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Coarse-grained subgrade fill has traditionally been considered frost-heave-insensitive. However, uneven frost heave in such materials has become a critical constraint for high-speed railways (HSRs) in cold regions. Short-wavelength uneven frost heave induces poor sleeper-ballast contact, leading to track geometry irregularities and localized sleeper hanging. Existing frost heave evaluation methods remain inadequate for diverse conditions. Unidirectional freezing tests were performed using a self-developed apparatus to analyze temperature evolution, moisture redistribution, and frost heave development under varying cold-end temperatures (− 2 to − 15 °C). The findings reveal that moderate temperatures (− 2 to − 5 °C) promoted water-vapor-dependent heave, while severe conditions (− 10 to − 15 °C) suppressed heave despite water supply. Combining these results with literature data, Random Forest (RF), Extreme Gradient Boosting (XGBoost), and Artificial Neural Network (ANN) models were developed to predict frost heave rates from seven factors, with XGBoost showing superior accuracy ( R² = 0.991 and RMSE  = 0.092 for the test set). Variable importance analysis identifies fines content, initial water content, and water supply condition as dominant controlling factors. The study provides a useful reference for the preliminary evaluation of the frost heave behavior of HSR subgrades.

Abstract FtsY is the receptor of the signal recognition particle that mediates the targeting of integral membrane proteins in bacteria. It was shown that in Escherichia coli, the N-terminal region of FtsY contributes to its interaction with the membrane, but it is not inserted into the membrane. However, this study presents evidence that in Streptomyces coelicolor, FtsY has a hydrophobic region at its N-terminus, which forms a membrane insertion structure and contributes significantly to the binding between FtsY and membrane. Through membrane protein extraction followed by immunoblotting, we demonstrated that deletion of the N-terminal residues 11–39 from the S. coelicolor FtsY (ScFtsY) drastically reduced its membrane-binding capability and that the N-terminus of ScFtsY alone was capable of targeting the soluble EGFP protein onto the membrane with high efficiency. Furthermore, in a labeling experiment with the membrane-impermeable probe Mal-PEG, the ScFtsY N-terminal region was protected by the membrane and was not labeled. This observation indicates that this region was inserted into the membrane.

Coarse-grained materials are widely used in high-speed railway construction, and it is of great significance to research its compaction characteristics due to the high quality control requirements. In this regard, a field compaction experiment was conducted at a subgrade near Bazhou Station of Beijing-Xiong’an Intercity Railway. The test results of the compaction effect were presented in this study at first. The roller-integrated compaction measurements (i.e., compaction meter value, CMV) were compared with several traditional in-situ tests (i.e., plate load test, light falling weight deflectometer test, and shear wave velocity test). Then the stability of CMV was evaluated by the proposed δ criterion. The spatial uniformity of compaction was further investigated. Based on the analysis, the target value of CMV was preliminarily determined. It showed that Evd was more variable than CMV. The results convincingly indicated that the compaction parameters increased with the increasing number of roller passes at first. A further increase in compaction effort could result in the decompaction of material when the compaction number up to a certain value. The stability analysis method proposed in this study showed its potency of quantifying the percentage of areas with acceptable compaction. The geostatistical analysis could reflect the spatial uniformity of compaction. Overall, the conducted study could provide a useful reference for geo-material compaction control in the transportation engineering.

Evaluating the accuracy of the satellite and reanalysis precipitation products is very important for understanding their uncertainties and potential applications. However, because of underestimation existing in commonly used evaluation benchmark, gauge precipitation data, it is necessary to investigate the influence of systematic errors in gauge data on the performance evaluation of satellite and reanalysis precipitation datasets. Daily satellite-based IMERG and model-based ERA5-Land, together with gauge precipitation data, were collected with the period from 2005 to 2016 over China in this study. Daily corrections for precipitation biases from wind-induced undercatch, wetting loss, and trace error were made for gauge measurements. A set of metrics, including relative bias, Kling-Gupta efficiency, frequency bias, and critical success index, were used to evaluate and intercompare the performances of IMERG and ERA5-Land against original and bias-corrected gauge data in different locations, years, seasons, climatic zones, classes of precipitation events, and precipitation phases. The results have shown that: After removing the bias in gauge data, the relative biases of IMERG and ERA5-Land both significantly decline. The noticeable changes of their accuracy occur and vary with different locations, years, seasons, climatic zones, and precipitation phases. Furthermore, the frequency biases of IMERG and ERA5-Land rise in no precipitation events and decline in light, moderate, heavy, and extreme precipitation events. The detection capability of IMERG and ERA5-Land in no and light precipitation events is also obviously affected. Therefore, this study has demonstrated the significant influence of systematic gauge precipitation errors on the assessment of IMERG and ERA5-Land and reinforces the necessity to remove negative bias in gauge data before using it as the benchmark.

