Effective Transmission Channel Research Articles

The covariability between temperature inversions and aerosol vertical distribution over China

Temperature inversions (TI) have a unique impact on the regulation of aerosol distribution. However, it remains unclear the covariability of TI and aerosol vertical distribution. To address this issue, ten years CALIPSO observations and the fifth-generation European Centre for Medium-Range Weather Forecasts atmospheric reanalysis system (ERA5) data from January 2008 to December 2017 across China were collected. The aim was to explore the relationship between TI and the aerosol vertical distribution. The characteristics of TI and aerosol vertical distribution have been analysed in the Taklimakan Desert (TD), North China (NC), South China (SC) and Sichuan Basin (SB). The results demonstrate that the frequency of TI, inversion strength (ΔT), and TI height (TIH) follow a similar seasonal pattern across the four areas. Specifically, they are highest in winter, followed by spring and autumn, and the least in summer. Notably, NC exhibits a significantly higher average frequency (10.3%) of TI during summertime compared to the other regions. This may be a result of the heating effect of the elevated black carbon aerosol on the upper atmosphere. Moreover, the observations demonstrate that aerosol optical depth (AOD) above the TIH in the four areas is greater during spring and summer months compared to autumn and winter. It indicates that there is an obvious aerosol high-level transport over the Chinese mainland in spring and summer. In winter months, most of the aerosols are located below the TIH. This phenomenon occurs due to the influence of a strong inversion layer and adverse atmospheric ventilation conditions. In addition, the average AOD below TIH increases with the ΔT increased in TD region, supporting the hypothesis that a strong inversion can suppress surface aerosols below the TI. Conversely, in NC and SC regions, the average AOD below (above) TIH decreases (increases) as the ΔT increases. It indicates that the strong atmospheric stability forms a more effective transmission channel, resulting in the accumulation of aerosols above TIH. These findings have important support for studying aerosol transport.

Novel in-situ deposited V2O5 nanorods array film sensor with enhanced gas sensing performance to n-butylamine

The regular and ordered arrangement of nanoarrays structure can provide effective transmission channels for the adsorption and desorption of gas molecules, and its excellent stability makes it have great advantages as a gas sensing material, which also poses challenges for the preparation of materials. In this work, V2O5 nanorods array was grown in-situ on ceramic tubes without seed layers by means of one-step solvothermal method. The structural characterization showed that the V2O5 nanorods array structure completely covered the surface of the ceramic tube. The gas sensing test results showed that the V2O5 nanorods array sensor had high response (100 ppm, Ra/Rg = 10.8), low detection limit (100 ppb), good reproducibility and long-term stability to n-butylamine. Its excellent sensing performance can be conributed to the fact that the array structure of nanorods can provide more active surfaces, and a great deal of gaps are formed between stacked nanorods, which is helpful to rapid response and recovery of gases. Moreover, from the perspective of the array structure of V2O5 nanorods and the chemical oxidation–reduction process, the possible detection mechanism of n-butylamine by the sensor was also discussed. The excellent gas sensing performance has the latent application prospect in the detection of trace amine gases.

Stock market reaction to the COVID-19 pandemic: an event study

The COVID-19 pandemic created unprecedented challenges for communities and economies around the world. Based on 13 leading global stock indices, the event study method is adopted in this research to explore the impact of the COVID-19 pandemic on the performance of the stock market indices in the short term. Regression results show that the global stock markets performed poorly in response to the COVID-19 pandemic. The findings of the event study imply that the stock markets reacted rapidly and negatively to the COVID-19 pandemic when lockdown restrictions were announced to contain the spread of the novel coronavirus. The Asian stock indices experienced more negative abnormal earnings than the stock indices of the countries outside Asia. Moreover, investor sentiments act as a wedge between financial investment decisions, returns, and fear of uncertainty caused by the pandemic. Furthermore, the panic experienced by investors may be an effective transmission channel through which the COVID-19 outbreak affects the returns on the stock market indices.

