A camera can include a camera body and a lens mounted to the camera body. New polyuronic acid derivatives, as a dispersant, according to the present invention characterized in that polyuronic acids are attached by reductively amination, through reducing termini of the polyuronic acids, to glyceryl poly triamine. The present method further includes decrypting the instance of media content from an encryption local to the source node. For a planar heater, the W layer comprises a plurality of conductive strands distributed on the substrate, with the strands generally parallel and serpentine shaped for a rectangular substrate, and extending along respective lines of longitude that merge at opposite poles of the substrate for a circular substrate. Because of this wide entrance, even a person sitting on a wheelchair or using any other aid can easily enter the photo compartment for photography.