5,754 research outputs found
Matter-wave 2D solitons in crossed linear and nonlinear optical lattices
It is demonstrated the existence of multidimensional matter-wave solitons in
a crossed optical lattice (OL) with linear OL in the direction and
nonlinear OL (NOL) in the direction, where the NOL can be generated by a
periodic spatial modulation of the scattering length using an optically induced
Feshbach resonance. In particular, we show that such crossed linear and
nonlinear OL allows to stabilize two-dimensional (2D) solitons against decay or
collapse for both attractive and repulsive interactions. The solutions for the
soliton stability are investigated analytically, by using a multi-Gaussian
variational approach (VA), with the Vakhitov-Kolokolov (VK) necessary criterion
for stability; and numerically, by using the relaxation method and direct
numerical time integrations of the Gross-Pitaevskii equation (GPE). Very good
agreement of the results corresponding to both treatments is observed.Comment: 8 pages (two-column format), with 16 eps-files of 4 figure
The quantized Hall conductance of a single atomic wire: A proposal based on synthetic dimensions
We propose a method by which the quantization of the Hall conductance can be
directly measured in the transport of a one-dimensional atomic gas. Our
approach builds on two main ingredients: (1) a constriction optical potential,
which generates a mesoscopic channel connected to two reservoirs, and (2) a
time-periodic modulation of the channel, specifically designed to generate
motion along an additional synthetic dimension. This fictitious dimension is
spanned by the harmonic-oscillator modes associated with the tightly-confined
channel, and hence, the corresponding "lattice sites" are intimately related to
the energy of the system. We analyze the quantum transport properties of this
hybrid two-dimensional system, highlighting the appealing features offered by
the synthetic dimension. In particular, we demonstrate how the energetic nature
of the synthetic dimension, combined with the quasi-energy spectrum of the
periodically-driven channel, allows for the direct and unambiguous observation
of the quantized Hall effect in a two-reservoir geometry. Our work illustrates
how topological properties of matter can be accessed in a minimal
one-dimensional setup, with direct and practical experimental consequences.
Density dependent gauge field inducing emergent SSH physics, solitons and condensates in a discrete nonlinear Schr\"odinger equation
We investigate a discrete non-linear Schr\"odinger equation with dynamical,
density-difference-dependent, gauge fields. We find a ground-state transition
from a plane wave condensate to a localized soliton state as the gauge coupling
is varied. Interestingly we find a regime in which the condensate and soliton
are both stable. We identify an emergent chiral symmetry, which leads to the
existence of a symmetry protected zero energy edge mode. The emergent chiral
symmetry relates low and high energy solitons. These states indicate that the
interaction acts both repulsively and attractively
Reversible effect of magnetic fields on human lymphocyte activation patterns: different sensitivity of naive and memory lymphocyte subsets.
The aim of this study was to investigate the influence of 50 Hz
magnetic or static magnetic fields of 0.5 mT on subsets of human
CD4+ T cells in terms of cytokine release/content, cell
proliferation and intracellular free calcium concentration.
CD4+ T cells can be divided into different subsets on the basis
of surface marker expression, such as CD45, and T cells can be
divided into naive (CD45RA+) and memory (CD45RA2) cells. In
this study, the effects of magnetic fields after 24 and 48 h of cell
culture were analyzed. We found that the CD4+CD45RA2 T
subset were more sensitive after 2 h of exposure. Decreases in
the release/content of IFN-c, in cell proliferation and in
intracellular free calcium concentrations were observed in
exposed CD4+CD45RA2 T cells compared to CD4+CD45RA+
T cells. The results suggest that exposure to the magnetic fields
induces a delay in the response to stimulants and that
modifications are rapidly reversible, at least after a short
exposure
Base sequence dependent sliding of proteins on DNA
The possibility that the sliding motion of proteins on DNA is influenced by
the base sequence through a base pair reading interaction, is considered.
Referring to the case of the T7 RNA-polymerase, we show that the protein should
follow a noise-influenced sequence-dependent motion which deviate from the
standard random walk usually assumed. The general validity and the implications
of the results are discussed.Comment: 12 pages, 3 figure
Laryngeal Candidiasis Mimicking Supraglottic Carcinoma by Prolonged Inhaled Steroid Therapy: A Case Report and Review of the Literature
Candidiasis is a rare entity reported as an isolated and primary laryngeal disease. In this condition, inhaled steroids were the single most common predisposing factor. Also mycotic infections of larynx are frequently seen in patients with immune insufficiency, although they have also been reported in individual with normal immune status. We report a case of isolated laryngeal Candidiasis in an immunocompetent individual, with an unusual presentation with exophytic lesion, edema, ulceration, white plaque, and pseudomembranous formation mimicking supraglottic carcinoma, to highlight the clinical of this condition and provide a review of the literature
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