Markets, Human Capital, and Inequality: Evidence from Rural China

Market reforms are generally credited with the rapid growth enjoyed by China's rural sector. This growth has not been without some cost, however, as inequality has also increased. Estimates suggest that the Gini rose from less than 0.20 to over 0.40 during this period. In this paper we go behind these numbers to explore the nature and causes of this inequality. To begin, we find that a considerable share of rural inequality is driven by local differences in household incomes, as opposed to regional income differences, that have been the focus of the previous literature. We then examine inter-household income differentials at the village level, exploring the links between education, market development, non-agricultural employment, and household income. To address these questions, we draw on a recently collected data set from Northeast China, that was collected by two of the authors in collaboration with Chinese colleagues in Hebei and Liaoning provinces in 1995. For purposes of comparison, we also draw on the Chinese Health and Nutrition Survey. We find that indeed, increasing rates of return to education and unevenly developed non-agricultural business opportunities contribute to the high levels of inequality in the countryside. Of most interest, however, is the implication that simultaneous improvements in educational attainment and off-farm market-development would allow more households to share in the rapid growth in rural China.http://deepblue.lib.umich.edu/bitstream/2027.42/39682/3/wp298.pd

Channel flow of rigid sphere suspensions: particle dynamics in the inertial regime

We consider suspensions of neutrally-buoyant finite-size rigid spherical particles in channel flow and investigate the relation between the particle dynamics and the mean bulk behavior of the mixture for Reynolds numbers $500 \le Re \le 5000$ and particle volume fraction $0\le \Phi \le 0.3$, via fully resolved numerical simulations. Analysis of the momentum balance reveals the existence of three different regimes: laminar, turbulent and inertial shear-thickening depending on which of the stress terms, viscous, Reynolds or particle stress, is the major responsible for the momentum transfer across the channel. We show that both Reynolds and particle stress dominated flows fall into the Bagnoldian inertial regime and that the Bagnold number can predict the bulk behavior although this is due to two distinct physical mechanisms. A turbulent flow is characterized by larger particle dispersion and a more uniform particle distribution, whereas the particulate-dominated flows is associated with a significant particle migration towards the channel center where the flow is smooth laminar-like and dispersion low.Interestingly, the collision kernel shows similar values in the different regimes, although the relative particle velocity and clustering clearly vary with inertia and particle concentration.Comment: 36 Pages, 12 figure

Effects of the finite particle size in turbulent wall-bounded flows of dense suspensions

We use interface-resolved simulations to study finite-size effects in turbulent channel flow of neutrally-buoyant spheres. Two cases with particle sizes differing by a factor of 2, at the same solid volume fraction of 20% and bulk Reynolds number are considered. These are complemented with two reference single-phase flows: the unladen case, and the flow of a Newtonian fluid with the effective suspension viscosity of the same mixture in the laminar regime. As recently highlighted in Costa et al. (PRL 117, 134501), a particle-wall layer is responsible for deviations of the statistics from what is observed in the continuum limit where the suspension is modeled as a Newtonian fluid with an effective viscosity. Here we investigate the fluid and particle dynamics in this layer and in the bulk. In the particle-wall layer, the near wall inhomogeneity has an influence on the suspension micro-structure over a distance proportional to the particle size. In this layer, particles have a significant (apparent) slip velocity that is reflected in the distribution of wall shear stresses. This is characterized by extreme events (both much higher and much lower than the mean). Based on these observations we provide a scaling for the particle-to-fluid apparent slip velocity as a function of the flow parameters. We also extend the flow scaling laws in to second-order Eulerian statistics in the homogeneous suspension region away from the wall. Finite-size effects in the bulk of the channel become important for larger particles, while negligible for lower-order statistics and smaller particles. Finally, we study the particle dynamics along the wall-normal direction. Our results suggest that 1-point dispersion is dominated by particle-turbulence (and not particle-particle) interactions, while differences in 2-point dispersion and collisional dynamics are consistent with a picture of shear-driven interactions

Universal Scaling Laws for Dense Particle Suspensions in Turbulent Wall-Bounded Flows

The macroscopic behavior of dense suspensions of neutrally-buoyant spheres in turbulent plane channel flow is examined. We show that particles larger than the smallest turbulence scales cause the suspension to deviate from the continuum limit in which its dynamics is well described by an effective suspension viscosity. This deviation is caused by the formation of a particle layer close to the wall with significant slip velocity. By assuming two distinct transport mechanisms in the near-wall layer and the turbulence in the bulk, we define an effective wall location such that the flow in the bulk can still be accurately described by an effective suspension viscosity. We thus propose scaling laws for the mean velocity profile of the suspension flow, together with a master equation able to predict the increase in drag as function of the particle size and volume fraction.Comment: Accepted for publication in PRL. Supplemental material include

Markets, Human Capital, and Inequality: Evidence from Rural China

Market reforms are generally credited with the rapid growth enjoyed by China's rural sector. This growth has not been without some cost, however, as inequality has also increased. Estimates suggest that the Gini rose from less than 0.20 to over 0.40 during this period. In this paper we go behind these numbers to explore the nature and causes of this inequality. To begin, we find that a considerable share of rural inequality is driven by local differences in household incomes, as opposed to regional income differences, that have been the focus of the previous literature. We then examine inter-household income differentials at the village level, exploring the links between education, market development, non- agricultural employment, and household income. To address these questions, we draw on a recently collected data set from Northeast China, that was collected by two of the authors in collaboration with Chinese colleagues in Hebei and Liaoning provinces in 1995. For purposes of comparison, we also draw on the Chinese Health and Nutrition Survey. We find that indeed, increasing rates of return to education and unevenly developed non-agricultural business opportunities contribute to the high levels of inequality in the countryside. Of most interest, however, is the implication that simultaneous improvements in educational attainment and off-farm market-development would allow more households to share in the rapid growth in rural China.

