Accurate prediction of bus arrival time is of great significance to improve passenger satisfaction and bus attraction. This paper presents the prediction model of bus arrival time based on support vector machine with genetic algorithm (GA-SVM). The character of the time period, the length of road, the weather, the bus speed and the rate of road usage are adopted as input vectors in Support Vector Machine (SVM), and the genetic algorithm search algorithm is combined to find the best parameters. Finally, the data from Bus No.249 in Shenyang, china are used to check the model. The experimental results show that the forecasting model is superior to the traditional SVM model and the Artificial Neural Network (ANN) model in terms of the same data, and is of higher accuracy, which verified the feasibility of the model to predict the bus arrival time.
C-type natriuretic peptides (CNP) play an inhibitory role in smooth muscle motility of the gastrointestinal tract, but the effect of CNP on delayed rectifier potassium currents is still unclear. This study was designed to investigate the effect of CNP on delayed rectifier potassium currents and its mechanism by using conventional whole-cell patch- clamp technique in guinea-pig gastric myocytes isolated by collagenase. CNP significantly inhibited delayed rectifier potassium currents [IK (V)] in dose-dependent manner, and CNP inhibited the peak current elicited by depolarized step pulse to 86.1±1.6 % (n=7, P<0.05), 78.4±2.6 % (n=10, P< 0.01) and 67.7±2.3 % (n=14, P<0.01), at concentrations of 0.01 μmol/l, 0.1 μmol/l and 1 μmol/l, respectively, at +60 mV. When the cells were preincubated with 0.1 μmol/l LY83583, a guanylate cyclase inhibitor, the 1 μmol/l CNP-induced inhibition of IK (V) was significantly impaired but when the cells were preincubated with 0.1 μmol/l zaprinast, a cGMP-sensitive phosphodiesterase inhibitor, the 0.01 μmol/l CNP-induced inhibition of IK (V) was significantly potentiated. 8-Br-cGMP, a membrane permeable cGMP analogue mimicked inhibitory effect of CNP on IK (V). CNP-induced inhibition of IK (V) was completely blocked by KT5823, an inhibitor of cGMP-dependent protein kinase (PKG). The results suggest that CNP inhibites the delayed rectifier potassium currents via cGMP-PKG signal pathway in the gastric antral circular myocytes of the guinea-pig., H. Y. Xu, X. Huang, M. Yang, J.-B. Sun, L.-H. Piao, Y. Zhang, L. Gao, W.-X. Xu., and Obsahuje bibliografii a bibliografické odkazy