10,078 research outputs found
2D Lattice Liquid Models
A family of novel models of liquid on a 2D lattice (2D lattice liquid models)
have been proposed as primitive models of soft-material membrane. As a first
step, we have formulated them as single-component, single-layered, classical
particle systems on a two-dimensional surface with no explicit viscosity. Among
the family of the models, we have shown and constructed two stochastic models,
a vicious walk model and a flow model, on an isotropic regular lattice and on
the rectangular honeycomb lattice of various sizes. In both cases, the dynamics
is governed by the nature of the frustration of the particle movements. By
simulations, we have found the approximate functional form of the frustration
probability, and peculiar anomalous diffusions in their time-averaged mean
square displacements in the flow model. The relations to other existing
statistical models and possible extensions of the models are also discussed.Comment: REVTeX4, 14 pages in double colomn, 12 figures; added references with
some comments, typos fixe
Analysis of a non-reversible Markov chain speedup by a single edge
We present a Markov chain example where non-reversibility and an added edge
jointly improve mixing time: when a random edge is added to a cycle of
vertices and a Markov chain with a drift is introduced, we get mixing time of
with probability bounded away from 0. If only one of the two
modifications were performed, the mixing time would stay .Comment: 15 pages, 5 figure
MASSCLEANcolors - Mass Dependent Integrated Colors for Stellar Clusters Derived from 30 Million Monte Carlo Simulations -
We present Monte Carlo models of open stellar clusters with the purpose of
mapping out the behavior of integrated colors with mass and age. Our cluster
simulation package allows for stochastic variations in the stellar mass
function to evaluate variations in integrated cluster properties. We find that
UBVK colors from our simulations are consistent with simple stellar population
(SSP) models, provided the cluster mass is large, Mcluster >= 10^6 M_Sun. Below
this mass, our simulations show two significant effects. First, the mean value
of the distribution of integrated colors moves away from the SSP predictions
and is less red, in the first 10^7 to 10^8 years in UBV colors, and for all
ages in (V - K). Second, the 1\sigma dispersion of observed colors increases
significantly with lower cluster mass. The former we attribute to the reduced
number of red luminous stars in most of the lower mass clusters and the later
we attribute to the increased stochastic effect of a few of these stars on
lower mass clusters. This later point was always assumed to occur, but we now
provide the first public code able to quantify this effect. We are completing a
more extensive database of magnitudes and colors as a function of stellar
cluster age and mass that will allow the determination of the correlation
coefficients among different bands, and improve estimates of cluster age and
mass from integrated photometry.Comment: 11 pages, 5 figures, submitted to Astrophysical Journal Letter
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