Cooperative communication with single relay selection is a simple but effective communication scheme for energy-constrained networks. In this paper, we propose a novel selective single-relay ...cooperative scheme, combining selective-relay cooperative communication with physical-layer power control. Based on the MAC-layer RTS-CTS signaling, a set of potential relays compute individually the required transmission power to participate in the cooperative communication, and compete within a window of fixed length. The "best" relay is selected in a distributed fashion with minimum signaling overhead. We derive power-control solutions corresponding to two policies on relay selection: one is to minimize the energy consumption per data packet, and the other is to maximize the network lifetime. Our numerical and simulation results confirm that the proposed scheme achieves significant energy savings and prolongs the network lifetime considerably.
Highly efficient and stable catalysts for the hydrogen evolution reaction, especially in alkaline conditions are crucial for the practical demands of electrochemical water splitting. Here, the ...synthesis of a novel RuAu single‐atom alloy (SAA) by laser ablation in liquid is reported. The SAA exhibits a high stability and a low overpotential, 24 mV@10 mA cm−2, which is much lower than that of a Pt/C catalyst (46 mV) in alkaline media. Moreover, the turnover frequency of RuAu SAA is three times that of Pt/C catalyst. Density functional theory computation indicates the excellent catalytic activity of RuAu SAAs originates from the relay catalysis of Ru and Au active sites. This work opens a new avenue toward high‐performance SAAs via fast quenching of immiscible metals.
A RuAu single‐atom alloy (SAA) is achieved by laser ablation in liquid. RuAu SAA exhibits high performance in the hydrogen evolution reaction through the relay catalysis of the Ru host (for water dissociation) and the Au dopant (for hydrogen evolution).
In this paper, we consider a clustered wireless sensor network where sensors within each cluster relay data packets to nearby clusters using cooperative communications. We propose a cooperative ...transmission scheme based on distributed space-time block coding and conduct a systematic analysis on the resulting energy consumption. Compared with existing work, our distinctions are twofold: (1) Only sensors that can correctly decode received packets participate in the cooperative transmission, where the number of cooperating nodes depends on both channel and noise realizations; and (2) we use packet-error-rate-based analysis rather than symbol-error-rate-based analysis. This is more realistic since error detection is usually done at the packet level via, e.g., cyclic-redundancy-check codes. Based on the analysis, we further minimize the overall energy consumption by power allocation between the intracluster and intercluster transmissions. With numerical methods, we investigate how energy consumption is affected by the transmit power allocation, the total number of sensors in a cluster, the end-to-end packet error rate requirement, and the relative magnitudes between the intracluster and intercluster distances. Comparisons with direct (noncooperative) transmission schemes demonstrate the significant energy-saving advantage of the proposed cooperative scheme.
This paper presents a multi-input-multi-output (MIMO) range migration algorithm (RMA) with range compensation for near-field millimeter-wave imaging. The proposed algorithm is derived based on the ...effective phase center principle and scalar diffraction theory. Compared with the original MIMO RMA, the propagation loss is compensated better, and the reconstructed image quality is improved significantly. In the process of image reconstruction, a multistatic array topology is transformed to a monostatic array, and the round-trip propagation is converted into unidirectional optical field propagation. The efficiency of the proposed algorithm is analyzed theoretically, and demonstrated experimentally. Numerical simulations and experimental results show that the propagation loss in range is properly compensated by the proposed algorithm.
Abstract
Nationwide prospective surveillance of all-age patients with acute respiratory infections was conducted in China between 2009‒2019. Here we report the etiological and epidemiological ...features of the 231,107 eligible patients enrolled in this analysis. Children <5 years old and school-age children have the highest viral positivity rate (46.9%) and bacterial positivity rate (30.9%). Influenza virus, respiratory syncytial virus and human rhinovirus are the three leading viral pathogens with proportions of 28.5%, 16.8% and 16.7%, and
Streptococcus pneumoniae
,
Mycoplasma pneumoniae
and
Klebsiella pneumoniae
are the three leading bacterial pathogens (29.9%, 18.6% and 15.8%). Negative interactions between viruses and positive interactions between viral and bacterial pathogens are common. A Join-Point analysis reveals the age-specific positivity rate and how this varied for individual pathogens. These data indicate that differential priorities for diagnosis, prevention and control should be highlighted in terms of acute respiratory tract infection patients’ demography, geographic locations and season of illness in China.
