Abstract: A cholinergic deep brain stimulator is provided that can be used to increase brain acetylcholine levels. This increase in acetylcholine levels improves cognition and may be used to remediate disorders in which cognitive loss is a prominent symptom including Alzheimer's Disease, vascular dementia, traumatic brain injury, or drug addiction.

Abstract: A dynamic fin system (DFS) achieves fin rotation passively via water flow so that no direct active control of fin rotation is required by the watercraft operator. The DFS, using a combination of fin rotation via at least one axle and resistive forces applied to a fin mounting tab, provides an assembly in which a fin can pivot from side to side in a reliable, effective and simple way. The DFS provides ease in turning and stability at a neutral position while minimizing the amount of flow resistance. The DFS provides a strong fin mounting, and uses a combination of an axle for rotational control, a resistive centering force, and a force preload for stabilizing the fin in the neutral position. The DFS provides a mount for a rotating fin in a watercraft hull that supports repositioning of the rotating fin axis both forward and rearward in the hull.