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Shrimp hemocyte iridescent virus (SHIV), which was first identified in white leg shrimp (Litopenaeus vannamei) in China in 2014, can cause extensive shrimp mortality and major economic losses in the shrimp farming industry in China. In this study, a novel real-time isothermal recombinase polymerase amplification (RPA) assay was developed using a TwistAmp exo kit for SHIV detection. First, five primers and a probe were designed for the major capsid protein gene (GenBank: KY681039.1) according to the TwistDx manual; next, the optimal primers were selected by a comparison experiment. The primers and probe were specific for SHIV and did not react with shrimp white spot syndrome virus (WSSV), shrimp infectious hypodermal and hematopoietic necrosis virus (IHHNV), shrimp enterocytozoon hepatopenaei (EHP), and macrobrachium rosenbergii nodavirus (MrNV) samples, as well as pathogens of acute hepatopancreatic necrosis disease (AHPND). The RPA assay reached a detection limit of 11 copies per reaction according to probit regression analysis. In addition, RPA assay detected the positive plasmid samples at concentration of 1000 copies/μL within 16.04 ± 0.72 min at a single low operation temperature (39 °C). The results proved that the proposed RPA method was an accurate, sensitive, affordable, and rapid detection tool that can be suitably applied for the diagnosis of SHIV in field conditions and in resource-poor settings. • Real-time RPA assay was developed first time to detect SHIV. • The specificity, repeatability, and sensitivity of RPA assay were measured. • The RPA assay provides a rapid, accurate, sensitive, affordable, and specific alternative for detection of SHIV. [ABSTRACT FROM AUTHOR]

Double-unit trains composed of the same type of high-speed trains (HSTs) are relatively common. The connection of different types of trains, however, has been rarely studied. Therefore, we adopted an improved delayed detached-eddy simulation (IDDES) method to investigate the aerodynamic characteristics on double-unit trains formed by different types of HSTs. Two standardized HSTs—Train A and Train B at present in China—are used to form four different cases (A-A, A-B, B-A, and B-B). We conducted algorithm validation and grid independence to ensure the reliability of numerical results. The results showed the drag of case B-B was smaller when the same HST units were connected, whereas the drag of case A-B was smaller when the different HST units were connected. Downstream the coupling region, the structures of vortex shedding presented obvious differences for each case, which further led to different fluctuation intensities in wake vortices. The order of the height of the wake vortices was as follows: h 1(A-A) > h 3(B-A) > h 2(A-B) > h 4(B-B). The tail of the upstream vehicle had a dominant influence on the slipstream peak in the coupling region. • The minimum drag of double-unit train formations with different combinations is obtained. • The discontinuous coupling region has an obvious influence on the downstream vortices. • The tail of the upstream vehicle has a dominant influence on the slipstream peak in the coupling region. [ABSTRACT FROM AUTHOR]

The harvesting of wind energy from the slipstream generated when a train passes through a tunnel is a new way to produce renewable energy. From the perspective of CFD (Computed fluid dynamics), a three-dimensional URANS (unsteady Reynolds-averaged Navier–Stokes) model was used to study the energy harvesting performance of wind turbines with different design parameters inside the tunnel during the entire process of a train passing through a tunnel. A higher value of offset distance of blades could promote the power efficiency of the wind turbine inside the wind tunnel. The maximum power efficiency with regard to overlap distance was found when an overlap distance is 0 m. The turbine with a negative twist angle yielded a better performance than the turbine with a positive twist angle. The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h. Given the tunnel distribution in China, 4.8 × 1012 J energy will be recovered each day by this way, which is sufficient to supply the emergency power for railway lighting. It can also effectively ease the pressure of daily lighting power in railway tunnels. • Harvesting wind energy from railway tunnels is considered feasible. • DFBI (dynamic fluid body interaction) was used to simulate the response of the turbine. • The power efficiency of turbines with various design parameters was quantitatively evaluated. • The optimal wind turbine can generate up to 157.9 W power when a train passes at 350 km/h. [ABSTRACT FROM AUTHOR]

