Browsing Mathematics Research Institute (MRI) by Title
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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 ... 
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 ...