To give blood you must: 1  Be in general good health.  Be at least 17 years old. (If you are 16 you can donate with a CBC consent form signed by your parent). There is no upper age limit as long as you have no health restrictions.
Specific radiative intensity. Specific (radiative) intensity is a quantity used in physics that describes electromagnetic radiation. It is a term used in much of the older scientific literature. The present-day SI term is spectral radiance, which can be expressed in base SI units as W mâ2 srâ1 Hzâ1.
Intensity is proportional to the square of the amplitude. So if amplitude is squared, intensity is quadrupled. Intensity varies in diagnostic ultrasound because it's highest at the center of the beam and falls off near the periphery. It also varies along direction of travel due to focusing and attenuation.