6,528 research outputs found
Integral Representations for the Class of Generalized Metaplectic Operators
This article gives explicit integral formulas for the so-called generalized
metaplectic operators, i.e. Fourier integral operators (FIOs) of Schr\"odinger
type, having a symplectic matrix as canonical transformation. These integrals
are over specific linear subspaces of R^d, related to the d x d upper left-hand
side submatrix of the underlying 2d x 2d symplectic matrix. The arguments use
the integral representations for the classical metaplectic operators obtained
by Morsche and Oonincx in a previous paper, algebraic properties of symplectic
matrices and time-frequency tools. As an application, we give a specific
integral representation for solutions to the Cauchy problem of Schr\"odinger
equations with bounded perturbations for every instant time t in R, even in the
so-called caustic points.Comment: 19 pages in Journal of Fourier Analysis and Applications, 201
An equation of state for purely kinetic k-essence inspired by cosmic topological defects
We investigate the physical properties of a purely kinetic k-essence model
with an equation of state motivated in superconducting membranes. We compute
the equation of state parameter and discuss its physical evolution via a
nonlinear equation of state. Using the adiabatic speed of sound and energy
density, we restrict the range of parameters of the model in order to have an
acceptable physical behavior. Furthermore, we analyze the evolution of the
luminosity distance with redshift by comparing (normalizing) it
with the CDM model. Since the equation of state parameter is
-dependent the evolution of the luminosity distance is also analyzed using
the Alcock-Paczy\'{n}ski test.Comment: 19 pages, 13 figures, typos corrected and references adde
Cosmological constraints for a two brane-world system with single equation of state
We present the study of two 3-brane system embedded in a 5-dimensional
space-time in which the fifth dimension is compactified on a
orbifold. Assuming isotropic, homogeneous, and static branes, it can be shown
that the dynamics of one brane is dominated by the other one when the metric
coefficients have a particular form. We study the resulting cosmologies when
one brane is dominated by a given single-fluid component.Comment: This work was presented at the VIII Taller of the DGFM, Tuxtla
Gutierrez, Chiapas, Mexico noviembre 22-26, 201
Two-brane system in a vacuum bulk with a single equation of state
We study the cosmology of a two-brane model in a five-dimensional spacetime,
where the extra spatial coordinate is compactifed on an orbifold. Additionally,
we consider the existence on each brane of matter fields that evolve in time.
Solving the Einstein equations in a vacuum bulk, we can show how the matter
fields in both branes are connected and they do not evolve independentlyComment: This work was presented at the IX Taller de la Division de
Gravitacion y Fisica Matematica, Colima 201
Algebraic treatment of the confluent Natanzon potentials
Using the so(2,1) Lie algebra and the Baker, Campbell and Hausdorff formulas,
the Green's function for the class of the confluent Natanzon potentials is
constructed straightforwardly. The bound-state energy spectrum is then
determined. Eventually, the three-dimensional harmonic potential, the
three-dimensional Coulomb potential and the Morse potential may all be
considered as particular cases.Comment: 9 page
One Size Does Not Fit All: Meeting the Health Care Needs of Diverse Populations
Proposes a framework for meeting patients' cultural and linguistic needs: policies and procedures that support cultural competence, data collection, population-tailored services, and internal and external collaborations. Includes a self-assessment tool
Analysis of biopharma raw materials by electrophoresis microchips with contactless conductivity detection
Detailed information concerning the composition of the raw materials employed in the production of biologics is important for the efficient control and optimization of bioprocesses. We demonstrate the application of electrophoresis microchips with capacitively-coupled contactless conductivity detection (C4D) to the analysis of wa-ter-soluble vitamins and metal cations in raw material solutions that are subse-quently fed into bioreactors for the production of biologics
- …
