Coverage Optimal Empirical Likelihood Inference for Regression Discontinuity Design

This paper proposes an empirical likelihood inference method for a general framework that covers various types of treatment effect parameters in regression discontinuity designs (RDD) . Our method can be applied for standard sharp and fuzzy RDDs, RDDs with categorical outcomes, augmented sharp and fuzzy RDDs with covariates and testing problems that involve multiple RDD treatment effect parameters. Our method is based on the first-order conditions from local polynomial fitting and avoids explicit asymptotic variance estimation. We investigate both firstorder and second-order asymptotic properties and derive the coverage optimal bandwidth which minimizes the leading term in the coverage error expansion. In some cases, the coverage optimal bandwidth has a simple explicit form, which the Wald-type inference method usually lacks. We also find that Bartlett corrected empirical likelihood inference further improves the coverage accuracy. Easily implementable coverage optimal bandwidth selector and Bartlett correction are proposed for practical use. We conduct Monte Carlo simulations to assess finite-sample performance of our method and also apply it to two real datasets to illustrate its usefulness

Inference on Individual Treatment Effects in Nonseparable Triangular Models

In nonseparable triangular models with a binary endogenous treatment and a binary instrumental variable, Vuong and Xu (2017) show that the individual treatment effects (ITEs) are identifiable. Feng, Vuong and Xu (2019) show that a kernel density estimator that uses nonparametrically estimated ITEs as observations is uniformly consistent for the density of the ITE. In this paper, we establish the asymptotic normality of the density estimator of Feng, Vuong and Xu (2019) and show that despite their faster rate of convergence, ITEs' estimation errors have a non-negligible effect on the asymptotic distribution of the density estimator. We propose asymptotically valid standard errors for the density of the ITE that account for estimated ITEs as well as bias correction. Furthermore, we develop uniform confidence bands for the density of the ITE using nonparametric or jackknife multiplier bootstrap critical values. Our uniform confidence bands have correct coverage probabilities asymptotically with polynomial error rates and can be used for inference on the shape of the ITE's distribution

Spin Fluctuation Induced Linear Magnetoresistance in Ultrathin Superconducting FeSe Films

The discovery of high-temperature superconductivity in FeSe/STO has trigged great research interest to reveal a range of exotic physical phenomena in this novel material. Here we present a temperature dependent magnetotransport measurement for ultrathin FeSe/STO films with different thickness and protection layers. Remarkably, a surprising linear magnetoresistance (LMR) is observed around the superconducting transition temperatures but absent otherwise. The experimental LMR can be reproduced by magnetotransport calculations based on a model of magnetic field dependent disorder induced by spin fluctuation. Thus, the observed LMR in coexistence with superconductivity provides the first magnetotransport signature for spin fluctuation around the superconducting transition region in ultrathin FeSe/STO films

Modified Dual-Site Langmuir Adsorption Equilibrium Models from A GCMC Molecular Simulation

In the modern industrial separation process, the pressure swing adsorption technology is widely used to separate and purify gases due to its low energy consumption, low cost, convenience, reliability, and environmental benignity. The basic elements of the design and application of the pressure swing adsorption process are adsorption isotherms at different temperatures for adsorbents. The dual-site Langmuir (DSL) adsorption equilibrium model is the mostly used model; however, this model is based on the assumption that the adsorption energy on the surface of an adsorbent is uniform and remains unchanged. Here, a grand canonical Monte Carlo (GCMC) molecular simulation was used to calculate the CO2 adsorption equilibrium on MIL-101 (Cr) at 298 K. MIL-101 (Cr) was chosen, as it has more a general pore structure with three different pores. The calculation results showed that the adsorption energies with different adsorption pressures fitted a normal distribution and the relationship of the average adsorption energies, E with pressures had a linear form described as: E = aP + c. With this relationship, the parameter b = k·exp(E/RT) in the DSL model was modified to b = k·exp((aP + c)/RT), and the modified DSL model (M-DSL) was used to correlate the adsorption equilibrium data on CO2-MIL-101 (Cr), C2H4-HHPAC, CH4-BPL, and CO2-H-Mordenite, showing better correlations than those of the DSL model. We also extended the parameter qm in the M-DSL model with the equation qm = k1 + k2T to adsorption equilibrium data for different temperatures. The obtained model (M-TDSL) was checked with the abovementioned adsorption equilibrium systems. The fitting results also indicated that the M-TDSL model could be used to improve the correlation of adsorption equilibrium data for different temperatures. The linear relationship between the average adsorption energy and adsorption pressure could be further tested in other adsorption equilibrium models to determine its universality

