Objective: This study was undertaken to evaluate the validity of the pregnancy prolongation index (PPI) as a measure of preterm labor treatment success. Study design: Analysis of prospectively collected maternal and n...Objective: This study was undertaken to evaluate the validity of the pregnancy prolongation index (PPI) as a measure of preterm labor treatment success. Study design: Analysis of prospectively collected maternal and neonatal data from a national clinical database (Matria Healthcare). Included were patients with singleton, twin, and triplet pregnancies who had outpatient surveillance initiated between 18 and 34 weeks and delivered at 24 to 36 6/7 weeks’ gestation with NICU admission. Each patient’s PPI core was calculated with the following equation: [(gestational age at delivery- gestational age at start of treatment) / (37.0 gestational age at start of treatment)] × .100% . The impact of increasing PPI score was measured against NICU length of stay as a surrogate gauge of neonatal morbidity. Data were further stratified by gestational type and reason for delivery. Results: Pregnancy outcomes of 12,642 patients (6,642 singletons, 4,326 twins, and 1,674 triplets) were analyzed. The PPI score increased in a direct, inverse linear relationship with decreasing number of NICU days. Conclusion: The PPI is a sensitive measure for the evaluation of treatment success in the inhibition of preterm labor and delivery.展开更多
This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges’ (1987) nonlinear dis...This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges’ (1987) nonlinear dispersion relationship, and accords well with the original empirical formula. Comparison of the calculating results with those obtained from the experimental data and those obtained from linear wave theory showed that the present water wave model considering the dispersion of phase velocity is rational and in good agreement with experiment data.展开更多
In view of the deviation of the fitting results of the classical exponential model and the hyperbolic model (the BB model) from several experiment data during intermediate stress period, a new constitutive model for...In view of the deviation of the fitting results of the classical exponential model and the hyperbolic model (the BB model) from several experiment data during intermediate stress period, a new constitutive model for the nonlinear normal deformation of rock joints under normal monotonous load is established with flexibility-deformation method. First of all, basic laws of the deformation of joints under normal monotonous load are discussed, based on which three basic conditions which the complete constitutive equation for rock joints under normal load should meet are put forward. The analysis of the modified normal con- stitutive model on stress-deformation curve shows that the general exponential model and the improved hyperbolic model are not complete in math theory. Flexibility-deformation monotone decreasing curve lying between flexibility-deformation curve of the classical exponential model and the BB model is chosen, which meets basic conditions of normal deformation mentioned before, then a new normal deformation constitutive model of rock joints containing three parameters is established. Two main forms of flexibility-deformation curve are analyzed and specific math formulas of the two forms are deduced. Then the range of the parameters in the g-δ model and the g-2 model and the correlative influence factor in geology are preliminarily discussed. Referring to different experiment data, the validating analysis of the g-δ model and the g-γ model shows that the g-2 model can be applied to both the mated joints and unmated joints. Besides, experiment data can be better fit with the g-2 model with respect to the BB model, the classical exponential model and the logarithm model.展开更多
In this paper, two sunflower equations are considered. Using delay T as a parameter and applying the global Hopf bifurcation theorem, we investigate the existence of global Hopf bifurcation for the sunflower equation....In this paper, two sunflower equations are considered. Using delay T as a parameter and applying the global Hopf bifurcation theorem, we investigate the existence of global Hopf bifurcation for the sunflower equation. Furthermore, we analyze the local Hopf bifurcation of the modified equation with nonlinear relation about stem's increase, including the occurrence, the bifurcation direction, the stability and the approximation expression of the bifurcating periodic solution using the theory of normal form and center manifold. Finally, the obtained results of these two equations are compared, which finds that the result about the period of their bifurcating periodic solutions is obviously different, while the bifurcation direction and stability are identical.展开更多
文摘Objective: This study was undertaken to evaluate the validity of the pregnancy prolongation index (PPI) as a measure of preterm labor treatment success. Study design: Analysis of prospectively collected maternal and neonatal data from a national clinical database (Matria Healthcare). Included were patients with singleton, twin, and triplet pregnancies who had outpatient surveillance initiated between 18 and 34 weeks and delivered at 24 to 36 6/7 weeks’ gestation with NICU admission. Each patient’s PPI core was calculated with the following equation: [(gestational age at delivery- gestational age at start of treatment) / (37.0 gestational age at start of treatment)] × .100% . The impact of increasing PPI score was measured against NICU length of stay as a surrogate gauge of neonatal morbidity. Data were further stratified by gestational type and reason for delivery. Results: Pregnancy outcomes of 12,642 patients (6,642 singletons, 4,326 twins, and 1,674 triplets) were analyzed. The PPI score increased in a direct, inverse linear relationship with decreasing number of NICU days. Conclusion: The PPI is a sensitive measure for the evaluation of treatment success in the inhibition of preterm labor and delivery.
文摘This paper presents a weakly nonlinear water wave model using a mild slope equation and a new explicit formulation which takes into account dispersion of wave phase velocity, approximates Hedges’ (1987) nonlinear dispersion relationship, and accords well with the original empirical formula. Comparison of the calculating results with those obtained from the experimental data and those obtained from linear wave theory showed that the present water wave model considering the dispersion of phase velocity is rational and in good agreement with experiment data.
基金supported by the National Natural Science Foundation of China (Grant Nos. 50879063 and 50979081) the National Basic Research Program of China ("973" Program) (Grant No. 2011CB013501)
文摘In view of the deviation of the fitting results of the classical exponential model and the hyperbolic model (the BB model) from several experiment data during intermediate stress period, a new constitutive model for the nonlinear normal deformation of rock joints under normal monotonous load is established with flexibility-deformation method. First of all, basic laws of the deformation of joints under normal monotonous load are discussed, based on which three basic conditions which the complete constitutive equation for rock joints under normal load should meet are put forward. The analysis of the modified normal con- stitutive model on stress-deformation curve shows that the general exponential model and the improved hyperbolic model are not complete in math theory. Flexibility-deformation monotone decreasing curve lying between flexibility-deformation curve of the classical exponential model and the BB model is chosen, which meets basic conditions of normal deformation mentioned before, then a new normal deformation constitutive model of rock joints containing three parameters is established. Two main forms of flexibility-deformation curve are analyzed and specific math formulas of the two forms are deduced. Then the range of the parameters in the g-δ model and the g-2 model and the correlative influence factor in geology are preliminarily discussed. Referring to different experiment data, the validating analysis of the g-δ model and the g-γ model shows that the g-2 model can be applied to both the mated joints and unmated joints. Besides, experiment data can be better fit with the g-2 model with respect to the BB model, the classical exponential model and the logarithm model.
文摘In this paper, two sunflower equations are considered. Using delay T as a parameter and applying the global Hopf bifurcation theorem, we investigate the existence of global Hopf bifurcation for the sunflower equation. Furthermore, we analyze the local Hopf bifurcation of the modified equation with nonlinear relation about stem's increase, including the occurrence, the bifurcation direction, the stability and the approximation expression of the bifurcating periodic solution using the theory of normal form and center manifold. Finally, the obtained results of these two equations are compared, which finds that the result about the period of their bifurcating periodic solutions is obviously different, while the bifurcation direction and stability are identical.