Integrated Sensing and Communications: Recent Advances and Ten Open Challenges

It is anticipated that integrated sensing and communications (ISAC) would be one of the key enablers of next-generation wireless networks (such as beyond 5G (B5G) and 6G) for supporting a variety of emerging applications. In this paper, we provide a comprehensive review of the recent advances in ISAC systems, with a particular focus on their foundations, system design, networking aspects and ISAC applications. Furthermore, we discuss the corresponding open questions of the above that emerged in each issue. Hence, we commence with the information theory of sensing and communications (S$\&$C), followed by the information-theoretic limits of ISAC systems by shedding light on the fundamental performance metrics. Next, we discuss their clock synchronization and phase offset problems, the associated Pareto-optimal signaling strategies, as well as the associated super-resolution ISAC system design. Moreover, we envision that ISAC ushers in a paradigm shift for the future cellular networks relying on network sensing, transforming the classic cellular architecture, cross-layer resource management methods, and transmission protocols. In ISAC applications, we further highlight the security and privacy issues of wireless sensing. Finally, we close by studying the recent advances in a representative ISAC use case, namely the multi-object multi-task (MOMT) recognition problem using wireless signals.Comment: 26 pages, 22 figures, resubmitted to IEEE Journal. Appreciation for the outstanding contributions of coauthors in the paper

Liquid–Liquid Phase‐Separated Systems from Reversible Gel–Sol Transition of Protein Microgels

Funder: Wellcome Trust; Id: http://dx.doi.org/10.13039/100010269Funder: Newman FoundationFunder: BBSRC; Id: http://dx.doi.org/10.13039/501100000268Funder: Cambridge Trust; Id: http://dx.doi.org/10.13039/501100003343Funder: Jardine FoundationFunder: Trinity College CambridgeFunder: Trinity College Krishnan‐Ang StudentshipFunder: Honorary Trinity‐Henry Barlow ScholarshipFunder: China Scholarship Council; Id: http://dx.doi.org/10.13039/501100004543Funder: Herchel Smith FundsFunder: Wolfson College Cambridge Junior Research FellowshipAbstract: Liquid–liquid phase‐separated biomolecular systems are increasingly recognized as key components in the intracellular milieu where they provide spatial organization to the cytoplasm and the nucleoplasm. The widespread use of phase‐separated systems by nature has given rise to the inspiration of engineering such functional systems in the laboratory. In particular, reversible gelation of liquid–liquid phase‐separated systems could confer functional advantages to the generation of new soft materials. Such gelation processes of biomolecular condensates have been extensively studied due to their links with disease. However, the inverse process, the gel–sol transition, has been less explored. Here, a thermoresponsive gel–sol transition of an extracellular protein in microgel form is explored, resulting in an all‐aqueous liquid–liquid phase‐separated system with high homogeneity. During this gel–sol transition, elongated gelatin microgels are demonstrated to be converted to a spherical geometry due to interfacial tension becoming the dominant energetic contribution as elasticity diminishes. The phase‐separated system is further explored with respect to the diffusion of small particles for drug‐release scenarios. Together, this all‐aqueous system opens up a route toward size‐tunable and monodisperse synthetic biomolecular condensates and controlled liquid–liquid interfaces, offering possibilities for applications in bioengineering and biomedicine

Intervening Effects of Total Alkaloids of Corydalis saxicola Bunting on Rats With Antibiotic-Induced Gut Microbiota Dysbiosis Based on 16S rRNA Gene Sequencing and Untargeted Metabolomics Analyses

Gut microbiota dysbiosis induced by antibiotics is strongly connected with health concerns. Studying the mechanisms underlying antibiotic-induced gut microbiota dysbiosis could help to identify effective drugs and prevent many serious diseases. In this study, in rats with antibiotic-induced gut microbiota dysbiosis treated with total alkaloids of Corydalis saxicola Bunting (TACS), urinary and fecal biochemical changes and cecum microbial diversity were investigated using 16S rRNA gene sequencing analysis and untargeted metabolomics. The microbial diversity results showed that 10 genera were disturbed by the antibiotic treatment, and two of them were obviously restored by TACS. The untargeted metabolomics analysis identified 34 potential biomarkers in urine and feces that may be the metabolites that are most related to the mechanisms underlying antibiotic-induced gut microbiota dysbiosis and the therapeutic effects of TACS treatment. The biomarkers were involved in six metabolic pathways, comprising pathways related to branched-chain amino acid (BCAA), bile acid, arginine and proline, purine, aromatic amino acid, and amino sugar and nucleotide sugar metabolism. Notably, there was a strong correlation between these metabolic pathways and two gut microbiota genera (g__Blautia and g__Intestinibacter). The correlation analysis suggested that TACS might synergistically affect four of these metabolic pathways (BCAA, bile acid, arginine and proline, and purine metabolism), thereby modulating gut microbiota dysbiosis. Furthermore, we performed a molecular docking analysis involving simulating high-precision docking and using molecular pathway maps to illuminate the way that ligands (the five main alkaloid components of TACS) act on a complex molecular network, using CYP27A1 (a key enzyme in the bile acid synthesis pathway) as the target protein. This study provides a comprehensive overview of the intervening effects of TACS on the host metabolic phenotype and gut microbiome in rats with gut microbiota dysbiosis, and it presents new insights for the discovery of effective drugs and the best therapeutic approaches

