The triple turreted castle has been in use by the Corps of Engineers since it was adopted in 1840. Prior to that time an insignia of a similar design was worn on the uniforms of the Corps of Cadets of the United States Military Academy since the Academy was under the supervision and direction of the Chief of Engineers.
The most common cause of energy crisis is a drop of cerebral perfusion (global ischemia), usually resulting from cardiac arrest or severe hypotension (shock). Sustained severe hypoglycemia, and seizures lasting 1-2 hours also cause permanent brain damage. Pure hypoxia in clinical settings is unusual.
Ischemia is the medical term for what happens when your heart muscle doesn't get enough oxygen. Ischemia usually happens because of a shortage of blood and oxygen to the heart muscle. It is usually caused by a narrowing or blockage of one or more of the coronary arteries (which supply blood to the heart muscle). In many cases ischemia is a temporary problem.