We numerically simulated long-distance, high-bit-rate, wavelength division multiplexed (WDM) transmission in dispersion-managed systems. We investigated return-to-zero (RZ) and nonreturn-to-zero (NRZ) modulation formats with amplitude and phase modulation. Consistent with earlier experiments, we find that the chirped return-to-zero (CRZ) modulation format has significant advantages over the NRZ...

Major shifts in many ecosystem-level properties of tropical forests have been observed, but the processes driving these changes are poorly understood. The forest on Barro Colorado Island (BCI) exhibited a 20% decrease in the number of trees and a 10% increase in average diameter. Using a metabolism-based zero-sum framework, we show that increases in per capita resource use at BCI, caused by inc...

A path-following problem for linear systems with unstable zero dynamics is solved. While the original control variable steers the system output along the path, the path parameter θ is used as an additional control to stabilize zero dynamics with a feedback law which is nonlinear due to the path constraint. A sufficient condition for solvability of the path-following problem is given in terms of...

This paper develops a change-point VAR model that isolates four major macroeconomic regimes in the US since the 1960s. The model identifies shocks to demand, supply, monetary policy, and spread yield using restrictions from a general equilibrium model. The analysis discloses important changes to the statistical properties of key macroeconomic variables and their responses to the identified shoc...

We give a simple criterion for checking Edwards’ hypothesis in certain zerotemperature, ferromagnetic spin-flip dynamics and use it to invalidate the hypothesis in various examples in dimension one and higher.

Oscillatory and synchronized activities involving widespread populations of neurons in neocortex are associated with the execution of complex sensorimotor tasks and have been proposed to participate in the 'binding' of sensory attributes during perceptual synthesis. How the brain constructs these coherent firing patterns remains largely unknown. Several mechanisms of intracortical synchronizati...

The Glauber dynamics of the pure and weakly-disordered random-bond 2d Ising model is studied at zero-temperature. The coarsening length scale, L(t), is extracted from the equal time correlation function. In the pure case, the persistence probability decreases algebraically with L(t). In the disordered case, three distinct regimes are identified: a short time regime where the behaviour is pure-l...

We present a detailed bifurcation scenario of zero-Prandtl number Rayleigh-Bénard convection using direct numerical simulations (DNS) and a 27-mode low-dimensional model containing the most energetic modes of DNS. The bifurcation analysis reveals a rich variety of convective flow patterns and chaotic solutions, some of which are common to that of the 13-mode model of Pal et al. [EPL 87, 54003 (...

The zero-temperature dynamics of simple models such as Ising ferromagnets provides, as an alternative to the mean-field situation, interesting examples of dynamical systems with many attractors (absorbing configurations, blocked configurations, zero-temperature metastable states). After a brief review of metastability in the mean-field ferromagnet and of the droplet picture, we focus our attent...

We consider a zero-range process with two species of interacting particles. The steady-state phase diagram of this model shows a variety of condensate phases in which a single site contains a finite fraction of all the particles in the system. Starting from a homogeneous initial distribution, we study the coarsening dynamics in each of these condensate phases, which is expected to follow a scal...