Inadequate water quality can mean that water is unsuitable for a variety of human uses, thus exacerbating freshwater scarcity. Previous large-scale water scarcity assessments mostly focused on the ...availability of sufficient freshwater quantity for providing supplies, but neglected the quality constraints on water usability. Here we report a comprehensive nationwide water scarcity assessment in China, which explicitly includes quality requirements for human water uses. We highlight the necessity of incorporating water scarcity assessment at multiple temporal and geographic scales. Our results show that inadequate water quality exacerbates China's water scarcity, which is unevenly distributed across the country. North China often suffers water scarcity throughout the year, whereas South China, despite sufficient quantities, experiences seasonal water scarcity due to inadequate quality. Over half of the population are affected by water scarcity, pointing to an urgent need for improving freshwater quantity and quality management to cope with water scarcity.
This article presents an adaptive control framework for dynamically reconfigurable battery (DRB) systems based on the deep reinforcement learning method. The proposed adaptive control framework ...relies on deep Q-network to learn the DRB system operations. By utilizing its model-free nature, the proposed framework can significantly reduce the complexity of building experiences or expert models for DRB systems as well as improve battery operating time by ensuring cell balancing. Extensive simulation and experimental study has been carried out with data gathered from a real-world DRB testbed, and the results show the effectiveness and efficiency of the proposed control framework.
Previous studies have showed clinical characteristics of patients with the 2019 novel coronavirus disease (COVID-19) and the evidence of person-to-person transmission. Limited data are available for ...asymptomatic infections. This study aims to present the clinical characteristics of 24 cases with asymptomatic infection screened from close contacts and to show the transmission potential of asymptomatic COVID-19 virus carriers. Epidemiological investigations were conducted among all close contacts of COVID-19 patients (or suspected patients) in Nanjing, Jiangsu Province, China, from Jan 28 to Feb 9, 2020, both in clinic and in community. Asymptomatic carriers were laboratory-confirmed positive for the COVID-19 virus by testing the nucleic acid of the pharyngeal swab samples. Their clinical records, laboratory assessments, and chest CT scans were reviewed. As a result, none of the 24 asymptomatic cases presented any obvious symptoms while nucleic acid screening. Five cases (20.8%) developed symptoms (fever, cough, fatigue, etc.) during hospitalization. Twelve (50.0%) cases showed typical CT images of ground-glass chest and 5 (20.8%) presented stripe shadowing in the lungs. The remaining 7 (29.2%) cases showed normal CT image and had no symptoms during hospitalization. These 7 cases were younger (median age: 14.0 years; P=0.012) than the rest. None of the 24 cases developed severe COVID-19 pneumonia or died. The median communicable period, defined as the interval from the first day of positive nucleic acid tests to the first day of continuous negative tests, was 9.5 days (up to 21 days among the 24 asymptomatic cases). Through epidemiological investigation, we observed a typical asymptomatic transmission to the cohabiting family members, which even caused severe COVID-19 pneumonia. Overall, the asymptomatic carriers identified from close contacts were prone to be mildly ill during hospitalization. However, the communicable period could be up to three weeks and the communicated patients could develop severe illness. These results highlighted the importance of close contact tracing and longitudinally surveillance via virus nucleic acid tests. Further isolation recommendation and continuous nucleic acid tests may also be recommended to the patients discharged.
Panoramic virtual reality video (PVRV) is becoming increasingly popular since it offers a true immersive experience. However, the ultra-high resolution of PVRV requires significant bandwidth and ...ultra-low latency for PVRV streaming, something that makes challenging the extension of this application to mobile networks. Besides bandwidth, the frequent perspective viewport rendering induces a heavy computational load on battery-constrained mobile devices. To attack these problems jointly, this paper proposes a PVRV streaming system that is designed for modern multiconnectivity-based millimeter wave (mmWave) cellular networks in conjunction with mobile edge computing (MEC). First, mmWave is deployed to support the high bandwidth needs of PVRV streaming. Next, the multiple mmWave links that tend to suffer from outages are coupled with a sub-6 GHz link to ensure disruption-free wireless communication. With the help of an MEC server, the tradeoff among link adaptation, transcoding-based chunk quality adaptation, and viewport rendering offloading is sought to improve the wireless bandwidth utilization and mobile device's energy efficiency. Simulation results show that the proposed scheme can improve the streaming performance in both energy efficiency and the quality of received viewport over the state-of-the-art schemes.
In the upcoming era of 5G, the number of base stations, edge computing nodes and data centers is believed to be three to five times more than that of 4G. Serious challenges on the deployment and ...operation of 5G networks and services arise, especially on how to build and maintain battery energy storage systems for sustainable 5G power feeding at low cost for all scenarios. Although battery has long been used as a major backup power in various communications systems, current battery systems essentially are "dumb devices." In the current battery systems, the charging/discharging energy flow is continuous due to the fixed series-parallel cell topology adopted by existing battery systems. The fixed topology also causes the "bucket effect" at the system level due to the fact that it is incapable of handling cell difference in a battery system, leading to a series of system-level problems in terms of power density, energy efficiency, cycle life, reliability, and safety. All these will make it very challenging for sustainable 5G power feeding, which will further affect the cost-effective deployment and operation of 5G networks and services. Thanks to the recent breakthrough of power electronics semiconductors, such as power metal-oxide- semiconductor field-effect transistor (MOSFET), silicon carbide (SiC) and gallium nitride (GaN) with their outstanding material properties, it becomes feasible to carry out digital energy processing operations at high switching speed, high voltage, and feverish temperature. By building a new digital "grid-to-chip" power train using high switching speed power semiconductors, traditional analog battery systems can be transformed into digital battery systems through energy digitization, which will significantly facilitate feasible 5G deployment and operation. In this article, we will propose and describe the basic concept of energy digitization, the design framework of the digital battery system including key components, modeling, and the performance evaluation of the digital battery system. Results of experiments and real-world applications show the effectiveness and efficiency of digital battery system, which offer a promising disruptive approach to sustainable 5G power feeding.
