I would say Frequency is how often you perform an activity, and Intensity is how hard/intensely you perform the activity.
The brain stem which is composed of the Pons, The Medulla, and the Midbrain serve a very vital function... They control the functions that keep you alive; Heart Rate, Respiratory Rate, Breathing input and output, Blood pressure, as well a vasomotor functions. So taking this into account, an injury to the brain stem is extremely bad, as that can and will most definitely be very lethal.
The reason why ethics differs when we're talking about people, companies, nations is that all of these have interests which may differ. What happens then with differing interests is that it also lead to different moral and value systems which again in turn lead to different ethics. Most usually, the actual source why ethics differ is either due to the interests or wishes of a particular social group mentioned here.