Selection bias, comparative advantage and heterogeneous returns to education: Evidence from China in 2000

This paper uses newly available Chinese micro data to estimate the return to college education for late 20th century China when allowing for heterogeneous returns among individuals selecting into schooling based on these differences. We use recently developed semiparametric methods to identify the parameters of interest. We demonstrate that heterogeneity among people in returns to schooling is substantial. People sort into schooling on the basis of the principle of comparative advantage, which we document to be an empirically important phenomenon in modern Chinese labor markets. Standard least squares or instrumental variable methods do not properly account for this sorting. Using new methods that do, we estimate the effect on earnings of sending a randomly selected person to college is a 43 % increase in lifetime earnings (nearly 11 % annually) in 2000 for young people in urban areas of six provinces of China. The effect of college on those who go is 13 %. Our evidence, and simple least squares evidence, suggests that after 20-plus years of economic reform with market orientation, the return to education has increased substantially in China, compared to the returns measured in the 1980’s and the early 1990’s.Education; returns to education

Selection Bias, Comparative Advantage and Heterogeneous Returns to Education

This paper uses newly available Chinese micro data to estimate the return to college education for late 20th century China when allowing for heterogeneous returns among individuals selecting into schooling based on these differences. We use recently developed semiparametric methods to identify the parameters of interest. We demonstrate that heterogeneity among people in returns to schooling is substantial. People sort into schooling on the basis of the principle of comparative advantage, which we document to be an empirically important phenomenon in modern Chinese labor markets. Standard least squares or instrumental variable methods do not properly account for this sorting. Using new methods that do, we estimate the effect on earnings of sending a randomly selected person to college is a 43% increase in lifetime earnings (nearly 11% annually) in 2000 for young people in urban areas of six provinces of China. The effect of college on those who go is 13%. Our evidence, and simple least squares evidence, suggests that after 20-plus years of economic reform with market orientation, the return to education has increased substantially in China, compared to the returns measured in the 1980's and the early 1990's.

Effects of protein modification on textural properties and water holding capacity of heat induced turkey breast meat gels

The main objectives of this research were to examine effects of protein modification (protein cleavage and crosslinking) on turkey meat gelation and to evaluate textural properties and water holding capacity of meat gels prepared from normal and PSE (pale, soft, exudative) turkey breast meat.First, the effect of protein degradation on turkey breast meat gelation was studied. To create different extent of proteolysis in the meat, á-chymotrypsin (EC 3.4.21.1) was added to normal and PSE meat batters at 0, 2.5, 5 and 10 ppm levels. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of cooked meat gels showed progressive protein hydrolysis with increasing enzyme level. Texture profile analysis and torsional analysis of the cooked meat gels showed an incremental deterioration in texture with increasing enzyme level. This inferior texture caused by proteolysis was similar to that observed in the gels made from PSE turkey meat alone. Pearson correlation coefficients indicated gel textural properties and expressible moisture were highly correlated to the degree of proteolysis, especially to that of myosin heavy chain (p < 0.001).The second study focused on modifying protein size to improve meat gelation, especially PSE meat gelation. Transglutaminase (TGase, EC 2.3.2.13) was chosen due to its ability to catalyze crosslinking of proteins. Pea protein isolate, an alternative to soy protein, was also evaluated as a meat protein extender. Textural profile and torsional gelometry analyses of the cooked meat gels showed TGase alone significantly (p < 0.05) increased gel texture, especially for those made from PSE meat. However, cook yield of the meat gels was compromised possibly due to steric effects. Addition of pea protein isolate alone improved cook yield and gel texture, especially for the gels made from PSE meat. The combination of TGase and pea protein produced the strongest meat gels, while maintaining a similar cook yield to the control. SDS-PAGE showed the disappearance of several protein bands contributed from the meat or pea protein with TGase addition, indicating that these likely were crosslinked and too large to enter the gel. Dynamic rheological analysis revealed TGase altered the viscoelastic properties of the meat or meat-pea protein mixtures and produced more elastic gels on cooling.This research indicated proteolysis had a dramatic impact on textural properties of turkey breast meat gels. Crosslinking of proteins catalyzed by TGase significantly improved gel texture, especially for the gels made from PSE meat. However, TGase-assisted crosslinking of proteins resulted in greater cooking losses unless an extender/adjunct such as pea protein was added

