1 In the mercury barometer, atmospheric pressure balances a column of mercury, the height of which can be precisely measured. 2  Of the many different varieties of mercury barometers, most variations arise from different techniques for measuring the height of the mercury column.
Recognizing the Symptoms of an HIV Rash. 1  1. Check for a rash that is red, slightly raised, and very itchy. 2  2. Note if the rash appears on your shoulders, chest, face, upper body, and hands. 3  3. Pay attention to other symptoms that may occur when you have HIV rash.  4. Be aware of the causes of HIV rash.
HIV symptoms. Within a month or two of HIV entering the body, 40% to 90% of people experience flulike symptoms known as acute retroviral syndrome (ARS). But sometimes HIV symptoms don't appear for yearsâsometimes even a decadeâafter infection. In the early stages of HIV infection, the most common symptoms are none, says Michael Horberg, MD, director of HIV/AIDS for Kaiser Permanente, in Oakland, Calif.