During times of public crises, governments must act swiftly to communicate crisis information effectively and efficiently to members of the public; failure to do so will inevitably lead citizens to ...become fearful, uncertain and anxious in the prevailing conditions. This pioneering study systematically investigates how Chinese central government agencies used social media to promote citizen engagement during the COVID-19 crisis. Using data scraped from ‘Healthy China’, an official Sina Weibo account of the National Health Commission of China, we examine how citizen engagement relates to a series of theoretically relevant factors, including media richness, dialogic loop, content type and emotional valence. Results show that media richness negatively predicts citizen engagement through government social media, but dialogic loop facilitates engagement. Information relating to the latest news about the crisis and the government's handling of the event positively affects citizen engagement through government social media. Importantly, all relationships were contingent upon the emotional valence of each Weibo post.
•This study investigates how to promote citizen engagement through government social media during the COVID-19 crisis.•Media richness negatively predicts citizen engagement, but dialogic loop facilitates engagement.•Information relating to the latest news and the government's handling positively affects citizen engagement.•All relationships were contingent upon the emotional valence of each Weibo post.
A novel frequency-selective rasorber (FSR) is proposed in this paper which has a nearly transparent window between two absorption bands. The FSR consists of a resistive sheet and a bandpass ...frequency-selective surface (FSS). The impedance conditions of absorption/transmission for both the resistive sheet and the bandpass FSS are theoretically derived based on equivalent circuit analysis. The insertion loss of FSR at the resonant frequency of lossless bandpass FSS is proven to be only related to the equivalent impedance of the resistive sheet. When the resistive sheet is in parallel resonance at the passband, a nearly transparent window can be achieved regardless of lossy properties. An interdigital resonator (IR) is designed to realize parallel resonance in the resistive element by extending one finger of a strip-type interdigital capacitor to connect the two separate parts of the capacitor. The IR is equivalent to a parallel LC circuit. Lumped resistors are loaded around the IR to absorb the incident wave at lower and upper absorption bands. With the bandpass FSS as the ground plane, the absorption performances at both the lower and upper bands around the resonant frequency are improved compared to a metal-plane-backed absorber structure. The FSR passband is designed at 10 GHz with an insertion loss of 0.2 dB. The band with a reflection coefficient below -10 dB extends from 4.8 to 15.5 GHz. A further extension to dual-polarized FSR is designed, fabricated, and measured to validate the proposed design.
This communication presents a novel frequency-selective surface (FSS) with high in-band transmission at high frequency and wideband absorption at low frequency. It consists of a resistive sheet and a ...metallic bandpass FSS separated by a foam spacer. The resistive element is realized by inserting a strip-type parallel LC (PLC) structure into the center of a lumped-resistor-loaded metallic dipole. The PLC resonates at the passband of the bandpass FSS and exhibits an infinite impedance, which splits the resistive dipole into two short sections per the surface current; this setup allows for high in-band transmission at high frequency. Below the resonance frequency, the PLC becomes finite inductive and the entire FSS performs as an absorber with the metallic FSS as a ground plane. The surface current distribution on the resistive element can be controlled at various frequencies via the PLC structure. The wideband absorption and high in-band transmission of the proposed design are verified by both numerical simulation and experimental measurements. The potential extension to polarization-insensitive designs is also discussed.
The production, consumption, and waste of plastics have been rapidly growing worldwide in the last decades. A variety of data are needed to characterize plastics stocks and flows across space, time, ...and life cycle to derive insights for developing strategies to address various sustainability challenges from plastics and plastics waste. Here we review data sources on plastics stocks and flows to identify data gaps and research needs. We categorize the reviewed data sources by life cycle stages of plastics including material production, semi‐manufacturing, manufacturing, additives, consumption, in‐use stock, end‐of‐life, waste treatment, and trade. We identify four data gaps in these existing data for characterizing plastics stocks and flows, including inconsistent classification, missing data, conflicting data, and inexplicit data for plastics products and waste. These data gaps represent critical research needs including common platform for data sharing, standard methods for data reconciliation and estimation, consistent data collection and reporting, and new approaches for data collection and curation. This review establishes the state‐of‐the‐art of plastics stock and flow data and develops a roadmap for a high‐quality, comprehensive characterization of plastics stocks and flows to develop management strategies to address the sustainability challenges of plastics production, consumption, waste, and pollution.
We explore the kinetic energy partitions between electrons and ions in the 2-D magnetostatic equilibria called Arnold–Beltrami–Childress (ABC) fields, using particle-in-cell (PIC) numerical ...simulations. We cover a wider range of ion–electron temperature combinations and get different results compared to previous studies of the Harris-layer-type magnetic reconnection simulations. We find that the initial ion–electron enthalpy ratio is an important indicator. The particle species that dominates the total enthalpy will also dominate the kinetic energy gains and the momentum distribution peaks, but the other species have higher nonthermal energy fractions because both species show similar maximum energies.
