Depression is a mental disorder, but at some times is not treated as one. Depression is never to be taken lightly, and should always be taken very seriously.    Some symptoms of depression are:   - Lack of interest in normally enjoyable activities.
IU (international unit): An international unit (IU) is an internationally accepted amount of a substance. This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines).The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable.For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol. Nonetheless, most IUs are quite handy and helpful in use as a means of standardizing measures.he definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For example, an IU of vitamin E is the specific biological activity of 0.671 milligrams of d-alpha-tocopherol.
The International System of Units (SI), commonly known as the metric system, is the international standard for measurement. The International Treaty of the Meter was signed in Paris on May 20, 1875 by seventeen countries, including the United States and is now celebrated around the globe as World Metrology Day.he SI is made up of 7 base units that define the 22 derived units with special names and symbols. The international prototype of the kilogram is the only remaining artifact used to define a base unit of the SI (rather than definition by a fundamental constant).