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THE BIG NEWS!! By now I expect that all of you have already heard about this from the others that went to the Aqua Corps TEK95 show and attended the Desktop Decompression session. But just in case you have not heard it already... Abysmal Diving Inc. acquires DCAP. Since 1993, Hamilton Research Ltd., and Abysmal Diving Inc. have pursued the goal of creating the finest Hyperbaric Software package possible. As a result of these joint efforts Abysmal Diving Inc. is pleased to announce the aquisition of DCAP (Decompression Computation and Analysis Program) from Hamilton Research Ltd. The availability of DCAP will allow Abysmal Diving to begin incorporating the powerfull DCAP technology directly into its chief program, Abyss, Advanced Dive Planning Software. The addition of this new technology to Abyss will complete the goal of both companies to create the premier diving and hyperbaric software program available anywhere in the= world. Abyss is a comprehensive and easy-to-use set of software packages with components for all levels of recreational and technical diving. Abyss, which is simple and intuitive to use, runs on personal computers and laptops under Microsoft Windows; it allows a diver to plan decompression, oxygen exposure, and gas logistics information for a wide range of custom diving patterns, and facilitates storage of dive logs and results in an electronic logbook. Abyss is the most sophisticated and versatile of the desktop dive planning programs that perform decompression computations. Abyss has been developed by Abysmal Diving president Christopher M. Parrett and colleagues. DCAP is a computational program for calculating and analyzing decompression tables and profiles was developed over the last 20-plus years by R.W. Bill Hamilton and David J. Kenyon. Conceived for laboratory use, DCAP uses any of several contemporary computational methods and has produced decompression tables for commercial, scientific, and specialized military diving; it has accomplished an impressive track record of diversified and successful applications. More recently DCAP has been instrumental in the development of the concept of technical diving and has been used for a variety of special operations in the sport diving realm. =20 The new entity will combine the Windows diversity and ease of use of Abyss with the extensive experience that has gone into DCAP. Dr. Hamilton and Mr. Kenyon will continue to work with DCAP, and Dr. Hamilton will act as a consultant to Abysmal Diving. A full amalgamation of these two diversified and sophisticated technologies will take some time, but major aspects of DCAP philosophy and experience will soon be seen in revisions of Abyss, and in due course new and greatly improved versions of both computational tools will become available. Present users of both systems will continue to be supported. For more information contact Chris Parrett at (303) 530-7248, fax (303 530-2808 or CompuServe 72233,457 or on the Internet at chris@ab*.co*. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D DCAP: =20 DECOMPRESSION COMPUTATION AND ANALYSIS PROGRAM DCAP is a comprehensive computer program that serves as a tool for the generation and analysis of decompression tables and profiles. DCAP is designed to be used by engineers, diving operations managers, doctors, hyperbaric technicians, physiologists, and various kinds of researchers=BEanyone who needs decompression information and who knows the necessary operational techniques and understands the physiological limits involved. Basic PC computer skills are helpful, but it is not necessary to be a programmer to use DCAP. To generate decompression tables with DCAP the User enters a set of instructions=BEabout one page long=BEinto a personal computer (PC); this describes the dive or dives to be done, the gases to be used, the profiles to be followed, the instructions to the diver, etc., and is called a Basecase. The Basecase also references other previously prepared computer files which define or specify many other variables to be used, such as the system of units, the computational model and its characteristics, ascent limits (M-values), the table printout configuration, and the output files to be generated. The Basecase is in diving and not computer terminology. =20 DCAP uses various computational models DCAP is a practical result of many years of collective experience in preparing and evaluating many types of decompression tables. A number of models or algorithms are used by decompression developers; those that work well rely heavily on experience. DCAP does not use any specific model, but rather it facilitates the computational and table production process with several different models, approaches, ascent constraints, and table configurations. Our experience is greatest with the neo-Haldanian or Haldane-Workman-Schreiner model designated Tonawanda IIa. DCAP controls half times and M-values, and can work with any gases and gas mixtures, in virtually any units. A Notebook file keep a record of what has been done, and a Graphics file plots profiles. =20 The DCAP User can control many operational and computational aspects of the tables being generated, including descent and ascent patterns, stop patterns, initial conditions including repetitive status, timing method, table display method, staging intervals, instructions to the diver or operator, etc., and a variety of additional output information. A single table or a family of related tables can be produced with a single Basecase. Tables can be displayed as a single dive to a page with detailed instructions, or schedules for numerous bottom times for the same depth can be printed on a single table. The user has wide control of timing and its display, and oxygen can be handled and its levels and toxicity monitored throughout a dive. Saturation decompression profiles can be prepared, with both ascending and descending excursions. Diving at altitude and flying after diving can be handled. The conservatism of a table can be changed in several ways. Analysis of previous and ongoing dives Virtually any exposure for which the time-pressure-gas profile is known can be analyzed by DCAP in terms of gas loadings and/or oxygen exposure. Likewise, an ongoing profile can be picked up and decompression continued. This can be used, for example, to track the exposure history of a complicated and difficult treatment of decompression sickness and to prepare an appropriate decompression. A comprehensive, indexed manual covering the basics of decompression physiology, computational methods, and the description and use of DCAP is furnished with the program. A library of sample Basecases and setup files is furnished. DCAP has been used for air, trimix, and deep heliox bounce dives; excursions from both nitrox and heliox saturation, including repetitive excursions, excursions requiring stops, and ascending excursions; saturation and saturation abort tables; submarine free ascent profiles; tables for constant-oxygen closed-circuit rebreathers; deep air and enriched air (nitrox) dives; deep dives with neon; modelling counterdiffusion and inert gas switching; multi-level cave dives, some with exceptionally deep or long exposures; tables for deep tunnel work; transfer procedures for the Hyperbaric Air Lock on Space Station Freedom; and many others. Sample Basecase forms are available to DCAP users for these dive types; model parameters and ascent constraints for many of these actual dives are= available. Maximum likelihood A new approach to decompression is building up around statistical approaches, especially the use of maximum likelihood. DCAP can produce an output file which can be edited for use with an external maximum likelihood program such as MAXLX (not part of DCAP, but available with it). Using this approach the probability of decompression sickness can be estimated for a given dive profile. These estimates depend on calibration based on data analyses; these are currently available for air, nitrogen, and helium based dives, and for trimix dives using both inert gases, but with a less specific calibration. Additional calibration values will become available. A more extensive maximum likelihood capability is planned for incorporation as one of DCAPs capabilities. What DCAP is not or does not do A potential user of DCAP should understand that the system does not immediately solve all decompression problems. A considerable store of experience comes with DCAP, but the relevance of available experience may vary considerably between different types of dive. DCAP itself cannot provide judgement as to choice of its many variables, but some examples and advice in this area are available from HRL as part of the DCAP package. The program requires a knowledge of diving physiology and operations, and some training and study of the DCAP system by the potential User in order to operate it effectively. The fact that a table was generated by DCAP does not specify how it was computed; DCAP can use many computational models and allows the constraints for these models to be specified. /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ Christopher M. Parrett, President, Abysmal Diving Inc. 6595 Odell Place, Suite G. Boulder Colorado, USA 80301 Ph.303-530-7248, fx 303-530-2808 Makers of ABYSS, Advanced Dive Planning Software. Available in English, French, German, Portuguese and Swedish. Abyss, Mixed Gas, Technical Nitrox, Recreational Air. Abyss, Technical Logbooks featuring 22 integrated databases. =20
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