39 research outputs found
Deterministic SR in a Piecewise Linear Chaotic Map
The phenomenon of Stochastic Resonance (SR) is observed in a completely
deterministic setting - with thermal noise being replaced by one-dimensional
chaos. The piecewise linear map investigated in the paper shows a transition
from symmetry-broken to symmetric chaos on increasing a system parameter. In
the latter state, the chaotic trajectory switches between the two formerly
disjoint attractors, driven by the map's inherent dynamics. This chaotic
switching rate is found to `resonate' with the frequency of an externally
applied periodic perturbation (multiplicative or additive). By periodically
modulating the parameter at a specific frequency , we observe the
existence of resonance where the response of the system (in terms of the
residence-time distribution) is maximum. This is a clear indication of SR-like
behavior in a chaotic system.Comment: 6 pages LaTex, 4 figure
Economic Inequality: Is it Natural?
Mounting evidences are being gathered suggesting that income and wealth
distribution in various countries or societies follow a robust pattern, close
to the Gibbs distribution of energy in an ideal gas in equilibrium, but also
deviating significantly for high income groups. Application of physics models
seem to provide illuminating ideas and understanding, complimenting the
observations.Comment: 7 pages, 2 eps figs, 2 boxes with text and 2 eps figs; Popular review
To appear in Current Science; typos in refs and text correcte
Sudoku Squares as Experimental Designs
Sudoku is a popular combinatorial puzzle. We give a brief overview of some mathematical features of a Sudoku square. Then we focus on interpreting Sudoku squares as experimental designs in order to meet a practical need
A characterization of Dirichlet distributions
AbstractJ. N. Darroch and D. Ratcliff (J. Amer. Statist. Assoc. 66 (1971), 641–643) have given a characterization of the Dirichlet distributions based on the properties of independence of various functions of the random variables (X1, X2, …, Xk) having a joint continuous distribution over the k-dimensional simplex: 0 ≤ x1 ≤ Σ xi ≤ 1. In this paper we provide a further characterization of this family of distributions essentially based on the properties of linear regression. Some extra conditions have been imposed and these are indeed indispensable
Design Issues for Generalized Linear Models: A Review
Generalized linear models (GLMs) have been used quite effectively in the
modeling of a mean response under nonstandard conditions, where discrete as
well as continuous data distributions can be accommodated. The choice of design
for a GLM is a very important task in the development and building of an
adequate model. However, one major problem that handicaps the construction of a
GLM design is its dependence on the unknown parameters of the fitted model.
Several approaches have been proposed in the past 25 years to solve this
problem. These approaches, however, have provided only partial solutions that
apply in only some special cases, and the problem, in general, remains largely
unresolved. The purpose of this article is to focus attention on the
aforementioned dependence problem. We provide a survey of various existing
techniques dealing with the dependence problem. This survey includes
discussions concerning locally optimal designs, sequential designs, Bayesian
designs and the quantile dispersion graph approach for comparing designs for
GLMs.Comment: Published at http://dx.doi.org/10.1214/088342306000000105 in the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org