Browsing Mathematics Research Institute (MRI) by Title
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Robust bursting to the origin: heteroclinic cycles with maximal symmetry equilibria
(World Scientific Publishing Company, 2005)Robust attracting heteroclinic cycles have been found in many models of dynamics with symmetries. In all previous examples, robust heteroclinic cycles appear between a number of symmetry broken equilibria. In this paper ... 
Semianalytical approach to criteria for ignition of excitation waves
(American Physical Society, 20151019)We consider the problem of ignition of propagating waves in onedimensional bistable or excitable systems by an instantaneous spatially extended stimulus. Earlier we proposed a method [I. Idris and V. N. Biktashev, Phys. ... 
The sensitivity of global climate model simulations to the representation of soil moisture heterogeneity
(American Meteorological Society, 2003)Improving the treatment of subgridscale soil moisture variations is recognized as a priority for the next generation of land surface schemes. Here, the impact of an improved representation of subgridscale soil moisture ... 
Southern Ocean buoyancy forcing of ocean ventilation and glacial atmospheric CO2
(Macmillan, 20150928)Atmospheric CO2 concentrations over glacial–interglacial cycles closely correspond to Antarctic temperature patterns. These are distinct from temperature variations in the mid to northern latitudes, so this suggests that ... 
The spiral windup and dissipation of vorticity and a passive scalar in a strained planar vortex
(Cambridge University Press, 1999)The response of a Gaussian vortex to a weak timedependent external strain field is studied numerically. The cases of an impulsive strain, an on–off step function, and a continuous random strain are considered. Transfers ... 
The spiral windup of vorticity in an inviscid planar vortex
(Cambridge University Press, 1998)The relaxation of a smooth twodimensional vortex to axisymmetry, also known as `axisymmetrization', is studied asymptotically and numerically. The vortex is perturbed at t = 0 and differential rotation leads to the windup ... 
Superparameterisation of ocean deep convection
(University of Exeter, 20111201)Subgrid scale processes play an important role in ocean and climate modelling. Typical examples include clouds in atmospheric models, flows over restricted topographies or the resolution of con vective plumes in ocean ... 
Synchronization of chaos in an array of three lasers
(American Physical Society, 1999)Synchronization of the chaotic intensity fluctuations of three modulated Nd:YAG lasers oriented in a linear array with either a modulated pump or loss is investigated experimentally, numerically, and analytically. ... 
Tangencies in invariant disc packings for certain planar piecewise isometries are rare
(Taylor & Francis, 2001)For planar piecewise isometries (PWIs) (twodimensional maps that restrict to isometries on some partition) there is a natural coding given by the itinerary of a trajectory between the pieces (atoms) of the partition on ... 
Thresholds for the formation of satellites in twodimensional vortices
(Cambridge University Press, 2008)This paper examines the evolution of a twodimensional vortex which initially consists of an axisymmetric monopole vortex with a perturbation of azimuthal wavenumber m = 2 added to it. If the perturbation is weak, then the ... 
Twostate intermittency near a symmetric interaction of saddlenode and Hopf bifurcations: a case study from dynamo theory
(Elsevier, 2004)We consider a model of a Hopf bifurcation interacting as a codimension 2 bifurcation with a saddlenode on a limit cycle, motivated by a loworder model for magnetic activity in a stellar dynamo. This model consists of ... 
Vortex motion in a weak background shear flow
(Cambridge University Press, 2004)A point vortex is introduced into a weak background vorticity gradient at finite Reynolds number. As the vortex spreads viscously so the background vorticity becomes wrapped around it, leading to enhanced diffusion of ... 
What is the spatial distribution of magnetic helicity injected in a solar active region?
(EDP Sciences, 2006)Context. Magnetic helicity is suspected to play a key role in solar phenomena such as flares and coronal mass ejections. Several investigations have recently computed the photospheric flux of magnetic helicity in active ...