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 mineral not made by the body, and important for the metabolism of carbohydrates and fats. You need it for brain function and to activate numerous chemical processes, including the regulation of insulin. Find it in liver, beef, apples, eggs, bananas, chicken, oysters, and green peppers.