7,962 research outputs found
Relative fixed-width stopping rules for Markov chain Monte Carlo simulations
Markov chain Monte Carlo (MCMC) simulations are commonly employed for
estimating features of a target distribution, particularly for Bayesian
inference. A fundamental challenge is determining when these simulations should
stop. We consider a sequential stopping rule that terminates the simulation
when the width of a confidence interval is sufficiently small relative to the
size of the target parameter. Specifically, we propose relative magnitude and
relative standard deviation stopping rules in the context of MCMC. In each
setting, we develop sufficient conditions for asymptotic validity, that is
conditions to ensure the simulation will terminate with probability one and the
resulting confidence intervals will have the proper coverage probability. Our
results are applicable in a wide variety of MCMC estimation settings, such as
expectation, quantile, or simultaneous multivariate estimation. Finally, we
investigate the finite sample properties through a variety of examples and
provide some recommendations to practitioners.Comment: 24 page
Edge States and Quantum Hall Effect in Graphene under a Modulated Magnetic Field
Graphene properties can be manipulated by a periodic potential. Based on the
tight-binding model, we study graphene under a one-dimensional (1D) modulated
magnetic field which contains both a uniform and a staggered component. New
chiral current-carrying edge states are generated at the interfaces where the
staggered component changes direction. These edge states lead to an unusual
integer quantum Hall effect (QHE) in graphene, which can be observed
experimentally by a standard four-terminal Hall measurement. When Zeeman spin
splitting is considered, a novel state is predicted where the electron edge
currents with opposite polarization propagate in the opposite directions at one
sample boundary, whereas propagate in the same directions at the other sample
boundary.Comment: 5 pages, 4 figure
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