The COVID-19 pandemic and unemployment: Evidence from mobile phone data from China.

Based on mobile phone records for 71 million users and location tracking information for one million users over almost three years, this study examines the labor market impacts of the COVID-19 pandemic in China's Guangdong province, whose GDP is larger than that of all but the top 12 countries in the world. Using a standard difference-in-differences framework, our analysis shows dramatic and protracted effects of the pandemic on the labor market: it increased unemployment by 72% and unemployment benefits claims by 57% even after the full reopening in 2020 relative to their levels in the same period in 2019. The impact was also highly heterogeneous, with women, workers older than 40, and migrants being more affected. Cities that rely more on export or that have a higher share of the hospitality industry in GDP but a lower share of the finance and healthcare industries experienced a more pronounced increase in unemployment. The lingering impact likely reflects the global transmission of the pandemic's effects through the supply chain and trade channels.

A simultaneous perturbation stochastic approximation algorithm for broadband noise control.

Simultaneous perturbation stochastic approximation (SPSA) algorithm, an algorithm without secondary path modeling, has been applied to active noise control by some researchers. Some extended versions of this algorithm have been also developed to improve its performance. However, these existing algorithms are mostly dedicated to controlling the periodic noise instead of the broadband noise. In particular, background noise is not taken into account when SPSA algorithms are applied to control broadband noise. In this paper, an algorithm combining the cost function with the SPSA algorithm to control broadband noise has been proposed. The suggested cost function is an inner product of the estimated cross-correlation function between a reference vector and the error signal. The elements of the reference vector are composed of the reference signals at different times. Moreover, the algorithm analysis is performed and the numerical simulations are carried out to demonstrate the validity of the proposed algorithm. The results illustrate that the proposed algorithm can effectively reduce broadband noise when interference noise exists in the control system. Furthermore, the proposed algorithm has better convergence performance than other SPSA algorithms.

Non-destructive Storage Time Prediction of Newhall Navel Oranges Based on the Characteristics of Rind Oil Glands.

How to non-destructively and quickly estimate the storage time of citrus fruit is necessary and urgent for freshness control in the fruit market. As a feasibility study, we present a non-destructive method for storage time prediction of Newhall navel oranges by investigating the characteristics of the rind oil glands in this paper. Through the observation using a digital microscope, the oil glands were divided into three types and the change of their proportions could indicate the rind status as well as the storage time. Images of the rind of the oranges were taken in intervals of 10 days for 40 days, and they were used to train and test the proposed prediction models based on K-Nearest Neighbors (KNN) and deep learning algorithms, respectively. The KNN-based model demonstrated explicit features for storage time prediction based on the gland characteristics and reached a high accuracy of 93.0%, and the deep learning-based model attained an even higher accuracy of 96.0% due to its strong adaptability and robustness. The workflow presented can be readily replicated to develop non-destructive methods to predict the storage time of other types of citrus fruit with similar oil gland characteristics in different storage conditions featuring high efficiency and accuracy.

Adaptation mitigates the negative effect of temperature shocks on household consumption.

Consumption plays an important role in economic growth, but little is known about its response to weather extremes. This paper examines the effect of temperature shocks on consumption using high-frequency and fine-scale data from the world's largest payment network. Our analysis shows that excessive heat and cold have a direct and immediate negative effect on various consumption activities in the short run, leading to an inverted U-shaped relationship between temperature and consumption. Consumption sensitivity varies by climate region, with cold regions being more sensitive to excessive heat. The long-run projections show that without adaptation, climate change would reduce aggregate consumption under both moderate and aggressive scenarios by the end of the century. However, no evidence of consumption reduction arises once adaptation is accounted for. The findings highlight the importance of incorporating the moderating role of adaptation in understanding consumption responses to climate change.

An active impulsive noise control algorithm with a post-adaptive filter and variable step size.

Active noise control algorithms aimed at reducing Gaussian noise have been studied. However, the performance of these algorithms can deteriorate if impulsive noise or other non-Gaussian noise such as piling noise exists. To solve this problem, an algorithm named the filtered-x affine projection sign algorithm with a post-adaptive filter is proposed to reduce impulsive noise. The proposed algorithm is based on the filtered-x affine projection sign algorithm and the post-adaptive filter structure. In addition, an algorithm with a variable step size is proposed to improve the performance of the filtered-x affine projection sign algorithm with a post-adaptive filter by using a convex combination strategy. The fixed step size in the convex combination is replaced with a linear function of the ratio between the estimated error signal and the estimated desired signal. The detailed derivation processes of the proposed algorithms are given. The computational complexities are analyzed. Numerical simulations are carried out to demonstrate the performance of the proposed algorithms. The results illustrate that the proposed algorithms can effectively reduce impulsive noise. At the same time, the algorithm with a variable step size has better convergence performance than the filtered-x affine projection sign algorithm with a post-adaptive filter.