Fog computing has the potential to liberate the computation-intensive mobile devices by task offloading. In this paper, we propose an online learning based task offloading algorithm for ...delay-sensitive applications in dynamic fog networks, which combines with the Combinatorial Multi-Armed Bandits (CMAB) framework. First, the proposed algorithm learns the sharing computing resources of fog nodes at a negligible computational cost. Then, we aim to minimize the task's offloading latency by jointly optimizing the task allocation decision and the spectrum scheduling. Finally, simulation results show that the proposed algorithm achieves much better delay performance than the traditional Upper Confidence Bound (UCB) algorithm and maintains ultra-low offloading delay in dynamic system state.
Cellular base stations (BSs) are equipped with backup batteries to obtain the uninterruptible power supply (UPS) and maintain the power supply reliability. While maintaining the reliability, the ...backup batteries of 5G BSs have some spare capacity over time due to the traffic-sensitive characteristic of 5G BS electricity load. Therefore, the spare capacity is dispatchable and can be used as flexibility resources for power systems. This paper evaluates the dispatchable capacity of the BS backup batteries in distribution networks and illustrates how it can be utilized in power systems. The BS reliability model is first established considering potential distribution network interruptions and the effects of backup batteries. Then, the analytical formula of the BS availability index is derived with respect to batteries' backup duration. The dispatchable capacity of BS backup batteries is evaluated in different distribution networks and with differing communication load levels. Furthermore, a potential application, daily operation optimization, is illustrated. Case studies show that the proposed methodology can effectively evaluate the dispatchable capacity and that dispatching the backup batteries can reduce 5G BS electricity bills while satisfying the reliability requirement.
Battery packs with a large number of battery cells are becoming more and more widely adopted in electronic systems, such as robotics, renewable energy systems, energy storage in smart grids, and ...electronic vehicles. Therefore, a well-designed battery pack is essential for battery applications. In the literature, the majority of research in battery pack design focuses on battery management system, safety circuit, and cell-balancing strategies. Recently, the reconfigurable battery pack design has gained increasing attentions as a promising solution to solve the problems existing in the conventional battery packs and associated battery management systems, such as low energy efficiency, short pack lifespan, safety issues, and low reliability. One of the most prominent features of reconfigurable battery packs is that the battery cell topology can be dynamically reconfigured in the real-time fashion based on the current condition (in terms of the state of charge and the state of health) of battery cells. So far, there are several reconfigurable battery schemes having been proposed and validated in the literature, all sharing the advantage of cell topology reconfiguration that ensures balanced cell states during charging and discharging, meanwhile providing strong fault tolerance ability. This survey is undertaken with the intent of identifying the state-of-the-art technologies of reconfigurable battery as well as providing review on related technologies and insight on future research in this emerging area.
Buyang Huanwu Decoction (BHD) is widely used in Chinese clinical practice for the treatment and prevention of ischemic cerebral vascular diseases. This study was designed to investigate the effects ...of BHD on ischemic stroke (IS) and its underlying mechanism.
The middle cerebral artery occlusion (MCAO) rat model and oxygen-glucose deprivation and reoxygenation (OGD/R) rat brain microvascular endothelial cell (RBMVEC) models were established. Brain infarction size and neurological score were calculated following MCAO surgery. Evans blue was used to measure blood brain barrier (BBB) permeability. Cell counting kit-8 (CCK-8) and TUNEL assays were performed to evaluate the cell viability and apoptosis of RBMVECs. Dual-luciferase reporter assay was used to analyze the transcriptional activities of apoptosis-related genes.
Results showed that higher infarction volume, neurological scores, and BBB permeability in the MCAO group rats were reduced after BHD treatment. Drug serum (DS) treatment had no impact on the normal RBMVECs’ cell viability and cell apoptosis. Besides, DS treatment decreased the lactate production, glucose uptake, and extracellular acidification rate in normal and OGD/R-induced RBMVECs. DS treatment downregulated the protein levels of pan-lysine lactylation (kla), histone H3 lysine 18 lactylation (H3K18la), and the transcriptional of apoptotic protease activating factor-1 (Apaf-1) in OGD/R-treated RBMVECs. In addition, Apaf-1 overexpression decreased cell viability and increased apoptosis and glycolysis activity of OGD/R-treated RBMVECs.
In summary, BHD inhibited glycolysis and apoptosis via suppressing the pan-kla and H3K18la protein levels and the Apaf-1 transcriptional activity, thus restraining the progression of IS.
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•BHD treatment showed neuroprotective effects on MCAO rats.•DS treatment increased viability and suppressed apoptosis of OGD/R-treated RBMVECs.•DS treatment decreased the glycolysis activity of OGD/R-treated RBMVECs.•DS treatment suppressed the H3 lysine 18 lactylation in RBMVECs.•DS treatment suppressed the Apaf-1 transcription activity in RBMVECs.
In this article we explore the security issues on physical layer for cognitive radio networks. First we give an overview on several existing security attacks to the physical layer in cognitive radio ...networks. We then discuss the related countermeasures on how to defend against these attacks. We further investigate one of the most important physical layer security parameters, the secrecy capacity of a cognitive radio network, and study the outage probability of secrecy capacity of a primary user from a theoretical point of view. Furthermore, we present performance results for secrecy capacity and outage probability between a node and its neighbors. Our work summarizes the current advances of the physical layer security and brings insights on physical layer security analysis in cognitive radio networks.
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