Design of Ultra-compact Graphene-based Superscatterers

The energy-momentum dispersion relation is a fundamental property of plasmonic systems. In this paper, we show that the method of dispersion engineering can be used for the design of ultra-compact graphene-based superscatterers. Based on the Bohr model, the dispersion relation of the equivalent planar waveguide is engineered to enhance the scattering cross section of a dielectric cylinder. Bohr conditions with different orders are fulfilled in multiple dispersion curves at the same resonant frequency. Thus the resonance peaks from the first and second order scattering terms are overlapped in the deepsubwavelength scale by delicately tuning the gap thickness between two graphene layers. Using this ultra-compact graphene-based superscatterer, the scattering cross section of the dielectric cylinder can be enhanced by five orders of magnitude.Comment: This paper has been accepted by IEEE Journal of Selected topics in Quantum Electronic

Effects of aromatizable and nonaromatizable androgens on the sex inversion of red-spotted grouper (Epinephelus akaara)

The effects of aromatizable 17α-methyltestosterone (MT) and non-aromatizable 17α-methyldihydrotestosterone (MDHT) on sex inversion in red-spotted grouper, Epinephelus akaara, were investigated. Fish were implanted with MT, MDHT and MT+AI (aromatase inhibitor, AI) respectively for one month. The results showed that the three treated groups turned into transitional stage with intersex gonads, which contained atretic oocytes and spermatogenic germ cells at all stages of spermatogenesis. The controls did not change sex. The gonads of more than half MT-implanted fish were in early transitional stages of sex inversion, whereas those of more than half MDHT and MT+AI-implanted fish were in late transitional stages of sex inversion. No difference in serum estradiol-17β (E2) levels between the controls and the treated groups were observed, whereas 11-ketotestosterone (11-KT) and testosterone (T) levels increased in all treated groups. Significantly lower gonadosomatic index (GSI) and gonadal aromatase activity were observed in the treated groups, which were in accordance with the lower mRNA expression of P450aromA. However, P450aromB mRNA expression increased in the MT group, while it did not change in the MDHT group. These results suggest that the sex inversion of red-spotted grouper by MT and MDHT implantation might be due to the suppression of P450aromA gene expression, and resulting in both the decrease of the ovarian estrogen –secretion, as well as the increase in the 11-KT levels. Furthermore, the main reason for MT being less effective than MDHT might be due to partial aromatization of MT to estrogen

Does political conflict affect bilateral trade or vice versa? Evidence from Sino-U.S. relations

This paper investigates the dynamic causal relationship between Sino-U.S. political conflict and bilateral trade using a time-varying (bootstrap) Granger full-sample causality test and sub-sample rolling window estimation. The result indicates that Sino-U.S. political conflict and bilateral trade may interact in various ways. Bilateral trade has both positive and negative effects on political conflict in several sub-phases, and in turn, political conflict has the same impacts on bilateral trade. In general, the relationship between Sino-U.S. political conflict and bilateral trade is not always consistent with the model of Polachek, which states bilateral trade has significantly reduced political conflict. In the face of a severe economic situation, China and the U.S. government should strengthen trade cooperation and seek common ground of economic interests in order to expand the improvement of political relations

Do house prices squeeze marriages in China?

This study reviews the threshold effect of house prices (HPs) on marriage (MR) in China by utilizing a panel threshold regression. The findings indicate that HPs have a positive impact on MR when the price is below the threshold value. Homeownership is an extremely important factor in MR in China, and MR without housing is considered incomplete. However, HPs have a negative effect on MR when the price is higher than the threshold value. Unemployment and female education have a negative effect on MR, while GDP per capita has a positive effect. These results are supported by the duration model, which shows that as HPs increase, the rate of MR decreases. The study makes a contribution on the asymmetric impact of high HPs on MR in China in the two regimes. The paper offers insight into the economic outlook on HPs and MR driven by societal and institutional changes, such as privatization and state ownership of enterprises, that have changed marriage behavior. Increasing HPs slow MR and may have a more serious impact on China than on other countries. The government should balance housing supply and demand by enhancing antimonopoly supervision in the private market. The government should establish policy measures to meet housing demand and create incentives to wed, which can relieve competition in marriage markets. Diversified investment, in turn, can control HPs

Spin Speed and Supportedness Correlation and Evolution of Galaxy-Halo Systems

Galaxy angular momenta (spins) contain valuable cosmological information, complementing with their positions and velocities. The baryonic spin direction of galaxies have been probed as a reliable tracer of their host halos and the primordial spin modes. Here we use the TNG100 simulation of the IllustrisTNG project to study the spin magnitude correlations between dark matter, gas and stellar components of galaxy-halo systems, and their evolutions across the cosmic history. We find that these components generate similar initial spin magnitudes from the same tidal torque in Lagrangian space. At low redshifts, the gas component still traces the spin magnitude of dark matter halo and the primordial spin magnitude. However, the traceability of stellar component depends on the $ex$ $situ$ stellar mass fraction, $f_{\rm acc}$. Our results suggest that the galaxy baryonic spin magnitude can also serve as a tracer of their host halo and the initial perturbations, and the similarity of their evolution histories affects the galaxy-halo correlations.Comment: 9 pages, 7 figures, comments welcom

Enhance or depress? The effect of trade on active females in the labour market

The objective of this study is to provide evidence for the existence of threshold effects in trade openness, which affects the female labour force participation rate (FLFPR) in Asian countries. The authors employ the proportion of export, import and total trade volume to gross domestic product to denote export and import dependency and trade openness, respectively. The panel threshold regression results indicate that there exists an optimal value in the correlation between trade openness and FLFPR below which an increase in trade openness will enhance the FLFPR; an adverse relationship exists when trade openness exceeds the threshold value. This relationship is attributed to the trade-off between the cost reduction effect and the technology channel. Furthermore, the authors further categorise trade openness into export and import dependency. The findings reveal that export dependency also has a single threshold effect on FLFPR, while import dependency exerts a negative effect on FLFPR regardless of threshold effect. Therefore, the government could promote female participation in the labour force by regulating the export policy

Modeling and analysis of hydraulic fracture complexity index in sandy conglomerate reservoirs based on genetic expression programming—A case study in Xinjiang Oilfield

The stimulation effect of oil wells is seriously affected by the complexity of hydraulic fractures, and the analysis of the factors that control the fracture complexity index has become the key to fracturing design in sandy conglomerate reservoirs. Based on the intrinsic relationship between geological engineering parameters and the fractures complexity index, a Genetic Expression Programming (GEP) method, which has broad advantages in solving multi-factor nonlinear fitting and black-box prediction problems, is proposed to analyze the hydraulic fracture complexity index. Combined with the geoengineering factors that affect the hydraulic fractures propagation, a comprehensive index calculation method is established to analyze the relative importance of these features and 18 reconstructed features were obtained by collecting the geoengineering parameter data of 118 fracturing sections in 8 fracturing wells in Jinlong oilfield. The principal component analysis was performed to eliminate the interaction between the features, and then a GEP-based fractures complexity index calculation model was developed. The partial dependence plot is used to analyze the influence of the main control feature (variable) on the hydraulic fracture complexity index. It showed that GEP model can achieve satisfactory performance (Training set: R = 0.861; Test set: R = 0.817) by statistical parameters. The results showed that the model can calculate the hydraulic fracture complexity index quickly and precisely. The influence of geological engineering control factors can be obtained. It proved that the GEP method can effectively analyze and evaluate the complexity in sandy conglomerate reservoirs