Channel sensing for holographic MIMO surfaces based on interference principle

The Holographic Multiple-Input and Multiple-Output (HMIMO) provides a new paradigm for building a more cost-effective wireless communication architecture. In this paper, we derive the principles of holographic interference theory for electromagnetic wave reception and transmission, whereby the optical holography is extended to communication holography and a channel sensing architecture for holographic MIMO surfaces is established. Unlike the traditional pilot-based MIMO channel estimation approaches, the proposed architecture circumvents the complicated processes like filtering, analog to digital conversion (ADC), down conversion. Instead, it relies on interfering the object waves with a pre-designed reference wave, and therefore reduces the hardware complexity and requires less time-frequency resources for channel estimation. To address the self-interference problem in the holographic recording process, we propose a phase shifting-based interference suppression (PSIS) method according to the structural characteristics of communication hologram and interference composition. We then propose a Prony-based multi-user channel segmentation (PMCS) algorithm to acquire the channel state information (CSI). Our theoretical analysis shows that the estimation error of the PMCS algorithm converges to zero when the number of HMIMO surface antennas is large enough. Simulation results show that under the holographic architecture, our proposed algorithm can accurately estimate the CSI in multi-user scenarios

A national cross-sectional study on the influencing factors of low HPV vaccination coverage in mainland China

BackgroundHPV vaccine can block the infection of high-risk human papillomavirus and is an important measure to effectively reduce the incidence of cervical cancer and precancerous lesions. However, the HPV vaccination rate is still low in China. There are many factors. Therefore, it is important to study the influencing factors to provide basis for promoting the formulation of vaccination strategies.MethodsThis study used a multi-stage sampling method to conduct a face-to-face questionnaire survey on women in different regions of China. The new general self-efficacy scale was used to measure the self-efficacy of the respondents. The short form of family health scale measured their family health. The t-test and binary Logistic regression analysis were used to screen the influencing factors of HPV vaccination. Restricted cubic spline model was used to analyze the influence trend of self-efficacy and family health on HPV vaccination rate.Results(1) The HPV vaccination rate was low, especially in the ≤18 group. The place of residence, capita household income/month, individual self-efficacy and family health had a significant impact on HPV vaccination. (2) The restricted cubic spline model showed that self-efficacy positively promoted HPV vaccination, the correlation strength was statistically significant (χ2 =27.64, P<0.001) and non-linear (χ2 = 12.49, P = 0.0004); The poor family health hindered HPV vaccination, and the association strength was statistically significant (χ2 = 47.81, P < 0.001) and non-linear (χ2 = 9.96, P = 0.0016).ConclusionIt is necessary to strengthen the health education of HPV vaccination knowledge in the population to eliminate the hesitancy of vaccination. Free HPV vaccination strategies should be developed and encourage people of appropriate age to receive as early as possible. Self-efficacy and family health should be enhanced to increase HPV vaccination rate, so as to achieve the goal of reducing the incidence of cervical cancer and protecting women's health

Rapid phenotypic evolution in multidrug-resistant Klebsiella pneumoniae hospital outbreak strains

L. v. D., L. P. S., X. D., H. W. and F. B. acknowledge financial support from the Newton Trust UK–China NSFC initiative (grants MR/P007597/1 and 81661138006). F. B. acknowledges support from the BBSRC GCRF scheme. H. W. additionally acknowledges support from China NSFC grant 81625014. H. C. acknowledges financial support from a 111 Talent Discipline Planning of PKUPH award for a 1-year visit at University College London. Data statement: All supporting data, code and protocols have been provided within the article or through supplementary data files. Nine supplementary tables and fifteen supplementary figures are available with the online version of this article.Peer reviewedPublisher PD

Role of mobile genetic elements in the global dissemination of the carbapenem resistance gene bla NDM

The mobile resistance gene blaNDM encodes the NDM enzyme which hydrolyses carbapenems, a class of antibiotics used to treat some of the most severe bacterial infections. The blaNDM gene is globally distributed across a variety of Gram-negative bacteria on multiple plasmids, typically located within highly recombining and transposon-rich genomic regions, which leads to the dynamics underlying the global dissemination of blaNDM to remain poorly resolved. Here, we compile a dataset of over 6000 bacterial genomes harbouring the blaNDM gene, including 104 newly generated PacBio hybrid assemblies from clinical and livestock-associated isolates across China. We develop a computational approach to track structural variants surrounding blaNDM, which allows us to identify prevalent genomic contexts, mobile genetic elements, and likely events in the gene’s global spread. We estimate that blaNDM emerged on a Tn125 transposon before 1985, but only reached global prevalence around a decade after its first recorded observation in 2005. The Tn125 transposon seems to have played an important role in early plasmid-mediated jumps of blaNDM, but was overtaken in recent years by other elements including IS26-flanked pseudo-composite transposons and Tn3000. We found a strong association between blaNDM-carrying plasmid backbones and the sampling location of isolates. This observation suggests that the global dissemination of the blaNDM gene was primarily driven by successive between-plasmid transposon jumps, with far more restricted subsequent plasmid exchange, possibly due to adaptation of plasmids to their specific bacterial hosts

A critical review of microplastic pollution in urban freshwater environments and legislative progress in China: Recommendations and insights