Effects of subsidy and tax rebate policies on green firm research and development efficiency in China

This study attempts to fill important knowledge gaps to explore the distinct symbolic influences of subsidy and tax rebate policies on green firm research and development (R&D) efficiency using the global Malmquist–Luenberger (GML) index method, while focusing on green industries in China. Our empirical results demonstrate that the subsidies and tax rebates received from local and central governments have significant U-shaped impacts on green firm R&D efficiency at the 10% significance level, and subsidies and tax rebates have significant and positive interactions with green firm R&D efficiency under the U-shaped effects of subsidies and tax rebates at the 1% significance level. Furthermore, subsidies and tax rebates play distinct transmission roles in influencing green firm R&D efficiency by stimulating R&D investment, boosting technical efficiency change, and facilitating technical progress change. • This article explores the fiscal policy-R&D efficiency nexus in green firms. • Subsidies and tax rebates have a U-shape relationship with R&D efficiency. • Tax rebates and subsidies have a positive interaction with R&D efficiency. • 4.Subsidies and tax rebates produce effective transmission channels on R&D efficiency.

Contagion Effect of Financial Markets in Crisis: An Analysis Based on the DCC–MGARCH Model

Global crises have created unprecedented challenges for communities and economies across the world, triggering turmoil in global finance and economy. This study adopts the dynamic conditional correlation multiple generalized autoregressive conditional heteroskedasticity (DCC–MGARCH) model to explore contagion effects across financial markets in crisis. The main findings are as follows: (1) the financial crisis and COVID-19 pandemic intensified the connection between the Chinese and US stock markets in the short term; (2) the dynamic conditional correlations (DCCs) during the COVID-19 pandemic are higher than those during the 2008 financial crisis owing to the further opening of the Chinese capital market, and financial institutions’ investments in the European market are higher than those in the American markets; (3) a stepwise increase is observed in the dynamic conditional correlation between the returns on the S&P 500 Index and SSEC during and after the onset of a destructive crisis; and (4) a unidirectional contagion effect exists between the Chinese market and US market, and the Hong Kong stock market contributes to the risk spillover. Effective transmission channels of external negative shocks may be investors’ sentiments, financial institutions, and the RMB exchange rate in the stock markets. This study provides useful suggestions to authorities formulating financial regulations and investors diversifying risk investments.

Construction of effective transmission channels by anchoring metal‐organic framework on side‐chain sulfonated poly(arylene ether ketone sulfone) for fuel cells

A series of novel organic-inorganic hybrid membranes assembled by side-chain type sulfonated poly(arylene ether ketone sulfone) with amino groups (Am-SPAEKS-DBS) and ZIF-67 were prepared. Am-SPAEKS-DBS containing double bonds was synthesized by condensation polymerization, and the AMPS was grafted onto the main chain by post sulfonation. ZIF-67 was prepared by an ordinary solvent method. The structures of ZIF-67, Am-SPAEKS-DBS, and hybrid membranes were analyzed by proton nuclear magnetic resonance (1H NMR), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD) and Fourier transform infrared (FT-IR). All hybrid membranes had good dimensional stability and excellent oxidation stability. In addition, the swelling ratios of all hybrid membranes were low (<17.46%) at even 100°C, and the oxidative stability was higher than 92%. The proton conductivities of this series of membranes were much higher (0.0540.069 S cm−1 at 30°C, 0.088-0.116 S cm−1 at 80°C) than pure membrane (0.038 S cm−1 at 30°C, 0.076 S cm−1 at 80°C). The experimental results exhibited that the comprehensive properties of hybrid membranes are good, and hybrid membranes had substantially possible as proton exchange membranes. Highlights Metal-organic frameworks were anchored on side-chain type organic polymer backbone. The hybrid PEMs showed good dimensional stability and excellent oxidation stability. The imidazole as a ligand in ZIF-67 contributes a part of the dissociated protons.