Microstructure and Soil Wear Resistance of D517 Coating Deposited by Electric Spark Deposition.

The abrasion failure is the key factor for prolonging the service life and energy saving of furrow openers. The hardness enhancement was reported to be an effective strategy to increase the wear resistance against the soil abrasion. D517 coatings were deposited on Q235 steel by electric spark to improve the wear-resistant property with an affordable cost for farmers. The wear behavior of the coatings was characterized in a pin on disk friction equipment and a homemade soil abrasion simulation system. The soil adhesion, which is highly related to energy consumption, was also evaluated. Results showed that D517 coatings revealed dendrite structure with some randomly distributed carbides. The electric current exerted a great influence on the microstructure, hardness, friction coefficient, and soil wear rate. The wear rate of samples deposited with 80 A and 90 A reduced to 79% and 84%, respectively, as compared with the normalized heat-treated 65 Mn steel after 6 h in soil. This work provides a promising solution to increase the wear resistance of furrow openers. It needs to be noted that the coating would increase the soil adhesion of the opener, which needs to be further explored to decrease the energy consumption.

A Deep Learning-Based Vision System Combining Detection and Tracking for Fast On-Line Citrus Sorting.

Defective citrus fruits are manually sorted at the moment, which is a time-consuming and cost-expensive process with unsatisfactory accuracy. In this paper, we introduce a deep learning-based vision system implemented on a citrus processing line for fast on-line sorting. For the citrus fruits rotating randomly on the conveyor, a convolutional neural network-based detector was developed to detect and temporarily classify the defective ones, and a SORT algorithm-based tracker was adopted to record the classification information along their paths. The true categories of the citrus fruits were identified through the tracked historical information, resulting in high detection precision of 93.6%. Moreover, the linear Kalman filter model was applied to predict the future path of the fruits, which can be used to guide the robot arms to pick out the defective ones. Ultimately, this research presents a practical solution to realize on-line citrus sorting featuring low costs, high efficiency, and accuracy.

Strain Effect on Thermoelectric Performance of InSe Monolayer.

Strain engineering is a practical method to tune and improve the physical characteristics and properties of two-dimensional materials, due to their large stretchability. Tensile strain dependence of electronic, phonon, and thermoelectric properties of InSe monolayer are systematically studied. We demonstrate that the lattice thermal conductivity can be effectively modulated by applying tensile strain. Tensile strain can enhance anharmonic phonon scattering, giving rise to the enhanced phonon scattering rate, reduced phonon group velocity and heat capacity, and therefore lattice thermal conductivity decreases from 25.9 to 13.1 W/mK when the strain of 6% is applied. The enhanced figure of merit indicates that tensile strain is an effective way to improve the thermoelectric performance of InSe monolayer.

Composition Dependence of Structural and Electronic Properties of Quaternary InGaNBi.

To realize feasible band structure engineering and hence enhanced luminescence efficiency, InGaNBi is an attractive alloy which may be exploited in photonic devices of visible light and mid-infrared. In present study, the structural, electronic properties such as bandgap, spin-orbit splitting energy, and substrate strain of InGaNBi versus In and Bi compositions are studied by using first-principles calculations. The lattice parameters increase almost linearly with increasing In and Bi compositions. By bismuth doping, the quaternary InGaNBi bandgap could cover a wide energy range from 3.273 to 0.651 eV for Bi up to 9.375% and In up to 50%, corresponding to the wavelength range from 0.38-1.9 µm. The calculated spin-orbit splitting energy are about 0.220 eV for 3.125%, 0.360 eV for 6.25%, and 0.600 eV for 9.375% Bi, respectively. We have also shown the strain of InGaNBi on GaN; it indicates that through adjusting In and Bi compositions, InGaNBi can be designed on GaN with an acceptable strain.

First-principles study of dehydration process of potassium dihydrogen phosphate crystal.

KDP crystal is showing a good property in high-power laser systems. However, working in a high-power environment is easy to have damaged-defect. Dehydration of KDP crystal is one of the damage phenomena. We explore the total energy and physical properties of the KDP crystal progressive dehydration by using First-principles calculations. It is found that the band gap of the KDP crystal gradually decreases with the deepening of dehydration, and there are many obvious defect states between 4 eV and 8 eV (the corresponding wavelength region is from 310 nm to 155 nm). It indicates that dehydration causes a reduction in the damage threshold of the KDP crystal. Our results indicate that these defect states are due to the change of hybridization type of P atoms, which is gradually transformed from original sp 3 hybridization to sp 2 hybridization in the dehydration process. An obvious redshift can be observed in the absorption spectrum, producing many distinct absorption peaks. All of the results can provide the good basis for deeply understanding the electronic and optical properties of the KDP crystal.

