In stochastic processes, chaos theory and time series analysis, detrended fluctuation analysis (DFA) is a method for determining the statistical self-affinity of a signal.
Sore throats caused by tonsillitis or streptococcus may trigger a canker sore even after the initial throat condition has subsided. Also known as an aphthous ulcer, canker sores are painful and unsightly, but they are not contagious.
1 See a doctor if canker sores are accompanied by fever, last more than three weeks, or the affected individual has difficulty swallowing.  Multiple factors may cause canker sores, including injury to the mouth, acidic or spicy foods, vitamin deficiencies, hormones, stress, or autoimmune disorders.