Roentgen (unit) absorbed dose in a wide range of matter. When measuring absorbed dose in a human due to external exposure, the SI unit the gray, or the related non-SI rad are used. From these can be developed the dose equivalents to consider biological effects from differing radiation types and target materials. These are equivalent dose, and effective dose for which the SI unit sievert or the non-SI rem are used. The following table shows radiation quantities in SI and non-SI units: Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays
The Invention of Art of human expression and embellishment. Reviewer Marc Spiegler called the book "a must-read for anyone active in the arts". The Invention of Art The Invention of Art: A Cultural History (2001) is an art history book by Dr. Larry Shiner (1934- ), Emeritus Professor of Philosophy, History, and Visual Arts at the University of Illinois, Springfield Shiner spent over a decade to finish the work of this book. The book sees fine art as a modern invention due to social transformations during the 18th century. David Clowney, writing for "Contemporary Aesthetics" summarizes the central thesis of this book. "In The