7,917 research outputs found
Increased prevalence of metabolic syndrome in patients with bipolar disorder compared to a selected control group-a Northern Netherlands LifeLines population cohort study
OBJECTIVES: Metabolic syndrome (MetS) is highly prevalent among patients with bipolar disorder (BD). The aims of this cross-sectional study were to determine the prevalence of MetS in Dutch BD subjects and compare it with a control group, to examine the association of demographic and clinical characteristics with MetS in BD, and to determine the extent to which metabolic dysregulation is treated in those patients. METHODS: 493 Dutch adult patients (≥ 18 years) with BD receiving psychotropic drugs and 493 matched control subjects were compared using data from the biobank Lifelines. We determined MetS according to the National Cholesterol Education Program Adult Treatment Panel III-Adapted (NCEP ATP III-A) criteria. The difference in the prevalence of MetS and the associations with characteristics were analyzed with logistic regression. RESULTS: BD subjects (30.6%) showed a significantly higher prevalence of MetS compared to the control group (14.2%) (p < .001, OR:2.67, 95% CI:1.94-3.66). Univariate analysis showed that smoking, body mass index (BMI) and antidepressant drug use were associated with MetS. Multivariate analysis showed that smoking (OR:2.01) was independently associated with MetS in BD. For hypertension, hyperglycemia and lipid disorder pharmacological treatment was provided to respectively 69.5%, 24% and 18.4% of the BD subjects in our sample. LIMITATIONS: Duration of illness of BD subjects was unknown. CONCLUSIONS: This study demonstrated a higher prevalence of MetS in Dutch BD subjects compared to persons without BD. In addition, a remarkable undertreatment of some of the components of MetS was found
Multidimensional solitons in periodic potentials
The existence of stable solitons in two- and three-dimensional (2D and 3D)
media governed by the self-focusing cubic nonlinear Schr\"{o}dinger equation
with a periodic potential is demonstrated by means of the variational
approximation (VA) and in direct simulations. The potential stabilizes the
solitons against collapse. Direct physical realizations are a Bose-Einstein
condensate (BEC) trapped in an optical lattice, and a light beam in a bulk Kerr
medium of a photonic-crystal type. In the 2D case, the creation of the soliton
in a weak lattice potential is possible if the norm of the field (number of
atoms in BEC, or optical power in the Kerr medium) exceeds a threshold value
(which is smaller than the critical norm leading to collapse). Both
"single-cell" and "multi-cell" solitons are found, which occupy, respectively,
one or several cells of the periodic potential, depending on the soliton's
norm. Solitons of the former type and their stability are well predicted by VA.
Stable 2D vortex solitons are found too.Comment: 13 pages, 3 figures, Europhys. Lett., in pres
Loop structure of the lowest Bloch band for a Bose-Einstein condensate
We investigate analytically and numerically Bloch waves for a Bose--Einstein
condensate in a sinusoidal external potential. At low densities the dependence
of the energy on the quasimomentum is similar to that for a single particle,
but at densities greater than a critical one the lowest band becomes
triple-valued near the boundary of the first Brillouin zone and develops the
structure characteristic of the swallow-tail catastrophe. We comment on the
experimental consequences of this behavior.Comment: 4 pages, 7 figure
Optical flow analysis reveals that Kinesin-mediated advection impacts on the orientation of microtubules in the Drosophila oocyte.
