The maximum value of ⟨ σv ⟩ / T 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 × 10 by the product of the second and third columns. It indicates the factor by which the other reactions occur more slowly than the 1 D – 1 T 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 1 D – 1 T 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 1 D – 1 T reaction and can be considered a measure of the economic potential.