The effect of windbreak wall types on their windproof effects on trains has been systematically investigated by comparing the flow field around a high-speed train behind three typical windbreak walls. These three typical windbreak walls are widely used along the windy railway lines in China, which include the earth embankment–type windbreak wall (EW), the road cutting–type windbreak wall (RW), and the straight reinforced concrete–type windbreak wall (SW). We compared the time-averaged crosswind-induced flows and aerodynamic performances of high-speed trains behind these three windbreak walls with the same height using numerical simulations. The results revealed that the windbreak wall geometric shape effects on the aerodynamic load coefficients varied according to the type of aerodynamic load and carriage marshalling positions but barely varied with yaw angles. The total drag coefficients of the train in the EW and RW were approximately 50–60% of that in the SW under the two smaller yaw angles and were only 30–40% for the largest yaw angle. For the absolute value of the side force and rolling moments coefficients, the maximum values for the head and middle cars both appeared in the RW, and the corresponding minimum values were obtained in the SW. The maximum and minimum values for the tail car were obtained at the SW and EW, respectively. The maximum of the rolling moment coefficient among three carriages in the SW was approximately 45–60% of that in the EW and only 30–40% of that in the RW. The time-averaged train surface pressure coefficient and flow patterns were similar between the EW and RW, which showed apparent differences from those in the SW. The SW provided a strong blocking effect on the incoming windward airflow and avoided the direct impact on the train. Compared with the RW, the uplifting effect of the EW's windward slope on the incoming flow further reduced the crosswind effect on trains. In addition, the dominating frequency characteristics of the aerodynamic loads were significantly affected by windbreak wall types. These findings provide a systematic understanding of the time-averaged aerodynamics of trains behind these three typical windbreak walls. • Simulations of crosswind-induced flows around high-speed trains behind three typical windbreak walls were conducted. • Time-averaged flow characteristics were analyzed for three different windbreak walls. • Train aerodynamic performances behind three typical windbreak walls were compared in detail. • The mechanism of windproof performance differences between three typical windbreak walls was systematically explored. [ABSTRACT FROM AUTHOR]

A multiscale framework is developed based on the spectral element method (SEM) and material point method (MPM) for the large-deformation analysis of coseismic landslides. At a regional scale, SEM is used to model elastic wave propagation from a seismic source to a local site with complex topography. At a local scale, the coseismic landslide process and large deformation behavior are simulated by a nonlinear MPM model. Therefore, the proposed SEM-MPM model is able to reproduce the entire coseismic landslide process, including triggering, sliding and deposition. In this study, the coupled SEM-MPM method is used to simulate the massive Hongshiyan landslide triggered by the 2014 M s 6.5 Ludian earthquake in China. The study shows that the domain reduction method is able to reproduce the complex wave field across the SEM and MPM platforms, especially the strong topographic amplification of ground motion on the mountain ridge, which triggered the catastropic failure of the Hongshiyan landslide. The simulated volume of the sliding mass, sliding velocity, and final deposition profile are comparable with the field data and previous numerical studies, showing that the SEM-MPM method is a promising physics-based numerical tool for an integrated study of coseismic landslides. • A multiscale SEM-MPM framework is developed for physics-based coseismic landslide analysis. • Large-scale wave propagation from source to local site is simulated by Spectral Element Method. • Local-scale large-deformation landslide process is simulated by nonlinear Material Point Method. • SEM and MPM is coupled through the domain reduction method. • Simulation results of Hongshiyan landslide agree well with field investigation. [ABSTRACT FROM AUTHOR]

Earthquake-induced landslides are one of the most catastrophic effects of earthquakes, as evidenced by many historic events over the past decades, such as the 1994 Northridge earthquake in California and the 2008 Wenchuan earthquake in China. Realistic prediction of coseismic landslides is crucial for the design of key infrastructure and to protect human lives in seismically active regions. To date, analytical methods for estimating coseismic landslides have been based on highly simplified models. In this study, an integrated Spectral Element Method (SEM)-Newmark model is developed to directly simulate three-dimensional wave field in complex topography on a regional scale, while the associated landslide is indicated by the Newmark sliding displacement analysis considering key model factors. Topographic amplification, soil response, near-field characteristics of earthquake shaking and hydrogeological conditions can be simulated, and their effects on coseismic landslides are studied. In this paper, two regional-scale case studies were conducted using the developed SEM-Newmark model, including landslide hazard assessment for natural terrain in the western part of Hong Kong island, and the massive landslides occurred during the 2014 M 6.5 Ludian earthquake in China. These case studies demonstrated that the proposed integrated model can be effectively used for regional-scale coseismic landslide hazard assessment under various earthquake scenarios and hydrogeological conditions. • Spectral Element Method and Newmark analyses are integrated for physics-based regional coseismic landslide assessment. • Two case studies are conducted, including natural terrain landslide in Hong Kong Island, and Hongshiyan landslide in China. • Effects of topographic amplification, near-fault ground-motion characteristics and hydrogeological conditions are studied. [ABSTRACT FROM AUTHOR]

