Who Should I Share Risk with? Gifts can tell:Theory and Evidence from Rural China

This paper studies how gift exchange may help to overcome limited commitment problem in risk sharing. When efficient contract enforcement is lacking, people rely on friends (or relatives) to share risk since emotional or moral cost of defaulting between friends can help to prevent moral hazard. The problem is how to distinguish between friends and non-friends? Gift expense serves as a signal of friendship since giving a gift is less costly for a friend than a non-friend due to altruism. The model re-evaluates the role of gift exchange in developing economies, and helps to rationalize the large amount of gift exchange in China (10% of living expenditure). As a signal, gift exchange improves the efficiency in risk sharing and facilitates favor exchange, but I also demonstrate that the welfare gains due to this improvement may be offset by increased inequality. By using a unique data set containing detailed records about gift exchange in rural China, the empirical study suggests gift expenses, as a signal, significantly increase the probability of risk sharing. I also show further empirical evidence to the theory by testing more model predictions

Essays on development economics and public economics

The first chapter is on a “dark” side of fiscal decentralization. I demonstrate, with Wendun Wang in a yardstick competition model, that as fiscal expenditure is decentralized, more public resources might be misallocated between visible public goods and invisible ones. To empirically verify our theoretical model, we employ U.S. state-level data and estimate the panel data model using various econometric approaches. The empirical results provide strong evidence that fiscal decentralization can lead to distortion in public expenditure and increases the poverty rate on regional level. The second chapter is jointly written with Yang Zhou and Erwin Bulte. By proposing a portfolio choice model based on a “quantity-quality tradeoff”, we explore fertility decisions taking into account the risk of human capital investment. Our theory highlights the detrimental effect of adult mortality risks on human capital investment, and predicts heterogeneous impacts on fertility choice across income groups. Our analysis helps to reconcile the conflicting empirical evidence regarding the impact of HIV/AIDS on fertility found in previous literature. The third chapter considers a mechanism that facilitates risk sharing when effective contract enforcement is lacking. The “emotional collateral” between friends may help people to regulate the limited commitment problem. I show that the mechanism can work effectively if gift expenses serve as signals that separate friends, who have “emotional collateral”, from non-friends. By using a unique data set containing detailed records about gift exchange in rural China, I find empirical evidence to support the association between gift expenses and risk sharing

Dress-up contest: a dark side of fiscal decentralization

A `dress-up contest' is a competition for the best public image, and fiscal decentralisation can lead to such contests between local governments. In this paper we model the dress-up contest and investigate how it a effects social welfare. We show that yardstick competition (due to fiscal decentralisation) forces local governments to allocate more resources to more visible public goods (such as cash assistance) than less visible goods (such as vendor payments) and thus starts dress-up contests. The resulting distortion of resource allocation causes a structural bias in public expenditure and further hurts social welfare. To empirically verify our theoretical model, we employ U.S. state-level data from 1992 to 2008, and we estimate the panel data model using various econometric approaches. The empirical results provide strong evidence that fiscal decentralisation can lead to distortion in public expenditure arising from dress-up contests. We also find that this distortion increases the regional poverty rate

Epigenetic Regulation of Prostate Cancer

Prostate cancer is (PCa) the second leading cause of cancer death in males in the United State, with 174,650 new cases and 31,620 deaths estimated in 2019. It has been documented that epigenetic deregulation such as histone modification and DNA methylation contributes to PCa initiation and progression. EZH2 (enhancer of zeste homolog 2), the catalytic subunit of the Polycomb Repressive Complex (PRC2) responsible for H3K27me3 and gene repression, has been identified as a promising target in PCa. In addition, overexpression of other epigenetic regulators such as DNA methyltransferases (DNMT) is also observed in PCa. These epigenetic regulators undergo extensive post-translational modifications, in particular, phosphorylation. AKT, CDKs, PLK1, PKA, ATR and DNA-PK are the established kinases responsible for phosphorylation of various epigenetic regulators

A novel soft clustering algorithm

AbstractPaper clustering problems in citation network is one of the hottest spots in data mining. However, traditional paper clustering algorithm stresses on the keywords analysis while ignores the “refer-to” relationship, which results in the problem of high time complexity and low accuracy. In this paper, we come up with a novel soft clustering algorithm in accordance with the complex priority and thegrouth theorem, and classify our algorithm into two steps: refer-to relationship analysis and keywords comparison. Experimental results show that our algorithm is able to greatly improve the search accuracy and efficiency