Fiscal Policy, Regional Disparity and Poverty in China: a General Equilibrium Approach

The main objective of this research is to analyze the effects of the fiscal dimension of China’s government transfer and preferential tax policy on regional income disparity and poverty reduction. Using a computable general equilibrium model with a three-region component, we find that the preferential tax policy on the eastern coastal region of China has a significant effect on household income, as well as on the FGT indicator. The simulation results suggest that tax policy is a more effective tool to counter against China’s regional disparity than government transfer.China, Regional Disparity, Fiscal Policy, Government Transfer, Preferential Policy, Poverty, CGE, FGT

Interfacial properties of reservoir fluids and rocks

Interfacial phenomena between CO2, brines or hydrocarbon, and carbonate rocks were investigated with the aim of understanding key aspects on CO2 storage and enhanced oil recovery (EOR) in carbonate reservoirs. The interfacial tensions between brines and CO2 were studied systematically with variation of the salt type and concentration under conditions applicable to the field. The results of the study indicate that, for strong electrolytes, the interfacial tension increases linearly with the positive charge concentration. Empirical models have been developed that represent the results as a function of temperature, pressure and molality with the small absolute average relative deviation of about 2 %. The interfacial tension measured between brine and crude oils indicated that interfacial tension has a strong dependence on both the viscosity of crude oil and the salinity of the brine. Molecular dynamics (MD) simulations of interfacial tension between water or brine and CO2 were carried out to investigate microscopic interfacial phenomena and to further understand the dependence of interfacial tension on temperature, pressure, and brine salinity. The simulation results were consistent with the experimental data obtained in this study. In particular, the simulations showed that the interfacial tension is linearly dependent on the positive charge concentration for strong electrolytes, most likely due to desorption of ions on the interface between brine and CO2. The contact angle of brine and crude oil on carbonate rocks was measured at both ambient and reservoir conditions. The results indicate that brine salinity has a strong effect on the wettability of the carbonate rock surface. This thesis provided the first attempt to explain the low salinity effect from the interactions between brine and rocks. Contact angle results and wettability index gathered from the NMR and Amott approaches measured on porous rocks were compared and found to be correlated in (crude oil + brine + calcite) systems at ambient condition. Molecular dynamics simulations of contact angle were carried out to give a deeper understanding of the underlying mechanism of the effect of brine salinity on wettabilty. Together with the experimental evidence, it can be concluded that increasing the salinity of brine results in an increase of the interfacial tension between calcite and brine. This is the first attempt to simulate contact angles by IFT simulations. Over all, interfacial phenomena between reservoir rocks and fluids were investigated by interfacial tension and contact angle measurement and by molecular simulation. Based on the wide range of experimental and simulation data obtained, this thesis provides a near complete understanding of the brine and CO2 interfacial behaviour under reservoir conditions. The empirical models obtained can predict reliably essentially any interfacial tension between brine and CO2 at reservoir conditions with given brine composition, temperature and pressure. MD simulations together with the experimental evidence, indicate that reducing the salinity of brine generally reduces the adhesion tension of crude oil in brine and calcite system. Thus proving that low salinity water flooding could potentially increase oil recovery from carbonate reservoir. More generally, low salinity aquifers are found to be more favourable for CO2 trapping

Modelling of Temporal‐Spatial Distribution of Airplane Wake Vortex for Scattering Analysis

Aircraft wake vortex is a pair of intensive counter‐rotating airflow generated by a flying aircraft. Wake vortex is one of the most dangerous hazards in aviation because it may cause a following aircraft to roll out of control, particularly during the taking off and landing phases. The real‐time detection of wake vortex is a frontier scientific problem emerging from many fields like aviation safety and atmospheric physics, and the dynamics and scattering characteristics of it remain as key problems to develop corresponding detection technologies. This chapter aims at presenting a simulation scheme for the dynamics of wake vortex under different weather conditions. For wake vortex generated in clear air, changes of the atmospheric dielectric constant produced by the density variation and water vapour variation are analysed; for wake vortex generated in rainy condition, the raindrop distribution in the wake vortex is also analysed. Both of them are essential for further analysing the scattering characteristics and developing new detection algorithms