Chemical structure of lipid A as found in E. coli. Lipid A is a lipid component of an endotoxin held responsible for the toxicity of gram-negative bacteria. It is the innermost of the three regions of the lipopolysaccharide (LPS), also called endotoxin molecule, and its hydrophobic nature allows it to anchor the LPS to the outer membrane.
watermark - Computer Definition. 1  A translucent mark or image in paper produced by pressing the paper in a mold or on a processing roll during the manufacturing process. The watermark is visible when the paper is held to a light. A watermark is used as a sign of authenticity in order to make the counterfeiting of currency and postage stamps more difficult, for example.
A digital watermark is a kind of marker covertly embedded in a noise-tolerant signal such as an audio, video or image data. It is typically used to identify ownership of the copyright of such signal. Watermarking is the process of hiding digital information in a carrier signal; the hidden information should, but does not need to, contain a relation to the carrier signal. Digital watermarks may be used to verify the authenticity or integrity of the carrier signal or to show the identity of its