Actually axxo2, that is the Capitalized Greek letter, Lambda.
Interestingly enough (related to the Advent's mental prowess):
In neurobiology, lambda denotes the exponential rate of decay of electric potential energy of a nerve's cell membrane each time it fires. Higher rates of lambda indicate increasingly active, or over excited, nerves due to above average stimulation of the brain's nerves at the probed (tested) location.