Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. : 445  Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure. Pressure is a standard mechanical quantity. Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and U.S. customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure, and the torr is defined as 1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer. Definition
Pressure is the amount of force applied perpendicular to the surface of an object per unit area. The symbol for it is "p" or P.
The IUPAC recommendation for pressure is a lower-case p.
However, upper-case P is widely used. The usage of P vs p depends upon the field in which one is working, on the nearby presence of other symbols for quantities such as power and momentum, and on writing style.
Polyarthritis is any type of arthritis that involves 5 or more joints simultaneously. It is usually associated with autoimmune conditions and may be experienced at any age and is not sex specific. Causes
Polyarthritis is most often caused by an auto-immune disorder such as rheumatoid arthritis, amyloidosis, psoriatic arthritis, and lupus erythematosus but can also be caused by infection with an alphavirus such as chikungunya virus and Ross River virus. This condition is termed alphavirus polyarthritis syndrome. Sindbis virus, which is endemic in Northern Europe, Africa, the Middle East, and Australia, is the most widely distributed of the alphaviruses causing polyarthritis, though infection is usually mild or asymptomatic. Associated conditions
It may be associated with bilateral edema in lower limbs, pain and joint swelling. Sometimes there is previous history of inflammatory joint problems and bilateral edema of lower limbs. Alphavirus Polyarthritis Syndrome has an incubation period of 3–21 days, depending on the specific virus, with either a gradual or sudden onset of fever, arthralgias, headache, and lymphadenitis and conjunctivitis in some forms. A maculopapular rash may present 4–8 days post symptom onset and may be accompanied by an increase in fever. Joint pains associated with this condition may recur for many months after initial illness for up to a year. See also
Polyarteritis nodosa


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