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.
While related, there are distinct differences between the two words and their meanings. Character is often used to define a personâs integrity, such as he has âupstanding characterâ or âhis character is lacking.â Character is actually a set of behavior traits that define what type of person you are.