目的通过流行病学调查比较面积骨密度(areal bone mineral density,aBMD)和体积骨密度(volumetric BMD,vBMD)对骨质疏松的检出率,从而探索出针对大骨骼和小骨骼人群骨质疏松诊断的校正诊断方法。方法采用GE-Lunar DPX双能X线吸收法骨密...目的通过流行病学调查比较面积骨密度(areal bone mineral density,aBMD)和体积骨密度(volumetric BMD,vBMD)对骨质疏松的检出率,从而探索出针对大骨骼和小骨骼人群骨质疏松诊断的校正诊断方法。方法采用GE-Lunar DPX双能X线吸收法骨密度测量仪测量腰椎和股骨颈骨密度,将仪器给的投影面积(cm^2)通过正方体数学模式(腰椎)和圆柱体数学模式(股骨颈)分别获得骨体积和vBMD(vBMD=骨矿物含量/骨体积),按世界卫生组织推荐20～39岁的aBMD和vBMD的标准差生成的T值定义正常、骨量减低和骨质疏松,骨质疏松诊断用世界卫生组织确立的T值诊断法。结果腰椎和股骨颈vBMD诊断骨质疏松症避免了aBMD引起的小骨误诊两部位分别为16%和11.6%,大骨漏诊在两部位分别为7%和18%。腰椎骨体积每小于均值10 cm^3,其aBMD的误诊率为1%;每大于均值10 cm^3,漏诊率为0.44%。股骨颈骨体积每小于均值1.0 cm^3,aBMD的误诊率为2.6%;每大于均值1.0 cm^3,漏诊率为4%。结论诊断骨质疏松用vBMD可以避免aBMD引起的大骨漏诊和小骨误诊的弊病。展开更多
Some unsaturated soils may undergo volumetric changes when submitted to an increase in its water content or are inundated under applied loads. This behavior is related to the volumetric instability when the water cont...Some unsaturated soils may undergo volumetric changes when submitted to an increase in its water content or are inundated under applied loads. This behavior is related to the volumetric instability when the water content is changed. Natural collapsible soils in Brazil are generally found in alluvial, colluvial and residual soils. There are known occurrences of natural collapsible soils in many states of Brasil. In the last two decades, many public projects have been developed in areas where the occurrence of collapsible soils has been associated to geotechnical problems. The present paper devoted to study the collapsible soils in the state of Pernambuco which has been associated with large engineering projects such as housing and irrigation canals. The geotechnical investigation program included test with a field apparatus, called Expanso-colapsometer, which allows the measurement of the field settlements of a small 0.10 m of diameter plate inserted at any depth inside an auger boring hole. Reconnaissance borings with SPT （standard penetration test）, investigation pits with undisturbed block sampling and disturbed samples for laboratory tests were also made in order to assess the type and characteristics of the soil. Field tests used the Expanso-colapsometer to measure the settlement of the soil in selected depths under controlled flooding. Laboratory work included double and standard oedometer tests with a controlled rate of water inflow of 1.0 mL/s. It was found that the volume change of the soils when flooded depends on their natural stress state （vertical stress, suction head and structure of soil）.展开更多
文摘目的通过流行病学调查比较面积骨密度(areal bone mineral density,aBMD)和体积骨密度(volumetric BMD,vBMD)对骨质疏松的检出率,从而探索出针对大骨骼和小骨骼人群骨质疏松诊断的校正诊断方法。方法采用GE-Lunar DPX双能X线吸收法骨密度测量仪测量腰椎和股骨颈骨密度,将仪器给的投影面积(cm^2)通过正方体数学模式(腰椎)和圆柱体数学模式(股骨颈)分别获得骨体积和vBMD(vBMD=骨矿物含量/骨体积),按世界卫生组织推荐20～39岁的aBMD和vBMD的标准差生成的T值定义正常、骨量减低和骨质疏松,骨质疏松诊断用世界卫生组织确立的T值诊断法。结果腰椎和股骨颈vBMD诊断骨质疏松症避免了aBMD引起的小骨误诊两部位分别为16%和11.6%,大骨漏诊在两部位分别为7%和18%。腰椎骨体积每小于均值10 cm^3,其aBMD的误诊率为1%;每大于均值10 cm^3,漏诊率为0.44%。股骨颈骨体积每小于均值1.0 cm^3,aBMD的误诊率为2.6%;每大于均值1.0 cm^3,漏诊率为4%。结论诊断骨质疏松用vBMD可以避免aBMD引起的大骨漏诊和小骨误诊的弊病。
文摘Some unsaturated soils may undergo volumetric changes when submitted to an increase in its water content or are inundated under applied loads. This behavior is related to the volumetric instability when the water content is changed. Natural collapsible soils in Brazil are generally found in alluvial, colluvial and residual soils. There are known occurrences of natural collapsible soils in many states of Brasil. In the last two decades, many public projects have been developed in areas where the occurrence of collapsible soils has been associated to geotechnical problems. The present paper devoted to study the collapsible soils in the state of Pernambuco which has been associated with large engineering projects such as housing and irrigation canals. The geotechnical investigation program included test with a field apparatus, called Expanso-colapsometer, which allows the measurement of the field settlements of a small 0.10 m of diameter plate inserted at any depth inside an auger boring hole. Reconnaissance borings with SPT （standard penetration test）, investigation pits with undisturbed block sampling and disturbed samples for laboratory tests were also made in order to assess the type and characteristics of the soil. Field tests used the Expanso-colapsometer to measure the settlement of the soil in selected depths under controlled flooding. Laboratory work included double and standard oedometer tests with a controlled rate of water inflow of 1.0 mL/s. It was found that the volume change of the soils when flooded depends on their natural stress state （vertical stress, suction head and structure of soil）.
