Abstract: A portion of an image field (e.g., a map) to be displayed on a display at a client device (e.g., a thin client such as a mobile phone) is downloaded on request from a server as a plurality of image tiles representing respective portions of the image field. A first image tile represents a portion at the center of the image to be displayed on the display and further image tiles represent portions surrounding the first tile. The total area of the image tiles exceeds the area of the display. Each tile is displayed as it becomes available. Additional files image can be requested automatically from the server in response to a user navigating to the edge of the displayed image.

Abstract: A recombinant protein having bacteriophage endosialidase enzymatic activity obtainable by expression from a recombinant vector comprising a DNA sequence encoding a bacteriophage endosialidase linked to a DNA sequence of an expression vector which express a polypeptide which adds to the N-terminus of the endosialidase, or an analogue of said protein, which is a mutant, functional fragment or derivative of said protein having endosialidase enzymatic activity.