what is the purpose of a recessed filter
Parliament (cigarette) Parliaments are one of few brands of cigarettes on the mainstream market to feature a recessed paper filter. Cigarette filters became common in most cigarettes in the 1950s. In the 1940s and 1950s, the brand was marketed for its unique filters, with advertisements reading, "Only the flavor touches your lips", and "Tobacco tastes best when the filter's recessed".[3] The brand also claimed that the recessed filter prevented tar from making contact with the smoker's mouth, unlike standard filters.[4][5][6] However, this recessed would also explain the popularity of the cigarette in another way: the sleeve would be suitable for snorting cocaine.[7]
Free water clearance Free water clearance can be used as an indicator of how the body is regulating water. A free water clearance of zero means the kidney is producing urine isosmotic with respect to the plasma. Values greater than zero imply that the kidney is producing dilute urine through the excretion of solute-free water. Values less than zero imply that the kidney is conserving water (likely under the influence of antidiuretic hormone, ADH), resulting in the production of concentrated urine.