In December 2019, a novel coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in Wuhan, China causing coronavirus disease-2019 (COVID-19). Numerous studies ...have shown varying degrees of liver damage in patients infected with SARS-CoV-2. However, in previous case studies of COVID-19, the exact cause of liver injury has not been clearly elucidated, nor is there clear evidence of the interaction between liver injury and COVID-19. This study will analyze the causes of liver injury in COVID-19 and the influence of liver-related complications on the treatment and prognosis of COVID-19.
Administration of exosomes derived from mesenchymal stromal cells (MSCs) could improve some neurologic conditions by transferring functional biomolecules to recipient cells. Furthermore, exosomes ...from hypoxic progenitor cells exerted better therapeutic effects in organ injury through specific cargoes. However, there are no related reports about whether exosomes derived from MSCs or hypoxia‐preconditioned MSCs (PC‐MSCs) could prevent memory deficits in Alzheimer disease (AD). In this study, the exosomes derived from MSCs or PC‐MSCs were systemically administered to transgenic APP/PS1 mice. The expression of miR‐21 in MSCs was significantly increased after hypoxic treatment. Injection of exosomes from normoxic MSCs could rescue cognition and memory impairment according to results of the Morris water maze test, reduced plaque deposition, and Aβ levels in the brain; could decrease the activation of astrocytes and microglia; could down‐regulate proinflammatory cytokines (TNF‐α and IL‐1β); and could up‐regulate anti‐inflammatory cytokines (IL‐4 and ‐10) in AD mice, as well as reduce the activation of signal transducer and activator of transcription 3 (STAT3) and NF‐κB. Compared to the group administered exosomes from normoxic MSCs, in the group administered exosomes from PC‐MSCs, learning and memory capabilities were significantly improved; the plaque deposition and Aβ levels were lower, and expression of growth‐associated protein 43, synapsin 1, and IL‐10 was increased; and the levels of glial fibrillary acidic protein, ionized calcium‐binding adaptor molecule 1, TNF‐α, IL‐1β, and activation of STAT3 and NF‐κB were sharply decreased. More importantly, exosomes from PC‐MSCs effectively increased the level of miR‐21 in the brain of AD mice. Additionally, replenishment of miR‐21 restored the cognitive deficits in APP/PS1 mice and prevented pathologic features. Taken together, these findings suggest that exosomes from PC‐MSCs could improve the learning and memory capabilities of APP/PS1 mice, and that the underlying mechanism may lie in the restoration of synaptic dysfunction and regulation of inflammatory responses through regulation of miR‐21.—Cui, G.‐H., Wu, J., Mou, F.‐F., Xie, W.‐H., Wang, F.‐B., Wang, Q.‐L., Fang, J., Xu, Y.‐W., Dong, Y.‐R., Liu, J.‐R., Guo, H.‐D. Exosomes derived from hypoxia‐preconditioned mesenchymal stromal cells ameliorate cognitive decline by rescuing synaptic dysfunction and regulating inflammatory responses in APP/PS1 mice. FASEB J. 32, 654–668 (2018). www.fasebj.org
Lung cancer is the leading cause of cancer-related human deaths. Exploration of the mechanisms underlying the metastasis of cancer stem-like cells (CSLCs) will open new avenues in lung cancer ...diagnosis and therapy. Here, we demonstrated that CSLCs-derived from lung adenocarcinoma (LAC) cells displayed highly invasive and migratory capabilities via expressing high levels of POU5F1 and MMP-2. We found that POU5F1 directly regulated MMP-2 transcription via interaction with the promoter of MMP-2. POU5F1 knockdown in LACSLCs reduced MMP-2 protein abundance, leading to inhibition of the cell invasion, migration and tumorigenesis potentials of LAC cells. Clinically, aberrantly high expressions of POU5F1 and MMP-2 were inversely correlated with the survival of LAC patients, and the double-positive POU5F1 and MMP-2 showed the worst prediction for the patient's poor survival. These results indicate that POU5F1 can bind to the MMP-2 promoter for the degradation of surrounding extracellular matrix, and therefore promote invasive and migratory capabilities of LACSLCs. Moreover, our data implicate that the pathological detection of the double-positive expressions for POU5F1 and MMP-2 will be useful as diagnostic and prognostic biomarkers in LAC to advance anti-metastasis therapy.
pH determines selectivity: The ligation of peptide hydrazides is a new method for protein chemical synthesis that is complementary to native chemical ligation. Peptide hydrazides may be the ...long‐sought reagent equivalent to a “thioester synthon”, one that is stable to the conditions of native chemical ligation.
PDF
