4,030 research outputs found
Free initial wave packets and the long-time behavior of the survival and nonescape probabilities
The behavior of both the survival S(t) and nonescape P(t) probabilities at
long times for the one-dimensional free particle system is shown to be closely
connected to that of the initial wave packet at small momentum. We prove that
both S(t) and P(t) asymptotically exhibit the same power-law decrease at long
times, when the initial wave packet in momentum representation behaves as O(1)
or O(k) at small momentum. On the other hand, if the integer m becomes greater
than 1, S(t) and P(t) decrease in different power-laws at long times.Comment: 4 pages, 3 figures, Title and organization changed, however the
results not changed, To appear in Phys. Rev.
Atomic quasi-Bragg diffraction in a magnetic field
We report on a new technique to split an atomic beam coherently with an
easily adjustable splitting angle. In our experiment metastable helium atoms in
the |{1s2s}^3S_1 M=1> state diffract from a polarization gradient light field
formed by counterpropagating \sigma^+ and \sigma^- polarized laser beams in the
presence of a homogeneous magnetic field. In the near-adiabatic regime, energy
conservation allows the resonant exchange between magnetic energy and kinetic
energy. As a consequence, symmetric diffraction of |M=0> or |M=-1> atoms in a
single order is achieved, where the order can be chosen freely by tuning the
magnetic field. We present experimental results up to 6th order diffraction (24
\hbar k momentum splitting, i.e., 2.21 m/s in transverse velocity) and present
a simple theoretical model that stresses the similarity with conventional Bragg
scattering. The resulting device constitutes a flexible, adjustable,
large-angle, three-way coherent atomic beam splitter with many potential
applications in atom optics and atom interferometry.Comment: 4 pages, 5 figure
Olanzapine causes hypothermia, inactivity, a deranged feeding pattern and weight gain in female Wistar rats
Olanzapine is an a-typical antipsychotic drug antagonizing predominantly 5-HT and dopamine but also histamine muscarin and a adrenergic receptors In humans Olanzapine induces weight gain and increases the risk of type 2 diabetes The underlying mechanisms of Olanzapine-induced weight gain are unclear To study this we administered Olanzapine (5 mg/kg) in female Wistar rats on a medium fat diet for 14 days via a permanent gastric catheter twice a day Just prior to the onset and at the middle of dark phase Food end water intake locomotor activity and body temperature were measured Olanzapine acutely induced hypothermia markedly decreased locomotor activity and increased body weight during 14 days of treatment Olanzapine treatment did not result in an alteration of 24 h food Intake but diurnal patterns of feeding behavior and body temperature were dramatically changed We conclude that in female Wistar rats Olanzapine has an acute hypothermic effect that the effect of Olanzapine on feeding behavior is secondary to the effect on activity and that Olanzapine-induced weight gain is primarily the result of reduction in locomotor activity (C) 2010 Elsevier Inc All rights reserve
Both resistance- and endurance-type exercise reduce the prevalence of hyperglycaemia in individuals with impaired glucose tolerance and in insulin-treated and non-insulin-treated type 2 diabetic patients
Aims/hypothesis The present study compares the impact of endurance- vs resistance-type exercise on subsequent 24 h blood glucose homeostasis in individuals with impaired glucose tolerance (IGT) and type 2 diabetes. Methods Fifteen individuals with IGT, 15 type 2 diabetic patients treated with exogenous insulin (INS), and 15 type 2 diabetic patients treated with oral glucose-lowering medication (OGLM) participated in a randomised crossover experiment. Participants were studied on three occasions for 3 days under strict dietary standardisation, but otherwise free-living conditions. Blood glucose homeostasis was assessed by ambulatory continuous glucose monitoring over the 24 h period following a 45 min session of resistance-type exercise (75% one repetition maximum), endurance-type exercise (50% maximum workload capacity) or no exercise at all. Results Average 24 h blood glucose concentrations were reduced from 7.4±0.2, 9.6±0.5 and 9.2±0.7 mmol/l during the control experiment to 6.9±0.2, 8.6±0.4 and 8.1±0.5 mmol/l (resistance-type exercise) and 6.8±0.2, 8.6±0.5 and 8.5±0.5 mmol/l (endurance-type exercise) over the 24 h period following a single bout of exercise in the IGT, OGLM and INS groups, respectively (p 10 mmol/l) was reduced by 35±7 and 33±11% over the 24 h period following a single session of resistanceand endurance-type exercise, respectively (p< 0.001 for both treatments). Conclusions/interpretation A single session of resistanceor endurance-type exercise substantially reduces the prevalence of hyperglycaemia during the subsequent 24 h period in individuals with IGT, and in insulin-treated and non-insulin-treated type 2 diabetic patients. Both resistance- and endurance-type exercise can be integrated in exercise intervention programmes designed to improve glycaemic control. Trial registration: Clinicaltrials.gov NCT00945165 Funding: The Netherlands Organization for Health Research and Development (ZonMw, the Netherlands). © 2011 The Author(s)