The orientation of microtubule networks is exploited by motors to deliver cargoes to specific intracellular destinations, and is thus essential for cell polarity and function. Reconstituted in vitro systems have largely contributed to understanding the molecular framework regulating the behavior of microtubule filaments. In cells however, microtubules are exposed to various biomechanical forces that might impact on their orientation, but little is known about it. Oocytes, which display forceful cytoplasmic streaming, are excellent model systems to study the impact of motion forces on cytoskeletons in vivo. Here we implement variational optical flow analysis as a new approach to analyze the polarity of microtubules in the Drosophila oocyte, a cell that displays distinct Kinesin-dependent streaming. After validating the method as robust for describing microtubule orientation from confocal movies, we find that increasing the speed of flows results in aberrant plus end growth direction. Furthermore, we find that in oocytes where Kinesin is unable to induce cytoplasmic streaming, the growth direction of microtubule plus ends is also altered. These findings lead us to propose that cytoplasmic streaming - and thus motion by advection - contributes to the correct orientation of MTs in vivo. Finally, we propose a possible mechanism for a specialised cytoplasmic actin network (the actin mesh) to act as a regulator of flow speeds; to counteract the recruitment of Kinesin to microtubules. [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text] [Media: see text]
Low-density, one-dimensional quantum gases in a split trap
We investigate degenerate quantum gases in one dimension trapped in a
harmonic potential that is split in the centre by a pointlike potential. Since
the single particle eigenfunctions of such a system are known for all strengths
of the central potential, the dynamics for non-interacting fermionic gases and
low-density, strongly interacting bosonic gases can be investigated exactly
using the Fermi-Bose mapping theorem. We calculate the exact many-particle
ground-state wave-functions for both particle species, investigate soliton-like
solutions, and compare the bosonic system to the well-known physics of Bose
gases described by the Gross-Pitaevskii equation. We also address the
experimentally important questions of creation and detection of such states.Comment: 7 pages, 5 figure
Steering proton migration in hydrocarbons using intense few-cycle laser fields
Proton migration is a ubiquitous process in chemical reactions related to
biology, combustion, and catalysis. Thus, the ability to control the movement
of nuclei with tailored light, within a hydrocarbon molecule holds promise for
far-reaching applications. Here, we demonstrate the steering of hydrogen
migration in simple hydrocarbons, namely acetylene and allene, using
waveform-controlled, few-cycle laser pulses. The rearrangement dynamics are
monitored using coincident 3D momentum imaging spectroscopy, and described with
a quantum-dynamical model. Our observations reveal that the underlying control
mechanism is due to the manipulation of the phases in a vibrational wavepacket
by the intense off-resonant laser field.Comment: 5 pages, 4 figure
Quasi-periodic vs. irreversible dynamics of an optically confined Bose-Einstein condensate
We consider the evolution of a dilute Bose-Einstein condensate in an optical
trap formed by a doughnut laser mode. By solving a one dimensional
Gross-Pitaevskii equation and looking at the variance and the statistical
entropy associated with the position of the system we can study the dynamical
behavior of the system. It is shown that for small condensates nonlinear
revivals of the macroscopic wave function are expected. For sufficiently large
and dense condensates irreversible dynamics takes place for which revivals of
regular dynamics appear as predicted in [9]. These results are confirmed by a
two dimensional simulation in which the scales of energy associated with the
two different directions mimic the experimental situation.Comment: 10 page
Continuous optical loading of a Bose-Einstein Condensate
The continuous pumping of atoms into a Bose-Einstein condensate via
spontaneous emission from a thermal reservoir is analyzed. We consider the case
of atoms with a three-level scheme, in which one of the atomic
transitions has a very much shorter life-time than the other one. We found that
in such scenario the photon reabsorption in dense clouds can be considered
negligible. If in addition inelastic processes can be neglected, we find that
optical pumping can be used to continuously load and refill Bose-Einstein
condensates, i.e. provides a possible way to achieve a continuous atom laser.Comment: 12 pages, 8 figure
Bogoliubov sound speed in periodically modulated Bose-Einstein condensates
We study the Bogoliubov excitations of a Bose-condensed gas in an optical
lattice. Of primary interest is the long wavelength phonon dispersion for both
current-free and current-carrying condensates. We obtain the dispersion
relation by carrying out a systematic expansion of the Bogoliubov equations in
powers of the phonon wave vector. Our result for the current-carrying case
agrees with the one recently obtained by means of a hydrodynamic theory.Comment: 16 pages, no figure
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