Asecond nerve impulse cannot be generated until proteins have been resynthesized the na ions have been pumped back into the cell the membrane potential has been reestablished all sodium gates are closed

The answer is ‘the membrane potential has been reestablished’ Ths occurs by pumping out sodium ions from the inside of the cell. This process is called repolarization. During depolarization, as impulse is carried across the cell, sodium ions channels open and the sodium outside of the cell enters the cell.

straight probes are used primarily for measuring flow as it is approaching the test area. its geometry allows the probe to be mounted so that it is in the direct line of airflow.