Feather These barbules have minute hooks called barbicels for cross-attachment. Down feathers are fluffy because they lack barbicels, so the barbules float free of each other, allowing the down to trap air and provide excellent thermal insulation. At the base of the feather, the rachis expands to form the hollow tubular "calamus" (or quill) which inserts into a follicle in the skin. The basal part of the calamus is without vanes. This part is embedded within the skin follicle and has an opening at the base (proximal umbilicus) and a small opening on the side (distal umbilicus). Hatchling birds of some
Calamus (DTP) LE 2015 (lite edition with restricted number of modules). Calamus is a RIP itself and handles various, adjustable raster dot sizes at the same time. It handles rasterization information per document, page or even per frame. It also uses a unique, notable method of "cutting raster dots", which means that a screen raster can be cropped or clipped at certain borders, given by the document layout elements. Thus, it does not require any external RIP for interpretation, rendering and screening of documents. Using a special module, Calamus supports dot rasterization (using the term "Star Screening") which is a frequency modulated