Background: Pre-operative accuracy of subcentimeter ground glass nodules (SGGNs) is a difficult problem in clinical practice, but there are few clinical studies on the benign and malignant prediction model of SGGNs. The aim of this study was to help identify benign and malignant lesions of SGGNs based on the imaging features of high resolution computed tomography (HRCT) and the general clinical data of patients, and to build a risk prediction model., Methods: This study retrospectively analyzed the clinical data of 483 patients with SGGNs who underwent surgical resection and were confirmed by histology from the First Affiliated Hospital of University of Science and Technology of China from August 2020 to December 2021. The patients were divided into the training set (n=338) and the validation set (n=145) according to 7:3 random assignment. According to the postoperative histology, they were divided into adenocarcinoma group and benign lesion group. The independent risk factors and models were analyzed by univariate analysis and multivariate Logistic regression. The receiver operator characteristic (ROC) curve was constructed to evaluate the model differentiation, and the calibration curve was used to evaluate the model consistency. The clinical application value of the decision curve analysis (DCA) evaluation model was drawn, and the validation set data was substituted for external verification., Results: Multivariate Logistic analysis screened out patients' age, vascular sign, lobular sign, nodule volume and mean-CT value as independent risk factors for SGGNs. Based on the results of multivariate analysis, Nomogram prediction model was constructed, and the area under ROC curve was 0.836 (95%CI: 0.794-0.879). The critical value corresponding to the maximum approximate entry index was 0.483. The sensitivity was 76.6%, and the specificity was 80.1%. The positive predictive value was 86.5%, and the negative predictive value was 68.7%. The benign and malignant risk of SGGNs predicted by the calibration curve was highly consistent with the actual occurrence risk after sampling 1,000 times using Bootstrap method. DCA showed that patients showed a positive net benefit when the predictive probability of the predicted model probability was 0.2 to 0.9., Conclusions: Based on preoperative medical history and preoperative HRCT examination indicators, the benign and malignant risk prediction model of SGGNs was established to have good predictive efficacy and clinical application value. The visualization of Nomogram can help to screen out high-risk groups of SGGNs, providing support for clinical decision-making.

Introduction: Influenza has been linked to the crowding in emergency departments (ED) across the world. The impact of the Coronavirus Disease 2019 (COVID-19) pandemic on China EDs has been quite different from those during past influenza outbreaks. Our objective was to determine if COVID-19 changed ED visit disease severity during the pandemic., Methods: This was a retrospective cross sectional study conducted in Nanjing, China. We captured ED visit data from 28 hospitals. We then compared visit numbers from October 2019 to February 2020 for a month-to-month analysis and every February from 2017 to 2020 for a year-to-year analysis. Inter-group chi-square test and time series trend tests were performed to compare visit numbers. The primary outcome was the proportion of severe disease visits in the EDs., Results: Through February 29 th 2020, there were 93 laboratory-confirmed COVID-19 patients in Nanjing, of which 40 cases (43.01%) were first seen in the ED. The total number of ED visits in Nanjing in February 2020, were dramatically decreased (n = 99,949) in compared to January 2020 (n = 313,125) and February 2019 (n = 262,503). Except for poisoning, the severe diseases in EDs all decreased in absolute number, but increased in proportion both in year-to-year and month-to-month analyses. This increase in proportional ED disease severity was greater in higher-level referral hospitals when compared year by year., Conclusion: The COVID-19 outbreak has been associated with decreases in ED visits in Nanjing, China, but increases in the proportion of severe ED visits., (Copyright © 2020 Elsevier Inc. All rights reserved.)