5,345 research outputs found
Periodic Radio Variability in NRAO 530: Phase Dispersion Minimization Analysis
In this paper, a periodicity analysis of the radio light curves of the blazar
NRAO 530 at 14.5, 8.0, and 4.8 GHz is presented employing an improved Phase
Dispersion Minimization (PDM) technique. The result, which shows two persistent
periodic components of and years at all three frequencies,
is consistent with the results obtained with the Lomb-Scargle periodogram and
weighted wavelet Z-transform algorithms. The reliability of the derived
periodicities is confirmed by the Monte Carlo numerical simulations which show
a high statistical confidence. (Quasi-)Periodic fluctuations of the radio
luminosity of NRAO 530 might be associated with the oscillations of the
accretion disk triggered by hydrodynamic instabilities of the accreted flow.
\keywords{methods: statistical -- galaxies: active -- galaxies: quasar:
individual: NRAO 530}Comment: 8 pages, 5 figures, accepted by RA
Machine-Learned Invertible Coarse Graining for Multiscale Molecular Modeling
Multiscale molecular modeling is widely applied in scientific research of
molecular properties over large time and length scales. Two specific challenges
are commonly present in multiscale modeling, provided that information between
the coarse and fine representations of molecules needs to be properly
exchanged: One is to construct coarse grained (CG) models by passing
information from the fine to coarse levels; the other is to restore finer
molecular details given CG configurations. Although these two problems are
commonly addressed independently, in this work, we present a theory connecting
them, and develop a methodology called Cycle Coarse Graining (CCG) to solve
both problems in a unified manner. In CCG, reconstruction can be achieved via a
tractable optimization process, leading to a general method to retrieve fine
details from CG simulations, which in turn, delivers a new solution to the CG
problem, yielding an efficient way to calculate free energies in a
rare-event-free manner. CCG thus provides a systematic way for multiscale
molecular modeling, where the finer details of CG simulations can be
efficiently retrieved, and the CG models can be improved consistently.Comment: 10 pages, 5 figures, plus S
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