Mendelian randomization(MR)is widely used in causal mediation analysis to control unmeasured confounding effects,which is valid under some strong assumptions.It is thus of great interest to assess the impact of violat...Mendelian randomization(MR)is widely used in causal mediation analysis to control unmeasured confounding effects,which is valid under some strong assumptions.It is thus of great interest to assess the impact of violations of these MR assumptions through sensitivity analysis.Sensitivity analyses have been conducted for simple MR-based causal average effect analyses,but they are not available for MR-based mediation analysis studies,and we aim to fill this gap in this paper.We propose to use two sensitivity parameters to quantify the effect due to the deviation of the IV assumptions.With these two sensitivity parameters,we derive consistent indirect causal effect estimators and establish their asymptotic propersties.Our theoretical results can be used in MR-based mediation analysis to study the impact of violations of MR as-sumptions.The finite sample performance of the proposed method is illustrated through simulation studies,sensitivity ana-lysis,and application to a real genome-wide association study.展开更多
A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to...A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to the proposed method and the grain size is the most important factor that affects the distribution of contact force.The proposed method is then verified by a series of laboratory experiments using glass beads and cobbles as granular material and a very thin pressure,indicating that film is firstly used in these experiments which give a reliable method to measure the contact force at each contact point.展开更多
The buffeting performance of kilometer-level high-speed railway suspension bridges has a great impact on the smooth operation of high-speed trains.To investigate the buffeting performance of the structure significantl...The buffeting performance of kilometer-level high-speed railway suspension bridges has a great impact on the smooth operation of high-speed trains.To investigate the buffeting performance of the structure significantly different from traditional suspension bridges,the first long-span high-speed railway suspension bridge,Wufengshan Yangtze River Bridge(WYRB),is taken as a numerical example to demonstrate the effects of structural parameters and wind field parameters on the buffeting responses.Based on the design information,the spatial finite element model(FEM)of WYRB is established before testing its accuracy.The fluctuating wind fields are simulated via both classical and stochastic wave based spectral representation method(SRM).Finite element method is further taken to analyze the parametric sensitivity on wind induced buffeting responses in time domain.The results show that the vertical displacement is more sensitive to the changing dead load than the lateral and torsional ones.The larger stiffness of the main girder and the lower sag-to-span ratio are both helpful to reduce the buffeting responses.Wind spectrum and coherence function are key influencing factors to the responses so setting proper wind field parameters are essential in the wind-resistant design stage.The analytical results can provide references for wind resistance analysis and selection of structural and fluctuating wind field parameters for similar long-span high-speed railway suspension bridges.展开更多
A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection an...A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection and random selection.On the basis of mean-field theory,this model under the two different selection mechanisms was analyzed.The analytic equations of distributions of the number of cliques that a vertex joins and the vertex strength of the model were given.It is proved that both distributions follow the scale-free power-law distribution in preferential selection mechanism and the exponential distribution in random selection mechanism,respectively.The analytic expressions of exponents of corresponding distributions were obtained.The agreement between the simulations and analytical results indicates the validity of the theoretical analysis.Finally,three real transport bus networks(BTNs) of Beijing,Shanghai and Hangzhou in China were studied.By analyzing their network properties,it is discovered that these real BTNs belong to a kind of weighted evolving network model with clique overlapping growth and random selection mechanism that was proposed in this context.展开更多
PCR-based DNA fingerprinting, REP-PCR(repetitive element PCR), RAPD(randomly amplified polymorphic DNA) and16 S r DNA sequence analyses were used to characterize 23 Acidithiobacillus ferrooxidans strains isolated from...PCR-based DNA fingerprinting, REP-PCR(repetitive element PCR), RAPD(randomly amplified polymorphic DNA) and16 S r DNA sequence analyses were used to characterize 23 Acidithiobacillus ferrooxidans strains isolated from different environments.(GTG)5 and BOXA1 R primer were selected for REP-PCR. Twenty arbitrary primers were used for RAPD to acquire DNA profiles from A. ferrooxidans. Both RAPD and REP-PCR produce complex banding patterns and show good discriminatory ability in differentiating closely related strains of A. ferrooxidans. The strains are clustered into 4 or 5 major groups and reveal genomic diversity using(GTG)5-PCR, BOX-PCR and RAPD analysis. Phylogenetic tree based on 16 S r DNA sequences of 23 strains and related strains shows that they are clustered into two distinct groups. Twelve strains are highly related to a new Acidithiobacillus named Acidithiobacillus ferrivorans. The results indicate that PCR-based methods are effective in revealing genetic diversity among A. ferrooxidans.展开更多
基金This work was supported by the National Natural Science Foundation of China(12171451,72091212).
