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Abstract Background Assessing the current status and identifying the mechanisms threatening endangered plants are significant challenges and fundamental to biodiversity conservation, particularly for protecting Tertiary relict trees and plant species with extremely small populations (PSESP). Ulmus elongata (Ulmus, Ulmaceae) with high values for the ornamental application, is a Tertiary relict tree species and one of the members from PSESP in China. Currently, the wild populations of U. elongata have been threatened by excessive deforestation and urbanization, but limited knowledges of its genetic diversity seriously hinder conservation efforts. Therefore, a further study on the genetic diversity and drivers of genetic pattern in U. elongata is crucial for preserving genetic resources and can serve as a reference for other Tertiary relict plants and PSESP under climate change. Results Here, a total of 12 populations from 70 individuals of U. elongata were collected covering its geographical distribution in China. Utilizing chloroplast genome datasets, we found that U. elongata exhibited remarkably low nucleotide diversity and gene flow (π = 0.00013, Nm = 0.03). Analysis of molecular variance (AMOVA) showed that genetic variation in U. elongata occurs mainly between eight clades (60.95%). The Mantel tests indicated a significant correlation between genetic differentiation and geographical distances (r = 0.3777, p

Ground seed detectors and interpolation methods are fundamental components of filtering algorithms. However, the performance of different detectors and interpolation methods typically varies, and few studies have been conducted on the adaptability of different detectors and interpolation methods to different terrains. Therefore, we compare three ground seed detectors (cylindrical neighborhood (CN), fixed grid (FG), and moving window (MW)) and three interpolation methods (triangulated irregular network (TIN), thin plate spline (TPS), and inverse distance weighting (IDW)). In addition, nine filters are constructed by combining the three ground seed detectors and the three interpolation methods to evaluate their comprehensive influences. To assess the performance of these detectors, interpolation methods, and filters, fifteen ISPRS-supplied light detection and ranging (LiDAR) benchmark datasets are utilized in the experiment. The findings indicate that the CN-TPS filter, which combines the CN detector and TPS method, achieves superior performance across mean Pg (99.16 % – correctly classified ground points divided by all extracted ground points), RMSE (0.44 m – root mean squared error), and total error (3.78 %). Moreover, the filtering methods are mainly affected by the performance of the ground seed detector and are less affected by the selected interpolation method. These results can be used to provide a valuable reference for designing an optimal LiDAR filtering algorithm for varied terrain types and applications.

Detection of invading bacteria is key to immunity. Here, the authors report cryo-electron microscopy structures of agonist-bound formyl peptide receptor 1 (FPR1), that reveal structural basis for recognition of bacteria-derived formyl peptides.

Abstract The emergence of highly transmissible SARS-CoV-2 variants has led to the waves of the resurgence of COVID-19 cases. Effective antivirals against variants are required. Here we demonstrate that a human-derived peptide 4H30 has broad antiviral activity against the ancestral virus and four Variants of Concern (VOCs) in vitro. Mechanistically, 4H30 can inhibit three distinct steps of the SARS-CoV-2 life cycle. Specifically, 4H30 blocks viral entry by clustering SARS-CoV-2 virions; prevents membrane fusion by inhibiting endosomal acidification; and inhibits the release of virions by cross-linking SARS-CoV-2 with cellular glycosaminoglycans. In vivo studies show that 4H30 significantly reduces the lung viral titers in hamsters, with a more potent reduction for the Omicron variant than the Delta variant. This is likely because the entry of the Omicron variant mainly relies on the endocytic pathway which is targeted by 4H30. Moreover, 4H30 reduces syncytia formation in infected hamster lungs. These findings provide a proof of concept that a single antiviral can inhibit viral entry, fusion, and release.

Simulation localization and mapping(SLAM) is a popular research problem in the field of driverless cars, but there are still some difficult problems to solve. The conventional SLAM algorithm does not take into account the dynamic objects in the environment, resulting in problems such as low bit pose estimation. In this study, we provide a deep learning-based SLAM scheme. In order to solve the problem of inaccurate feature point extraction in a dynamic environment, this paper adopts image pyramid to distribute feature points uniformly and extracts feature points by using the adaptive thresholding method. To address the problem of incomplete dynamic object mask segmentation, an improved Mask R-CNN network was proposed to improve the integrity of the mask edges by adding an edge detection end to the Mask R-CNN network. To address the problem of incomplete dynamic feature point rejection, this study uses a motion consistency detection algorithm to detect dynamic feature points, and uses the remaining static features for bit pose estimation. The experimental results on the TUM R-GBD dataset show that the absolute trajectory error of the SLAM algorithm in this study is reduced by 93.2% on average compared to the ORB-SLAM2 algorithm. Compared to the Dyna-SLAM algorithm, the absolute trajectory error of the algorithm in this study was reduced by 36.6% on average.