Markets, Human Capital, and Inequality: Evidence from Rural China

Market reforms are generally credited with the rapid growth enjoyed by China's rural sector. This growth has not been without some cost, however, as inequality has also increased. Estimates suggest that the Gini rose from less than 0.20 to over 0.40 during this period. In this paper we go behind these numbers to explore the nature and causes of this inequality. To begin, we find that a considerable share of rural inequality is driven by local differences in household incomes, as opposed to regional income differences, that have been the focus of the previous literature. We then examine inter-household income differentials at the village level, exploring the links between education, market development, non-agricultural employment, and household income. To address these questions, we draw on a recently collected data set from Northeast China, that was collected by two of the authors in collaboration with Chinese colleagues in Hebei and Liaoning provinces in 1995. For purposes of comparison, we also draw on the Chinese Health and Nutrition Survey. We find that indeed, increasing rates of return to education and unevenly developed non-agricultural business opportunities contribute to the high levels of inequality in the countryside. Of most interest, however, is the implication that simultaneous improvements in educational attainment and off-farm market-development would allow more households to share in the rapid growth in rural China.

The Influence of Nanoporous Crystalline Structure on Low Molecular Weight Mass Transport in Syndiotactic Polystyrene

Solid-state structure, crystalline morphology, crystallization kinetics, thermal, free volume, and gas transport properties of semicrystalline syndiotactic polystyrene (sPS) and ethylene vinyl alcohol copolymers (EVOH) have been investigated. Solid-state structure of sPS after crystallization from the melt and glassy state was examined by differential scanning calorimetry (DSC), density and wide angle x-ray diffraction analysis (WAXD). The measurements confirmed low density of syndiotactic polystyrene crystalline forms, which in the case of α and δe was smaller and in the case of β and γ crystalline forms was slightly larger than the density of the glassy amorphous sPS. Positron annihilation lifetime spectroscopy (PALS) experiments have been carried out to study the free volume properties of these materials. The diffusion characteristics of amorphous, α, and β forms of sPS were successfully measured via a custom made dynamic gas permeation system utilizing a mass-spectrometer. It was shown experimentally that the amorphous and β forms demonstrate similar diffusion. Conversely, experimental results as well as molecular dynamics simulations have shown that the unique “superstructure,” packing of triplets forming hexagonally shaped nanochannels along the chain direction, found in the α form of sPS, facilitate high diffusion rates parallel to the chain direction in larger permeants (greater than 2.6Å). This was attributed to a transition from a nearly 3-dimensional behavior for small permeant size, to a 1-dimensional behavior for larger permeant sizes. Larger permeants are confined to the hexagonally shaped nanochannels between the triplets in the α form, and cannot move between parallel channels. The smaller permeants, however, can move relatively freely between neighboring channels, resulting in a 3-dimensional diffusion behavior. The vapor sorption of several industrial and chemical simulants within semicrystalline domains of syndiotactic polystyrene was studied with a quartz crystal microbalance. To increase the overall sensitivity of the sensing medium a new method for sample preparation was proposed. This method has utilized the ability to prepare high degrees of γ phase crystallinity, through supercritical CO2, to generate highly δe crystalline samples via crystalline-crystalline solid state transitions. Sorption characteristics are established as a function of crystalline fraction and chemical properties of the test analytes. It has been demonstrated experimentally that increased crystallinity directly influences the sensitivity of the sensing medium. The use of δe crystalline phase sPS as a sensing medium in cooperation with QCM to selectively detect the chemical warfare simulant 2-chloroethyl ethyl sulfide was shown. Transport in a broad range of ethylene vinyl alcohol copolymers (EVOH) as it is related to hydrogen bonding interaction through a measure of free volume and cohesive energy characteristics was conducted. Solid state structure was probed utilizing wide angle x-ray diffraction, differential scanning calorimetry, density measurements, and positron annihilation lifetime spectroscopy, to directly study free volume behavior. Characteristic FTIR spectra of EVOH copolymers demonstrate that the width and intensity of the OH stretching vibration increase with increasing vinyl alcohol content. The measure of intermolecular interaction, cohesive energy density (CED), was calculated through group contribution methods and also obtained using molecular dynamics computer simulations. Oxygen transport characteristics of the copolymers, i.e. permeability, diffusivity, and solubility were measured and correlations were made between vinyl alcohol content, free volume, and CED

Physical properties of SrSn4 single crystals

We present detailed thermodynamic and transport measurements on single crystals of the recently discovered binary intermetallic superconductor, SrSn4. We find this material to be a slightly anisotropic three-dimensional, strongly-coupled, possibly multi-band, superconductor. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of -0.068 K/kbar. Band structure calculations are consistent with experimental data on Sommerfeld coefficient and upper superconducting critical field anisotropy and suggest complex, multi-sheet Fermi surface formed by four bands.Comment: Figure 11 correcte

Physical properties of single crystalline BaSn5

We present a comprehensive study of the binary intermetallic superconductor, BaSn5. High-quality single crystalline BaSn5 was grown out of Sn flux. Detailed thermodynamic and transport measurements were performed to study BaSn5's normal and superconducting state properties. This material appears to be a strongly coupled, multiband superconductor. Hc2(T)is almost isotropic. De Haas-van Alphen oscillations were observed and two effective masses were estimated from the FFT spectra. Hydrostatic pressure causes a decrease in the superconducting transition temperature at the rate of ~ -0.053 K/kbar.Comment: 8 pages and 9 figure