Since the discourse community itself is intangible, it is easier to imagine discourse communities in terms of the fora in which they operate. The hypothetical journal and email list can each be seen as an example of a forum, or a concrete, local manifestation of the operation of the discourse community.
Daily nausea can be caused by stress. An ulcer in the small intestine may cause chronic nausea. Excessive consumption of caffeine can cause nausea. A person may develop chronic nausea in relation to a peptic ulcer. Indigestion is one of the most common causes of nausea.
Nausea is a non-specific symptom, which means that it has many possible causes. Some common causes of nausea are motion sickness, dizziness, migraine, fainting, low blood sugar, gastroenteritis (stomach infection) or food poisoning. Nausea is a side effect of many medications including chemotherapy, or morning sickness in early pregnancy.