Xerography or electrophotography is a dry photocopying technique. Its fundamental principle was invented by Hungarian physicist PÃ¡l SelÃ©nyi and based on SelÃ©nyi's publications Chester Carlson applied for and was awarded U.S. Patent 2,297,691 on October 6, 1942. The technique was originally called electrophotography.
A retrospective, generally, is a look back at events that took place, or works that were produced, in the past. As a noun, retrospective has specific meanings in medicine, software development, popular culture and the arts. It is applied as an adjective, synonymous with the term retroactive, to laws, standards, and awards.
Retrolisthesis. is the term used to define a degenerative and an acute spine condition in which a single vertebra gets displaced and moves backwards onto the vertebra lying immediately below it.Vertebrae are the bones that make up the spinal column and are separated from each other by cushioning intervertebral discs.s the term used to define a degenerative and an acute spine condition in which a single vertebra gets displaced and moves backwards onto the vertebra lying immediately below it.