Occasionally accessory bones are found in the carpus, but of more than 20 such described bones, only four (the central, styloid, secondary trapezoid, and secondary pisiform bones) are considered to be proven accessory bones. Sometimes the scaphoid, triquetrum, and pisiform bones are divided into two.
perforce definition: by or through necessity; necessarilyOrigin of perforceMiddle English par force from OFr: see per and force...
Permeability Coefficient. The permeability coefficient, P (or simply the permeability) is defined as the transport flux of material through the membrane per unit driving force per unit membrane thickness. It's value must be experimentally determined. The barrer is the commonly used unit for gas separation and it is defined as: