Derangement:
In combinatorial mathematics, a derangement is a permutation of the elements of a set, such that no element appears in its original position. In other words, a derangement is a permutation that has no fixed points. [Wikipedia]
Noted in “A mysterious blood-clotting complication is killing coronavirus patients,” Ariana Eunjung Cha, WaPo:
The body’s cardiovascular system often is described as a network of one-way streets that connect the heart to other organs. Blood is the transport system, responsible for moving nutrients to the cells and waste away from them. A common cold or a cut on the finger can lead to changes that help repair the damage, but when the body undergoes a more significant trauma, the blood can overreact, leading to an imbalance that can cause excessive clots or bleeding — and sometimes both.
Scientists call this “hemostatic derangement.” In math, a derangement is a permutation in which no element is in its original position.
Harlan Krumholz, a cardiac specialist at the Yale-New Haven Hospital Center, said no one knows whether blood complications are a result of a direct assault on blood vessels, or a hyperactive inflammatory response to the virus by the patient’s immune system.
“One of the theories is that once the body is so engaged in a fight against an invader, the body starts consuming the clotting factors, which can result in either blood clots or bleeding. In Ebola, the balance was more toward bleeding. In covid-19, it’s more blood clots,” he said.
