Fibers are like tiny little rods or tubes-much longer than they are wide. Just about any fiber that you can think of is a polymer. (I guess that if it's a metal, it's called a wire, not a fiber!). Fibers can be natural-from plant or animals, or synthetic-made by people.
Accessory uses and structures. (A) A structure or use which is clearly incidental to a principal structure or use, and is located on the same lot with the principal structure or use, is an accessory use. All accessory uses are subject to the restrictions in this section.
Expiration. Accessory muscles may also be used when a person exhales. According to Loyola University Health System, typical exhalation is a passive act that occurs naturally without using any muscles. A person may begin to use accessory muscles while breathing out if he feels he is retaining air within the lungs. This is known as forced expiration, and it uses accessory muscles in the abdomen and the chest.