400 research outputs found
Phase fluctuations in atomic Bose gases
We improve on the Popov theory for partially Bose-Einstein condensed atomic
gases by treating the phase fluctuations exactly. As a result, the theory
becomes valid in arbitrary dimensions and is able to describe the
low-temperature crossover between three, two and one-dimensional Bose gases,
which is currently being explored experimentally. We consider both homogeneous
and trapped Bose gases.Comment: 4 pages. Title changed Major changes involve extension of theory to
include trapped Bose gases. Deletion of reference to and comparison with
hydrogen experiment. Due to these changes, second author added. Modified
manuscript accepted for PR
Examining the Impact of Job Security, Organizational Climate and Engagement on Motivation Level of Employees at IMC PVT LTD
The aim of this paper is to find out the relationship of Motivation with organization climate, engagement, and job security in a service organization, where the company is going through rightsizing. Moreover the company is also utilizing temp staff. This study finds out as to how employees working in the organization perceive it and how much they feel connected to it. Is there any variation on their Motivation regarding job security keeping in view the economic crises in the Country
Unidirectional flow of flat-top solitons
We numerically demonstrate the unidirectional flow of flat-top solitons when
interacting with two reflectionless potential wells with slightly different
depths. The system is described by a nonlinear Schr\"{o}dinger equation with
dual nonlinearity. The results show that for shallow potential wells, the
velocity window for unidirectional flow is larger than for deeper potential
wells. A wider flat-top solitons also have a narrow velocity window for
unidirectional flow than those for thinner flat-top solitons.Comment: 5 pages, 7 figure
Toisintokuume : Infektio, joka tulee huomioida maahantulijan kuumetaudin erotusdiagnostiikassa
English summaryPeer reviewe
Dimensional and Temperature Crossover in Trapped Bose Gases
We investigate the long-range phase coherence of homogeneous and trapped Bose
gases as a function of the geometry of the trap, the temperature, and the
mean-field interactions in the weakly interacting limit. We explicitly take
into account the (quasi)condensate depletion due to quantum and thermal
fluctuations, i.e., we include the effects of both phase and density
fluctuations. In particular, we determine the phase diagram of the gas by
calculating the off-diagonal one-particle density matrix and discuss the
various crossovers that occur in this phase diagram and the feasibility of
their experimental observation in trapped Bose gases.Comment: One figure added, typos corrected, refernces adde
Association study of two interleukin-1 gene loci with essential hypertension in a Pakistani Pathan population
An association study of IL-1 beta -511C/T and IL-1 RN 86 bp VNTR polymorphisms with essential hypertension was carried out in a sample population of 500 Pakistani Pathan subjects selected randomly, comprising groups of 235 subjects with hypertension and 265 controls. The distribution of both genotypes and alleles was not statistically different in cases and controls. In conclusion, IL-1 beta -511C/T and IL-1 RN 86 bp VNTR do not contribute to the aetiology of essential hypertension in the Pakistani Pathan population investigated here
Quadrupole collective modes in trapped finite-temperature Bose-Einstein condensates
Finite temperature simulations are used to study quadrupole excitations of a
trapped Bose-Einstein condensate. We focus specifically on the m=0 mode, where
a long-standing theoretical problem has been to account for an anomalous
variation of the mode frequency with temperature. We explain this behavior in
terms of the excitation of two separate modes, corresponding to coupled motion
of the condensate and thermal cloud. The relative amplitudes of the modes
depends sensitively on the temperature and on the frequency of the harmonic
drive used to excite them. Good agreement with experiment is found for
appropriate drive frequencies.Comment: 4 pages, 3 figure
Metabolite and Lipid Biomarkers Associated With Intraocular Pressure and Inner Retinal Morphology: ¹H NMR Spectroscopy Results From the UK Biobank
Purpose: The purpose of this study was to assess metabolites associated with intraocular pressure (IOP) and inner retina structure. / Methods: We cross-sectionally assessed 168 non-fasting plasma metabolites measured by nuclear magnetic resonance (NMR) spectroscopy with IOP (n = 28,195), macular retinal nerve fiber layer thickness (mRNFL; n = 10,584), and macular ganglion cell inner plexiform layer thickness (mGCIPL; n = 10,554) in the UK Biobank. We used multiple linear regression models adjusting for various covariates with probit-transformed metabolite levels as predictors for each outcome. Each estimate represents the difference in outcome variable per standard deviation increase in the probit-transformed metabolite values. We used the number of effective (NEF) tests and false discovery rate (FDR) to adjust for multiple comparisons for metabolites and metabolite classes, respectively. / Results: In individual metabolite analysis, multiple amino acids, especially branched-chain amino acids, were associated with lower IOP (-0.12 mm Hg; 95% confidence interval = -0.16 to -0.07; NEF = 2.7E-05). Albumin, 3 hydroxybutyrate, lactate, and several lipids were associated with higher IOP (range = 0.07 to 0.18 mm Hg, NEF = ≤ 0.039). In IOP-adjusted analyses, five HDL-related metabolites were associated with thinner mRNFL (-0.15 microns for all metabolites, NEF = ≤ 0.027), whereas five LDL-related metabolites were associated with thicker mGCIPL (range = 0.17 to 0.20 microns; NEF = ≤ 0.044). In metabolite class analysis, the lipid components of lipoproteins (cholesterol, triglycerides, etc.) were not associated with our outcomes (FDR > 0.2 for all); yet multiple lipoproteins were significantly (FDR < 0.05) associated with all outcomes. / Conclusions: Branched-chain amino acids were associated with lower IOP, HDL metabolites were associated with thinner mRNFL, and LDL metabolites were associated with thicker mGCIPL
Extension of Bogoliubov theory to quasi-condensates
We present an extension of the well-known Bogoliubov theory to treat low
dimensional degenerate Bose gases in the limit of weak interactions and low
density fluctuations. We use a density-phase representation and show that a
precise definition of the phase operator requires a space discretisation in
cells of size . We perform a systematic expansion of the Hamiltonian in
terms of two small parameters, the relative density fluctuations inside a cell
and the phase change over a cell. The resulting macroscopic observables can be
computed in one, two and three dimensions with no ultraviolet or infrared
divergence. Furthermore this approach exactly matches Bogoliubov's approach
when there is a true condensate. We give the resulting expressions for the
equation of state of the gas, the ground state energy, the first order and
second order correlations functions of the field. Explicit calculations are
done for homogeneous systems.Comment: 32 pages, 2 figures; typos corrected in revised versio
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