Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of t...Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of the signal characteristics,such as the generation mechanism,the geophysical properties,and the significance of the corresponding rock physics,remains unclear,which makes it difficult to both scientifically evaluate and take full advantage of the different types of geophones.In this paper,the mechanism by which seismic waves are generated is studied based on the spring–damped vibration theory.The physical characteristics of the three above-mentioned signal types and the relationships among the physical properties of the signals and medium are analyzed,as well as the signalto-noise ratio(SNR),resolution,and spectrum characteristics.Based on laboratory tests,field experiments,and applications,we obtained the following conclusions.The acceleration signal reflects the elastic characteristics of the medium and the change rules,and the signal strength is positively correlated with physical property changes.The acceleration signal has favorable attributes,such as small distortion,high fidelity,strong high-frequency amplitudes,and a wide frequency band.Therefore,the acceleration signal is more suitable for high-precision seismic exploration of complex media.In addition,the P-wave acceleration signal more accurately reflects the elastic Young modulus,shear modulus,and density changes than the velocity signal.However,the sensitivity decreases with increasing shear modulus and density.For the S-wave,the acceleration signal is more sensitive to the shear modulus and density than the velocity signal.展开更多
Objective:To assess the efficacy and safety of mulberry twig alkaloids(Sangzhi alkaloids,SZ-A)for treatment of type 2 diabetes in a randomized,double-blind,placebo-controlled multicenter clinical trial.Methods:A total...Objective:To assess the efficacy and safety of mulberry twig alkaloids(Sangzhi alkaloids,SZ-A)for treatment of type 2 diabetes in a randomized,double-blind,placebo-controlled multicenter clinical trial.Methods:A total of 200 patients were randomized to receive SZ-A(n=100)or placebo(n=100)for 16 weeks.The data analysis system for electronic data capture clinical trial central randomization system was used for randomization and dispensing of drugs.The primary outcome was the change in glycosylated hemoglobin(Hb A1c)level.The secondary outcome included the proportions of cases with Hb A1c<7.0%and Hb A1c<6.5%,fasting blood glucose(FBG),postprandial blood glucose(PBG),area under curve for the PBG(AUC_(0-2h)),body weight,and body mass index(BMI).Adverse events(AEs),severe adverse events(SAEs),treatment-related adverse events(TAEs),gastrointestinal disorders(GDs),blood pressure,routine blood tests,and liver and kidney function were monitored.Results:Compared with baseline,the change of Hb A1c at week 16 was-0.80%(95%CI:-0.98%to-0.62%)and-0.09%(95%CI:-0.27%to 0.09%)in SZ-A group and placebo group,respectively.The proportion of patients with Hb A1c<7%and<6.5%was higher in the SZ-A group than in the placebo group(46.8%vs.21.6%and 29.9%vs.10.8%).The observed values and changes in FBG,1 h-PBG,2 h-PBG,and AUC_(0-2h) differed significantly between groups(P<0.001),but differences were not significant in body weight and BMI(P>0.05).The incidence rates of AEs,TAEs,and GDs differed significantly between groups(P=0.010,P=0.005,and P=0.006,respectively),whereas the incidence rates of SAEs showed no significant differences between groups(P=1.000).Conclusion:SZ-A are effective and safe for treatment of type 2 diabetes.展开更多
基金supported by the National Major Science and Technology Project of“the 13th Five-year Plan”(No.2017ZX05005004003)。
文摘Although various types of geophones are applied in seismic exploration,there are only three common types of signals produced by geophones:displacement,velocity,and acceleration signals.Currently,our understanding of the signal characteristics,such as the generation mechanism,the geophysical properties,and the significance of the corresponding rock physics,remains unclear,which makes it difficult to both scientifically evaluate and take full advantage of the different types of geophones.In this paper,the mechanism by which seismic waves are generated is studied based on the spring–damped vibration theory.The physical characteristics of the three above-mentioned signal types and the relationships among the physical properties of the signals and medium are analyzed,as well as the signalto-noise ratio(SNR),resolution,and spectrum characteristics.Based on laboratory tests,field experiments,and applications,we obtained the following conclusions.The acceleration signal reflects the elastic characteristics of the medium and the change rules,and the signal strength is positively correlated with physical property changes.The acceleration signal has favorable attributes,such as small distortion,high fidelity,strong high-frequency amplitudes,and a wide frequency band.Therefore,the acceleration signal is more suitable for high-precision seismic exploration of complex media.In addition,the P-wave acceleration signal more accurately reflects the elastic Young modulus,shear modulus,and density changes than the velocity signal.However,the sensitivity decreases with increasing shear modulus and density.For the S-wave,the acceleration signal is more sensitive to the shear modulus and density than the velocity signal.
基金Supported by the National Major Science and Technology Projects of China(No.2013ZX09101005)。
文摘Objective:To assess the efficacy and safety of mulberry twig alkaloids(Sangzhi alkaloids,SZ-A)for treatment of type 2 diabetes in a randomized,double-blind,placebo-controlled multicenter clinical trial.Methods:A total of 200 patients were randomized to receive SZ-A(n=100)or placebo(n=100)for 16 weeks.The data analysis system for electronic data capture clinical trial central randomization system was used for randomization and dispensing of drugs.The primary outcome was the change in glycosylated hemoglobin(Hb A1c)level.The secondary outcome included the proportions of cases with Hb A1c<7.0%and Hb A1c<6.5%,fasting blood glucose(FBG),postprandial blood glucose(PBG),area under curve for the PBG(AUC_(0-2h)),body weight,and body mass index(BMI).Adverse events(AEs),severe adverse events(SAEs),treatment-related adverse events(TAEs),gastrointestinal disorders(GDs),blood pressure,routine blood tests,and liver and kidney function were monitored.Results:Compared with baseline,the change of Hb A1c at week 16 was-0.80%(95%CI:-0.98%to-0.62%)and-0.09%(95%CI:-0.27%to 0.09%)in SZ-A group and placebo group,respectively.The proportion of patients with Hb A1c<7%and<6.5%was higher in the SZ-A group than in the placebo group(46.8%vs.21.6%and 29.9%vs.10.8%).The observed values and changes in FBG,1 h-PBG,2 h-PBG,and AUC_(0-2h) differed significantly between groups(P<0.001),but differences were not significant in body weight and BMI(P>0.05).The incidence rates of AEs,TAEs,and GDs differed significantly between groups(P=0.010,P=0.005,and P=0.006,respectively),whereas the incidence rates of SAEs showed no significant differences between groups(P=1.000).Conclusion:SZ-A are effective and safe for treatment of type 2 diabetes.
