Growth fluctuations in a class of deposition models

We compute the growth fluctuations in equilibrium of a wide class of deposition models. These models also serve as general frame to several nearest-neighbor particle jump processes, e.g. the simple exclusion or the zero range process, where our result turns to current fluctuations of the particles. We use martingale technique and coupling methods to show that, rescaled by time, the variance of the growth as seen by a deterministic moving observer has the form |V-C|*D, where V and C is the speed of the observer and the second class particle, respectively, and D is a constant connected to the equilibrium distribution of the model. Our main result is a generalization of Ferrari and Fontes' result for simple exclusion process. Law of large numbers and central limit theorem are also proven. We need some properties of the motion of the second class particle, which are known for simple exclusion and are partly known for zero range processes, and which are proven here for a type of deposition models and also for a type of zero range processes.Comment: A minor mistake in lemma 5.1 is now correcte

Measure concentration for Euclidean distance in the case of dependent random variables

Let q^n be a continuous density function in n-dimensional Euclidean space. We think of q^n as the density function of some random sequence X^n with values in \BbbR^n. For I\subset[1,n], let X_I denote the collection of coordinates X_i, i\in I, and let \bar X_I denote the collection of coordinates X_i, i\notin I. We denote by Q_I(x_I|\bar x_I) the joint conditional density function of X_I, given \bar X_I. We prove measure concentration for q^n in the case when, for an appropriate class of sets I, (i) the conditional densities Q_I(x_I|\bar x_I), as functions of x_I, uniformly satisfy a logarithmic Sobolev inequality and (ii) these conditional densities also satisfy a contractivity condition related to Dobrushin and Shlosman's strong mixing condition.Comment: Published by the Institute of Mathematical Statistics (http://www.imstat.org) in the Annals of Probability (http://www.imstat.org/aop/) at http://dx.doi.org/10.1214/00911790400000070

Framing the Game: Objections to Bapat’s Game-Theoretic Modeling of the Afghan Surge

In a recently published article in the prestigious journal Foreign Policy Analysis, Navin A. Bapat uses a rationalist approach to explain key bargaining processes related to the Afghanistan conflict, concluding that “the Afghan mission may continue for political reasons until it is impossible to sustain militarily.” The article captures the essence of the strategic situation in Afghanistan: the losing dynamic involved. This brief commentary in response is an attempt to shed light on where the tenets of Bapat’s game-theoretic model may be erroneous, even while the model does produce conclusions that appear valid overall

Multiple shocks in bricklayers' model

In bricklayers' model, which is a generalization of the misanthrope processes, we show that a nontrivial class of product distributions is closed under the time-evolution of the process. This class also includes measures fitting to shock data of the limiting PDE. In particular, we show that shocks of this type with discontinuity of size one perform ordinary nearest neighbor random walks only interacting, in an attractive way, via their jump rates. Our results are related to those of Belitsky and Schuetz on the simple exclusion process, although we do not use quantum formalism as they do. The structures we find are described from a fixed position. Similar ones were found in a paper by Balazs, as seen from the random position of the second class particle.Comment: More detailed explanations and a few additional arguments are added, the paper is hopefully more clear now. LaTeX 2e, 22 pages, submitted to Journal of Stat. Phy