As the disk rotates faster, the pulse frequency increases accordingly. Since the relationship between pulse frequency and rotational velocity is linear, it is a simple matter to use the pulse frequency as an indication of speed. The output pulses can be transformed into speed units by measuring their frequency, and then multiplying the frequency by an appropriate scale factor.
The life expectancy of a person with dementia is unpredictable, and the disease can progress for up to around 10 years. It is estimated that a third of people with dementia at any one time will be in the later stages of the disease.
Common causes of irreversible dementias: 1  Alzheimer's disease or Senile Dementia of the Alzheimer's type (SDAT) 2  Progressive mental deterioration spanning a long period of time (3-20 years)  Affects 60 percent of those diagnosed with irreversible dementia.