156,755 research outputs found
Quantum wideband traveling-wave analysis of a degenerate parametric amplifier
We develop a wideband traveling-wave formalism for analyzing quantum mechanically a degenerate parametric amplifier. The formalism is based on spatial differential equations-spatial Langevin equations-that propagate temporal Fourier components of the field operators through the nonlinear medium. In addition to the parametric nonlinearity, the Langevin equations include absorption and associated fluctuations, dispersion (phase mismatching), and pump quantum fluctuations. We analyze the dominant effects of phase mismatching and pump quantum fluctuations on the squeezing produced by a degenerate parametric amplifier
Jeans instability of interstellar gas clouds in the background of weakly interacting massive particles
Criterion of the Jeans instability of interstellar gas clouds which are
gravitationally coupled with weakly interacting massive particles is revisited.
It is established that presence of the dark matter always reduces the Jeans
length, and in turn, Jeans mass of the interstellar gas clouds. Astrophysical
implications of this effect are discussed.Comment: version accepted in ApJ, Nov. 1, 1998 issue, vol. 50
Integrated Project Teams: The MoD's New Hot Potato?
Since the announcement of Smart Procurement, much has been written on the
potential benefits that IPTs will hopefully bring. It is supposed that they will
improve the interface with industry, create a better understanding of
requirements and establish an environment where industry is motivated to perform
and so reduce cost, risk and time into service while improving product quality.
The formation of a team should provide continuity, consistency, flexibility and
~ increased performance due to the integration of a wide-range of functional
activities and decision-making, as well as increased motivation. These may well
be gallant objectives, but how achievable are they? What obstacles does the MoD
face in the implementation of the IPTs? Have they grasped a 'hot potato'
Correction: A correlated topic model of Science
Correction to Annals of Applied Statistics 1 (2007) 17--35
[doi:10.1214/07-AOAS114]Comment: Published in at http://dx.doi.org/10.1214/07-AOAS136 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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