in the x direction, the water wants to flow in that direction) For a given hydraulic. conductivity, the vertical flow rate depends on the sum of the gravitational potential energy. gradient per unit weight of water (dz/dz =1) and the vertical gradient in soil water pressure.
Origin and spread of the 1278insTATC mutation causing TayâSachs disease in Ashkenazi Jews: Genetic drift as a robust and parsimonious hypothesis. Human Genetics 114 (4): 366â376. pmid 14727180.
Individuals with Tay-Sachs Disease lack an enzyme called hexosaminidase (Hex A). The child loses all motor skills and becomes blind, deaf and unresponsive. Death usually occurs by the age of four. The carrier rate in the Ashkenazi Jewish population is approximately 1 in 25. More rare than the infantile type is Late Onset Tay-Sachs Disease, where the progression of symptoms is slower and milder.