We present results from a 484 km wide-angle seismic profilie acquired in the northwest part of the South China Sea （SCS） during OBS2006 cruise. The line that runs along a previously acquired multi-channel seismic li...We present results from a 484 km wide-angle seismic profilie acquired in the northwest part of the South China Sea （SCS） during OBS2006 cruise. The line that runs along a previously acquired multi-channel seismic line （SO49-18） crosses the continental slope of the northern margin, the Northwest Subbasin （NWSB） of the South China Sea, the Zhongsha Massif and partly the oceanic basin of the South China Sea. Seismic sections recorded on 13 ocean-bottom seismometers were used to identify refracted phases from the crustal layer and also reflected phases from the crust-mantle boundary （Moho）. Inversion of the traveltimes using a simple start model reveals crustal images in the study area. The velocity model shows that crustal thickness below the continental slope is between 14 and 23 kin. The continental part of the line is characterized by gentle landward mantle uplift and an abrupt oeeanward one. The velocities in the lower crust do not exceed 6.9 km/s. With the new data we can exclude a high-velocity lower crustal body （velocities above 7.0 kin/s） at the location of the line. We conclude that this part of the South China Sea margin developed by a magma-poor rifting. Both, the NWSB and the Southwest Sub-basin （SWSB） reveal velocities typical for oceanic crust with crustal thickness between 5 and 7 kin. The Zhongsha Massif in between is extremely stretched with only 6-10 km continental crust left. Crustal velocity is below 6.5 kin/s; possibly indicating the absence of the lower crust. Multi-channel seismic profile shows that the Yitongansha Uplift in the slope area and the Zhongsha Massif are only mildly deformed. We considered them as rigid continent blocks which acted as rift shoulders of the main rift subsequently resulting in the formation of the Northwest Sub-basin. The extension was mainly accommodated by a ductile lower crustal flows, which might have been extremely attenuated and flow into the oceanic basin during the spreading stage. We compared the crustal structures along the norther展开更多
Background： Current evidence links atrial fibrillation （AF） to the inflammation. Inflammatory indexes such as high-sensitive C-reactive protein （hs-CRP） have been related to the development and persistence of AF....Background： Current evidence links atrial fibrillation （AF） to the inflammation. Inflammatory indexes such as high-sensitive C-reactive protein （hs-CRP） have been related to the development and persistence of AF. However, the role of inflammation in the atrial electrophysiological remodeling indexed by P-wave dispersion （Pa） remains unclear. Methods： The study consisted of 71 patients with lone paroxysmal AF （AF group） and 71 age- and gender-matched controls of paroxysmal supraventricular tachycardia without history of AF （control group）. Electrocardiography, P hs-CRP, and other clinical characteristics were compared between the two groups. Results： There was no significant difference between the two groups regarding age, gender, hyperlipidemia, etc. Compared to controls, left atrial diameter （44 ± 7 vs 39 ± 7 mm）, Pd （49 ± 13 vs 26 ± 8 ms）, and hs-CRP （2.17 [1.46-2.89] vs 1.12 [0.74-1.41] rag/L） were increased （P 〈 0.05）, respectively. Linear regression identified hs-CRP as an independent correlation ofPd level both in the total population and the AF group （r = 0.464 and 0.313; P 〈 0.001, respectively）. Multiple logistic regression revealed hs-C RP as an independent determinant of AF （odds ratio [OR] =l 5.430, 95% confidence interval： 6.031-39.476： P 〈0.001）. Further adjusted tbr Pd, both Pd and hs-CRP were independent predictors for AF, but the OR for hs-CRP in predicting AF has been attenuated from 15.430 to 6.246. Conclusions： In lone AF, P and plasma hs-CRP concentration are inter-associated and related to AF. The interaction between hs-CRP and AF may be mediated by Pe, suggesting an important role of inflammation in the atrial electrophysiological remodeling predisposing to AF.展开更多
Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The ba...Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The basic data required may be obtained from visual observation and laboratory or field tests.However,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters needed.As an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this problem.In this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron mine.Moreover,rock joint measurements and sampling for laboratory tests were conducted.The results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave velocity.An equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.展开更多
Background Nominal atrioventricular （AV） interval in dual chamber pacemaker （DDD） is not the best AV delay in the majority of patients with atrioventricular block. To find a simple method for optimizing AV delay a...Background Nominal atrioventricular （AV） interval in dual chamber pacemaker （DDD） is not the best AV delay in the majority of patients with atrioventricular block. To find a simple method for optimizing AV delay adjustment, we assessed surface electrocardiography （ECG） for optimizing AV delay during dual chamber pacing. Methods DDD pacemakers were implanted in 46 patients with complete, or almost complete, AV block. Optimal AV delay was achieved by programming an additional delay of 100 ms, to the width of intrinsic P wave or to the interval between pacing spike to the end of P wave on surface ECG. Leit ventricular （LV） end diastolic and end systolic volumes, ejection fraction and diastolic parameters were measured by Doppler echocardiography during both nominal and optimal AV delay pacing.Results Compared to nominal AV delay setting, LV end diastolic volume increased [to （53.2±11.3） ml from （50.2 ± 10.2） ml, P〈0.05], end systolic volume decreased [to （26.1 ± 9.0） ml from （27.9 ± 8.2） ml, P〈0.05] during adjusted AV delay pacing, resulting in an increase in LV ejection fraction [to （68.2±5.3）% from （64.5±4.3）%, P〈0.05]. LV diastolic filling and isovolumic relaxation time were not significantly changed.Conclusion Optimization of AV delay by surface ECG is a simple method to improve LV systolic function during dual chamber pacing.展开更多
基金financially supported by the National Basic Research Program(973) of China(No. 2007CB41170403)the National Natural Science Foundation of China(No.91028006 and 41074066)
文摘We present results from a 484 km wide-angle seismic profilie acquired in the northwest part of the South China Sea （SCS） during OBS2006 cruise. The line that runs along a previously acquired multi-channel seismic line （SO49-18） crosses the continental slope of the northern margin, the Northwest Subbasin （NWSB） of the South China Sea, the Zhongsha Massif and partly the oceanic basin of the South China Sea. Seismic sections recorded on 13 ocean-bottom seismometers were used to identify refracted phases from the crustal layer and also reflected phases from the crust-mantle boundary （Moho）. Inversion of the traveltimes using a simple start model reveals crustal images in the study area. The velocity model shows that crustal thickness below the continental slope is between 14 and 23 kin. The continental part of the line is characterized by gentle landward mantle uplift and an abrupt oeeanward one. The velocities in the lower crust do not exceed 6.9 km/s. With the new data we can exclude a high-velocity lower crustal body （velocities above 7.0 kin/s） at the location of the line. We conclude that this part of the South China Sea margin developed by a magma-poor rifting. Both, the NWSB and the Southwest Sub-basin （SWSB） reveal velocities typical for oceanic crust with crustal thickness between 5 and 7 kin. The Zhongsha Massif in between is extremely stretched with only 6-10 km continental crust left. Crustal velocity is below 6.5 kin/s; possibly indicating the absence of the lower crust. Multi-channel seismic profile shows that the Yitongansha Uplift in the slope area and the Zhongsha Massif are only mildly deformed. We considered them as rigid continent blocks which acted as rift shoulders of the main rift subsequently resulting in the formation of the Northwest Sub-basin. The extension was mainly accommodated by a ductile lower crustal flows, which might have been extremely attenuated and flow into the oceanic basin during the spreading stage. We compared the crustal structures along the norther
