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sures indicate that the flow is chaotic [8]. More detailed evidence is required in order to determine if the system investigated here displays true elastic turbulence [21], for example measurement of flow velocity fluctuations and their spectral scaling properties. 

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The PMT signal is dependent on dye concentration, possible thinning effects [24], and flow velocities. To reduce such effects the PMT signal is normalized by the average voltage. To study the development of the instability versus driving voltage, the PMT signal fluctuations, ˜ δ$_{PMT}$ , defined as var ( V 〈 V 〉 $^{)}$, where var(V) is the variance of the PMT voltage signal from the average 〈 V 〉 , are measured for various driving potentials. The precise location of the 

