15,053 research outputs found
On the limit of non-standard q-Racah polynomials
The aim of this article is to study the limit transitions from non-standard
q-Racah polynomials to big q-Jacobi, dual q-Hahn, and q-Hahn polynomials such
that the orthogonality properties and the three-term recurrence relations
remain valid
On the Krall-type Askey-Wilson Polynomials
In this paper the general Krall-type Askey-Wilson polynomials are introduced.
These polynomials are obtained from the Askey-Wilson polynomials via the
addition of two mass points to the weight function of them at the points
. Several properties of such new family are considered, in particular the
three-term recurrence relation and the representation as basic hypergeometric
series
Limit relations between -Krall type orthogonal polynomials
In this paper, we consider a natural extension of several results related to
Krall-type polynomials introducing a modification of a -classical linear
functional via the addition of one or two mass points. The limit relations
between the -Krall type modification of big -Jacobi, little -Jacobi,
big -Laguerre, and other families of the -Hahn tableau are established.Comment: 19 Pages, 3 tables, 1 figur
On the Properties of Special Functions on the linear-type lattices
We present a general theory for studying the difference analogues of special
functions of hypergeometric type on the linear-type lattices, i.e., the
solutions of the second order linear difference equation of hypergeometric type
on a special kind of lattices: the linear type lattices. In particular, using
the integral representation of the solutions we obtain several
difference-recurrence relations for such functions. Finally, applications to
-classical polynomials are given
Dark photon searches with atomic transitions
Dark matter could be made up of dark photons, massive but very light
particles whose interactions with matter resemble those of usual photons but
suppressed by a small mixing parameter. We analyze the main approaches to dark
photon interactions and how they can be applied to direct detection experiments
which test different ranges of masses and mixings. A new experiment based on
counting dark photons from induced atomic transitions in a target material is
proposed. This approach appears to be particularly appropriate for dark photon
detection in the meV mass range, extending the constraints in the mixing
parameter by up to eight orders of magnitude with respect to previous
experiments.Comment: 16 pages, 3 figure
The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method
Using the formal analysis made by Bohm in his book, {\em "Quantum theory"},
Dover Publications Inc. New York (1979), to calculate approximately the phase
time for a transmitted and the reflected wave packets through a potential
barrier, we calculate the phase time for a semiconductor system formed by
different mesoscopic layers. The transmitted and the reflected wave packets are
analyzed and the applicability of this procedure, based on the stationary phase
of a wave packet, is considered in different conditions. For the applicability
of the stationary phase method an expression is obtained in the case of the
transmitted wave depending only on the derivatives of the phase, up to third
order. This condition indicates whether the parameters of the system allow to
define the wave packet by its leading term. The case of a multiple barrier
systems is shown as an illustration of the results. This formalism includes the
use of the Transfer Matrix to describe the central stratum, whether it is
formed by one layer (the single barrier case), or two barriers and an inner
well (the DBRT system), but one can assume that this stratum can be comprise of
any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph
Few-body decay and recombination in nuclear astrophysics
Three-body continuum problems are investigated for light nuclei of
astrophysical relevance. We focus on three-body decays of resonances or
recombination via resonances or the continuum background. The concepts of
widths, decay mechanisms and dynamic evolution are discussed. We also discuss
results for the triple decay in connection with resonances and
density and temperature dependence rates of recombination into light nuclei
from -particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Wetland-based passive treatment systems for gold ore processing effluents containing residual cyanide, metals and nitrogen species
Gold extraction operations generate a variety of wastes requiring responsible disposal in compliance with current environmental regulations. During recent decades, increased emphasis has been placed on effluent control and treatment, in order to avoid the threat to the environment posed by toxic constituents. In many modern gold mining and ore processing operations, cyanide species are of most immediate concern. Given that natural degradation processes are known to reduce the toxicity of cyanide over time, trials have been made at laboratory and field scales into the feasibility of using wetland-based passive systems as low-cost and environmentally friendly methods for long-term treatment of leachates from closed gold mine tailing disposal facilities. Laboratory experiments on discrete aerobic and anaerobic treatment units supported the development of design parameters for the construction of a field-scale passive system at a gold mine site in northern Spain. An in situ pilot-scale wetland treatment system was designed, constructed and monitored over a nine-month period. Overall, the results suggest that compost-based constructed wetlands are capable of detoxifying cyanidation effluents, removing about 21.6% of dissolved cyanide and 98% of Cu, as well as nitrite and nitrate. Wetland-based passive systems can therefore be considered as a viable technology for removal of residual concentrations of cyanide from leachates emanating from closed gold mine tailing disposal facilities
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