4,724 research outputs found
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
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
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
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
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
Analysis of water-soluble vitamins in biopharma raw materials by electrophoresis micro-chips 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. The analytical
methods used in these applications must be simple and fast as well as be easily transferable from
one site to another. In that context, microchipâbased electrophoresis represents a promising tool
for application in the analysis of raw materials in biologics. Using electrophoresis microâchips,
analysis times can be reduced to seconds and high separation efficiencies can be achieved using
extremely low volume samples, minimal reagent consumption and waste generation, low
cost/disposability, portability and ease of massâproduction [1].
Additionally the use of Capacitively Coupled Contactless Conductivity Detection (C4D) offers a
rather simple and yet sensitive method for detection of ionic species. Recently, C4D has gained
much popularity as onâchip detection in electrophoresis microâchips [2]. The main reason for this
is that there is no physical contact of the detection electrodes with the electrolyte solution.
Therefore, the integration of this detection mode within the analytical system is rather simple.
Furthermore, the background noise is significantly reduced leading to lower detection limits than
the conventional contact conductivity detection.
Vitamins are present at very low concentrations in biopharma raw materials and are usually
determined using HPLC and CE methods [3]. Electrophoresis microâchips are a very good
alternative to these techniques due to the shorter analysis time and yet very good resolution,
among others.
In this paper, we present the application of electrophoresis microâchips with C4D detection to the
analysis of waterâsoluble vitamins in raw materials used for the production of biologics in
bioreactors. For that purpose, hybrid PDMS/glass chips were fabricated by using standard
photolithographic techniques (Figure 1). The chip structure contains an extremely long channel of
101 mm (50 x 50 ÎŒm width x depth). Figure 2 shows the setup used for vitamins detection
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
- âŠ