Cooperation of Combinatorial Solvers for Air Traffic Management and Control

In the context of the SESAR project, Air Traffic Control (ATC) and Management (ATM) in Europe is undergoing a paradigm shift to be able to accommodate the current traffic growth forecast: many expert-based systems will be enhanced by optimization software to improve the decisionmaking process and regulation planning. Current state-of-the-art combinatorial optimization techniques that are applied to ATC and ATM include approximation algorithms like metaheuristics (e.g. Genetic Algorithm, Tabu Search, Simulated Annealing, etc.) and complete algorithms like Constraint Programming (CP) and Mixed Integer Programming. However, the large scale of the considered instances and the handling of their inherent uncertainties result in very hard problems, which can hinder or even defeat either of the previously mentioned optimization methods alone. To overcome these difficulties and improve the resolution efficiency of standard algorithms, we propose to study the generic cooperation of any set of combinatorial solvers by sharing solutions, optimization bounds and possibly other information in order to speed up the overall process. In this thesis, we have specified and implemented a distributed system which is able to integrate any combinatorial solver with the suitable interface, adapt existing solvers to take into account and provide information on the state of the search from and to other solvers, and applied this framework to two ATC and ATM problems: the en-route conflict resolution problem and the Gate Allocation Problem (GAP). For the first one, we have presented a new generic framework for the modeling and resolution of en-route conflicts in three dimensions as well as a large set of realistic instances, which have been solved with the cooperation of a Memetic Algorithm and Integer Linear Programming (ILP) solver. For the GAP, we have presented a new CP model, as well as new optimization constraints to maximize the robustness of the schedule, and search strategies together with their parallel cooperation. The solver, implemented with the FaCiLe CP library, outperforms a state-of-the-art ILP solver on real instances

Investigation of Ce3+ Adsorption by Sn(OH)X by the Gravimetric Method

In this work, the adsorption of Ce3+ by Sn(OH)2, SnO, and Sn(OH)4 was investigated. By comparing the mass of cerium oxalate caused by the adsorbed Ce3+, Sn(OH)2 and Sn(OH)4 have the ability to adsorb Ce3+, while Sn(OH)4 has a stronger adsorption capacity of Ce3+. However, SnO does not have the ability. The possible mechanism of Sn(OH)X adsorption Ce3+ was further discussed. And the result indicates that the hydroxide can adsorb cations by means of anionic groups on its surface in the solution so that the cations can be enriched on the hydroxide surface. The paper provides a new method for adjusting the microstructure of catalysts, which has a promising prospect in the field of catalysts preparation

Departure Management with Robust Gate Allocation

International audienceThe Airport Collaborative Decision Making (A-CDM) concept yields concrete and promising solutions for airports, in terms of traffic punctuality and predictability, with possible delay, noise and pollution reduction. A key feature of A-CDM is the Departure Management (DMAN): runway takeoff sequences can be anticipated such that a significant part of the delay can be shifted at the gate, engines off, without penalizing the remaining traffic. During this process, an increase in the gate occupancy for delayed departures is unavoidable, therefore the airport layout must provide enough gates and their allocation must be robust enough w.r.t. departures delay. In this paper, we introduce a method to estimate the gate delays due to the DMAN pre-departure scheduling, then we propose a robust gate allocation algorithm and assess its performance with current and increased traffic at Paris-Charles-de-Gaulle international airport. Results show a significant reduction in the number of gate conflicts, when comparing such a robust gate allocation to current practice

Variable pitch approach for performance improving of straight-bladed VAWT at rated tip speed ratio

This paper presents a new variable pitch (VP) approach to increase the peak power coefficient of the straight-bladed vertical-axis wind turbine (VAWT), by widening the azimuthal angle band of the blade with the highest aerodynamic torque, instead of increasing the highest torque. The new VP-approach provides a curve of pitch angle designed for the blade operating at the rated tip speed ratio (TSR) corresponding to the peak power coefficient of the fixed pitch (FP)-VAWT. The effects of the new approach are exploited by using the double multiple stream tubes (DMST) model and Prandtl’s mathematics to evaluate the blade tip loss. The research describes the effects from six aspects, including the lift, drag, angle of attack (AoA), resultant velocity, torque, and power output, through a comparison between VP-VAWTs and FP-VAWTs working at four TSRs: 4, 4.5, 5, and 5.5. Compared with the FP-blade, the VP-blade has a wider azimuthal zone with the maximum AoA, lift, drag, and torque in the upwind half-cycle, and yields the two new larger maximum values in the downwind half-cycle. The power distribution in the swept area of the turbine changes from an arched shape of the FP-VAWT into the rectangular shape of the VP-VAWT. The new VP-approach markedly widens the highest-performance zone of the blade in a revolution, and ultimately achieves an 18.9% growth of the peak power coefficient of the VAWT at the optimum TSR. Besides achieving this growth, the new pitching method will enhance the performance at TSRs that are higher than current optimal values, and an increase of torque is also generated