1 Never use a microwave or conventional oven to pre-heat your flask. 2  If your flask has not been used for some time, rinse with warm water to remove any residual odours.  DO NOT overfill your flask. Leave sufficient space in the neck to fit the stopper.
Prevalence is a measure of disease that allows us to determine a person's likelihood of having a disease. Therefore, the number of prevalent cases is the total number of cases of disease existing in a population.
as for period prevalence (above) except that the assessment is made at a specific point in time rather than over a period, a rather impractical exercise. prevalence rate. the number of patients who have the disease at a particular time, divided by the population at risk of having the disease at that time.