To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
Because solar flares form in the same active regions as sunspots, they are connected to these smaller, less violent events. Flares tend to follow the same 11-year cycle. At the peak of the cycle, several flares may occur each day, with an average lifetime of only 10 minutes. The enormous sunspot of 2014 fired off several powerful solar flares.