The maximum value of <σv>/T2 is taken from a previous table. The "penalty/bonus" factor is that related to a non-hydrogenic reactant or a single-species reaction. The values in the column "inverse reactivity" are found by dividing 1.24 by the product of the second and third columns. It indicates the factor by which the other reactions occur more slowly than the - reaction under comparable conditions. The column "Lawson criterion" weights these results with "E"ch and gives an indication of how much more difficult it is to achieve ignition with these reactions, relative to the difficulty for the - reaction. The next-to-last column is labeled "power density" and weights the practical reactivity by "E"fus. The final column indicates how much lower the fusion power density of the other reactions is compared to the - reaction and can be considered a measure of the economic potential.