Freshwater systems are vitally important, supporting diversity and providing a range of ecosystem services. In China, rapid urbanization (over 800 million urban population) has led to multiple anthropogenic pressures that threaten urban freshwater environments. Microplastics (<5 mm) result from intensive production and use of plastic materials, but their effects in urban freshwater environments remain poorly understood. Rising concerns over the ecological effects of microplastics have resulted in increased attention being given to this contaminant in Chinese freshwater systems. Some studies provide quantitative data on contamination loads, but in general relevant knowledge in freshwater environment remains narrow in China, and lacking adequate understanding of threshold levels for detrimental effects. Notably, non-standardized sample collection and processing techniques for point and non-point sources have hindered comparisons of contamination loads and associated risk. Meanwhile, legislative frameworks for managing microplastics in China remain in their infancy. This manuscript critically reviews what is known of the nature and magnitude of microplastic pollution in Chinese freshwater environments, and summarizes relevant Chinese legislation. It provides recommendations for improving the legislative framework in China and identifies research gaps that need to be addressed to improve management and regulatory strategies for dealing with microplastic pollution in Chinese urban freshwater environments

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals &lt;1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Simulation calculation of 3D electric field and natural flashover analysis of ice‐covered silicone rubber insulator

Abstract The effects of uneven icing, number of icicles, inclination angle of icicle, ice pallets and arc ignition on the electric field are ignored for the two‐dimensional axisymmetric model of ice‐covered insulator. Therefore, a 3D simulation model was developed in this paper. The average electric field strength of air gap (Eav) and maximum field strength of icicle tip (Emax) were determined to characterize the influence of various factors on the electric field distortion degree. The results show that compared with the insulator without ice and with a dry ice, the supply voltage is almost entirely applied to all icicle air gaps for a wet ice‐covered insulator. Eav is independent of icicle diameter and icicle number but increases with the increment of icicle length and icicle inclination angle. Emax raises with the increase of icicle length, icicle number, icicle inclination angle and icicle diameter. As the source of electric field distortion, the ice pallets on the surface of the sheds rise the field strength of air gap. Based on the simulation analysis and natural icing test, the applied voltage is redistributed in the remaining air gaps when an arc occurs in the gap near the high‐voltage terminal, thereby causing the subsequent flashover

3D Pedestrian Detection in Farmland by Monocular RGB Image and Far-Infrared Sensing

The automated driving of agricultural machinery is of great significance for the agricultural production efficiency, yet is still challenging due to the significantly varied environmental conditions through day and night. To address operation safety for pedestrians in farmland, this paper proposes a 3D person sensing approach based on monocular RGB and Far-Infrared (FIR) images. Since public available datasets for agricultural 3D pedestrian detection are scarce, a new dataset is proposed, named as “FieldSafePedestrian”, which includes field images in both day and night. The implemented data augmentations of night images and semi-automatic labeling approach are also elaborated to facilitate the 3D annotation of pedestrians. To fuse heterogeneous images of sensors with non-parallel optical axis, the Dual-Input Depth-Guided Dynamic-Depthwise-Dilated Fusion network (D5F) is proposed, which assists the pixel alignment between FIR and RGB images with estimated depth information and deploys a dynamic filtering to guide the heterogeneous information fusion. Experiments on field images in both daytime and nighttime demonstrate that compared with the state-of-the-arts, the dynamic aligned image fusion achieves an accuracy gain of 3.9% and 4.5% in terms of center distance and BEV-IOU, respectively, without affecting the run-time efficiency

Fitness Cost of Daptomycin-Resistant Staphylococcus aureus Obtained from in Vitro Daptomycin Selection Pressure

Daptomycin-resistant (DAP-R) Staphylococcus aureus strains are well documented, but have not been reported in China. To elucidate the evolution adaptability and fitness cost of DAP-R S. aureus, three DAP susceptible strains, Pre3 (MRSA, ST239-t037), Pre5 (MRSA, ST239-t037), and Pre14b (MSSA, ST188-t189), were isolated from patients with bloodstream infections, and serially passaged in Mueller–Hinton broth with a gradient of DAP concentration to select for resistance. Highly DAP-R mutants were obtained after screening for 34 passages. The DAP minimum inhibitory concentrations increased from 0.5 μg/ml in the parent strains to 16 μg/ml in the mutants, which remained tolerant to 4 μg/ml of DAP for more than 160 generations. The growth of the three mutant strains was slower than that of the parent strains, with relative fitness cost of 34.8%, 19.2%, and 15.0%, respectively. The in vitro serum tolerance of the mutants was decreased, and the lethality and pathogenicity in mice were weakened (P &lt; 0.01). Transmission electron microscopy found that the cell walls of the mutants were significantly thicker (from 38.6% to 75.4%) than those of the parent cells. Mutation L826F of mprF was found in Post14b, G299V, and L473I of mprF and Y225N of walK were found in Post3, while T345A of mprF, S52N of graS, and F473I of walK were found in Post5. Thus, stable DAP-R mutants could be obtained from a middle-short term of in vitro DAP selection, and according to their fitness cost, some prevention and control work may be done to cope with DAP-R S. aureus that may appear in China in the future