Mononucleosis, commonly called mono, is an illness caused by the Epstein-Barr virus. Although it's rarely serious, mono can cause bothersome symptoms that last several weeks.
Complex systems. Complex systems present problems both in mathematical modelling and philosophical foundations. The study of complex systems is an approach to science that investigates how relationships between parts give rise to the collective behaviors of a system and how the system interacts and forms relationships with its environment.
1 : a branch of science concerned with the interrelationship of organisms and their environments. 2 : the totality or pattern of relations between organisms and their environment. 3 : human ecology. 4 : environment, climate the moral ecology; also : an often delicate or intricate system or complex the ecology of language.