The autonomic nervous system has two divisions: The sympathetic division acts to energize the body, preparing it for action. The parasympathetic division acts to calm the body, allowing it to rest. Our everyday activities are controlled by the interaction between the sympathetic and parasympathetic nervous systems.
Update: N2Aos is now available for Kindle Fire HD and Kindle Fire HD 8.9. And you get the full Android experience here, including access to the Google Play store and all the other features offered by Android 4.2 (excepting what's not available via hardware, of course).
Samsung has made big strides in Android tablets, accounting for the lion's share of Android sales. That is, unless you count the Amazon Kindle Fire, which is the biggest-selling Android tablet in the United States, accounting for 59 percent of all Android tablets sold. The Kindle Fire is not sold in many countries, so its effect on Android tablet sales stats elsewhere is negligible. But as Amazon.com ramps up Kindle Fire sales -- and more important -- content distribution -- in other countries, you'll likely see Android tablet sales stats rise.