Are physicians' prescribing decisions sensitive to drug prices? Evidence from a free-antibiotics program.

This paper investigates whether patient-level factors, in particular cost considerations, affect the physicians' prescribing decisions. In the context of a natural experiment, we examine the effect of the first US commercial free-antibiotics program on retail antibiotic sales. We find an overall increase in antibiotic prescriptions under the program and substitutions to covered antibiotics from not-covered antibiotics. The shift away from not-covered antibiotics, particularly from those without covered equivalents, indicates a change in the physicians' prescribing decisions. We locate stronger program effects in low-income areas. Our findings, robust to a variety of specifications, are in contrast with previous literature.

The diffusion mechanism of water transport in amine-cured epoxy networks.

In the present work, time-resolved attenuated total reflection Fourier transform infrared spectroscopy (ATR-IR), near-infrared (NIR) spectroscopy, and generalized two-dimensional (2D) correlation analysis were used to investigate water diffusion processes and the state of water molecules in six different epoxy resins. Positron annihilation lifetime spectroscopy (PALS) experimental results and IR results suggested that water diffusion is controlled by local chain reorientation and bond dissociation of water molecules from epoxy networks. Dynamic mechanical analysis (DMA) results of glass transition temperatures of epoxy resins after immersion in hot water correlated well with the PALS and IR results. In addition, four types of water molecules, termed nonbonded (S(0)), single bonded (S(1)), loosely double hydrogen bonded (S(2L)), and tightly double bonded (S(2T)), were detected. It was likewise found, as verified by rough estimation, that water molecules with double hydrogen bonds mostly accomplished diffusion.

Study of the infrared spectral features of an epoxy curing mechanism.

In this work, the isothermal curing process of diglycidyl ether of bisphenol A (DGEBA) cured with 4,4'-diaminodiphenylmethane (DDM) was monitored in situ by mid-infrared (MIR) and near-infrared (NIR) spectroscopy. With the help of generalized two-dimensional (2D) correlation analysis, the results obtained showed that, during curing, the change of amine and epoxy groups was simultaneous, taking place prior to the change of hydroxyl groups, followed by the change of CH(2)/CH groups, resulting from the ring-opening reaction of epoxy groups. In addition, 2D MIRxNIR hetero-spectral correlation analysis and second-derivative analysis were also employed, by means of which direct evidence of the curing mechanism could be obtained and obscure NIR band assignments in the overlapped CH combination region could be made.

Formation of fibril structures in polymerizable, rod-coil-oligomer-modified epoxy networks.

This paper describes the in situ preparation of fibrils in epoxy networks in which the fibril-like structures are cured polymerizable rod-coil oligomers. The epoxy-terminated alpha,omega-modified PEO oligomers, which are ABA rod-coil-rod oligomers with a poly(ethylene oxide) coil unit and two aromatic azomethine liquid-crystalline rod units, were synthesized and then further blended with an epoxy precursor. Uniform nanoscale columnar structures were observed in the neat rod-coil oligomers as well as in the crosslinked liquid-crystalline state. During the curing of the blends, the supramolecular nanoscale columnar structures of the rod-coil oligomers are transformed into polymeric fibrils where the epoxy functional end groups have co-reacted with epoxy precursors to form a crosslinked network.

Water diffusion behavior in epoxy resins with various fluorine contents.

In this work, novolac resin with perfluorinated side chains was synthesized and cured with o-Cresol novolac epoxy resin to obtain epoxy resins with various fluorine contents. Attenuated total reflection Fourier transform infrared spectroscopy (ATR/FT-IR) was used to monitor the in situ water diffusion process in these systems. The diffusion coefficient of water first increased and then slightly decreased with increasing fluorine content, which could be attributed to two opposite effects induced by perfluorinated side chains: enhanced hydrophobicity and increased free volume. In addition, generalized two-dimensional (2D) correlation analysis was employed to investigate both the sorption and the desorption process of water diffusion, and two kinds of water molecules, named bound and free water, were found. It was interesting to find that in the sorption process, the change in the population of bound water molecules occurs earlier than the change in the population of free water molecules, while in the desorption process, the sequence was reversed.

Polymerization-induced viscoelastic phase separation in polyethersulfone-modified epoxy systems.

The polymerization-induced phase-separation process of polyethersulfone (PES)-modified epoxy systems was monitored in situ continuously on a single sample throughout the entire curing process by using optical microscopes, time-resolved light scattering (TRLS), scanning electronic microscopes (SEM), and a rheometry instrument. At specific PES content a viscoelastic transformation process of phase inversion morphology to bicontinuous was found with an optical microscope. The rheological behavior during phase separation corresponds well with the morphology development. Light-scattering results monitoring the phase-separation process of systems with final phase inversion morphology show a typical exponential decay procedure of scattering vector qm. The characteristic relaxation time of phase separation can be described well by the WLF equation.