Transcranial Doppler (TCD), first described in 1982 [1], is a noninvasive ultrasound (US) study that involves the use of a low-frequency (â¤2 MHz) transducer probe to insonate the basal cerebral arteries through relatively thin bone windows.
Details. as.character and is.character are generic: you can write methods to handle specific classes of objects, see InternalMethods. Further, for as.character the default method calls as.vector, so dispatch is first on methods for as.character and then for methods for as.vector.
For other uses, see Characterization (disambiguation). Characterization or characterisation is the concept of creating characters for a narrative. It is a literary element and may be employed in dramatic works of art or everyday conversation. Characters may be presented by means of description, through their actions, speech, thoughts and interactions with other characters.