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.
View Full Document. Character data is composed of letters, symbols, and numerals that will not be used in arithmetic operations. â¢ CPU stands for Central Processing Unit. It contains two parts: ALU (Arithmetic/Logic Unit) and CU (Control Unit). â¢ CU (Control Unit) fetches instructions one by one for execution.