Introduction. Diagenesis encompasses all the physical and chemical processes that affect sediments and sedimentary rocks in the portion of the rock cycle that includes the period of burial between deposition and weathering, and also between deposition and the onset of metamorphism.hysical grain rearrangement in very early diagenesis of unconsolidated sediment is an important control on the subsequent path of chemical diagenesis because of the effects on permeability and grain surface characteristics.
Definition of proportion. 1 : harmonious relation of parts to each other or to the whole : balance, symmetry. 2a : proper or equal share each did her proportion of the workb : quota, percentage. 3 : the relation of one part to another or to the whole with respect to magnitude, quantity, or degree : ratio.
Prevalence is the proportion of the total number of cases to the total population and is more a measure of the burden of the disease on society with no regard to time at risk or when subjects may have been exposed to a possible risk factor.ncidence should not be confused with prevalence, which is the proportion of cases in the population at a given time rather than rate of occurrence of new cases.