Fig. 4.

(a) Spatially-averaged ACF function of the same spheroid at 37°C and 20°C. The ACF are not normalized to illustrate that increased intracellular motion does not modify the near zero lag amplitude, which is a measure of signal strength. Temperature control at 37°C increases α (0.08 to 0.13), and reduce the fast T₁ (0.7 to 0.36 s) and slow T₂ (9 to 3.4 s) decorrelation times. (b) Typical residual from the biexponential fit, which show fluctuations of normalized amplitude 1%. (c) Same data as (a) in the frequency domain. Increased intracellular motion at 37° increase the slope of the spectrum in the [0.1-1] Hz band, and its high frequency plateau by 5dB.