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.
An acronym, PAIRS, can help you recall the five methods of characterization: physical description, action, inner thoughts, reactions, and speech. Physical description-the character's physical appearance is described. For example, characters might be described as tall, thin, fat, pretty, etc.