422 research outputs found
Lump-like Structures in Scalar-field Models
In this work we investigate the presence of lump-like solutions in models
described by a single real scalar field. We take advantage of a procedure
recently used to describe explicit analytical solutions and we study several
distinct models, showing how the parameters can be used to control the specific
features of the lump-like structures. The proposed models are of direct
interest to the construction of q-balls, to induce tachyonic excitations and
gravitating structures of nontopological profile on braneworld models with a
single extra dimension, to map solitons in optical fibers, and to describe
collective excitations in Bose-Einstein condensates.Comment: 7 pages, 11 figure
Nonlinear Schrodinger equation with chaotic, random, and nonperiodic nonlinearity
In this paper we deal with a nonlinear Schr\"{o}dinger equation with chaotic,
random, and nonperiodic cubic nonlinearity. Our goal is to study the soliton
evolution, with the strength of the nonlinearity perturbed in the space and
time coordinates and to check its robustness under these conditions. Comparing
with a real system, the perturbation can be related to, e.g., impurities in
crystalline structures, or coupling to a thermal reservoir which, on the
average, enhances the nonlinearity. We also discuss the relevance of such
random perturbations to the dynamics of Bose-Einstein Condensates and their
collective excitations and transport.Comment: 4 pages, 6 figure
Solitons with Cubic and Quintic Nonlinearities Modulated in Space and Time
This work deals with soliton solutions of the nonlinear Schroedinger equation
with cubic and quintic nonlinearities. We extend the procedure put forward in a
recent Letter and we solve the equation in the presence of linear background,
and cubic and quintic interactions which are modulated in space and time. As a
result, we show how a simple parameter can be used to generate brightlike or
darklike localized nonlinear waves which oscillate in several distinct ways,
driven by the space and time dependence of the parameters that control the
trapping potential, and the cubic and quintic nonlinearities.Comment: 4 pages, 6 figures; version to appear in PRE, R
Solitons with Cubic and Quintic Nonlinearities Modulated in Space and Time
This work deals with soliton solutions of the nonlinear Schroedinger equation
with cubic and quintic nonlinearities. We extend the procedure put forward in a
recent Letter and we solve the equation in the presence of linear background,
and cubic and quintic interactions which are modulated in space and time. As a
result, we show how a simple parameter can be used to generate brightlike or
darklike localized nonlinear waves which oscillate in several distinct ways,
driven by the space and time dependence of the parameters that control the
trapping potential, and the cubic and quintic nonlinearities.Comment: 4 pages, 6 figures; version to appear in PRE, R
Solitons of two-component Bose-Einstein condensates modulated in space and time
In this paper we present soliton solutions of two coupled nonlinear
Schodinger equations modulated in the bspace and time. The approach allows us
to obatin solitons with large variety of solutions depending on the
nonlinearity and the potential profiles. As examples we show three cases with
soliton solution in such system, one of them with potential varying between
repulsive and attractive behavior and the others with nonlinearity localized
and delocalized, respectively.Comment: 18 pages, 8 figure
A new species of Tunga perforating the osteoderms of its armadillo host in Argentina and redescription of the male of Tunga terasma
A new species of Tunga (Siphonaptera: Tungidae) collected from armadillos in Argentina is described. The new species is characterized by large and pigmented eyes, the presence of two bristles on antennal segment II, two bristles at the base of the maxilla, and a discoid neosome compressed anteroposteriorly. The gravid female is located in the carapace of the host, perforating the osteoderms. The new species resembles Tunga penetrans and Tunga terasma in general appearance. However, it differs by the greater anteroposterior compression of the neosome, a more angular head, and a manubrium with a pointed proximal end and convex ventral margin (the proximal end of the manubrium is rounded or slightly pointed in T. terasma, and the ventral margin is straight in both T. penetrans and T. terasma). In addition, specimens of T. penetrans have more bristles in antennal segments II and III, and lack bristles in the posterior tibia.
This is the first report of a species of Tunga perforating the osteoderms of its host and thereby showing a high degree of specialization. Tunga terasma is recorded for the first time in Argentina; the male is described again and the characteristics of the species amended. This information may be useful in epidemiological studies of diseases caused by species of Tunga.Centro de Estudios Parasitológicos y de Vectore
Health literacy, quality of life and burden of informal caregivers in Portugal
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