Recent experiments by our group demonstrate that three-dimensional scroll waves can rotate around filaments that end in the wake of a traveling excitation pulse. This unexpected finding corrects our current understanding that filaments end only at the system’s boundary or close in on themselves. Our results are not only of general interest to the theory of wave patterns in excitable systems but potentially also relevant to biomedical research as certain cardiac arrythmia and sudden cardiac death in humans are linked to the same class of vortex patterns.

This study by Dr. Tamás Bánsági Jr., Chris Palczewski and the group's PI, Oliver Steinbock, is published in J. Phys. Chem. A 111, 2492-2497, 2007 and highlighted on the issue's cover page. The actual data featured on the cover of J. Phys. Chem. were reconstructed using optical tomography of three-dimensional wave patterns in the 1,4-cyclohexanedione-Belousov-Zhabotinsky reaction which for several years has been our group's favorite model reaction.

As shown above (a-d), the vortex structures nucleate during the collision of three nonrotating excitation pulses. This mechanism was only recently dicovered by our group and has been published in Phys. Rev. Lett 97, 198301, 1-4, 2006. The general nucleation scenario and the unexpected wave-termination of filaments are direct consequences of the system’s anomalous dispersion relation. Vortex filaments are found to expand with about twice the speed of their anchoring wave fronts. Filament expansion is accompanied by the build-up of phase differences in spiral rotation creating strongly twisted wave structures.

This material is based upon work supported by the National Science Foundation under the PI's Grant No. 0513912.

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