1 For best results from your flask, before use, pre-fill for about 3 minutes, using either hot water for hot drinks or cold water for chilled drinks. 2  Never use a microwave or conventional oven to pre-heat your flask.  If your flask has not been used for some time, rinse with warm water to remove any residual odours.
2. : the degree to which something is prevalent; especially: the percentage of a population that is affected with a particular disease at a given time.
Prevalence is often expressed as a percentage, calculated by multiplying the ratio by 100. The above study expresses prevalence as a percentage, thus the prevalence of incontinence is 8.5% (or rounded is 9%). Another common way of expressing prevalence, particularly if the prevalence is low, is as the number of cases per 100,000 of the population. For example, it is easier to state the result as â66 cases per 100,000 peopleâ than to say the prevalence is 0.00066. Le and Boen (1995) provide further examples of the calculation of prevalence.