IntroductionThe ageing population faces a growing burden of poor cardiovascular-kidney-metabolic (CKM) health, which is receiving increasing attention globally. The proposed China Cardiovascular-Kidney-Metabolic Cohort-Weinan Research (CKM-CARE) aims to establish a regional surveillance system in an underdeveloped city in northwest China to collect comprehensive and dynamic data on the CKM prevalence and progression in Chinese population, to inform better CKM care and effective intervention strategies.Methods and analysisThe CKM-CARE study will leverage individual-level data from the regional electronic health record (EHR) system of Weinan City, Shaanxi Province, to establish an ambispective longitudinal cohort for CKM care and outcomes research. Between January 2020 and November 2024, 551 736 valid adult participants registered in the Weinan EHR system were included in CKM-CARE, with 442 299 individuals (80.2%) identified as having CKM stages 1–4. The study will integrate data from multiple sources, including administrative, clinical, laboratory, pharmaceutical, inpatient and outpatient electronic medical records (EMRs), and chronic disease management databases. Follow-up for CKM disease progression and related adverse clinical events will be conducted until December 2029 through linkage with the regional systems for death surveillance, chronic disease management and EMRs. The CKM-CARE study will provide a valuable big data resource to support data-driven CKM health management and policymaking in China.Ethics and disseminationThe CKM-CARE study has been reviewed and approved by the ethics committee of Peking University First Hospital (number: 2024 R480-001) and the local health authority. The privacy and confidentiality of residents registered in the regional health information system will be strictly protected throughout the study process. Study findings will be disseminated through peer-reviewed journal publications, conferences and seminar presentations.

Flash droughts, as sub-seasonal phenomena, are characterized by their rapid onset and significant impact on terrestrial ecosystems. However, understanding how vegetation responds to flash droughts and the mechanisms governing vegetation recovery remains elusive. Here, we analysed the response of vegetation productivity to flash droughts and identified the most relevant drivers controlling vegetation recovery using two soil moisture datasets (ERA5-land and Global Land Data Assimilation System) and two satellite-based vegetation productivity proxies (gross primary productivity, and solar-induced chlorophyll fluorescence). Our results show that South China and Northeast China stand out as hotspots for flash droughts, with higher frequency and speed. Notably, although the frequency of flash droughts in cropland is relatively low, and their speed is very high, with a median of 10.9% per pentad. Most ecosystems can recover to their normal state within 25 d. Vegetation with shallow roots, such as cropland and grassland, responds rapidly to flash droughts. Ecosystems generally exhibit extended response time with increasing plant rooting depth. The recovery rate of vegetation productivity from flash droughts is mainly controlled by vegetation physiology (decline rate of productivity upon exposure to flash drought) and modulated by flash drought characteristics, especially severity for forests and speed for cropland and grassland. This study provides valuable insights into the mechanisms underlying vegetation responses to flash droughts.

A bstract A precise determination of the CKM angle γ from B s 0 oscillations in B s 0 → D s ∓ K ± decays offers a critical test of the Standard Model and probes for new physics. We present a comprehensive study on the prospects of measuring γ at a future Tera- Z factory, utilizing the baseline detector concept of the Circular Electron Positron Collider (CEPC). A two-dimensional simultaneous fit framework, incorporating flavor tagging, decay time resolution modeling, and acceptance corrections, is developed using full Monte Carlo simulations of B s 0 → D s ∓ → K ∓ K ± π ∓ K ± decays and inclusive background processes. The effective flavor tagging power reaches 23.6%, while the decay time resolution is determined to be 26 fs. Projecting to full statistics of signal events across three dominant D s − decay channels, we estimate a statistical precision of σ ( γ ) = 0 . 69 ° , which corresponds to 4.1 Tera- Z boson equivalent data. This study has established the feasibility of sub-degree level γ measurements at a Z factory, highlighting its unique advantages in time-dependent CP violation studies through ultra-precise vertexing and background suppression capabilities.

