Browsing Mathematics by Title
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Controlling unstable chaos: stabilizing chimera states by feedback
(American Physical Society, 2014)We present a control scheme that is able to find and stabilize an unstable chaotic regime in a system with a large number of interacting particles. This allows us to track a high dimensional chaotic attractor through a ... 
Convergence to local random attractors
(Taylor & Francis, 2003)Random attractors allow one to classify qualitative and quantitative aspects of the longtime behaviour of stochastically forced systems viewed as random dynamical systems (RDS) in an analogous way to attractors for ... 
Correcting the finiteensemble bias of the ignorance score
(Royal Meteorological Society, 2015)This study considers the application of the Ignorance Score (also known as the Logarithmic Score) in the context of ensemble verification. In particular, we consider the case where an ensemble forecast is transformed to a ... 
Countertraveling waves in rotating RayleighBénard convection.
(American Physical Society, 2008)Linear and nonlinear countertraveling waves in a fluidfilled annular cylinder with realistic noslip boundary conditions uniformly heated from below and rotating about a vertical axis are investigated. When the gap of ... 
Criteria for robustness of heteroclinic cycles in neural microcircuits.
(BioMed Central / SpringerOpen, 2011)We introduce a test for robustness of heteroclinic cycles that appear in neural microcircuits modeled as coupled dynamical cells. Robust heteroclinic cycles (RHCs) can appear as robust attractors in LotkaVolterratype ... 
Critical fronts in initiation of excitation waves
(American Physical Society, 2007)We consider the problem of initiation of propagating waves in a onedimensional excitable fiber. In the FitzHughNagumo theory, the key role is played by "critical nucleus" and "critical pulse" solutions whose (center) ... 
Critical layer and radiative instabilities in shallowwater shear flows
(Cambridge University Press, 20140623)In this study a linear stability analysis of shallowwater flows is undertaken for a representative Froude number $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let ... 
Cycling chaos: its creation, persistence and loss of stability in a model of nonlinear magnetoconvection
(Elsevier, 1998)We examine a model system where attractors may consist of a heteroclinic cycle between chaotic sets; this `cycling chaos' manifests itself as trajectories that spend increasingly long periods lingering near chaotic invariant ... 
Cycling chaotic attractors in two models for dynamics with invariant subspaces
(American Institute of Physics, 2004)Nonergodic attractors can robustly appear in symmetric systems as structurally stable cycles between saddletype invariant sets. These saddles may be chaotic giving rise to "cycling chaos." The robustness of such attractors ... 
Decelerating defects and nonergodic critical behaviour in a unidirectionally coupled map lattice
(Elsevier, 2003)We examine a coupled map lattice (CML) consisting of an infinite chain of logistic maps coupled in one direction by inhibitory coupling. We find that for sufficiently strong coupling strength there are dynamical states ... 
Declining summer snowfall in the Arctic: Causes, impacts and feedbacks
(Springer Verlag, 2012)Recent changes in the Arctic hydrological cycle are explored using in situ observations and an improved atmospheric reanalysis data set, ERAInterim. We document a pronounced decline in summer snowfall over the Arctic Ocean ... 
Delayed static output feedback control of a network of double integrator agents
(Elsevier, 201311)This paper considers a network of vehicles moving in a two dimensional plane. The overall network, described by a collection of double integrator dynamics, is controlled by a novel distributed static output feedback ... 
Dengue epidemic early warning system for Brazil
(UNISDR Scientific and Technical Advisory Group, 2015)The problem Brazil has reported more cases of dengue fever than anywhere else in the world this century1. Many cities have tropical and subtropical climate conditions that allow the dengue mosquito to thrive during warmer, ... 
Dependency of global mean precipitation on surface temperature
(American Geophysical Union (AGU), 2008)We investigate the causes of temperature dependent changes in global precipitation in contemporary General Circulation Models (GCMs) subjected to a doubling of atmospheric CO2 concentration. By analyzing the energy budget ... 
Designing heteroclinic and excitable networks in phase space using two populations of coupled cells
(Springer Verlag, 20150610)We give a method for realizing an arbitrary directed graph (with no onecycles) as a heteroclinic or an excitable dynamic network in the phase space of a system of coupled cells of two types. In each case, the system is ... 
The development of an early warning system for climatesensitive disease risk with a focus on dengue epidemics in Southeast Brazil
(2013)Previous studies demonstrate statistically significant associations between disease and climate variations, highlighting the potential for developing climatebased epidemic early warning systems. However, limitations include ... 
Diffusion and the formation of vorticity staircases in randomly strained twodimensional vortices
(Cambridge University Press, 2009)The spreading and diffusion of twodimensional vortices subject to weak external random strain fields is examined. The response to such a field of given angular frequency depends on the profile of the vortex and can be ... 
Digital clocks: simple Boolean models can quantitatively describe circadian systems
(Royal Society, 2012)The gene networks that comprise the circadian clock modulate biological function across a range of scales, from gene expression to performance and adaptive behaviour. The clock functions by generating endogenous rhythms ... 
Disciplines, geography, and gender in the framing of climate change
(American Meteorological Society, 2010)No abstract available 
Discrete computation using a perturbed heteroclinic network
(Elsevier, 2005)Transient synchronization into clusters appears in many biological and physical systems and seems to be important for computation within neural systems. In this paper we show how one can robustly and effectively perform ...