CEO empowering leadership and corporate entrepreneurship : the roles of TMT information elaboration and environmental dynamism

In this paper we investigate the relationship between chief executive officer (CEO) empowering leadership and corporate entrepreneurship. In addition, the mediating role of information elaboration in top management teams (TMTs) and the moderating role of environmental dynamism are examined. Drawing on the information exchange/sharing perspective, we hypothesize that CEO empowering leadership has a positive effect on corporate entrepreneurship, and TMT information elaboration mediates the relationship above. Furthermore, we find that environmental dynamism positively moderates the relationship between empowering leadership and information elaboration, and negatively moderates the relationship between information elaboration and corporate entrepreneurship. Data from a sample of Chinese firms provide empirical evidence in support of these hypotheses

Simulation and Optimization of Distillation Processes for Separating the Methanol–Chlorobenzene Mixture with Separate Heat-Pump Distillation

The methanol–chlorobenzene mixture has a larger relative volatility in the low composition range than in the high composition range. Based on this characteristic, the mixture can be effectively separated by separate heat-pump distillation (SHPD) with significant energy savings. The binary interaction parameters of the UNIQUAC equation were used to predict the vapor–liquid equilibrium by means of the binary interaction parameters included in the Aspen Plus database. To minimize the overall annual operating costs, simulations for SHPD were carried out using Aspen Plus software, including the RadFrac and Compr blocks, and the optimal operating conditions, such as the split-point concentration, were determined. Simulations for conventional distillation, conventional heat-pump distillation, and multieffect distillation processes were also carried out for comparison. The simulated results showed that the SHPD process has obvious advantages over the other distillation processes in the assessment of energy savings and overall economic efficiency

Analysis of Aroma Components of Raw Pu'er Tea in Lincang City Based on Multivariate Statistical Analysis

In order to accurately evaluate the aroma quality of raw Pu'er tea in Lincang City, the aroma components of 16 raw Pu'er teas were systematically analyzed and comprehensively evaluated by multivariate statistical analysis. A total of 48 aroma components were detected, with 11 aroma components were more than 2.00% content. Among them, linalool was the most abundant component and the content was 24.68%. For the aroma types, the alcohols were accounted for the largest proportion with a mean of 46.55%, followed by aldehydes with a mean of 26.81%, while ketones, esters and other components were responsible for little proportion. Multivariate statistical analysis showed that the raw Pu'er teas obtained form in southern region were clearly distinguished from those in northern region. The concentration of alcohols and esters was significantly higher in southern region than those in northern region, whereas aldehyde, ketones and other components were remarkably lower. Altitude may be an important reason for the difference of aroma components of Pu'er raw tea in the south and north regions. Furthermore, 23 aroma components were identified based on variable importance in projection (VIP) score>1, which might be responsible for the discrimination of raw Pu'er teas in southern and northern region. Linalool, isoflolone, ketones, alcohols, aldehydes, β-cyclocitral, α-cyclocitral, 2,2,6-trimethyl-cyclohexanone, nerol and β-ionone play siginificant role in the differentiation of raw Pu'er tea harvested from different regions. This study would provide some theoretical basis for accurately understanding the aroma quality of Lincang Pu'er raw tea, and also provide ideas and methods for the study on the quality evaluation and origin determination of Lincang Pu'er raw tea

Simulation and Optimization of Distillation Processes for Separating a Close-Boiling Mixture of <i>n</i>‑Butanol and Isobutanol

Separation of close-boiling mixtures by conventional distillation consumes a large amount of energy because of the very high reflux ratio required. Mechanical vapor recompression heat pumps (MVRHPs) can recycle the energy of the vapor and can thus be used in such distillation processes to save energy. Three different distillation schemes, namely, conventional distillation, top MVRHP distillation, and bottom-flashing MVRHP distillation, were simulated for the separation of the close-boiling mixture of <i>n</i>-butanol and isobutanol using Aspen Plus to determine the economically best option. The research results indicate that, compared to conventional distillation, the energy savings for bottom-flashing MVRHP distillation and top MVRHP distillation can reach 67.92% and 72.92%, respectively, and the TACs correspondingly decrease by 71.74% and 75.57%

Covalently Bonded Ni Sites in Black Phosphorene with Electron Redistribution for Efficient Metal-Lightweighted Water Electrolysis

Highlights Black phosphorene (BP) was functionalized by the ionized Ni through an in situ electrochemical exfoliation method. Just 1.5 wt% Ni-functionalized BP can stably deliver the efficient alkaline H2/O2 evolution electrocatalysis. Optimized intermediate chemisorption is enabled by Ni–P covalent bonding and electron redistributed surface