We extend the Becker-Tomes model to a rural economy with farm-nonfarm occupational dualism to study intergenerational educational mobility in rural China and India. Using data free of coresidency ...bias, we find that fathers’ nonfarm occupation and education were complementary in determining sons schooling in India, but separable in China. Sons faced lower mobility in India irrespective of fathers’ occupation. Sensitivity analysis using the Altonji et al. (J. Polit. Econ.
113
(1), 151–84, 2005) approach suggests that genetic correlations alone could explain the intergenerational persistence in China, but not in India. Farm-nonfarm differences in returns to education, and geographic mobility are plausible mechanisms behind the contrasting cross-country evidence.
Higher-order exceptional points (EPs), which appear as multifold degeneracies in the spectra of non-Hermitian systems, are garnering extensive attention in various multidisciplinary fields. However, ...constructing higher-order EPs still remains a challenge due to the strict requirement of the system symmetries. Here we demonstrate that higher-order EPs can be judiciously fabricated in parity–time (
PT
)-symmetric staggered rhombic lattices by introducing not only on-site gain/loss but also non-Hermitian couplings. Zero-energy flatbands persist and symmetry-protected third-order EPs (EP3s) arise in these systems owing to the non-Hermitian chiral/sublattice symmetry, but distinct phase transitions and propagation dynamics occur. Specifically, the EP3 arises at the Brillouin zone (BZ) boundary in the presence of on-site gain/loss. The single-site excitations display an exponential power increase in the
PT
-broken phase. Meanwhile, a nearly flatband sustains when a small lattice perturbation is applied. For the lattices with non-Hermitian couplings, however, the EP3 appears at the BZ center. Quite remarkably, our analysis unveils a dynamical delocalization-localization transition for the excitation of the dispersive bands and a quartic power increase beyond the EP3. Our scheme provides a new platform toward the investigation of the higher-order EPs and can be further extended to the study of topological phase transitions or nonlinear processes associated with higher-order EPs.
This dissertation studies two structural frameworks in empirical studies of Industrial Organization: two-sided matching models and simultaneous auction/contest models. Both models involve two ...disjoint sides of players: matching occurs between firms and workers, schools and students, and so forth; in an auction or contest, there always exists an auctioneer or contest designer on one side and bidders or contestants on the opposite. First, empirical studies of two-sided matching markets reveal that sorting patterns between potential employers and employees may be driven by unobserved heterogeneity on both sides and preferences over multidimensional wage contracts. Therefore, in Chapter 2, I study a generalized matching model with Non-Transferrable Utility (NTU), i.e. a two-stage model where employers firstly set wage contracts for their jobs, workers then match with the jobs in a decentralized way. I propose a strategy that exploits the variation in agent- and match-specific characteristics from finite-sized repeated markets to identify and estimate the preference primitives in the presence of two-sided unobserved heterogeneity, assuming employers share a vertical preference over workers. I further suggest a likelihood-based estimation strategy that tackles the dimensionality issue emerging from the existence of global players of the repeated game, and show its performance via Monte Carlo simulation analyses.In Chapter 3, I apply the model and identification method developed in Chapter 2 to study recently fast-growing online labor markets that match skilled labor to short-term jobs using a contest-based mechanism. Despite the anecdotal evidence showing both firms and workers benefiting from largely decreased meeting friction and increased flexibility on the platform, it is economically substantial to quantitatively reveal the preference structure of both parties, which may include unobserved factors to researchers. I, therefore, adopt the two-stage model where firms set wage contracts for their jobs before programmers choose coding projects simultaneously. I then use the identification strategy that exploits the variation in agent- and match-specific characteristics from finite-sized repeated markets to estimate workers' latent skill levels and jobs' latent complexity levels. Using individual-level data from a leading online tournament-based labor market, TopCoder.com, which matches workers worldwide with short-term software developing tasks, I find a multidimensional preference beyond cash motives when workers consider which jobs to take. Using the results from the estimation, I further study the elements regarding market design that could leverage off the matching mechanisms to improve the total surplus generated from such markets.While this "crowdsourcing" market can be modeled as a matching process between firms with temporary jobs and workers, I would also like to capture the strategic interaction of workers after they match with an individual job. Within the same job, workers exert e ort to win pre-determined cash prizes according to the rank order of their delivered work. This can be naturally modeled in a (multi-prize) contest environment. A central concern is to recover the underlying preferences of workers, which again requires the full knowledge of the unobserved heterogeneity, or types, of both workers and jobs. Chapter 4 develops a new method to identify and estimate primitives in simultaneous contests with multiple prizes. I establish a two-stage game where bidders/contestants first choose one among multiple auctions/contests, then in the second stage, they compete within each auction/contest by submitting their bids simultaneously, contributing their efforts to win over the pre-determined prize based on the rank order. I show that by observing their first-stage choice probability combined with the second-stage bidding strategy, I can non-parametrically identify the joint distribution of unobserved heterogeneity on both sides of the market. I then present an estimation strategy and show the performance of Monte Carlo experiments.
