Equation 22 · Part 1 · Einstein's Random Walk and the Mathematics of Genetic Drift
Symbol D
What this part means
a constant, fixed once by temperature and viscosity.
Its job in the formula
D is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol D→Article meaning
Where the article explains it
One honest difference is worth stating rather than smoothing over: Einstein’s D is a constant, fixed once by temperature and viscosity, while Kimura’s V(p) depends on the frequency itself, so the spread is fastest near p=0.5 and vanishes at the boundaries — an allele already fixed or already lost has nothing left to drift into [ 7 ] .
The passage around this formula
The same second-derivative operator acts on a diffusion term in both; only the variable and the coefficient it multiplies have changed. One honest difference is worth stating rather than smoothing over: Einstein’s D is a constant, fixed once by temperature and viscosity, while Kimura’s V(p) depends on the frequency itself, so the spread is fastest near p=0.5 and vanishes at the boundaries — an allele already fixed or already lost has nothing left to drift into [ 7 ] . The operator is identical; the coefficient it acts on has learned something about the biology.
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.