BACKGROUND/AIM The Global initiative for chronic obstructive lung diseases (GOLD) reports a staging system for chronic obstructive pulmonary disease (COPD) based on airflow limitations at rest. Cardiopulmonary exercise testing (CPET) is used in surveys to determine the remaining working capacity concerning the degree of disability and the disability benefit payment after rehabilitation in patie...

Let $R$ be a commutative ring with identity. Let $G(R)$ denote the maximal graph associated to $R$, i.e., $G(R)$ is a graph with vertices as the elements of $R$, where two distinct vertices $a$ and $b$ are adjacent if and only if there is a maximal ideal of $R$ containing both. Let $Gamma(R)$ denote the restriction of $G(R)$ to non-unit elements of $R$. In this paper we study the various graphi...