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.
Constant mild nausea can stem from physical trauma such as brain injury or concussion or from meningitis, an infection in the lining of the brain. Nausea also can be a side effect of medications. Cancer treatments such as chemotherapy may cause constant mild nausea and a frequent urge to vomit. This term is misleading, though, since nausea can strike at any time throughout the day and may or may not be accompanied by vomiting.