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.
ecology). Ecologists study these interactions in order to understand the abundance and diversity of life within. Earth's ecosystemsâin other words, why there are so many plants and animals, and why there. are so many different types of plants and animals (Fig. 1).