Farm system boundaries: Discussion of system boundaries in Chapter 3 mainly relates to farms of this type. Briefly, boundaries of Type 2 farm systems (and of Types 1, 3 and 4) segregate them distinctly from the external world, but the boundaries between individual farms are relatively weak.
What is Chromium? Chromium is a steel-gray lustrous metal that is important as an additive in the manufacture of steel alloys (chrome steel, chrome-nickel steel, stainless steel) and greatly increases the durability and resistance of these metals; hence its use in metal prosthetic implants.
Chromium is an essential trace mineral that has received much attention as a dietary supplement because good dietary sources of chromium are scarce and intake is generally low. There is debate, however, regarding optimal amounts and exactly how chromium works in the body. In recent years, some very elegant work has revealed that chromium augments the actions of insulin, which is consistent with studies showing that long-term use effectively controls blood sugar (glucose) levels in people with intolerance to carbohydrates.