American Soveriegn Wealth Fund
Brad Stetser at rge monitor has a great write up on the question of central bank interventions that MG suggested was relevent in comments.
The explanation is a narrative and has many links. However, it needs to be read over there, as I do not know how to break it into parts. The size and scope of new world banks interventions in the US dilemma is well developed for a short article. It is also his area of particular knowledge.