Here's what I found a while back when seeking info about tumor necrosis. 1) Necrosis in the tumor means that the cancer cells in that area are dead. The pathologic finding of necrosis suggests a fast-growing cancer. This often happens because the tumor runs out of blood supply in the central portion. Without a blood supply, the tumor cells cannot live.
Football cleats also come in the removable and molded variety. Molded cleats tend to be less expensive and are often required for youth play for safety reasons. Detachable football cleats are made of rubber, hard plastic or metal and come in a variety of lengths for use on different playing surfaces.
Rugby league is played with a prolate spheroid shaped football which is inflated with air. A referee will stop play immediately if the ball does not meet the requirements of size and shape. Traditionally made of brown leather, modern footballs are synthetic and manufactured in a variety of colours and patterns.