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.
Stress or tissue injury is thought to be the cause of simple canker sores. Certain foods -- including citrus or acidic fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes, and strawberries) -- can trigger a canker sore or make the problem worse.. A. A. Canker sores are small, shallow ulcers that appear in the mouth and often make eating and talking uncomfortable. There are two types of canker sores 1  : Simple canker sores. 2  These may appear three or four times a year and last up to a week. 3  They typically occur in people between 10 and 20 years of age.