Well although I explained it as changing t and constant alpha, what’s being plotted is actually t*alpha, so if you prefer you could consider it being t=1 and alpha = 0, 0.11 and 0.22.

The reason I chose that value for alpha is because that seemed to be quite consistent in the first few months of the DAI exchange. But the formula is not complex so very easy to plot for any value of alpha you are interested in. Historic alpha for the various exchanges can be calculated from Uniswap data.