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.
The method an author uses to develop characters in a work. In direct characterization, the author straightforwardly states the character's traits. With indirect characterization, those traits are implied through what the character says, does, how the character dresses, interacts with other characters, etc.