Nomadic conquests have helped shape world history, yet we know little about why they occurred. Using a unique climate and dynastic data set from historical China dating from 221 this study finds that ...the likelihood of nomadic conquest increases with less rainfall proxied by drought disasters, which drove pastoral nomads to attack agrarian Chinese for survival. Moreover, consistent with the dynastic cycle hypothesis, the likelihood of China being conquered increases with the number of years earlier that a Chinese dynasty had been established (and hence was weaker, on average) relative to a rival nomadic regime. These results survive a variety of robustness checks.
The focus of this research is evolutionary low-carbon supply chain enterprise behavior and the strategic issues associated with government low-carbon policies and the emerging low-carbon market. A ...two-level supply chain consisting of a retailer and a manufacturer is established. A Stackelberg game approach employed to solve four retailer and manufacturer low-carbon strategy combinations, after which these strategies are further analyzed using an evolutionary theoretical game approach, from which an evolutionary stability strategy (ESS) is determined. The ESS indicated that: 1) in the low-carbon technology development stage, only one player (the manufacturer or the retailer) should employ low-carbon behavior; and 2) in the advanced low-carbon technology stage, only the retailer should employ low-carbon behavior. These positive results achieved economic, environmental and social Pareto improvements that complied with the government low-carbon requirements, catered to the low-carbon consumer demand, and improved supply chain economic and environmental performances. Finally, the impact of the changes from the government low-carbon policies, consumer sensitivities, and retailer carbon financing interest/subsidy rates on the ESS were analyzed, from which it was found: 1) the government could encourage enterprises to reduce carbon emissions by controlling carbon prices rather than imposing a carbon cap; 2) the enterprises need to focus on consumer sensitivities as the increase of these will reduce the long-term operational carbon emissions; and 3) retailers could stabilize the evolutionary supply chain system by lowering the carbon financing interest rate.
•Low-carbon strategies are analyzed by evolutionary game theory.•Four low-carbon strategy combination models for supply chain enterprises are built.•Low-carbon policy and low-carbon market are considered.•The influence of external and internal factors on evolution is analyzed.•Managerial insights about improving supply chain performance are presented.
This paper proposes an adaptive control for a class of nonlinear mechanisms with guaranteed transient and steady-state performance. A performance function characterizing the convergence rate, maximum ...overshoot, and steady-state error is used for the output error transformation, such that stabilizing the transformed system is sufficient to achieve the tracking control of the original system with a priori prescribed performance. A continuously differentiable friction model is adopted to account for the friction nonlinearities, for which primary model parameters are online updated. A novel high-order neural network with only a scalar weight is developed to approximate unknown nonlinearities and to dramatically diminish the computational costs. Comparative experiments on a turntable servo system are included to verify the reliability and effectiveness.
Industrial biotechnology aims to produce chemicals, materials and biofuels to ease the challenges of shortage on petroleum. However, due to the disadvantages of bioprocesses including energy ...consuming sterilization, high fresh water consumption, discontinuous fermentation to avoid microbial contamination, highly expensive stainless steel fermentation facilities and competing substrates for human consumption, industrial biotechnology is less competitive compared with chemical processes. Recently, halophiles have shown promises to overcome these shortcomings. Due to their unique halophilic properties, some halophiles are able to grow in high pH and high NaCl containing medium under higher temperature, allowing fermentation processes to run contamination free under unsterile conditions and continuous way. At the same time, genetic manipulation methods have been developed for halophiles. So far, halophiles have been used to produce bioplastics polyhydroxyalkanoates (PHA), ectoines, enzymes, and bio-surfactants. Increasing effects have been made to develop halophiles into a low cost platform for bioprocessing with advantages of low energy, less fresh water consumption, low fixed capital investment, and continuous production.
•Industrial biotechnology is less competitive compared with chemical processes.•Halophiles allow fermentation processes to run contamination free under unsterile conditions and continuous way.•Halophiles have been used to produce bioplastics polyhydroxyalkanoates (PHA), ectoines, enzymes, and bio-surfactants.•Genetic manipulation methods have been developed for halophiles.
A common set of functional characteristics of cancer cells is that cancer cells consume a large amount of glucose, maintain high rate of glycolysis and convert a majority of glucose into lactic acid ...even in the presence of oxygen compared to that of normal cells (Warburg's Effects). In addition, cancer cells exhibit substantial alterations in several energy metabolism pathways including glucose transport, tricarboxylic acid (TCA) cycle, glutaminolysis, mitochondrial respiratory chain oxidative phosphorylation and pentose phosphate pathway (PPP). In the present work, we focused on reviewing the current knowledge about the dysregulation of the proteins/enzymes involved in the key regulatory steps of glucose transport, glycolysis, TCA cycle and glutaminolysis by several oncogenes including c-Myc and hypoxia inducible factor-1 (HIF-1) and tumor suppressor, p53, in cancer cells. The dysregulation of glucose transport and energy metabolism pathways by oncogenes and lost functions of the tumor suppressors have been implicated as important biomarkers for cancer detection and as valuable targets for the development of new anticancer therapies.
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