A precise determination of the CKM angle γ from $$ {B}_s^0 $$ B s 0 oscillations in $$ {B}_s^0\\to {D}_s^{\\mp }{K}^{\\pm } $$ B s 0 → D s ∓ K ± decays offers a critical test of the Standard Model and probes for new physics. We present a comprehensive study on the prospects of measuring γ at a future Tera- Z factory, utilizing the baseline detector concept of the Circular Electron Positron Collider (CEPC). A two-dimensional simultaneous fit framework, incorporating flavor tagging, decay time resolution modeling, and acceptance corrections, is developed using full Monte Carlo simulations of $$ {B}_s^0\\to {D}_s^{\\mp}\\left(\\to {K}^{\\mp }{K}^{\\pm }{\\pi}^{\\mp}\\right){K}^{\\pm } $$ B s 0 → D s ∓ → K ∓ K ± π ∓ K ± decays and inclusive background processes. The effective flavor tagging power reaches 23.6%, while the decay time resolution is determined to be 26 fs. Projecting to full statistics of signal events across three dominant $$ {D}_s^{-} $$ D s − decay channels, we estimate a statistical precision of σ ( γ ) = 0 . 69 ° , which corresponds to 4.1 Tera- Z boson equivalent data. This study has established the feasibility of sub-degree level γ measurements at a Z factory, highlighting its unique advantages in time-dependent CP violation studies through ultra-precise vertexing and background suppression capabilities.

Purpose Patent processus vaginalis (PPV) is usually observed in pediatric abdominal surgery; however, robotic single-port surgery in repairing processus vaginalis has not been reported in children. Herein, we present our clinical experiences in single-port robotic surgeries for PPV repair to evaluate both efficacy and safety. Methods Retrospective analysis of patients underwent single-port robotic-assisted laparoscopic surgery for genitourinary diseases from May 2020 and May 2023 in our center. Among these patients, 21 children had PPV repaired at the same time. The case characteristics and follow-up data were recorded. Results Twenty-one of the 53 children were found to have PPV during genitourinary surgery. The simultaneous treatment of the primary disease and PPV with a single-port robotic-assisted platform was both convenient and safe. There was no significant increase in total operation time, and no excessive intraoperative hemorrhage was observed in any of the operations. There were no complications observed on follow-up. Conclusion With a high incidence of PPV in children, a single-port robotic-assisted procedure is feasible and effective if simultaneously performed when addressing a primary abdominal disease.

The physics potential of measuring $$ {B}_{(s)}^0 $$ B s 0 → π 0 π 0 and $$ {B}_{(s)}^0 $$ B s 0 → ηη decays via four-photon final states at Tera- Z phase of CEPC or FCC-ee is investigated in this paper. We propose an electromagnetic calorimeter (ECAL) with both high energy resolution and excellent separation power to efficiently reconstruct π 0 and η from hadronic final states with high photon multiplicity. The resulting B -meson mass resolution is approximately 30 MeV, allowing 3 σ separation between B 0 and $$ {B}_s^0 $$ B s 0 . With the assistance of the b -jet tagging, the relative sensitivities to B 0 → π 0 π 0 , $$ {B}_s^0 $$ B s 0 → π 0 π 0 , B 0 → ηη , and $$ {B}_s^0 $$ B s 0 → ηη signal strengths at Tera- Z are projected as 0.45%, 4.5%, 18%, and 0.95%, respectively. Their dependence on various detector performances is also discussed. In addition, B 0 → π 0 π 0 and its two isospin-related modes are paid special attention due to their roles in the determination of the CKM angle α ( ϕ 2 ). The anticipated precisions of their branching-ratio and CP -asymmetry measurements at Tera- Z are evaluated. We show that the measurement of the time-integrated B 0 → π 0 π 0 CP asymmetry at Tera- Z is complementary to B -factory ones. The precision on α combining Z - and B -factory results reaches 0 . 4 ° , lower than the systematic uncertainties attached to isospin breaking.