Propagation constant a conductor. The skin effect causes R along the conductor to be approximately dependent on frequency according to Losses in the dielectric depend on the loss tangent (tan "δ") of the material divided by the wavelength of the signal. Thus they are directly proportional to the frequency. The attenuation constant for a particular propagation mode in an optical fiber is the real part of the axial propagation constant. In electromagnetic theory, the phase constant, also called phase change constant, parameter or coefficient is the imaginary component of the propagation constant for a plane wave. It represents the change in phase
Genetic distance and Reynolds, Weir and Cockerham's genetic distance, listed below. In all the formulae in this section, formula_1 and formula_2 represent two different populations for which formula_3 loci have been studied. Let formula_4 represent the formula_5 allele at the formula_6 locus. In 1972, Masatoshi Nei published what came to be known as Nei's standard genetic distance. This distance has the nice property that if the rate of genetic change (amino acid substitution) is constant per year or generation then Nei's standard genetic distance ("D") increases in proportion to divergence time. This measure assumes that genetic differences are caused by mutation and