hamamelis. n. 1. (Plants) any of several trees or shrubs constituting the hamameliaceous genus Hamamelis, native to E Asia and North America and cultivated as ornamentals.See witch hazel.. (Plants) any of several trees or shrubs constituting the hamameliaceous genus Hamamelis, native to E Asia and North America and cultivated as ornamentals.
Diffusion tensor imaging (DTI). A refinement of magnetic resonance imaging that allows the doctor to measure the flow of water and track the pathways of white matter in the brain. DTI is able to detect abnormalities in the brain that do not show up on standard MRI scans.
Demographic transition. Demographic transition (DT) refers to the transition from high birth and death rates to lower birth and death rates as a country or region develops from a pre-industrial to an industrialized economic system.