1,651 research outputs found
Quantum tunneling dynamics of an interacting Bose-Einstein condensate through a Gaussian barrier
The transmission of an interacting Bose-Einstein condensate incident on a
repulsive Gaussian barrier is investigated through numerical simulation. The
dynamics associated with interatomic interactions are studied across a broad
parameter range not previously explored. Effective 1D Gross-Pitaevskii equation
(GPE) simulations are compared to classical Boltzmann-Vlasov equation (BVE)
simulations in order to isolate purely coherent matterwave effects. Quantum
tunneling is then defined as the portion of the GPE transmission not described
by the classical BVE. An exponential dependence of transmission on barrier
height is observed in the purely classical simulation, suggesting that
observing such exponential dependence is not a sufficient condition for quantum
tunneling. Furthermore, the transmission is found to be predominately described
by classical effects, although interatomic interactions are shown to modify the
magnitude of the quantum tunneling. Interactions are also seen to affect the
amount of classical transmission, producing transmission in regions where the
non-interacting equivalent has none. This theoretical investigation clarifies
the contribution quantum tunneling makes to overall transmission in
many-particle interacting systems, potentially informing future tunneling
experiments with ultracold atoms.Comment: Close to the published versio
A Bose-condensed, simultaneous dual species Mach-Zehnder atom interferometer
This paper presents the first realisation of a simultaneous Rb
-Rb Mach-Zehnder atom interferometer with Bose-condensed atoms. A number
of ambitious proposals for precise terrestrial and space based tests of the
Weak Equivalence Principle rely on such a system. This implementation utilises
hybrid magnetic-optical trapping to produce spatially overlapped condensates
with a duty cycle of 20s. A horizontal optical waveguide with co-linear Bragg
beamsplitters and mirrors is used to simultaneously address both isotopes in
the interferometer. We observe a non-linear phase shift on a non-interacting
Rb interferometer as a function of interferometer time, , which we
show arises from inter-isotope scattering with the co-incident Rb
interferometer. A discussion of implications for future experiments is given.Comment: 7 pages, 5 figures. The authors welcome comments and feedback on this
manuscrip
Rebranding P.o Eka-mira sebagai Upaya Mempertahankan Brand Loyalty
Public transportation or public transport is a means of transportation when the passengers not traveling use his own vehicle. Public transportation deliberately provided for residents to fulfill transportation they do daily needs. With using a public transportation, many benefits that can be obtained the community. Business competition that is more strict now this caused many companies involved in the fulfillment of the needs and consumer advocacy. It is means that each companies should put orientation in customer satisfaction as the main objective of. Po Eka-Mira is the company that moves in transportation service, especially transport service passengers that provides armada-armada good in economy class and executive class. To the specifications bus, the economy class bus named Mira and an executive class bus named Eka. The research was done by using the method the qualitative study is by applying interview, Observation , documentation , and the literature study to get the data used as a support making the concept of design rebranding. The result of design rebranding this is to anticipate consumers who move ( brand loyalty ) to a product competitors because products competitors who has experienced reform in the design and services . Design for that rebranding it is certainly are also to be used to getting a new consumer
Optically guided linear Mach Zehnder atom interferometer
We demonstrate a horizontal, linearly guided Mach Zehnder atom interferometer
in an optical waveguide. Intended as a proof-of-principle experiment, the
interferometer utilises a Bose-Einstein condensate in the magnetically
insensitive |F=1,mF=0> state of Rubidium-87 as an acceleration sensitive test
mass. We achieve a modest sensitivity to acceleration of da = 7x10^-4 m/s^2.
Our fringe visibility is as high as 38% in this optically guided atom
interferometer. We observe a time-of-flight in the waveguide of over half a
second, demonstrating the utility of our optical guide for future sensors.Comment: 6 pages, 3 figures. Submitted to Phys. Rev.
Observation of a Modulational Instability in Bose-Einstein condensates
We observe the breakup dynamics of an elongated cloud of condensed Rb
atoms placed in an optical waveguide. The number of localized spatial
components observed in the breakup is compared with the number of solitons
predicted by a plane-wave stability analysis of the nonpolynomial nonlinear
Schr\"odinger equation, an effective one-dimensional approximation of the
Gross-Pitaevskii equation for cigar-shaped condensates. It is shown that the
numbers predicted from the fastest growing sidebands are consistent with the
experimental data, suggesting that modulational instability is the key
underlying physical mechanism driving the breakup.Comment: 6 pages, 5 figure
In vitro comparison of conventional film and direct digital imaging in the detection of approximal caries
This is the published version. Copyright 2014 British Institute of Radiology.Objectives: To compare the diagnostic accuracy of conventional film, unenhanced direct digital and inversion grayscale direct digital imaging in the detection of approximal caries.
Methods: 150 approximal surfaces of extracted permanent molars and premolars were selected for the study on the basis of varying lesion depth. The teeth were radiographed using Ektaspeed Plus film; digital images were made with a Schick CMOS-APS sensor. 7 examiners evaluated 58 randomized images of each modality. Histological sectioning of the teeth was used to verify the presence and extent of decay.
Results: No significant difference was found between the diagnostic accuracies of the three imaging modalities (P=0.226). Analysis of the diagnostic accuracy of the three modalities on lesion depth showed no statistically significant interaction; however, the main effect of the lesion depth was significant (P<0.001, η2=0.936).
Conclusions: The overall diagnostic accuracy of the three modalities in the detection of approximal carious lesions was comparable. All three modalities performed poorly in the detection of enamel lesions
Consumption of an omega-3 fatty acids product, INCELL AAFA™, reduced side-effects of CPT-11 (irinotecan) in mice
INCELL AAFA™, an omega-3 polyunsaturated fatty acid product containing a high concentration of long chain fatty acids, was tested for its ability to ameliorate the harmful side effects of CPT-11 chemotherapy including: leukopenia, anaemia, asthenia, weight loss and liver involvement. Four groups of mice were fed an AIN-76 diet modified to contain: 10% w/w corn oil (CO), 0% AAFA™; 9% CO, 1% AAFA™; 8% CO, 2% AAFA™; or 7% CO, 3% AAFA™. After 2 weeks on the diets, half of the mice received CPT-11 chemotherapy (60 mg kg−1 q 4 days, i.v.) the rest of the mice received vehicle for 2 weeks. It was found that 2% AAFA™ in the diet of the CPT-11 treated mice: decreased apoptotic figures in the duodenal crypts; markedly suppressed the inflammatory eicosanoid, prostaglandin E2 in the liver; prevented liver hypertrophy; improved white blood cell counts; significantly increased red blood cell counts; decreased numbers of CPT-11 induced immature red blood cell and micronuclei in red blood cells of the peripheral blood; increased eicosapentaenoic acid and docosahexaenoic acid in liver cell membranes and maintained normal grooming behaviour. Thus 2% AAFA™ in the diet reduced the side effects of CPT-11 treatment in mice
Inelastic collisions of CaH with He at cryogenic temperatures
Using helium buffer gas cooling, we have prepared dense samples of ground-state molecular calcium monohydride (CaH X 2Σ) at cryogenic temperatures. We have used optical pumping to polarise the spin state of the CaH molecules and we have measured the inelastic collisions of molecular CaH with atomic helium at temperatures from 2 to 7 K. The measured CaH electronic spin depolarisation rate coefficient increases rapidly with increasing temperature, increasing from 2 × 10−13 cm3 s−1 to over 10−11 cm3 s−1. The strong dependence of rate coefficient on temperature is attributed to the CaH population in the first excited rotational state
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