An enumeration district is a geographic area determined for purposes of taking the census. In one city there may be many enumeration districts, so once you enter a city, county, or state, you can narrow your results by entering street level information, or investigate enumeration district maps, or descriptions.
P wave. 1. a longitudinal earthquake wave that travels through the interior of the earth and is usually the first conspicuous wave to be recorded by a seismograph. Also called primary wave. Compare L wave, S wave. The P wave is admitted to be the wave of auricular contraction. p wave.
Therefore, each small 1-mm square represents 0.04 sec (40 msec) in time and 0.10 mV in voltage. Because the recording speed is standardized, one can calculate the heart rate from the intervals between different waves. P wave (atrial depolarization) The P wave represents the wave of depolarization that spreads from the SA node throughout the atria, and is usually 0.08 to 0.10 seconds (80-100 ms) in duration. The brief isoelectric (zero voltage) period after the P wave represents the time in which the impulse is traveling within the AV node (where the conduction velocity is greatly retarded) and the bundle of His.