Introduction: Many individuals test positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA after recovering from the coronavirus disease (COVID-19), but the incidence of reactivation is unknown. We, therefore, estimated the incidence of reactivation among individuals who had recovered from COVID-19 and determined its predictors. Methods: In this retrospective cohort study, patients with COVID-19 were followed up for at least 14 days after two consecutive negative SARS-CoV-2 polymerase chain reaction test results obtained ≥24 h apart, and the frequency of SARS-CoV-2 reactivation was assessed. Results: Of the 109 patients, 29 (27%) experienced reactivation, and seven (24%) of these were symptomatic. The mean period for the real-time PCR tests for SARS-CoV-2 from negative to positive results was 17 days. Compared with patients without reactivation, those with reactivation were significantly younger and more likely to have a lymphocyte count of

Abstract Background Hydroa Vacciniforme-like Lymphoproliferative Disorder (HV-LPD) is the name given to a group of Epstein-Barr virus (EBV)-associated diseases. It resembles hydroa vacciniforme (HV), the rarest form of photosensitivity, and is a T-cell disorder associated with an Epstein-Barr virus infection. The majority of diagnosed cases occur in East Asia and South America. It is rare in the United States and Europe. Multiple studies have revealed the clinical manifestation of an enlarged liver, but no gold standard such as pathology has yet supported this as a clinical sign of HV-LPD. Case presentation Here, we report a case of a 34-year-old Asian female with definite liver invasion. The patient had complained of a recurring facial rash for many years. The patient was admitted to the hospital because of an enlarged liver. After hospitalization, she was given an EB virus nucleic acid test. The EB virus nucleic acid test was positive, and pathological examination suggested that HV-LPD had invaded the skin, bone marrow, and liver. After being given antiviral treatment, the patient’s symptoms were mitigated. Conclusions Our case confirms the liver damage was caused by HV-LPD and the effectiveness of antiviral treatment.

When building a map of a dynamic environment, simultaneous localization and mapping systems have problems such as poor robustness and inaccurate pose estimation. This paper proposes a new mapping method based on the ORB-SLAM2 algorithm combined with the YOLOv5 network. First, the YOLOv5 network of the tracing thread is used to detect dynamic objects of each frame, and to get keyframes with detection of dynamic information. Second, the dynamic objects of each image frame are detected using the YOLOv5 network, and the detected dynamic points are rejected. Finally, the global map is constructed using the keyframes after eliminating the highly dynamic objects. The test results using the TUM dataset show that when the map is constructed in a dynamic environment, compared with the ORB-SLAM2 algorithm, the absolute trajectory error of our algorithm is reduced by 97.8%, and the relative positional error is reduced by 59.7%. The average time consumed to track each image frame is improved by 94.7% compared to DynaSLAM. In terms of algorithmic real-time performance, this paper’s algorithm is significantly better than the comparable dynamic SLAM map-building algorithm DynaSLAM.

Municipal solid waste (MSW) treatment is one of the major contributors to carbon emissions. The improvement in MSW treatment carbon emission efficiency is crucial for China to achieve its CO2 emission targets. Firstly, this study used the super-efficiency SBM-DEA model to calculate the MSW treatment carbon emission efficiency in 31 provinces in China from 2010 to 2019. The results show that the MSW treatment carbon emission efficiency in all provinces except Shanghai and Jiangsu is less than 1, and the provinces with high efficiency are mainly located in eastern China. Secondly, the spatial auto correlation model and spatial Markov chain are used to test the regional differences and the spatial spillover effect of efficiency. The results show that the national average efficiency shows a fluctuating downward trend, and only the western region achieves a gradual increase. The regional differences in China’s MSW processing efficiency of carbon emissions show a fluctuating upward trend, and the regional background affects the spatiotemporal evolution pattern of the efficiency. Finally, the special error model was used to analyze the factors and influence paths that affect the efficiency, and to find that the degree of government intervention as an influencing factor that restricts the improvement of efficiency. Based on the research results, we put forward countermeasures and suggestions to improve the MSW treatment carbon emission efficiency in each province and the country as a whole.

The peptidyl nucleoside blasticidin S (BS) produced by Streptomyces griseochromogenes was the first non-mercurial fungicide used to prevent rice blast and increasingly used as a selection reagent in transgenic study. Acylation by addition of a leucine residue at the beta amine group of arginine side chain of demethylblasticidin S (DBS) has been proposed as a novel self-resistance to the cytotoxic biosynthetic intermediate. But the resultant product leucyldemethylblasticidin S (LDBS) has not been isolated as a metabolite, and LDBS synthetase activity remained to be demonstrated in S. griseochromogenes. In this study, we isolated LDBS in a BS heterologous producer S. lividans WJ2 upon the deletion of blsL, which encodes a S-Adenosyl methionine-dependent methyltransferase. Purified BlsL efficiently methylated LDBS at the delta N of beta-arginine to generate the ultimate intermediate LBS, but nearly didn’t methylate DBS to final product BS. Above experiments demonstrated that LDBS is indeed an intermediate in BS biosynthetic pathway, and acylation of beta-amino group of arginine side chain is prerequisite for efficient guanidine N-methylation in addition to being a self-resistance mechanism.

Through the laboratory test, the mechanical properties of cementsoil with adding desulfurization gypsum, fly ash, and polypropylene fiber were studied. Three different percentages (0%, 0.5%, and 1.0%) of polypropylene fiber were mixed into new cementsoil for which the cement content is 15% of the dry soil weight, the desulfurization gypsum content is 2% of the dry soil weight, and the fly ash content is 1.0% of the dry soil weight. The new cementsoil strength reinforced with polypropylene fiber was studied by triaxial test under different polypropylene fiber mixing ratio, different age, and different confining pressure. The experimental results show that, compared with ordinary soil, the deviatoric stress and the peak shear strength reinforced with polypropylene fiber have different amplitude increase. At the same time, the internal friction angle of new cementsoil with polypropylene fiber increases slightly with the growth of the age. The stress-strain curve of the polypropylene fiber cementsoil has the typical work hardening characteristic and has the characteristics of bulge fracture.