The strength of warm frozen soils in permafrost is fundamentally significant to estimate and predict the ground settlements from construction activities. A study was therefore initiated to assess the strength and its ...The strength of warm frozen soils in permafrost is fundamentally significant to estimate and predict the ground settlements from construction activities. A study was therefore initiated to assess the strength and its behaviors of undisturbed and reconstituted frozen soils at temperatures close to 0 ℃. A series of triaxial compression tests(TCT) were performed by using a developed testing apparatus and a matching specimen-preparation method. The confinement was applied from air pressure, the temperature in the specimen was maintained using two-end refrigeration, and multi-stage loading on a single specimen was adopted to determine the strength. The test results showed that the strength, both for the undisturbed and reconstituted frozen-soil specimens, was significantly dependent on the temperatures and independent of the applied confining pressures. Additionally, the strength of undisturbed frozen soils was about 1.6 times more than that for reconstituted frozen soils. These observations were closely associated with the structures existing between pore-ice and gravels with large diameters.展开更多
Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the no...Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the normal values of 3D-left ventricular(LV)and left atrial(LA)volume and function in a nationwide,population-based cohort of healthy Han Chinese adults.A total of 1117 healthy volunteers aged 18–89 years were enrolled from 28 collaborating laboratories in China.Two sets of 3D echocardiographic instruments were used,and full-volume echocardiographic images were recorded and transmitted to a core laboratory for image analysis with a vendor-independent off-line workstation.Finally,866 volunteers(mean age of 48.4 years,402 men)were qualified for final analysis.Most parameters exhibited substantial differences between different sex and age groups,even after indexation by body surface area.The normal ranges of 3D-LV and 3D-LA volume and function differed from those recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines,presented by the World Alliance Societies of Echocardiography(WASE)study,and from the 2D values in the EMINCA study.The normal reference values of 3D echocardiography-derived LV and LA volume and function were established for the first time in healthy Han Chinese adults.Normal ranges of 3D-LV and 3D-LA echocardiographic measurements stratified with sex,age,and race should be recommended for clinical applications.展开更多
基金supported by National Natural Science Foundation of China (No. 51304209)the Natural Science Foundation of Jiangsu Province of China (No. BK20141135)the Fundamental Research Funds for the Central Universities (No. 2015QNA63)
文摘The strength of warm frozen soils in permafrost is fundamentally significant to estimate and predict the ground settlements from construction activities. A study was therefore initiated to assess the strength and its behaviors of undisturbed and reconstituted frozen soils at temperatures close to 0 ℃. A series of triaxial compression tests(TCT) were performed by using a developed testing apparatus and a matching specimen-preparation method. The confinement was applied from air pressure, the temperature in the specimen was maintained using two-end refrigeration, and multi-stage loading on a single specimen was adopted to determine the strength. The test results showed that the strength, both for the undisturbed and reconstituted frozen-soil specimens, was significantly dependent on the temperatures and independent of the applied confining pressures. Additionally, the strength of undisturbed frozen soils was about 1.6 times more than that for reconstituted frozen soils. These observations were closely associated with the structures existing between pore-ice and gravels with large diameters.
文摘Current guidelines encourage large studies in a diverse population to establish normal reference ranges for three-dimensional(3D)echocardiography for different ethnic groups.This study was designed to establish the normal values of 3D-left ventricular(LV)and left atrial(LA)volume and function in a nationwide,population-based cohort of healthy Han Chinese adults.A total of 1117 healthy volunteers aged 18–89 years were enrolled from 28 collaborating laboratories in China.Two sets of 3D echocardiographic instruments were used,and full-volume echocardiographic images were recorded and transmitted to a core laboratory for image analysis with a vendor-independent off-line workstation.Finally,866 volunteers(mean age of 48.4 years,402 men)were qualified for final analysis.Most parameters exhibited substantial differences between different sex and age groups,even after indexation by body surface area.The normal ranges of 3D-LV and 3D-LA volume and function differed from those recommended by the American Society of Echocardiography and the European Association of Cardiovascular Imaging guidelines,presented by the World Alliance Societies of Echocardiography(WASE)study,and from the 2D values in the EMINCA study.The normal reference values of 3D echocardiography-derived LV and LA volume and function were established for the first time in healthy Han Chinese adults.Normal ranges of 3D-LV and 3D-LA echocardiographic measurements stratified with sex,age,and race should be recommended for clinical applications.