Flexible and lightweight porous polyether sulfone/Cu composite film with bidirectional differential structure for electromagnetic interference shielding and heat conduction

Lightweight porous conductive polymer composite materials (CPCs) are up-and-coming electromagnetic interference (EMI) shielding materials. However, fair-sized thickness (>1 mm) and limited thermal conductivity hinder their application in modern integrated and miniaturized electronics. Herein, flexible bidirectional differential porous carbon fillers (C-fillers)/polyether sulfone (PES)/Cu (PCPES/Cu) composite films are fabricated via phase inversion technology followed by magnetron sputtering process. The bidirectional differential structure features with a top porous C-fillers/PES (PCPES) film and a bottom sputtering highly-conductive Cu thin layer. The PCPES film possesses hierarchical pore structure that is derived from mass transfer between solvent and nonsolvent. Owing to the bidirectional differential structure, an “absorption-reflection-reabsorption” shielding process is created to strengthen EMI shielding performance and relieve secondary microwave reflection in PCPES/Cu composite film. Its shielding effectiveness is as high as 59.7 dB, and specific SE/t is up to 6982.5 dB cm2 g−1. Notably, the reflection coefficient falls to 0.73, below other shielding materials with similar thickness. Further, the Cu thin layer can construct effective transmission channel of phonons in the plane direction, allowing thermal conductivity enhancement. The flexible lightweight EMI shielding composite films with satisfied thermal conductivity have extensive application prospects, such as aerospace, wearable electronics, and portable electronics.

Global economic fluctuations and human development: how is the impact transmitted in Egypt?

Purpose This paper aims to investigate the relationship between global economic fluctuations and human development through four transmission channels (foreign direct investment (FDI), official development aid (ODA), remittances and export earnings) in Egypt as an open developing economy, in the period 1990–2015. Design/methodology/approach The paper uses a vector autoregressive model, which implies examining the impulse response functions and variance decompositions. Findings The results indicate that human development is negatively affected by global economic fluctuations through the four channels, namely, ODA, FDI, export earnings and remittances. In addition, the most effective transmission channels are FDI in the short run and export earnings in the long run. Originality/value While a large body of literature addresses the direct impact of business cycles and economic shocks on human development, only some studies focus on the indirect impact. The contribution is to identify the indirect impact of global economic fluctuations on human development in a developing economy, considering four transmission channels and to determine the most important of these channels. Moreover, using the human development index is an addition in this paper as most previous literature depends on other human development indicators such as children’s health, employment and schooling.

Tunable electromagnetic and broadband microwave absorption of SiO2-coated FeSiAl absorbents

SiO2-coated FeSiAl absorbents were prepared by StÖber method. The microstructure, complex permittivity and complex permeability of the samples synthetized with different tetraethyl orthosilicate (TEOS) content were systematically explored. The results show that the microwave absorption properties of the SiO2-coated FeSiAl absorbents were enhanced significantly by controlling the TEOS content. The sample synthetized with 10 ml TEOS exhibits the minimum reflection loss of −21.4 dB at 11.1 GHz and the effective absorption bandwidth of 3.8 GHz in 8.6–12.4 GHz. The superior microwave absorption performance was attributed to the multi-effects of the effective transmission channel, dielectric loss, and magnetic loss. Therefore, the introduction of insulating layer in ferromagnetic absorbents can be qualified as favorable absorbents for broadband and efficient microwave absorption.

Industry risk transmission channels and the spillover effects of specific determinants in China’s stock market: A spatial econometrics approach

This paper uses a spatial econometrics approach to study the industry risks in China’s stock market. We comprehensively consider the real linkage and information risk transmission channels and analyze the risk spillovers of specific determinants. Our empirical results show the following: 1) The real linkage channel and information channel are both effective transmission channels for driving spillover effects, and the information channel is of the utmost importance. 2) The spillover effects of specific determinants exist and are persistent. The superposition of spillover effects may lead to extreme risk. 3) The transmission channels and spillover effects are asymmetric in different regimes.

