9,703 research outputs found
Entrepreneurship as nexus of change: the syncretistic production of the future
This paper deals with the issue of how the future is created and the mechanisms through which it is produced and conceived. Key to this process appears to be social interaction and how it is used to bring about change. Examining the entrepreneurial context by qualitative longitudinal research techniques, the study considers the situations of three entrepreneurs. It demonstrates that the web of relationships in which individuals are engaged provide the opportunity to enact the environment in new ways, thus producing organizations for the future. It further provides empirical evidence for a Heideggerian reading of strategy-as-practice, extending this conceptualization to account for the temporal dimension
Nonlinear Band Gap Transmission in Optical Waveguide Arrays
The effect of nonlinear transmission in coupled optical waveguide arrays is
theoretically investigated via numerical simulations on the corresponding model
equations. The realistic experimental setup is suggested injecting the beam in
a single boundary waveguide, linear refractive index of which () is larger
than one () of other identical waveguides in the array. Particularly, the
effect holds if , where is a linear coupling constant
between array waveguides, is a carrier wave frequency and is a
light velocity. Making numerical experiments in case of discrete nonlinear
Schr\"odinger equation it is shown that the energy transfers from the boundary
waveguide to the waveguide array above certain threshold intensity of the
injected beam. This effect is explained by means of the creation and
propagation of gap solitons in full analogy with the similar phenomenon of
nonlinear supratransmission [F. Geniet, J. Leon, PRL, {\bf 89}, 134102, (2002)]
in case of discrete sine-Gordon lattice.Comment: 4 pages, 6 figures. Phys. Rev. Lett. (in press
A simple operational interpretation of the fidelity
This note presents a corollary to Uhlmann's theorem which provides a simple
operational interpretation for the fidelity of mixed states.Comment: 1 pag
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Effect of side chains on the dielectric properties of alkyl esters derived from palm kernel oil
Alkyl ester derivatives were synthesized from laboratory purified palm kernel oil. The steps in the synthesis involved transesterification of palm kernel oil to produce a methyl ester, followed by epoxidation and then the grafting of side chains by esterification with propionic and butyric anhydride. The dielectric and thermal properties of the ester derivatives were analyzed and compared with the methyl ester. The melting point of the ester derivatives were found to reduce with side chain attachment and antioxidant improved its thermal stability. The dielectric loss was dominated by mobile charged particles and the chemical modification appeared to increase the rate at which electric double layer was formed at the electrode-liquid interface. The esters possessed excellent breakdown strengths suggesting that the processing to optimize their physical properties did not have a negative influence on their electrical breakdown strength. This product may prove useful as an insulation fluid in Electrical Power Transformers
MODERATION OF LOWER LIMB MUSCULAR ACTIVITY DURING JUMP LANDING BY THE APPLICATION OF ANKLE TAPING
Ground reaction forces were measured using a Kistler force platform when 8 female subjects, wearing their own shoes, landed as they received a netball chest pass. Simultaneously electromyography recordings were made of three ankle muscles. The peak impact (total 2.3 BW; vertical 2.2 BW) and landing (total 1.8 BW; vertical 1.8 BW) forces were similar whether the ankle was taped or not (p>0.05). Statistical analysis of the electromyography data indicated that, for the subject group as a whole, the peak muscular activity of the gastrocnemius medius (p=0.031), tibialis anterior (p=0.018) and peroneus longus (p=0.019) muscles was significantly reduced during landing when the ankle was taped using zinc oxide tape
Collective excitations of atomic Bose-Einstein condensates
We apply linear-response analysis of the Gross-Pitaevskii equation to obtain
the excitation frequencies of a Bose-Einstein condensate confined in a
time-averaged orbiting potential trap. Our calculated values are in excellent
agreement with those observed in a recent experiment.Comment: 11 pages, 2 Postscript figures, uses psbox.tex for automatic figure
inclusion. More info at http://amo.phy.gasou.edu/bec.htm
Localized matter-waves patterns with attractive interaction in rotating potentials
We consider a two-dimensional (2D) model of a rotating attractive
Bose-Einstein condensate (BEC), trapped in an external potential. First, an
harmonic potential with the critical strength is considered, which generates
quasi-solitons at the lowest Landau level (LLL). We describe a family of the
LLL quasi-solitons using both numerical method and a variational approximation
(VA), which are in good agreement with each other. We demonstrate that kicking
the LLL mode or applying a ramp potential sets it in the Larmor (cyclotron)
motion, that can also be accurately modeled by the VA.Comment: 13 pages, 11 figure
Effects of temperature upon the collapse of a Bose-Einstein condensate in a gas with attractive interactions
We present a study of the effects of temperature upon the excitation
frequencies of a Bose-Einstein condensate formed within a dilute gas with a
weak attractive effective interaction between the atoms. We use the
self-consistent Hartree-Fock Bogoliubov treatment within the Popov
approximation and compare our results to previous zero temperature and
Hartree-Fock calculations The metastability of the condensate is monitored by
means of the excitation frequency. As the number of atoms in the
condensate is increased, with held constant, this frequency goes to zero,
signalling a phase transition to a dense collapsed state. The critical number
for collapse is found to decrease as a function of temperature, the rate of
decrease being greater than that obtained in previous Hartree-Fock
calculations.Comment: 4 pages LaTeX, 3 eps figures. To appear as a letter in J. Phys.
Two point correlations of a trapped interacting Bose gas at finite temperature
We develop a computationally tractable method for calculating correlation
functions of the finite temperature trapped Bose gas that includes the effects
of s-wave interactions. Our approach uses a classical field method to model the
low energy modes and treats the high energy modes using a Hartree-Fock
description. We present results of first and second order correlation
functions, in position and momentum space, for an experimentally realistic
system in the temperature range of to . We also characterize
the spatial coherence length of the system. Our theory should be applicable in
the critical region where experiments are now able to measure first and second
order correlations.Comment: 9 pages, 4 figure
One-dimensional Bose chemistry: effects of non-integrability
Three-body collisions of ultracold identical Bose atoms under tight
cylindrical confinement are analyzed. A Feshbach resonance in two-body
collisions is described by a two-channel zero-range interaction. Elimination of
the closed channel in the three-body problem reduces the interaction to a
one-channel zero-range one with an energy dependent strength. The related
problem with an energy independent strength (the Lieb-Liniger-McGuire model)
has an exact solution and forbids all chemical processes, such as three-atom
association and diatom dissociation, as well as reflection in atom-diatom
collisions. The resonant case is analyzed by a numerical solution of the
Faddeev-Lovelace equations. The results demonstrate that as the internal
symmetry of the Lieb-Liniger-McGuire model is lifted, the reflection and
chemical reactions become allowed and may be observed in experiments.Comment: 5 pages, 4 figure
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