24,465 research outputs found
Inflationary NonGaussianity from Thermal Fluctuations
We calculate the contribution of the fluctuations with the thermal origin to
the inflationary nonGaussianity. We find that even a small component of
radiation can lead to a large nonGaussianity. We show that this thermal
nonGaussianity always has positive . We illustrate our result in
the chain inflation model and the very weakly dissipative warm inflation model.
We show that is general in such models. If we allow
modified equation of state, or some decoupling effects, the large thermal
nonGaussianity of order or even can be
produced. We also show that the power spectrum of chain inflation should have a
thermal origin. In the Appendix A, we made a clarification on the different
conventions used in the literature related to the calculation of .Comment: 20 pages, 1 figure. v2, v3: references and acknowledgments update
Generalized Space-time Noncommutative Inflation
We study the noncommutative inflation with a time-dependent noncommutativity
between space and time. From the numerical analysis of power law inflation,
there are clues that the CMB spectrum indicates a nonconstant noncommutative
inflation. Then we extend our treatment to the inflation models with more
general noncommutativity and find that the scalar perturbation power spectrum
depends sensitively on the time varying of the spacetime noncommutativity. This
stringy effect may be probed in the future cosmological observations.Comment: 15 pages, 2 figure
Signatures of Bose-Einstein condensation in an optical lattice
We discuss typical experimental signatures for the Bose-Einstein condensation
(BEC) of an ultracold Bose gas in an inhomogeneous optical lattice at finite
temperature. Applying the Hartree-Fock-Bogoliubov-Popov formalism, we calculate
quantities such as the momentum-space density distribution, visibility and peak
width as the system is tuned through the superfluid to normal phase transition.
Different from previous studies, we consider systems with fixed total particle
number, which is of direct experimental relevance. We show that the onset of
BEC is accompanied by sharp features in all these signatures, which can be
probed via typical time-of-flight imaging techniques. In particular, we find a
two-platform structure in the peak width across the phase transition. We show
that the onset of condensation is related to the emergence of the higher
platform, which can be used as an effective experimental signature.Comment: 5 pages, 3 figure
Management of e-technology in China
"e" technology is bringing about many challenges for companies, in particular for their managers. This concerns a vast range of business processes in many sectors of the economy and in nearly every country of the world. In rapidly industrializing China, companies and other organizations are actively finding their way by adapting, developing and exploiting new e-technologies. The paper's focus is the identification of the management issues in implementing e-technology in China. The paper reports on research into difficulties of establishing and operating e-business in China. In particular, it discusses management related to e-technology sharing and application. A brief review of literature is followed by the analysis of three recent case studies: an international IT services alliance, a financial services provider and an international manufacturing joint venture. All case companies are applying e-technology in China, but the role of e-technology differs in the three cases: adding a service line to the existing business processes; developing a new business process; and increasing efficiency and effectiveness in business processes. The conclusions present the emerging management issues: cooperation is a key asset in networking; the choice of business models plays an important role; adequate management attention for details such as a training program is require
A theoretical study of ozone isotopic effects using a modified ab initio potential energy surface
A modified ab initio potential energy surface (PES) is used for calculations of ozone recombination and isotopic exchange rate constants. The calculated low-pressure isotopic effects on the ozone formation reaction are consistent with the experimental results and with the theoretical results obtained earlier [J. Chem. Phys. 116, 137 (2002)]. They are thereby relatively insensitive to the properties of these PES. The topics discussed include the dependence of the calculated low-pressure recombination rate constant on the hindered-rotor PES, the role of the asymmetry of the potential for a general X + YZ reaction (Y[not-equal]Z), and the partitioning to form each of the two recombination products: XYZ and XZY
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