voltage to more positive potentials, and produced currents with faster kinetics of activation; sensitivity to the VGSC blocker tetrodotoxin (TTX) was not affected. The NGF-induced increase in peak VGSC current density was suppressed by both the pan-trk antagonist K252a, and the protein kinase A (PKA) inhibitor KT5720. NGF did not affect the Nav1.7 mRNA level, but the total VGSC alpha-subunit protein level was upregulated. NGF potentiated the cells' migration in Transwell assays, and this was not affected by TTX. We concluded that NGF upregulated functional VGSC expression in Mat-LyLu cells, with PKA as a signaling intermediate, but enhancement of migration by NGF was independent of VGSC activity
On the Explanation of the Paramagnetic Meissner Effect in Superconductor/Ferromagnet Heterostructures
An increase of the magnetic moment in superconductor/ferromagnet (S/F)
bilayers V(40nm)/F [FFe(1,3nm), Co(3nm), Ni(3nm)] was observed using SQUID
magnetometry upon cooling below the superconducting transition temperature Tc
in magnetic fields of 10 Oe to 50 Oe applied parallel to the sample surface. A
similar increase, often called the paramagnetic Meissner effect (PME), was
observed before in various superconductors and superconductor/ferromagnet
systems. To explain the PME effect in the presented S/F bilayers a model based
on a row of vortices located at the S/F interface is proposed. According to the
model the magnetic moment induced below Tc consists of the paramagnetic
contribution of the vortex cores and the diamagnetic contribution of the
vortex-free region of the S layer. Since the thickness of the S layer is found
to be 3-4 times less than the magnetic field penetration depth, this latter
diamagnetic contribution is negligible. The model correctly accounts for the
sign, the approximate magnitude and the field dependence of the paramagnetic
and the Meissner contributions of the induced magnetic moment upon passing the
superconducting transition of a ferromagnet/superconductor bilayer
Pseudoduality Between Symmetric Space Sigma Models
We study the pseudoduality transformation on the symmetric space sigma
models. We switch the Lie group valued pseudoduality equations to Lie algebra
valued ones, which leads to an infinite number of pseudoduality equations. We
obtain an infinite number of conserved currents on the tangent bundle of the
pseudodual manifold. We show that there can be mixing of decomposed spaces with
each other, which leads to mixings of the following expressions. We obtain the
mixing forms of curvature relations and one loop renormalization group beta
functions by means of these currents.Comment: 33 pages, typos corrected and some new references adde
Part of the D - dimensional Spiked harmonic oscillator spectra
The pseudoperturbative shifted - l expansion technique PSLET [5,20] is
generalized for states with arbitrary number of nodal zeros. Interdimensional
degeneracies, emerging from the isomorphism between angular momentum and
dimensionality of the central force Schrodinger equation, are used to construct
part of the D - dimensional spiked harmonic oscillator bound - states. PSLET
results are found to compare excellenly with those from direct numerical
integration and generalized variational methods [1,2].Comment: Latex file, 20 pages, to appear in J. Phys. A: Math. & Ge
Position-dependent mass models and their nonlinear characterization
We consider the specific models of Zhu-Kroemer and BenDaniel-Duke in a
sech-mass background and point out interesting correspondences with the
stationary 1-soliton and 2-soliton solutions of the KdV equation in a
supersymmetric framework.Comment: 8 Pages, Latex version, Two new references are added, To appear in
J.Phys.A (Fast Track Communication
Analytical Solutions of Klein-Gordon Equation with Position-Dependent Mass for q-Parameter Poschl-Teller potential
The energy eigenvalues and the corresponding eigenfunctions of the
one-dimensional Klein-Gordon equation with q-parameter Poschl-Teller potential
are analytically obtained within the position-dependent mass formalism. The
parametric generalization of the Nikiforov-Uvarov method is used in the
calculations by choosing a mass distribution.Comment: 10 page
d-Dimensional generalization of the point canonical transformation for a quantum particle with position-dependent mass
The d-dimensional generalization of the point canonical transformation for a
quantum particle endowed with a position-dependent mass in Schrodinger equation
is described. Illustrative examples including; the harmonic oscillator,
Coulomb, spiked harmonic, Kratzer, Morse oscillator, Poschl-Teller and Hulthen
potentials are used as reference potentials to obtain exact energy eigenvalues
and eigenfunctions for target potentials at different position-dependent mass
settings.Comment: 14 pages, no figures, to appear in J. Phys. A: Math. Ge
- …