A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision ...A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision detection algorithm. By decomposing the whole space into relative positions and geometric features of the sphere and the primitive considered, closed form distance formula are got. These calculations are very useful in the real time collision detection in which primitives are used as bounding volumes of complex objects.展开更多
Persistent organic pollutants （POPs） persisting in the environment, which accumulate in human and animal tissue and bio-magnify in food-chains, would have significant impacts on human health and the environment. Thu...Persistent organic pollutants （POPs） persisting in the environment, which accumulate in human and animal tissue and bio-magnify in food-chains, would have significant impacts on human health and the environment. Thus, the present study was designed to investigate the accumulation of organic pollutants in prawn from streams of Sialkot, Pakistan. Fresh water prawn Macrobrachium lamarrei was captured from streams of study area. Samples were prepared for extraction of selected organic pollutants and then analyzed through gas chromatograph-electron capture detector （GC-ECD）. Results of current study showed that five pesticide residues, i.e., B-HCH, Lindane, DDD, 2, 4-DDT and 4, 4-DDT were detected in composite prawn sample. The rest of POPs residues were not found in prawn. The ratio of a-HCH/γ-HCH indicated an input of technical HCH and long range transport, while the ratio of DDT/（DDD ＋ DDE） showed recent use of DDT to the study area. The high values of TEC-HQ and PEC-HQ of POPs in the studied prawn samples depicted risk posed to health.展开更多
文摘A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision detection algorithm. By decomposing the whole space into relative positions and geometric features of the sphere and the primitive considered, closed form distance formula are got. These calculations are very useful in the real time collision detection in which primitives are used as bounding volumes of complex objects.
文摘Persistent organic pollutants （POPs） persisting in the environment, which accumulate in human and animal tissue and bio-magnify in food-chains, would have significant impacts on human health and the environment. Thus, the present study was designed to investigate the accumulation of organic pollutants in prawn from streams of Sialkot, Pakistan. Fresh water prawn Macrobrachium lamarrei was captured from streams of study area. Samples were prepared for extraction of selected organic pollutants and then analyzed through gas chromatograph-electron capture detector （GC-ECD）. Results of current study showed that five pesticide residues, i.e., B-HCH, Lindane, DDD, 2, 4-DDT and 4, 4-DDT were detected in composite prawn sample. The rest of POPs residues were not found in prawn. The ratio of a-HCH/γ-HCH indicated an input of technical HCH and long range transport, while the ratio of DDT/（DDD ＋ DDE） showed recent use of DDT to the study area. The high values of TEC-HQ and PEC-HQ of POPs in the studied prawn samples depicted risk posed to health.
