The characteristic time for the first reaction is about one billion years even at the high densities and temperatures of the core, due to the necessity for the weak force to cause beta decay before the nucleons can adhere ( which rarely happens in the time they tunnel toward each other, to be close enough to do so ).
32.
Where r = hA / C is a positive constant characteristic of the system, which must be in units of time ^ {-1 }, and is therefore sometimes expressed in terms of a characteristic time constant t _ 0 given by : r = 1 / t _ 0 =-( dT ( t ) / dt ) / \ Delta T.
33.
R = hA / C is a positive constant characteristic of the system, which must be in units of s ^ {-1 }, and is therefore sometimes expressed in terms of a characteristic time constant t _ 0 given by : r = 1 / t _ 0 = \ Delta T / ( dT ( t ) / dt ).
34.
The " Seasonal Pattern Specifier " must meet four criteria : depressive episodes at a particular time of the year; remissions or mania / hypomania at a characteristic time of year; these patterns must have lasted two years with no nonseasonal major depressive episodes during that same period; and these seasonal depressive episodes outnumber other depressive episodes throughout the patient's lifetime.
