Functional brain imaging has tremendous applications. The existing methods for functional brain imaging include functional Magnetic Resonant Imaging (fMRI), scalp electroencephalography (EEG), implanted EEG, magnetoencephalography (MEG) and Positron Emission Tomography (PET), which have been widely and successfully applied to various brain imaging studies. To develop a new method for functional brain imaging, here we show that the dielectric at a brain functional site has a dynamic nature, varying with local neuronal activation as the permittivity of the dielectric varies with the ion concentration of the extracellular fluid surrounding neurons in activation. Therefore, the neuronal activation can be sensed by a radiofrequency (RF) electromagnetic (EM) wave propagating through the site as the phase change of the EM wave varies with the permittivity. Such a dynamic nature of the dielectric at a brain functional site provides the basis for an RF EM wave approach to detecting and imaging neuronal activation at brain functional sites, leading to an RF EM wave approach to functional brain imaging.

The reduction of carbon emissions from land use (CELU) is critical for China to achieve carbon neutrality, which may be greatly facilitated by carbon trading policies. Previous studies of the emission reduction effects of carbon trading policies focused mostly on the reduction of carbon source emissions, and there is a lack of research from the comprehensive perspective of carbon sources and carbon sinks. Understanding the effect of carbon trading policies on emission reduction from the perspective of CELU may help to improve the evaluation system of carbon trading policies, as well as provide important implications for the construction of China’s carbon trading market in the context of global carbon neutrality. Here, based on China’s current carbon-trading pilot areas, quasi-natural experiments were conducted by using the CELU data from 2005 to 2017, the synthetic control method (SCM) and the mediation effect model, aiming to empirically study the reduction effect and mechanism of carbon trading policies on CELU. The following main findings were obtained. (1) Carbon trading policies have had a significant reduction effect on the average CELU of the pilot areas by at least four million tons per year during the study period. (2) The carbon emission reduction effect of carbon trading policies has certain regional heterogeneity. (3) Carbon trading policies reduce CELU through the intermediate effect of energy structure, whose contribution rate reaches 30.433%. (4) Carbon trading policies did not achieve the Porter effect of technological progress during the study period, and technological progress has no significant intermediate effect on the reduction of CELU by carbon trading policy. Based on the above findings, the following policy implications can be proposed. Carbon trading and carbon offset should be studied from a comprehensive perspective of land use; regional heterogeneity should be considered when promoting the carbon emission trading system nationwide; and the energy structure should be optimized continuously.

Land-use transition (LUT) refers to the change in the land-use form corresponding to the regional economic and social development. At different stages of LUT, changes in the land-use scale and structure may lead to carbon source transfer by affecting industrial transfer and carbon sinks, resulting in changes in the total carbon emission transfer (CET) from the land use in the whole region. The clarification of the relationship between LUT and CET is of great importance for the sustainable development of the regional economy and society and the realization of carbon peak and carbon neutrality. In this paper, we firstly conducted a theoretical analysis of the nonlinear relationship between LUT and CET, then took the Middle Reaches of the Yangtze River in China as an example to explore the characteristics of LUT and CET, and finally constructed a threshold regression model to verify their nonlinear relationship. The following main findings were obtained. (1) From 2000 to 2020, profound LUT had occurred in the Middle Reaches of the Yangtze River, with continuous decreases in farmland, substantial increases in construction land, and a first decrease and then increase in forest land; farmland is the main contributor to construction land and forest with a contribution rate exceeding 60%. (2) During the study period, the CET in the Middle Reaches of the Yangtze River exhibited certain regular characteristics. The phase characteristics of the carbon sink changes follow an intensification–moderation–reintensification–remoderation pattern, and those of the carbon source transfer and net carbon emissions follow an intensification–reintensification–moderation–remoderation pattern. In addition, carbon sink changes are far from enough to offset the effect of carbon source transfer. (3) The nonlinear relationship between LUT and CET was confirmed by the threshold effect at the economic development level, industrial optimization level, and technological progress level. The nonlinear relationship between the LUT and the carbon sink changes in the Middle Reaches of the Yangtze River is on the left side of the U-shaped curve and that between the LUT and the carbon source transfer or net carbon emissions is on the left side of the inverted U-shaped curve.

A wet steam humidity measurement method based on microwave differential technique is presented in this paper. The calculation model of equivalent dielectric constant of wet steam at different temperature and pressure is established. The measurement system is designed, which substitutes additional instrument for integrated module and uses two resonators to counteract system error. The principle of system is deduced, and the relationship of variation of steam humidity and output of system is given. System is simulated by use the S parameter of practical resonator. Data show that humidity and system output have high linear relationship. The consistency of theory and simulated data shown the validity of this theory and can be used for the online measurement of flowing wet steam. The accuracy of system in this paper can reach ±0.1% near the temperature 30 .

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