The automatic cab signal system shall be arranged so that cab signals will be continuously controlled in accordance with conditions described in Â§ 236.205 that obtain at least stopping distance in advance. Â§ 236.512 Cab signal indication when locomotive enters block where restrictive conditions obtain.
Dissolved oxygen (DO) is a measure of the quantity of free oxygen molecules in water. The concentration of DO is an important indicator of the health of an aquatic ecosystem because oxygen is essential for almost all forms of life. Oxygen is necessary for respiration and for some chemical reactions.
A liter of blood can dissolve 200 cc of oxygen gas, which is much more than water can dissolve. After being carried in blood to a body tissue in need of oxygen, O2 is handed-off to an enzyme (monooxygenase) that also has an active site with an atom of iron.