4,757 research outputs found
Three-Dimensional Nonlinear Lattices: From Oblique Vortices and Octupoles to Discrete Diamonds and Vortex Cubes
We construct a variety of novel localized states with distinct topological
structures in the 3D discrete nonlinear Schr{\"{o}}dinger equation. The states
can be created in Bose-Einstein condensates trapped in strong optical lattices,
and crystals built of microresonators. These new structures, most of which have
no counterparts in lower dimensions, range from purely real patterns of dipole,
quadrupole and octupole types to vortex solutions, such as "diagonal" and
"oblique" vortices, with axes oriented along the respective directions
and . Vortex "cubes" (stacks of two quasi-planar vortices
with like or opposite polarities) and "diamonds" (discrete skyrmions formed by
two vortices with orthogonal axes) are constructed too. We identify stability
regions of these 3D solutions and compare them with their 2D counterparts, if
any. An explanation for the stability/instability of most solutions is
proposed. The evolution of unstable states is studied as well.Comment: 4 pages, 4 figures, submitted January 200
Dynamics and Manipulation of Matter-Wave Solitons in Optical Superlattices
We analyze the existence and stability of bright, dark, and gap matter-wave
solitons in optical superlattices. Then, using these properties, we show that
(time-dependent) ``dynamical superlattices'' can be used to controllably place,
guide, and manipulate these solitons. In particular, we use numerical
experiments to displace solitons by turning on a secondary lattice structure,
transfer solitons from one location to another by shifting one superlattice
substructure relative to the other, and implement solitonic ``path-following'',
in which a matter wave follows the time-dependent lattice substructure into
oscillatory motion.Comment: 6 pages, revtex, 6 figures, to appear in Physics Letters A; minor
modifications from last versio
Phylogenetic signal in amphibian sensitivity to copper sulfate relative to experimental temperature
The release of large quantities of chemicals into the environment represents a major source of environmental disturbance. In recent years, the focus of ecotoxicology has shifted from describing the effects of chemical contaminants on individual species to developing more integrated approaches for predicting and evaluating long term effects of chemicals across species and ecosystems. Traditional ecotoxicology is typically based on data of sensitivity of a few surrogate species to a contaminant and often considers little variability in chemical sensitivity within and among taxonomic groups. This approach assumes that evolutionary history and phylogenetic relatedness among species have little or no impact on species’ sensitivity to chemical compounds. Few studies have tested this assumption. Using phylogenetic comparative methods and published data for amphibians, we show that sensitivity to copper sulfate, a commonly used pesticide, exhibits a strong phylogenetic signal when controlling for experimental temperature. Our results indicate that evolutionary history needs to be accounted for to make accurate predictions of amphibian sensitivity to this contaminant under different temperature scenarios. Since physiological and metabolic traits showing high phylogenetic signal likely underlie variation in species sensitivity to chemical stressors, future studies should evaluate and predict species vulnerability to pollutants using evolutionarily informed approaches
Families of Matter-Waves for Two-Component Bose-Einstein Condensates
We produce several families of solutions for two-component nonlinear
Schr\"{o}dinger/Gross-Pitaevskii equations. These include domain walls and the
first example of an antidark or gray soliton in the one component, bound to a
bright or dark soliton in the other. Most of these solutions are linearly
stable in their entire domain of existence. Some of them are relevant to
nonlinear optics, and all to Bose-Einstein condensates (BECs). In the latter
context, we demonstrate robustness of the structures in the presence of
parabolic and periodic potentials (corresponding, respectively, to the magnetic
trap and optical lattices in BECs).Comment: 6 pages, 4 figures, EPJD in pres
Granitos postcinemáticos de tendencia alcalina en Ossa Morena: el stock de la Cardenchosa (prov. de Córdoba)
El stock de La Cardenchosa forma part d'un grup de granits post-cinemàtics de tendència alcalina d'edat posttournaisiana i que afloren en la zona d'Ossa Morena. Aquests granits presenten com trets característics l'allargament N-S dels seus afloraments, el seu emplaçament superficial, la presència de fàcies leucocràtiques i l'íntima connexió dels jaciments de fluorita i/o barita. La composició química i menirelògica del stock de La Cardenchosa és comparada amb altres de la mateixa regió
Exploring Rigidly Rotating Vortex Configurations and their Bifurcations in Atomic Bose-Einstein Condensates
In the present work, we consider the problem of a system of few vortices as it emerges from its experimental realization in the field of atomic
Bose-Einstein condensates. Starting from the corresponding equations of motion,
we use a two-pronged approach in order to reveal the configuration space of the
system's preferred dynamical states. On the one hand, we use a Monte-Carlo
method parametrizing the vortex "particles" by means of hyperspherical
coordinates and identifying the minimal energy ground states thereof for and different vortex particle angular momenta. We then complement this
picture with a dynamical systems analysis of the possible rigidly rotating
states. The latter reveals all the supercritical and subcritical pitchfork, as
well as saddle-center bifurcations that arise exposing the full wealth of the
problem even at such low dimensional cases. By corroborating the results of the
two methods, it becomes fairly transparent which branch the Monte-Carlo
approach selects for different values of the angular momentum which is used as
a bifurcation parameter.Comment: 12 pages, 7 figures. New improved result
Fracciones nitrogenadas y aminoácidos libres del queso de Los Pedroches
Se ha examinado el contenido en las principales fracciones nitrogenadas y en aminoácidos libres de 16 muestras de queso maduro, típico del Valle de Los Pedroches (Córdoba), elaborado artesanalmente por otros tantos productores. El contenido medio en las diferentes fracciones nitrogenadas (en % del N total) fue el siguiente: N soluble 40,47, N no proteico 19,23, N amínico 9,70, N amoniacal 3,38. El índice de Savini (coeficiente de degradación) fue, por término medio, de 13. El contenido en tirosina y triptófano solubles fue, respectivamente, de 396 y 176 mg/100 g de queso. Cromatográficamente se detectaron 14 aminoácidos libres, 8 de ellos esenciales para el hombre. En todos los quesos se detectó om, lys, asp, glu, pro, gly, ala, leu, val y ser; en casi todos arg, thr, met y phe. Predominaron cuantitativamente leu, val, lys y glu
On the Environmental Dependence of Cluster Galaxy Assembly Timescale
We present estimates of CN and Mg overabundances with respect to Fe for
early-type galaxies in 8 clusters over a range of richness and morphology.
Spectra were taken from the Sloan Digital Sky Survey (SDSS) DR1, and from WHT
and CAHA observations. Abundances were derived from absorption lines and single
burst population models, by comparing galaxy spectra with appropriately
broadened synthetic model spectra. We detect correlations between [Mg/CN] and
[CN/Fe] and cluster X-ray luminosity. No correlation is observed for [Mg/Fe].
We also see a clear trend with the richness and morphology of the clusters.
This is interpreted given varying formation timescales for CN, Mg and Fe, and a
varying star formation history in early-type galaxies as a function of their
environment: intermediate-mass early-type galaxies in more massive clusters are
assembled on shorter timescales than in less massive clusters, with an upper
limit of ~1 Gyr.Comment: Accepted for publication in ApJ Letter
- …