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.
Next, some more definitions: Primitive Character = Plesiomorphy A character which is in the state shared by the common ancestor of the group. Derived Character = Apomorphy A character in a new state, not the primitive one. Shared Character: A character shared by all the members of the group.Shared Derived Character = Synapomorphy A character which is in a new state and shared by all the member of the group.Unique Derived Character = Autapomorphy A character found only in that taxon.Is a synapomorphy when discussed at the level of the members of a taxon.hared Derived Character = Synapomorphy A character which is in a new state and shared by all the member of the group. Unique Derived Character = Autapomorphy A character found only in that taxon. Is a synapomorphy when discussed at the level of the members of a taxon.