文摘Mendelian randomization(MR)is widely used in causal mediation analysis to control unmeasured confounding effects,which is valid under some strong assumptions.It is thus of great interest to assess the impact of violations of these MR assumptions through sensitivity analysis.Sensitivity analyses have been conducted for simple MR-based causal average effect analyses,but they are not available for MR-based mediation analysis studies,and we aim to fill this gap in this paper.We propose to use two sensitivity parameters to quantify the effect due to the deviation of the IV assumptions.With these two sensitivity parameters,we derive consistent indirect causal effect estimators and establish their asymptotic propersties.Our theoretical results can be used in MR-based mediation analysis to study the impact of violations of MR as-sumptions.The finite sample performance of the proposed method is illustrated through simulation studies,sensitivity ana-lysis,and application to a real genome-wide association study.
基金Project(51079047)supported by the National Natural Science Foundation of ChinaProject Funded by the Priority Academic Program of Jiangsu Higher Education Institutions,China
文摘A probabilistic method based on principle of maximum entropy was employed to analyze the randomness of contact force between geomembrane and granular material.The contact force distribution is exponential according to the proposed method and the grain size is the most important factor that affects the distribution of contact force.The proposed method is then verified by a series of laboratory experiments using glass beads and cobbles as granular material and a very thin pressure,indicating that film is firstly used in these experiments which give a reliable method to measure the contact force at each contact point.
基金Projects(51908125,51978155) supported by the National Natural Science Foundation of ChinaProject(W03070080)supported by the National Ten Thousand Talent Program for Young Top-notch Talents,China+1 种基金Project(BK20190359)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(BE2018120) supported by the Key Research and Development Plan of Jiangsu Province,China。
文摘The buffeting performance of kilometer-level high-speed railway suspension bridges has a great impact on the smooth operation of high-speed trains.To investigate the buffeting performance of the structure significantly different from traditional suspension bridges,the first long-span high-speed railway suspension bridge,Wufengshan Yangtze River Bridge(WYRB),is taken as a numerical example to demonstrate the effects of structural parameters and wind field parameters on the buffeting responses.Based on the design information,the spatial finite element model(FEM)of WYRB is established before testing its accuracy.The fluctuating wind fields are simulated via both classical and stochastic wave based spectral representation method(SRM).Finite element method is further taken to analyze the parametric sensitivity on wind induced buffeting responses in time domain.The results show that the vertical displacement is more sensitive to the changing dead load than the lateral and torsional ones.The larger stiffness of the main girder and the lower sag-to-span ratio are both helpful to reduce the buffeting responses.Wind spectrum and coherence function are key influencing factors to the responses so setting proper wind field parameters are essential in the wind-resistant design stage.The analytical results can provide references for wind resistance analysis and selection of structural and fluctuating wind field parameters for similar long-span high-speed railway suspension bridges.
基金Projects(60874080,60504027) supported by the National Natural Science Foundation of ChinaProject(20060401037) supported by the National Postdoctor Science Foundation of China
文摘A novel weighted evolving network model based on the clique overlapping growth was proposed.The model shows different network characteristics under two different selection mechanisms that are preferential selection and random selection.On the basis of mean-field theory,this model under the two different selection mechanisms was analyzed.The analytic equations of distributions of the number of cliques that a vertex joins and the vertex strength of the model were given.It is proved that both distributions follow the scale-free power-law distribution in preferential selection mechanism and the exponential distribution in random selection mechanism,respectively.The analytic expressions of exponents of corresponding distributions were obtained.The agreement between the simulations and analytical results indicates the validity of the theoretical analysis.Finally,three real transport bus networks(BTNs) of Beijing,Shanghai and Hangzhou in China were studied.By analyzing their network properties,it is discovered that these real BTNs belong to a kind of weighted evolving network model with clique overlapping growth and random selection mechanism that was proposed in this context.
基金Project(2010CB630901)supported by the National Basic Research Program of China
文摘PCR-based DNA fingerprinting, REP-PCR(repetitive element PCR), RAPD(randomly amplified polymorphic DNA) and16 S r DNA sequence analyses were used to characterize 23 Acidithiobacillus ferrooxidans strains isolated from different environments.(GTG)5 and BOXA1 R primer were selected for REP-PCR. Twenty arbitrary primers were used for RAPD to acquire DNA profiles from A. ferrooxidans. Both RAPD and REP-PCR produce complex banding patterns and show good discriminatory ability in differentiating closely related strains of A. ferrooxidans. The strains are clustered into 4 or 5 major groups and reveal genomic diversity using(GTG)5-PCR, BOX-PCR and RAPD analysis. Phylogenetic tree based on 16 S r DNA sequences of 23 strains and related strains shows that they are clustered into two distinct groups. Twelve strains are highly related to a new Acidithiobacillus named Acidithiobacillus ferrivorans. The results indicate that PCR-based methods are effective in revealing genetic diversity among A. ferrooxidans.
