A person or thing that closely resembles another, as in Our grandson is a carbon copy of his dad. Originally this term meant a copy of a document made by using carbon paper. The linguistic transfer to other kinds of duplicate survived the demise of carbon paper (replaced by photocopiers, computer printers, and other more sophisticated devices). [ c. 1870 ]
The severity of symptoms depends on whether the injury is mild, moderate or severe. 1  Mild traumatic brain injury, also known as a concussion, either doesn't knock you out or knocks you out for 30 minutes or less. 2  Moderate traumatic brain injury causes unconsciousness lasting more than 30 minutes. Symptoms of moderate traumatic brain injury are similar to those of mild traumatic brain injury but more serious and longer-lasting. Severe traumatic brain injury knocks you out for more than 24 hours. Symptoms of severe traumatic brain injury are also similar to those of mild traumatic brain injury but more serious and longer-lasting.
The aforementioned Dr. Fink believed the brain might remain conscious as long as 15 seconds; that's how long cardiac arrest victims last before blacking out. (Dr. Fink's colleague put the window of awareness at 5 seconds.) He also pointed out that people have remained alert after having had their spinal cords severed.his was proven when a scientist condemned to the guillotine in the 1700s told his assistant to watch and that he would blink as many times as he could. The assistant counted fifteen to twenty blinks after the head was severed, the blinks coming at intervals of about one second. So the head does remain briefly alive.