9,240 research outputs found
My Western Rose
https://digitalcommons.library.umaine.edu/mmb-vp/6001/thumbnail.jp
Nonlinear Scattering of a Bose-Einstein Condensate on a Rectangular Barrier
We consider the nonlinear scattering and transmission of an atom laser, or
Bose-Einstein condensate (BEC) on a finite rectangular potential barrier. The
nonlinearity inherent in this problem leads to several new physical features
beyond the well-known picture from single-particle quantum mechanics. We find
numerical evidence for a denumerably infinite string of bifurcations in the
transmission resonances as a function of nonlinearity and chemical potential,
when the potential barrier is wide compared to the wavelength of oscillations
in the condensate. Near the bifurcations, we observe extended regions of
near-perfect resonance, in which the barrier is effectively invisible to the
BEC. Unlike in the linear case, it is mainly the barrier width, not the height,
that controls the transmission behavior. We show that the potential barrier can
be used to create and localize a dark soliton or dark soliton train from a
phonon-like standing wave.Comment: 15 pages, 15 figures, new version includes clarification of
definition of transmission coefficient in general nonlinear vs. linear cas
Hartree-Fock-Bogoliubov Model and Simulation of Attractive and Repulsive Bose-Einstein Condensates
We describe a model of dynamic Bose-Einstein condensates near a Feshbach
resonance that is computationally feasible under assumptions of spherical or
cylindrical symmetry. Simulations in spherical symmetry approximate the
experimentally measured time to collapse of an unstably attractive condensate
only when the molecular binding energy in the model is correct, demonstrating
that the quantum fluctuations and atom-molecule pairing included in the model
are the dominant mechanisms during collapse. Simulations of condensates with
repulsive interactions find some quantitative disagreement, suggesting that
pairing and quantum fluctuations are not the only significant factors for
condensate loss or burst formation. Inclusion of three-body recombination was
found to be inconsequential in all of our simulations, though we do not
consider recent experiments [1] conducted at higher densities
Maternal obesity has little effect on the immediate offspring but impacts on the next generation
Maternal obesity during pregnancy has been linked to an increased risk of obesity and cardiometabolic disease in the offspring, a phenomenon attributed to developmental programming. Programming effects may be transmissible across generations through both maternal and paternal inheritance, although the mechanisms remain unclear. Using a mouse model, we explored the effects of moderate maternal diet-induced obesity (DIO) on weight gain and glucose-insulin homeostasis in first-generation (F1) and second-generation offspring. DIO was associated with insulin resistance, hyperglycemia and dyslipidemia before pregnancy. Birth weight was reduced in female offspring of DIO mothers (by 6%, P = .039), and DIO offspring were heavier than controls at weaning (males by 47%, females by 27%), however there were no differences in glucose tolerance, plasma lipids, or hepatic gene expression at 6 months. Despite the relative lack of effects in the F1, we found clear fetal growth restriction and persistent metabolic changes in otherwise unmanipulated second-generation offspring with effects on birth weight, insulin levels, and hepatic gene expression that were transmitted through both maternal and paternal lines. This suggests that the consequences of the current dietary obesity epidemic may also have an impact on the descendants of obese individuals, even when the phenotype of the F1 appears largely unaffected
System for the measurement of oscillator instability
System for measuring phase and frequency fluctuations of high precision oscillator
Bose-Einstein condensates in standing waves: The cubic nonlinear Schroedinger equation with a periodic potential
We present a new family of stationary solutions to the cubic nonlinear
Schroedinger equation with a Jacobian elliptic function potential. In the limit
of a sinusoidal potential our solutions model a dilute gas Bose-Einstein
condensate trapped in a standing light wave. Provided the ratio of the height
of the variations of the condensate to its DC offset is small enough, both
trivial phase and nontrivial phase solutions are shown to be stable. Numerical
simulations suggest such stationary states are experimentally observable.Comment: 4 pages, 4 figure
An examination of business occupier relocation decision making : distinguishing small and large firm behaviour
This paper explores how business occupiers decide whether and where to relocate. It captures the experience and behaviour of a range of sizes and types of business occupier and subjects their decision-making processes to detailed scrutiny. A linear three-stage decision model is used to sequence and structure interviews with individuals who have intimate involvement with the relocation of 28 firms and organizations in Tyne and Wear, in the north-east of England. The 'constant comparative' method is used to analyse the interview data, from which emerges 18 key concepts, comprising 51 characteristic components. Using an axial approach, these are organized into 10 cross-cutting themes that represent the main areas of consideration or influence on the thinking of the people involved in determining whether a firm or organization should relocate and, if so, where to. The resulting analysis finds that organizations adopt varying degrees of sophistication when making relocation decisions; small firms are more inclined to make decisions based on constrained information; larger organizations adopt a more complex approach. Regardless of firm size, key individuals exert considerable influence over the decision-making process and its outcome
Does Co-Creation of Service Recovery Create Value for Customers? The Underlying Mechanism of Motivation and the Role of Operant Resources
International audienceThis study focuses on the underlying mechanism that leads to co‐recovery behaviour and favourable co‐created value as response to a service failure. It argues that consumers’ ability to integrate their operant resources (e.g., knowledge and skills) to co‐recover from a service failure motivates them to express higher value co‐recovery in‐role behaviour and hence enjoy higher hedonic and utilitarian values. To test this claim, our study investigates the impact of consumers’ ability to co‐recover on value co‐recovery in‐role behaviour by taking into account extrinsic and intrinsic motivation as mediators. The results reveal that extrinsic motivation only partially mediates the relationship between ability to co‐recover and value co‐recovery in‐role behaviour. Furthermore, the outcomes demonstrate that value co‐recovery in‐role behaviour increases utilitarian value but decreases hedonic valu
Testing Scalar-Tensor Gravity with Gravitational-Wave Observations of Inspiralling Compact Binaries
Observations of gravitational waves from inspiralling compact binaries using
laser-interferometric detectors can provide accurate measures of parameters of
the source. They can also constrain alternative gravitation theories. We
analyse inspiralling compact %binaries in the context of the scalar-tensor
theory of Jordan, Fierz, Brans and Dicke, focussing on the effect on the
inspiral of energy lost to dipole gravitational radiation, whose source is the
gravitational self-binding energy of the inspiralling bodies. Using a
matched-filter analysis we obtain a bound on the coupling constant of Brans-Dicke theory. For a neutron-star/black-hole binary, we find that
the bound could exceed the current bound of from
solar-system experiments, for sufficiently low-mass systems. For a neutron star and a black hole we find that a bound
is achievable. The bound decreases with
increasing black-hole mass. For binaries consisting of two neutron stars, the
bound is less than 500 unless the stars' masses differ by more than about . For two black holes, the behavior of the inspiralling binary is
observationally indistinguishable from its behavior in general relativity.
These bounds assume reasonable neutron-star equations of state and a detector
signal-to-noise ratio of 10.Comment: 10 pages, (3 figures upon request), WUGRAV-94-
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