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| a screen or mat covered with a dark material for shielding a camera lens from excess light or glare. |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
haematocrit
diagnostic procedure for the analysis of blood. The name is also used for the apparatus in which this procedure is performed and for the results of the analysis. In the procedure, an anticoagulant is added to a blood sample held in a calibrated tube. The tube is allowed to stand for one hour, after which the sedimentation rate (how rapidly blood cells settle out from plasma) is determined. Most acute generalized infections and some local infections raise the rate of sedimentation. A raised sedimentation rate may be among the first signs of an otherwise hidden disease.
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