Abstract: A mathematical model that models gas exchange of a central compartment with an environment having a model gas is provided. The central compartment is modeled to be in direct fluid communication with a plurality of peripheral compartments and with the environment to exchange the model gas therewith. Using a measure of an inert gas in a breathing mixture over a period of exposure of a person to the breathing mixture as a measure of the model gas in the environment over the time period, a measure of the model gas in the central compartment can be calculated according to the model. A risk of decompression sickness to the person resulting from the exposure can then be calculated based on the calculated measure of the model gas in the central compartment.

Abstract: A mathematical model that models gas exchange of a central compartment with an environment having a model gas is provided. The central compartment is modeled to be in direct fluid communication with a plurality of peripheral compartments and with the environment to exchange the model gas therewith. Using a measure of an inert gas in a breathing mixture over a period of exposure of a person to the breathing mixture as a measure of the model gas in the environment over the time period, a measure of the model gas in the central compartment can be calculated according to the model. A risk of decompression sickness to the person resulting from the exposure can then be calculated based on the calculated measure of the model gas in the central compartment.

Abstract: An electronic map for selectively displaying routes to various locations in a building such as a shopping mall is disclosed. The map displays a floor plan indicating a plurality of stations (shops, public telephones, washrooms, etc.) and paths connecting the various stations. A particular station can be selected at a keyboard, and a path extending from the location of the map to the selected station is then visually indicated, as with a string of light emitting diodes physically located on the map. In a multi-level building where several floor plans are displayed the map can visually indicate a path extending from the map to, for example, a stairwell, the vertical direction to be taken on the stairwell, and a continuation of the path from the stairwell to a station on another level.