An Empirical Research of Concentration of China’s Civil Aviation Industry

With China’s sustained and rapid economic development, China’s civil aviation industry gradually market-oriented, and has undergone several major reforms, gradual deregulation. At the same time, industry concentration showed a gradual downward trend. The internationally accepted measure of industrial concentration of two indicators: Industry moderate and HHI index. We described and analyzed the industry concentration and development trends on China’s civil aviation industry, and we got the main factors of the change of industry concentration. Also put forward policy recommendations

Modeling Heterogeneity in Direct Infectious Disease Transmission in a Compartmental Model

Mathematical models have been used to understand the transmission dynamics of infectious diseases and to assess the impact of intervention strategies. Traditional mathematical models usually assume a homogeneous mixing in the population, which is rarely the case in reality. Here, we construct a new transmission function by using as the probability density function a negative binomial distribution, and we develop a compartmental model using it to model the heterogeneity of contact rates in the population. We explore the transmission dynamics of the developed model using numerical simulations with different parameter settings, which characterize different levels of heterogeneity. The results show that when the reproductive number, [GRAPHICS] , is larger than one, a low level of heterogeneity results in dynamics similar to those predicted by the homogeneous mixing model. As the level of heterogeneity increases, the dynamics become more different. As a test case, we calibrated the model with the case incidence data for severe acute respiratory syndrome (SARS) in Beijing in 2003, and the estimated parameters demonstrated the effectiveness of the control measures taken during that period

The Molecular Cloning and Expression Analysis of a CYP71 Gene in Ginkgo biloba L.

Cytochrome P450 monooxygenases (CYPs) are a group of redox proteins that catalyze various oxidative reactions in plant secondary metabolism. To explore the function of the CYP71 gene in Ginkgo biloba under biotic and abiotic stresses, a full-length CYP gene, designated GbCYP71, was first isolated and characterized from leaves of G. biloba. It contained a 1512-bp open reading frame (ORF) encoding 503 amino-acid-deduced polypeptide whose theoretical molecular weight was 56.9 kDa. The genomic DNA sequence of GbCYP71 contained two exons and one intron. The cDNA of GbCYP71 was subcloned in a pET-32a vector and then transformed into E. coli strain BL21 (DE3). A protein with a molecular weight of 76.4 kDa was subsequently identified and found to be consistent with the above theoretical value. Transient expression analysis revealed that the GbCYP71 protein may be located in the G. biloba cell cytoplasm. GbCYP71 was expressed in almost all ginkgo tissues, including leaves, stamens, gynoecia, stems and, preferentially, roots. Expression-profiling analyses revealed that GbCYP71 can be induced by salinity stress and phytohormone signals, including salicylic acid, abscisic acid, methyl jasmonate and ethephon, but is repressed by heat and cold stresses. These results indicate that GbCYP71 mainly functions in responding to biotic and abiotic stresses

Research on interface slippage of fiber reinforced composite ceramics

Based on the microscopic characteristics of fiber reinforced composite ceramics, the slippage stress at the interface of composite ceramics under external loading is analyzed. The relation between the applied strain of the triangular symmetrical eutectic and the load of composite ceramics is confirmed. And the maximum shear stress that the triangular symmetrical eutectic can endure is computed. The yield shear stress was calculated by the hardness and fracture toughness of composite ceramics. When the maximum shear stress which the triangular symmetrical eutectic can bear is equal to the yield shear stress, the slipping stress of micro-mechanical interface in composite ceramics is obtained. The results showed that fiber inclusions in the eutectic having smaller dimension and larger volume content would provide larger partial plastic deformation of composite ceramics

LEDミニライダーによる近距離大気の可視化

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