The Diaspora and economic development in Africa

While the dominant collective belief asserts that brain drain is detrimental to the development of small economies, new studies hold the reverse view. This paper aims at studying the role of the Diaspora in the economic development of low-income countries with particular focus on African countries. It analyzes both the overall effect and the specific effect of emigration according to the level of education of emigrants. While the empirical results for all developing countries fail to establish an unambiguous relationship between the Diaspora and economic development, those concerning African countries establish a clear and unambiguous relationship. The African Diaspora, especially the high-skilled Diaspora, contributes positively, significantly and robustly to the improvement of income in Africa. These findings challenge the dominant collective belief. Improvements in human capital, total factor productivity and democracy are effective transmission channels of this impact. In addition, while high-skilled emigrants have an overall greater impact on economic development and democracy, those with a low level of education contribute more to remittances to Africa.

Growth-enhancing Effect of Openness to Trade and Migrations: What is the Effective Transmission Channel for Africa?

This paper investigates the growth-enhancing effect of openness to trade and to migration by focusing on African countries. Relying on robust estimation techniques dealing with both endogeneity and omitted variables issues, our results show a varying impact of openness for Africa depending on the type of the partner country. Specifically, while trade between Africa and industrialized countries has a clear and robust positive impact on Africa's standards of living, trade with developing countries fails to be growth-enhancing. Moreover, our findings show that migration has no significant effect on per capita income in Africa regardless of the partner. Finally, exploring the trade openness transmission channel, we establish that the growth-enhancing effect of Africa's trade with industrialized countries mainly occurs through an improvement in total factor productivity.

Measuring sovereign risk spillovers and assessing the role of transmission channels: A spatial econometrics approach

We contribute to the literature on international risk spillovers by developing a unified framework based on spatial econometrics that enables us to address the following questions: (i) what are the effective transmission channels – real linkages and informational channels – of international risk spillovers across countries and/or regions, (ii) what are the most dominant ones, and (iii) which countries are most at risk for their environment and which are suffering the most from international exposure. Our analysis, based on 41 advanced and emerging economies from 2008Q1 to 2012Q4, shows that among the considered channels for explaining international spillovers of sovereign bond spreads, the informational channel is of utmost importance. Our results challenge previous findings from the literature in which the empirical strategy did not accommodate altogether important features of country spillovers, such as the co-existence of multiple transmission channels in the presence of contemporaneous and time-lagged interactions. Ultimately, our stress-testing analysis reveals important insights on countries prone either to international spillovers, international exposure or both at the regional and the worldwide level.

Does acoustic adaptation drive vertical stratification? A test in a tropical cricket assemblage

In species-rich assemblages, differential utilization of vertical space can be driven by resource availability. For animals that communicate acoustically over long distances under habitat-induced constraints, access to an effective transmission channel is a valuable resource. The acoustic adaptation hypothesis suggests that habitat acoustics imposes a selective pressure that drives the evolution of both signal structure and choice of calling sites by signalers. This predicts that species-specific signals transmit best in native habitats. In this study, we have tested the hypothesis that vertical stratification of calling heights of acoustically communicating species is driven by acoustic adaptation. This was tested in an assemblage of 12 coexisting species of crickets and katydids in a tropical wet evergreen forest. We carried out transmission experiments using natural calls at different heights from the forest floor to the canopy. We measured signal degradation using 3 different measures: total attenuation, signal-to-noise ratio (SNR), and envelope distortion. Different sets of species supported the hypothesis depending on which attribute of signal degradation was examined. The hypothesis was upheld by 5 species for attenuation and by 3 species each for SNR and envelope distortion. Only 1 species of 12 provided support for the hypothesis by all 3 measures of signal degradation. The results thus provided no overall support for acoustic adaptation as a driver of vertical stratification of coexisting cricket and katydid species.