742 research outputs found
Naturally graded quasi-filiform Leibniz algebras
AbstractThe classification of naturally graded quasi-filiform Lie algebras is known; they have the characteristic sequence (n−2,1,1) where n is the dimension of the algebra. In the present paper we deal with naturally graded quasi-filiform non-Lie–Leibniz algebras which are described by the characteristic sequence C(L)=(n−2,1,1) or C(L)=(n−2,2). The first case has been studied in [Camacho, L.M., Gómez, J.R., González, A.J., Omirov, B.A., 2006. Naturally graded 2-filiform Leibniz Algebra and its applications, preprint, MA1-04-XI06] and now, we complete the classification of naturally graded quasi-filiform Leibniz algebras. For this purpose we use the software Mathematica (the program used is explained in the last section)
Controlled transport of solitons and bubbles using external perturbations
We investigate generalized soliton-bearing systems in the presence of
external perturbations. We show the possibility of the transport of solitons
using external waves, provided the waveform and its velocity satisfy certain
conditions. We also investigate the stabilization and transport of bubbles
using external perturbations in 3D-systems. We also present the results of real
experiments with laser-induced vapor bubbles in liquids.Comment: 26 pages, 24 figure
Multistable Solitons in the Cubic-Quintic Discrete Nonlinear Schr\"odinger Equation
We analyze the existence and stability of localized solutions in the
one-dimensional discrete nonlinear Schr\"{o}dinger (DNLS) equation with a
combination of competing self-focusing cubic and defocusing quintic onsite
nonlinearities. We produce a stability diagram for different families of
soliton solutions, that suggests the (co)existence of infinitely many branches
of stable localized solutions. Bifurcations which occur with the increase of
the coupling constant are studied in a numerical form. A variational
approximation is developed for accurate prediction of the most fundamental and
next-order solitons together with their bifurcations. Salient properties of the
model, which distinguish it from the well-known cubic DNLS equation, are the
existence of two different types of symmetric solitons and stable asymmetric
soliton solutions that are found in narrow regions of the parameter space. The
asymmetric solutions appear from and disappear back into the symmetric ones via
loops of forward and backward pitchfork bifurcations.Comment: To appear Physica D. 23 pages, 13 figure
Multistable Solitons in Higher-Dimensional Cubic-Quintic Nonlinear Schroedinger Lattices
We study the existence, stability, and mobility of fundamental discrete
solitons in two- and three-dimensional nonlinear Schroedinger lattices with a
combination of cubic self-focusing and quintic self-defocusing onsite
nonlinearities. Several species of stationary solutions are constructed, and
bifurcations linking their families are investigated using parameter
continuation starting from the anti-continuum limit, and also with the help of
a variational approximation. In particular, a species of hybrid solitons,
intermediate between the site- and bond-centered types of the localized states
(with no counterpart in the 1D model), is analyzed in 2D and 3D lattices. We
also discuss the mobility of multi-dimensional discrete solitons that can be
set in motion by lending them kinetic energy exceeding the appropriately
crafted Peierls-Nabarro barrier; however, they eventually come to a halt, due
to radiation loss.Comment: 12 pages, 17 figure
Towards the characterization of individual users through Web analytics
We perform an analysis of the way individual users navigate in the Web. We
focus primarily in the temporal patterns of they return to a given page. The
return probability as a function of time as well as the distribution of time
intervals between consecutive visits are measured and found to be independent
of the level of activity of single users. The results indicate a rich variety
of individual behaviors and seem to preclude the possibility of defining a
characteristic frequency for each user in his/her visits to a single site.Comment: 8 pages, 4 figures. To appear in Proceeding of Complex'0
Potential Mechanisms Involved in Palmitoylethanolamide-Induced Vasodepressor Effects in Rats
Palmitoylethanolamide is an endogenous lipid that exerts complex vascular effects, enhances the effects of endocannabinoids and induces a direct hypotension, but the mechanisms involved have been poorly explored. Hence, this study investigated in Wistar pithed rats the role of CB1, CB2, TRPV1 and GPR55 receptors in the inhibition by palmitoylethanolamide of the vasopressor responses produced by sympathetic stimulation or exogenous noradrenaline. Frequency- and dose-dependent vasopressor responses were analysed before and during intravenous (i.v.) continuous infusions of palmitoyle
Modulated Amplitude Waves in Bose-Einstein Condensates
We analyze spatio-temporal structures in the Gross-Pitaevskii equation to
study the dynamics of quasi-one-dimensional Bose-Einstein condensates (BECs)
with mean-field interactions. A coherent structure ansatz yields a
parametrically forced nonlinear oscillator, to which we apply Lindstedt's
method and multiple-scale perturbation theory to determine the dependence of
the intensity of periodic orbits (``modulated amplitude waves'') on their wave
number. We explore BEC band structure in detail using Hamiltonian perturbation
theory and supporting numerical simulations.Comment: 5 pages, 4 figs, revtex, final form of paper, to appear in PRE
(forgot to include \bibliography command in last update, so this is a
correction of that; the bibliography is hence present again
Electroweak Precision Observables within a Fourth Generation Model with General Flavour Structure
We calculate the contributions to electroweak precision observables (EWPOs)
due to a fourth generation of fermions with the most general (quark-)flavour
structure (but assuming Dirac neutrinos and a trivial flavour structure in the
lepton sector). The new-physics contributions to the EWPOs are calculated at
one-loop order using automated tools (FeynArts/FormCalc). No further
approximations are made in our calculation. We discuss the size of non-oblique
contributions arising from Z--quark--anti-quark vertex corrections and the
dependence of the EWPOs on all CKM mixing angles involving the fourth
generation. We find that the electroweak precision observables are sensitive to
two of the fourth-generation mixing angles and that the corresponding
constraints on these angles are competitive with those obtained from flavour
physics. For non-trivial 4x4 flavour structures, the non-oblique contributions
lead to relative corrections of several permille and should be included in a
global fit
Dynamics of trapped bright solitons in the presence of localized inhomogeneities
We examine the dynamics of a bright solitary wave in the presence of a
repulsive or attractive localized ``impurity'' in Bose-Einstein condensates
(BECs). We study the generation and stability of a pair of steady states in the
vicinity of the impurity as the impurity strength is varied. These two new
steady states, one stable and one unstable, disappear through a saddle-node
bifurcation as the strength of the impurity is decreased. The dynamics of the
soliton is also examined in all the cases (including cases where the soliton is
offset from one of the relevant fixed points). The numerical results are
corroborated by theoretical calculations which are in very good agreement with
the numerical findings.Comment: 8 pages, 5 composite figures with low res (for high res pics please
go to http://www.rohan.sdsu.edu/~rcarrete/ [Publications] [Publication#41
Microscopic transition potential: Determination of and coupling constants
A transition potential, based on an effective
quark-quark interaction and a constituent quark cluster model for baryons, is
derived in the Born-Oppenheimer approach. The potential shows significant
differences with respect to those obtained by a direct scaling of the
nucleon-nucleon interaction. From its asymptotic behavior we extract the values
of and coupling constants in a
particular coupling schemeComment: 15 eps figures, Accepted for publication in Phys. Rev.
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