文摘Background： Current evidence links atrial fibrillation （AF） to the inflammation. Inflammatory indexes such as high-sensitive C-reactive protein （hs-CRP） have been related to the development and persistence of AF. However, the role of inflammation in the atrial electrophysiological remodeling indexed by P-wave dispersion （Pa） remains unclear. Methods： The study consisted of 71 patients with lone paroxysmal AF （AF group） and 71 age- and gender-matched controls of paroxysmal supraventricular tachycardia without history of AF （control group）. Electrocardiography, P hs-CRP, and other clinical characteristics were compared between the two groups. Results： There was no significant difference between the two groups regarding age, gender, hyperlipidemia, etc. Compared to controls, left atrial diameter （44 ± 7 vs 39 ± 7 mm）, Pd （49 ± 13 vs 26 ± 8 ms）, and hs-CRP （2.17 [1.46-2.89] vs 1.12 [0.74-1.41] rag/L） were increased （P 〈 0.05）, respectively. Linear regression identified hs-CRP as an independent correlation ofPd level both in the total population and the AF group （r = 0.464 and 0.313; P 〈 0.001, respectively）. Multiple logistic regression revealed hs-C RP as an independent determinant of AF （odds ratio [OR] =l 5.430, 95% confidence interval： 6.031-39.476： P 〈0.001）. Further adjusted tbr Pd, both Pd and hs-CRP were independent predictors for AF, but the OR for hs-CRP in predicting AF has been attenuated from 15.430 to 6.246. Conclusions： In lone AF, P and plasma hs-CRP concentration are inter-associated and related to AF. The interaction between hs-CRP and AF may be mediated by Pe, suggesting an important role of inflammation in the atrial electrophysiological remodeling predisposing to AF.
文摘Engineering rock mass classification,based on empirical relations between rock mass parameters and engineering applications,is commonly used in rock engineering and forms the basis for designing rock structures.The basic data required may be obtained from visual observation and laboratory or field tests.However,owing to the discontinuous and variable nature of rock masses,it is difficult for rock engineers to directly obtain the specific design parameters needed.As an alternative,the use of geophysical methods in geomechanics such as seismography may largely address this problem.In this study,25 seismic profiles with the total length of 543 m have been scanned to determine the geomechanical properties of the rock mass in blocks Ⅰ,Ⅲ and Ⅳ-2 of the Choghart iron mine.Moreover,rock joint measurements and sampling for laboratory tests were conducted.The results show that the rock mass rating（RMR） and Q values have a close relation with P-wave velocity parameters,including P-wave velocity in field(V;).P-wave velocity in the laboratory(V;) and the ratio of V;V;(i.e.K;= V;/V;.However,Q value,totally,has greater correlation coefficient and less error than the RMR,In addition,rock mass parameters including rock quality designation（RQD）,uniaxial compressive strength（UCS）,joint roughness coefficient（JRC） and Schmidt number（RN） show close relationship with P-wave velocity.An equation based on these parameters was obtained to estimate the P-wave velocity in the rock mass with a correlation coefficient of 91%.The velocities in two orthogonal directions and the results of joint study show that the wave velocity anisotropy in rock mass may be used as an efficient tool to assess the strong and weak directions in rock mass.
文摘Background Nominal atrioventricular （AV） interval in dual chamber pacemaker （DDD） is not the best AV delay in the majority of patients with atrioventricular block. To find a simple method for optimizing AV delay adjustment, we assessed surface electrocardiography （ECG） for optimizing AV delay during dual chamber pacing. Methods DDD pacemakers were implanted in 46 patients with complete, or almost complete, AV block. Optimal AV delay was achieved by programming an additional delay of 100 ms, to the width of intrinsic P wave or to the interval between pacing spike to the end of P wave on surface ECG. Leit ventricular （LV） end diastolic and end systolic volumes, ejection fraction and diastolic parameters were measured by Doppler echocardiography during both nominal and optimal AV delay pacing.Results Compared to nominal AV delay setting, LV end diastolic volume increased [to （53.2±11.3） ml from （50.2 ± 10.2） ml, P〈0.05], end systolic volume decreased [to （26.1 ± 9.0） ml from （27.9 ± 8.2） ml, P〈0.05] during adjusted AV delay pacing, resulting in an increase in LV ejection fraction [to （68.2±5.3）% from （64.5±4.3）%, P〈0.05]. LV diastolic filling and isovolumic relaxation time were not significantly changed.Conclusion Optimization of AV delay by surface ECG is a simple method to improve LV systolic function during dual chamber pacing.
