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Reduced gradient bubble model
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<p>The reduced gradient bubble model (RGBM) is an <a href="/facts/Algorithm/fnl5NmRt">algorithm</a> developed by <a href="/facts/Bruce_Wienke/x5m1WXAb">Bruce Wienke</a> for calculating <a href="/facts/Decompression_stop/eBKHl82s">decompression stops</a> needed for a particular <a href="/facts/Dive_profile/BCffhVPt">dive profile</a>. It is related to the <a href="/facts/Varying_Permeability_Model/nKqdIhBh">Varying Permeability Model</a>. but is conceptually different in that it rejects the gel-bubble model of the varying permeability model. </p><p>It is used in several <a href="/facts/Dive_computer/rHHCAMHG">dive computers</a>, particularly those made by <a href="/facts/Suunto/u4Pg5f1h">Suunto</a>, Aqwary, <a href="/facts/Mares_(scuba_equipment)/M9GoG4n0">Mares</a>, HydroSpace Engineering, and Underwater Technologies Center. It is characterised by the following assumptions: blood flow (<a href="/facts/Perfusion/EFVLNUTg">perfusion</a>) provides a limit for tissue gas penetration by <a href="/facts/Diffusion/KbAxroBa">diffusion</a>; an <a href="/facts/Exponential_distribution/yY3EdV0u">exponential distribution</a> of sizes of bubble seeds is always present, with many more small seeds than large ones; bubbles are permeable to gas transfer across surface boundaries under all pressures; the <a href="/facts/John_Scott_Haldane/Fll9zPL0">haldanean</a> <a href="/facts/B%C3%BChlmann_decompression_algorithm/Cel7P4N4">tissue compartments</a> range in <a href="/facts/Half_time_(physics)/y9PqBXFt">half time</a> from 1 to 720 minutes, depending on <a href="/facts/Breathing_gas/1sUAT6mt">gas mixture</a>. </p><p>Some manufacturers such as Suunto have devised approximations of Wienke's model. Suunto uses a modified haldanean nine-compartment model with the assumption of reduced off-gassing caused by bubbles. This implementation offers both a depth ceiling and a depth floor for the decompression stops. The former maximises tissue off-gassing and the latter minimises bubble growth. The model has been correlated and validated in a number of published articles using collected dive profile data. </p>