This article presented processing-mechanical property relationship of thin microcellular poly(ethylene terephthlate) (PET) sheet prepared by compression molding. The results showed that the ...saturation time and the lower-plate temperature had more effects on the mechanical property. The upper-plate temperature and the PET thickness also had some effects on the mechanical property. The upper-plate temperature had more pronounced effect on the specific tensile strength than on any other mechanical parameters. Besides, there was little dependence of the mechanical property on the saturation pressure and the blowing agent content.
In the E-Commerce system, sellers disseminate commodity information, as well buyers look for befitting commodities via the sellers' websites. Yet, the scale and source of commodity information have ...been increasing fleetly along with the quick development of E-Commerce. So sellers are insensible of how to find target market efficiently, and buyers could not find their needed commodities puzzled by the ocean of information. The intelligent agent technology (IAT) can provide good means to resolve the information matching between the seller and buyer in E-Commerce. The IAT can collect, index and filter the domain model and user model knowledge that acquired automatically, and then submit the interested and useful information to the users automatically. This paper presents the holistic framework of personalized service model, and then implements the model by clustering analysis and collaborative filtering recommendation.
Higher-order exceptional points (EPs), which appear as multifold degeneracies in the spectra of non-Hermitian systems, are garnering extensive attention in various multidisciplinary fields. However, ...constructing higher-order EPs still remains as a challenge due to the strict requirement of the system symmetries. Here we demonstrate that higher-order EPs can be judiciously fabricated in PT -symmetric staggered rhombic lattices by introducing not only on-site gain/loss but also nonHermitian couplings. Zero-energy flatbands persist and symmetry-protected third-order EPs (EP3) arise in these systems owing to the non-Hermitian chiral/sublattice symmetry, but distinct phase transitions and propagation dynamics occur. Specifically, the EP3 arises at the Brillouin zone (BZ) boundary in the presence of on-site gain/loss. The single-site excitations display an exponential power increase in the PT -broken phase. Meanwhile, a nearly flatband sustains when a small lattice perturbation is applied. For the lattices with non-Hermitian couplings, however, the EP3 appears at the BZ center. Quite remarkably, our analysis unveils a dynamical delocalization-localization transition for the excitation of the dispersive bands and a quartic power increase beyond the EP3. Our scheme provides a new platform towards the investigation of the higher-order EPs, and can be further extended to the study of topological phase transitions or nonlinear processes associated with higher-order EPs.
We propose to enhance the generation of a phonon laser by exploiting optical superradiance. In our scheme, the optomechanical cavity contains a movable membrane, which supports a mechanical mode, and ...the superradiance cavity can generate the coherent collective light emissions by applying a transverse pump to an ultracold intracavity atomic gas. The superradiant emission turns out to be capable of enhancing the phonon laser performance. This indicates a new way to operate a phonon laser with the assistance of coherent atomic gases trapped in a cavity or lattice potentials.
This paper extends the Becker-Tomes model of intergenerational educational mobility to a rural economy characterized by farm-nonfarm occupational dualism and provides a comparative analysis of rural ...China and rural India. The model builds a micro-foundation for the widely used linear-in-levels estimating equation. Returns to education for parents and productivity of financial investment in children’s education determine relative mobility, as measured by the slope, while the intercept depends, among other factors, on the degree of persistence in nonfarm occupations. Unlike many existing studies based on coresident samples, our estimates of intergenerational mobility do not suffer from truncation bias. The sons in rural India faced lower educational mobility compared with the sons in rural China in the 1970s to 1990s. To understand the role of genetic inheritance, Altonji et al. (2005) biprobit sensitivity analysis is combined with the evidence on intergenerational correlation in cognitive ability in economics and behavioral genetics literature. The observed persistence can be due solely to genetic correlations in China, but not in India. Father’s nonfarm occupation was complementary to his education in determining a sons’ schooling in India, but separable in China. There is evidence of emerging complementarity for the younger cohorts in rural China. Structural change in favor of the nonfarm sector contributed to educational inequality in rural India. Evidence from supplementary data on economic mechanisms suggests that the model provides plausible explanations for the contrasting roles of occupational dualism in intergenerational educational mobility in rural India and rural China.
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