Excitability is an emergent supra-threshold response to localized stimulation of sufficiently large amplitude that results in excitation of adjacent sites while the perturbation at the original location decays back to equilibrium. As such, excitability has numerous significant biological applications owing to action potential dynamics in neural and cardiac systems. Lately, there are also increasing technological interests, examples of which include electrochemistry, gas discharge systems, translational pipe flows, nonlinear optics, semiconductors, liquid crystals and exothermic combustion.
Thus far recent studies have centered on the evolution of developed waves while the mechanisms of the generation of excitable waves has received less attention even though the understanding of the details of this mechanism is of paramount importance in the control of excitability. Using spatial dynamics methods, I will demonstrate  two novel counter-intuitive properties to excitable media:
- Realization of how in isotropic media a transient pacemaker (that is invoked by single a perturbation) generates distinct excitable wave trains;
- Existence and stability of "drifting" pulses under directional field.
Importantly, the results are derived using global bifuractions and thus are of general theoretical framework, i.e., properties that are model independent.