Eventually I figured out that the spiral was created from a single ellipse that rotates and scales at an exponential rate. The shape spends a lot of time small and slowly rotating, but as it accelerates, it spins and grows faster.

Four clinical cues (S4 model) predict a subgroup of ambulatory patients likely to have underlying depressive and anxiety disorders.11 The presence of 2 or more of these clinical cues signals the need for a more detailed psychological evaluation.