40,953 research outputs found
A new rejection sampling method without using hat function
This paper proposes a new exact simulation method, which simulates a realisation from a proposal density and then uses exact simulation of a Langevin diffusion to check whether the proposal should be accepted or rejected. Comparing to the existing coupling from the past method, the new method does not require constructing fast coalescence Markov chains. Comparing to the existing rejection sampling method, the new method does not require the proposal density function to bound the target density function. The new method is much more efficient than existing methods for certain problems. An application on exact simulation of the posterior of finite mixture models is presented
Pseudogap and incommensurate magnetic fluctuations in YBa_2Cu_3O_{6. 6}
Unpolarized inelastic neutron scattering is used to study the temperature and
wave vector dependence of the dynamical magnetic susceptibility,
, of a well characterized single crystal
( K). We find that a pseudogap opens in the spin fluctuation spectrum
at temperatures well above . We speculate that the appearance of the low
frequency incommensurate fluctuations is associated with the opening of the
pseudogap. To within the error of the measurements, a gap in the spin
fluctuation spectrum is found in the superconducting state.Comment: 6 pages, 3 ps figs, Proceedings of ICNS, Physica B, to be publishe
Relay Selection for Cooperative NOMA
This letter studies the impact of relay selection (RS) on the performance of
cooperative non-orthogonal multiple access (NOMA). In particular, a two-stage
RS strategy is proposed, and analytical results are developed to demonstrate
that this two-stage strategy can achieve the minimal outage probability among
all possible RS schemes, and realize the maximal diversity gain. The provided
simulation results show that cooperative NOMA with this two-stage RS scheme
outperforms that with the conventional max-min approach, and can also yield a
significant performance gain over orthogonal multiple access
Observation of Magnetic Moments in the Superconducting State of YBaCuO
Neutron Scattering measurements for YBaCuO have identified
small magnetic moments that increase in strength as the temperature is reduced
below and further increase below . An analysis of the data shows
the moments are antiferromagnetic between the Cu-O planes with a correlation
length of longer than 195 \AA in the - plane and about 35 \AA along the
c-axis. The origin of the moments is unknown, and their properties are
discusssed both in terms of Cu spin magnetism and orbital bond currents.Comment: 9 pages, and 4 figure
Plancherel-Rotach asymptotic expansion for some polynomials from indeterminate moment problems
We study the Plancherel--Rotach asymptotics of four families of orthogonal
polynomials, the Chen--Ismail polynomials, the Berg-Letessier-Valent
polynomials, the Conrad--Flajolet polynomials I and II. All these polynomials
arise in indeterminate moment problems and three of them are birth and death
process polynomials with cubic or quartic rates. We employ a difference
equation asymptotic technique due to Z. Wang and R. Wong. Our analysis leads to
a conjecture about large degree behavior of polynomials orthogonal with respect
to solutions of indeterminate moment problems.Comment: 34 pages, typos corrected and references update
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