Somewhat more formally, for a set Ï of properties and relations, a Ï-representation of some structure X is a structure Y that is the image of X under a s homomorphism that preserves Ï. The label representation is sometimes also applied to the homomorphism itself.
Melanoma. This cancer begins in the melanocytes, the cells that provide the skinâs color. Melanoma is one of the deadliest forms of skin cancer because it can spread rapidly inside the body. Approximately one American dies from melanoma every hour.
Melanoma occurs when something goes awry in the melanin-producing cells (melanocytes) that give color to your skin. Normally, skin cells develop in a controlled and orderly way â healthy new cells push older cells toward your skin's surface, where they die and eventually fall off. But when some cells develop DNA damage, new cells may begin to grow out of control and can eventually form a mass of cancerous cells. Just what damages DNA in skin cells and how this leads to melanoma isn't clear. It's likely that a combination of factors, including environmental and genetic factors, causes melanoma. Still, doctors believe exposure to ultraviolet (UV) radiation from the sun and from tanning lamps and beds is the leading cause of melanoma. UV light doesn't cause all melanomas, especially those that occur in places on your body that don't receive exposure to sunlight.