Deformable and Robust Core–Shell Protein Microcapsules Templated by Liquid–Liquid Phase‐Separated Microdroplets

Abstract: Microcapsules are a key class of microscale materials with applications in areas ranging from personal care to biomedicine, and with increasing potential to act as extracellular matrix (ECM) models of hollow organs, tissues, or biomolecular condensates. Such capsules are conventionally generated from non‐ECM materials including synthetic polymers. Here, robust microcapsules with controllable shell thickness from physically‐ and enzymatically‐crosslinked gelatin are fabricated, and a core–shell architecture is achieved by exploiting a liquid–liquid phase‐separated aqueous system in a one‐step microfluidic process. Microfluidic mechanical testing reveals that the mechanical robustness of thicker‐shell capsules could be controlled through modulation of the shell thickness. Furthermore, the microcapsules demonstrate environmentally‐responsive deformation, including buckling driven by osmosis and external mechanical forces. A sequential release of cargo species is obtained through the degradation of the capsules. Stability measurements show the capsules are stable at 37 °C for more than 2 weeks. Finally, through gel–sol transition, microgels function as precursors for the formation of all‐aqueous liquid–liquid phase‐separated systems that are two‐phase or multiphase. These smart capsules that can undergo phase transition are promising models of hollow biostructures, microscale drug carriers, and building blocks or compartments for active soft materials and robots

Engineering soft matter for cell biology from a biophysical point of view

Cells– the key building blocks of life – are responsible for the majority of the processes behind biological function. Some of the greatest advances in cell biology have been under- pinned by technological innovations developed in soft matter physics. In this thesis, I have focused on applying biophysical views and tools to study bio-relevant soft matter systems, including the biomolecular condensates in cell nucleus and the bio-materials for cell culture applications. First, I describe a new role of a chromatin regulator protein, HMGA1a, that can undergo liquid-liquid phase separation in the nucleus. This has been achieved by brings together modeling and experiments to arrive at the essential role of intrinsically disordered sequence as well as the protein-DNA interactions. This sheds light on HMGAs phase separation as an emergent biophysical factor in regulating chromatin structure, and further highlight phase separation as a likely critical factor for nuclear chromatin organization. Second, I describe a microfluidic device, developed for simultaneous mechanical analysis of a large number of bio-relevant soft micron-scale objects. The applicability of this method is demonstrated by characterising the mechanical properties of gelatin composed protein mcirogels. Afterwards, I extend the microfluidic and bio-material expertise to a massive production of cell-laden microgels for cancer mciroenvironment research. This has been achieved by the development of a high-throughput micro-encapsulation platform and the 3D culture of cancer spheroid mcirogels. By applying the former mechanical testing method to the cultured spheroid-laden agarose mcirogels, I present the stiffness of the matrix affect the growth of cancer spheroids. Furthermore, I show that multiple cell lines (i.e. A549 cancer cells and IMR90 fibroblast cells) can be encapsulated and co-cultured in the agarose microgels as the in vitro models. Together with xenografting results, I hypothesise that proliferation of JAG1 expressing A549 cancer cells can be positively modulated through the NOTCH-mediated signalling of the stromal cells, such as IMR90. This thesis represents an interdisciplinary approach to address the challenges of biological fundamentals and applications. It is part of an ongoing exploration that synergistically com- bines physical tools with biological systems to generate innovative insights, comprehensions, methods and techniques.China Scholarship Counci

