目的以CBCT对样本牙根吸收的诊断结果为金标准,检验全景片(OPG)及根尖片对正畸相关牙根吸收(RRAOF)定性及分级半定量诊断结果的准确性。方法纳入完成固定正畸治疗的32例患者的121颗上前牙,正畸治疗前后均拍摄OPG、上前牙根尖片、上前牙C...目的以CBCT对样本牙根吸收的诊断结果为金标准,检验全景片(OPG)及根尖片对正畸相关牙根吸收(RRAOF)定性及分级半定量诊断结果的准确性。方法纳入完成固定正畸治疗的32例患者的121颗上前牙,正畸治疗前后均拍摄OPG、上前牙根尖片、上前牙CBCT。由3名放射专科医生按照Levander and Malmgren分度法对纳入样本的3种图像的牙根吸收程度分别进行评估,并以CBCT的诊断结果为金标准,检验OPG及根尖片对相同样本牙根吸收定性及分级半定量诊断结果的准确性。结果OPG、根尖片对相同样本RRAOF的定性及分级半定量诊断结果,与CBCT相比较均存在统计学差异(P<0.05)。根尖片和OPG对RRAOF定性诊断的敏感性分别为71.6%和78.4%,特异性分别为25.5%和51.1%,准确度分别为53.7%和67.8%。结论根尖片与OPG对正畸相关牙根吸收的诊断准确性较差。展开更多
Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and C...Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and CH4 uptake of a for-est soil were studied in laboratory by the method of orthogonal design. It was observed under laboratory conditions in this study that there were significant correlations between N2O emission rate, CH4 oxidation rate, soil pH and temperature. Nevertheless, N2O emission rate also showed a significant positive correlation with CH4 oxidation rate. The results suggested that pH and temperature were important factors controlling N2O emission and CH4 oxidation under this experiment conditions.展开更多
In western China seismic wave fields are very complicated and have low signal to noise ratio.In this paper,we focus on complex wave field research by forward modeling and indicate that density should not be ignored in...In western China seismic wave fields are very complicated and have low signal to noise ratio.In this paper,we focus on complex wave field research by forward modeling and indicate that density should not be ignored in wave field simulation if the subsurface physical properties are quite different.We use the acoustic wave equation with density in the staggered finite-difference method to simulate the wave fields.For this purpose a complicated geologic structural model with rugged surfaces,near-surface low-velocity layers,and high-velocity outcropping layers was designed.Based on the instantaneous wave field distribution,we analyzed the mechanism forming complex wave fields.The influence of low velocity layers on the wave field is very strong.A strong waveguide occurs between the top and base of a low velocity layer,producing multiples which penetrate into the earth and form strong complex wave fields in addition to reflections from subsurface interfaces.For verifying the correctness of the simulated wave fields,prestack depth migration was performed using different algorithms from the forward modeling.The structure revealed by the stacked migration profile is same as the known structure.展开更多
文摘目的以CBCT对样本牙根吸收的诊断结果为金标准,检验全景片(OPG)及根尖片对正畸相关牙根吸收(RRAOF)定性及分级半定量诊断结果的准确性。方法纳入完成固定正畸治疗的32例患者的121颗上前牙,正畸治疗前后均拍摄OPG、上前牙根尖片、上前牙CBCT。由3名放射专科医生按照Levander and Malmgren分度法对纳入样本的3种图像的牙根吸收程度分别进行评估,并以CBCT的诊断结果为金标准,检验OPG及根尖片对相同样本牙根吸收定性及分级半定量诊断结果的准确性。结果OPG、根尖片对相同样本RRAOF的定性及分级半定量诊断结果,与CBCT相比较均存在统计学差异(P<0.05)。根尖片和OPG对RRAOF定性诊断的敏感性分别为71.6%和78.4%,特异性分别为25.5%和51.1%,准确度分别为53.7%和67.8%。结论根尖片与OPG对正畸相关牙根吸收的诊断准确性较差。
基金This paper was supported by Chinese Academy of Sciences.
文摘Soil samples were taken from depth of 0-12 cm in virgin broad-leaved Korean pine mixed forest in Changbai Moun-tain in July 2000. The effects of temperature, soil water content, pH, NH4+ and NO3- on N2O emission and CH4 uptake of a for-est soil were studied in laboratory by the method of orthogonal design. It was observed under laboratory conditions in this study that there were significant correlations between N2O emission rate, CH4 oxidation rate, soil pH and temperature. Nevertheless, N2O emission rate also showed a significant positive correlation with CH4 oxidation rate. The results suggested that pH and temperature were important factors controlling N2O emission and CH4 oxidation under this experiment conditions.
基金supported in part by the National Natural Science Foundation of China(Grant No.40974069)PetroChina Innovation Foundation(Grant No.2009D-5006-03-01)+1 种基金National Key Basic Research Development Program(GrantNo.2007CB209601)National Major Science and Technology Program(Grant Nos.2008ZX05010-002 and 2008ZX05024-001)
文摘In western China seismic wave fields are very complicated and have low signal to noise ratio.In this paper,we focus on complex wave field research by forward modeling and indicate that density should not be ignored in wave field simulation if the subsurface physical properties are quite different.We use the acoustic wave equation with density in the staggered finite-difference method to simulate the wave fields.For this purpose a complicated geologic structural model with rugged surfaces,near-surface low-velocity layers,and high-velocity outcropping layers was designed.Based on the instantaneous wave field distribution,we analyzed the mechanism forming complex wave fields.The influence of low velocity layers on the wave field is very strong.A strong waveguide occurs between the top and base of a low velocity layer,producing multiples which penetrate into the earth and form strong complex wave fields in addition to reflections from subsurface interfaces.For verifying the correctness of the simulated wave fields,prestack depth migration was performed using different algorithms from the forward modeling.The structure revealed by the stacked migration profile is same as the known structure.