On-the-fly Uniformization of Time-Inhomogeneous Infinite Markov Population Models
This paper presents an on-the-fly uniformization technique for the analysis
of time-inhomogeneous Markov population models. This technique is applicable to
models with infinite state spaces and unbounded rates, which are, for instance,
encountered in the realm of biochemical reaction networks. To deal with the
infinite state space, we dynamically maintain a finite subset of the states
where most of the probability mass is located. This approach yields an
underapproximation of the original, infinite system. We present experimental
results to show the applicability of our technique
Changes in Eicosanoid and Tumour Necrosis Factor-α Production by Rat Peritoneal Macrophages During Carrageenin-Induced Peritonitis
Changes and correlations in cytokine and eicosanoid production by
blood monocytes, non-purified and purified peritoneal cells during a
carrageenin-induced peritonitis were investigated for a period of
ten days. The cells were isolated and stimulated in
vitro. Cytokine and eicosanoid production of the non-purified
fraction increased steadily during peritonitis. During the whole
episode of peritonitis the production capacity of granulocytes was
very low and hardly any effect on the production capacity of
macrophages (MÏ•) was observed. Cytokine and eicosanoid production of the
non-purified fraction was mainly due to the presence of MÏ•. The production capacity of the peripheral blood monocytes was not
similar to that of the peritoneal MÏ•
Field-induced magnetic transitions in the quasi-two-dimensional heavy-fermion antiferromagnets Ce_{n}RhIn_{3n+2} (n=1 or 2)
We have measured the field-dependent heat capacity in the tetragonal
antiferromagnets CeRhIn and CeRhIn, both of which have an
enhanced value of the electronic specific heat coefficient
mJ/mol-Ce K above . For the specific heat data at zero
applied magnetic field are consistent with the existence of an anisotropic
spin-density wave opening a gap in the Fermi surface for CeRhIn while
CeRhIn shows behavior consistent with a simple antiferromagnetic
magnon. From these results, the magnetic structure, in a manner similar to the
crystal structure, appears more two-dimensional in CeRhIn than in
CeRhIn where only about 12% of the Fermi surface remains ungapped
relative to 92% for CeRhIn. When both compounds behave in a
manner expected for heavy fermion systems as both and the electronic
heat capacity decrease as field is applied. When the field is applied in the
tetragonal basal plane (), CeRhIn and CeRhIn have very
similar phase diagrams which contain both first- and second-order field-induced
magnetic transitions .Comment: 15 pages, 4 figure
Notes on Stein-Sahi representations and some problems of non harmonic analysis
We discuss one natural class of kernels on pseudo-Riemannian symmetric
spaces.Comment: 40p
Minimal Model for Sand Dunes
We propose a minimal model for aeolian sand dunes. It combines an analytical
description of the turbulent wind velocity field above the dune with a
continuum saltation model that allows for saturation transients in the sand
flux. The model provides a qualitative understanding of important features of
real dunes, such as their longitudinal shape and aspect ratio, the formation of
a slip face, the breaking of scale invariance, and the existence of a minimum
dune size.Comment: 4 pages, 4 figures, replaced with publishd versio
Advancement of photonic integration technology for space applications: A x-band scan-on-receive synthetic aperture radar receiver with electro-photonic beamforming and frequency downconversion capability
Synthetic Aperture Radar is a well-known technique for remote sensing applications with great advantages like uninterrupted imaging capabilities even at night or in presence of cloud cover. However, spaceborne SAR sensors face major challenges such as cost and size, which are among the barriers against their applicability for future constellations of low-Earth observation applications. SAR sensors are not compact and require large or medium-sized satellites, which cost hundreds million dollars. To solve these challenges, the recently started SPACEBEAM project, funded by the European Commission, aims at developing a novel SAR Scan-on-Receive approach, exploiting a hybrid integrated optical beamforming network (iOBFN). The compactness and frequency flexibility of the proposed photonic solution complies with the requirements of future constellations of low-Earth orbit satellites in terms of size, weight, power consumption, and cost (SWaP-C). In the design of the SCORE SAR receiver module, we target the development of an X-band receiver having a large swath width of 50 km (5 times wider than state-of-art spaceborne SAR systems), although at the same time enabling a fine spatial resolution of 1.5 m in both along-track and across-track directions. In this paper, we present specifications and preliminary design of the SCORE-SAR receiver at equipment level, where we aim at the realization of a hermetically packaged hybrid InP/TriPleXâ„¢ photonic integrated circuit (PIC) for this application. We target the design for the PIC as well as for the RF front-end and control electronics, enabling the electro-photonic frequency down-conversion of the RF signals and the fast control of iOBFN with <300 ns switching time
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