Targeted Poverty Alleviation and Children’s Academic Performance in China

This paper estimates the causal impact of China's targeted poverty alleviation program on the academic achievement of students from poor households. We use the longitudinal academic records of a cohort of students from all middle schools in a nationally designated poor county in China. Using the difference-in-differences approach, we show that targeted poverty alleviation improves the scholastic performance of girls and their achievement rank among peer students. However, we find no such empirical evidence for boys. Our findings suggest that the new anti-poverty program in China has the potential to ameliorate the intergenerational transmission of low socioeconomic status to girls by promoting their human capital accumulation

Compensating for Academic Loss: Online Learning and Student Performance during the COVID-19 Pandemic

The outbreak of the COVID-19 pandemic has led to widespread school shutdowns, and many schools have opted for education using online learning platforms. Using administrative data from three middle schools in China, this paper estimates the causal effects of online learning on student performance. Using the difference-in-differences approach, we show that online education improves students’ academic achievement by 0.22 of a standard deviation, relative to those who stopped receiving learning support from their school during the COVID-19 lockdown. All else equal, students from a school having access to recorded online lessons delivered by external higher-quality teachers have achieved more progress in academic outcomes than those accessing lessons recorded by teachers in their own school. We find no evidence that the educational benefits of distance learning differ for rural and urban students. However, there is more progress in the academic achievement of students using a computer for online education than that of those using a smartphone. Last, low achievers benefit the most from online learning while there is no significant impact for top students. Our findings have important policy implications for educational practices when lockdown measures are implemented during a pandemic

Analysis of the Applicable Rate of Environmental Tax through Different Tax Rate Scenarios in China

Faced with increasing conflicts between economic and environmental development, it is extremely urgent to promote the green growth of enterprises. As an incentive environmental regulation measure, an environmental tax has been proven to effectively alleviate environmental problems and reduce corporate pollutant emissions. From the perspective of environmental tax equity and efficiency, this study collects more than 100,000 enterprises’ pollutant-discharge and pollutant-discharge fee data from 4300 pollutant disposal enterprises in Yunnan Province, China in 2017. The study analyzes the marginal abatement cost (MAC) of water pollution and air pollution in key industries by using the MAC accounting method. Under the three scenarios of low, medium and high tax rates set by the study, the study evaluates the applicable tax rates of environmental tax of enterprises under different tax rates. The main findings of the study are: (1) the MAC of pollutants in various industries is quite different in different industries; (2) the environmental tax rate of 2018 is generally low and is not enough to encourage enterprises to reduce more pollution; (3) most enterprises will not invest a large amount of funds to carry out technological transformation for green production, without the government’s mandatory environmental regulation measure. The study recommends that the government needs to increase the environmental tax rate, gradually approach the cost of corporate pollutant-treatment and force the technological transformation of enterprises. At the same time, the government itself needs to do a good job of tax neutrality, increase the compensation for environmental protection behaviors of enterprises, and encourage green development of enterprises. Finally, the taxation supervision should be strengthened, and the tax violations of enterprises should be checked strictly for avoidance of tax cuts against rules

Infrastructure, land prices and the environment in developing economies

This thesis presents contributions on the economic impacts of energy infrastructure constraints and air pollution in the developing world. I begin by investigating the impact of unreliable power supply on worker reallocation in Chinese manufacturing firms. This study contributes to the literature by highlighting the causal relationships between the quality of energy infrastructure and labour market outcomes. I find that frequent power outages significantly increase the pace at which long-term workers are reallocated. The impacts on the reallocation of temporary workers are much weaker and statistically insignificant. Evidence suggests that these impacts are driven in part by firms' decreased labour demand and the relative wages of long-term workers.In India, to cope with the poor public electricity provision problem, many enterprises install private generators. I examine whether the adoption of such private remedial infrastructure can enhance a firm's marginal profit from production capital, and consequently, increase the investment rate. Using Indian firm-level data, the key findings suggest a heterogeneous treatment effect of private generator adoption on the investment rate. That is, firms that are the least likely to install generators however would benefit the most and have a larger impact on their investment in other production capital.Traditional energy production and use results in air pollution, which is now recognized as an increasing concern for developing countries. To evaluate the economic impact of air pollution in China, I analyze the causal association between air pollution and urban land prices using a unique land conveyance dataset. To address the endogeneity issue of air pollution, I exploit the systematic effects of the interactions between atmospheric circulation and topographical features on the dispersion of local air pollutants. Results suggest that air pollution significantly influences land prices. Each 1% increase in average annual air pollution reduces urban land prices by approximately 1.4%. These effects vary across land types: there is a large and negative effect on residential land, but the effects on industrial or commercial land are both small and positive