Hives on dark skin. Hives are a skin reaction that causes red or white itchy welts. The welts vary in size and appear and fade repeatedly as the reaction runs its course. Chronic hives are a condition in which the welts last more than six weeks or recur over months or years.Chronic hives usually aren't life-threatening. But the condition can be very uncomfortable and interfere with sleep and daily activities. Often, the cause of chronic hives is not clear.In some cases, chronic hives are a sign of an underlying health problem, such as thyroid disease or lupus. You can try various treatments to relieve your symptoms. For many people, antihistamine and anti-itch medications provide relief from chronic hives.hronic hives are a condition in which the welts last more than six weeks or recur over months or years. Chronic hives usually aren't life-threatening. But the condition can be very uncomfortable and interfere with sleep and daily activities. Often, the cause of chronic hives is not clear.
longitudinal magnetization. 1  of a material or medium in a manner in which the magnetic flux is essentially parallel to the long axis of the influencing field. 2  In magnetic recording, 3  of a material or medium essentially in the same direction as the material or medium is traveling.
A longitudinal survey is a correlational research study that involves repeated observations of the same variables over long periods of time â often many decades. It is a type of observational study.