17 research outputs found
Curved planar quantum wires with Dirichlet and Neumann boundary conditions
We investigate the discrete spectrum of the Hamiltonian describing a quantum
particle living in the two-dimensional curved strip. We impose the Dirichlet
and Neumann boundary conditions on opposite sides of the strip. The existence
of the discrete eigenvalue below the essential spectrum threshold depends on
the sign of the total bending angle for the asymptotically straight strips.Comment: 7 page
Gravitational traces of bumblebee gravity in metric-affine formalism
This work explores various manifestations of bumblebee gravity within the
metric--affine formalism. We investigate the impact of Lorentz violation
parameter, denoted as , on the modification of the \textit{Hawking}
temperature. Our calculations reveal that as increases, the values of the
\textit{Hawking} temperature attenuate. To examine the behavior of massless
scalar perturbations, specifically the \textit{quasinormal} modes, we employ
the WKB method. The transmission and reflection coefficients are determined
through our calculations. The outcomes indicate that a stronger
Lorentz--violating parameter results in slower damping oscillations of
gravitational waves. To comprehend the influence of the \textit{quasinormal}
spectrum on time--dependent scattering phenomena, we present a detailed
analysis of scalar perturbations in the time--domain solution. Additionally, we
conduct an investigation on shadows, revealing that larger values of
correspond to larger shadow radii. Lastly, we explore the concept of time delay
within this framework.Comment: 29 pages and 7 figure
Astrocytic Ion Dynamics: Implications for Potassium Buffering and Liquid Flow
We review modeling of astrocyte ion dynamics with a specific focus on the
implications of so-called spatial potassium buffering, where excess potassium
in the extracellular space (ECS) is transported away to prevent pathological
neural spiking. The recently introduced Kirchoff-Nernst-Planck (KNP) scheme for
modeling ion dynamics in astrocytes (and brain tissue in general) is outlined
and used to study such spatial buffering. We next describe how the ion dynamics
of astrocytes may regulate microscopic liquid flow by osmotic effects and how
such microscopic flow can be linked to whole-brain macroscopic flow. We thus
include the key elements in a putative multiscale theory with astrocytes
linking neural activity on a microscopic scale to macroscopic fluid flow.Comment: 27 pages, 7 figure
NLTE models of line-driven stellar winds I. Method of calculation and first results for O stars
New numerical models of line-driven stellar winds of late O stars are
presented. Statistical equilibrium (NLTE) equations of the most abundant
elements are solved. Properly obtained occupation numbers are used to calculate
consistent radiative force and radiative heating terms. Wind density, velocity
and temperature are calculated as a solution of model hydrodynamical equations.
Contrary to other published models we account for a multicomponent wind nature
and do not simplify the calculation of the radiative force (e.g. using force
multipliers). We discuss the convergence behaviour of our models. The ability
of our models to predict correct values of mass-loss rates and terminal
velocities of selected late O stars (mainly giants and supergiants) is
demonstrated. The systematic difference between predicted and observed terminal
velocities reported in the literature has been removed. Moreover, we found good
agreement between the theoretical wind momentum-luminosity relationship and the
observed one for Cyg OB2 supergiants.Comment: Accepted for publication in A&A. 17 page
The effect of tightly-bound water molecules on scaffold diversity in computer-aided de novo ligand design of CDK2 inhibitors
We have determined the effects that tightly bound water molecules have on the de novo design of cyclin-dependent kinase-2 (CDK2) ligands. In particular, we have analyzed the impact of a specific structural water molecule on the chemical diversity and binding mode of ligands generated through a de novo structure-based ligand generation method in the binding site of CDK2. The tightly bound water molecule modifies the size and shape of the binding site and we have found that it also imposed constraints on the observed binding modes of the generated ligands. This in turn had the indirect effect of reducing the chemical diversity of the underlying molecular scaffolds that were able to bind to the enzyme satisfactorily