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Aortic dissection ( AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. [3] In most cases, this is associated with a sudden onset of severe chest or back pain, often described as "tearing" in character.
An aortic aneurysm is an enlargement (dilatation) of the aorta to greater than 1.5 times normal size. They usually cause no symptoms except when ruptured. Occasionally, there may be abdominal, back, or leg pain. The prevalence of abdominal aortic aneurysm ("AAA") has been reported to range from 2 to 12% and is found in about 8% of men more than 65 years of age.
The human immunodeficiency virus (HIV) is a retrovirus that attacks the immune system.It can be managed with treatment. Without treatment it can lead to a spectrum of conditions including acquired immunodeficiency syndrome (AIDS). Effective treatment for HIV-positive people (people living with HIV) involves a life-long regimen of medicine to suppress the virus, making the viral load undetectable.
Manufacturing and early history The demon core (like the core used in the bombing of Nagasaki) was, when assembled, a solid 6.2-kilogram (14 lb) sphere measuring 8.9 centimeters (3.5 in) in diameter.It consisted of three parts: two plutonium-gallium hemispheres and a ring, designed to keep neutron flux from "jetting" out of the joined surface between the hemispheres during implosion.
