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.
(This is the most commonly asked question) Oxygen levels are commonly measured by two techniques. The first is a blood gas in which a blood sample is taken directly from an artery. This is the most accurate assessment of oxygen. The normal oxygen level using this technique is 80-100 (mmHg). The second technique is bloodless and is called pulse oximetry. The result here is not a direct measurement of oxygen but rather represents the percentage of hemoglobin that is saturated with oxygen.