The answer to your question is,
The Scientific Method
-Mabel <3
Technological Change. First radio broadcast of Message: President Calvin Coolidge, 1923. First television broadcast of Message: President Harry Truman, 1947.
The change in Helen's work hours (night shift) may cause Helen to be at increased risk for heart disease. The effects of shift work can manifest in various forms of illness, one is problems in the cardiovascular system. The reason is because the cardiovascular system in all mammals is highly organised with regard to time and when the time is different organized (the time we should sleep we work) that can lead to certain conditions.