Hebei Seismological Bureau

It is well known that the viscoelastic relaxation of the upper mantle may last a long time after large earthquakes. About forty years after the 1976 M7.8 Tangshan earthquake, the postseismic surface deformation is still up to ~ 2 mm/yr. In this work, we have developed three-dimensional viscoelastic finite element models to study the rheological properties of the lower crust and upper mantle constrained from the postseismic deformation of the 1976 Tangshan earthquake. In our model, the viscoelastic relaxation is represented by the bi-viscous Burgers rheology. Transient Kelvin viscosity is assumed to be one order of magnitude lower than that of the steady Maxwell viscosity. Following previous studies, we simulate the afterslip of the fault through a 2-km weak shear zone attached to the fault. Afterslip plays an important role in controlling the early postseismic deformation, but the decadal postseismic deformation is mostly controlled by the viscoelastic relaxation of the lower crust and upper mantle. Preliminary model results have determined the viscosities of the lower curst and upper mantle to be at the order of 1019 Pa s and 8 x 1019 Pa s, respectively. Test models indicate that earthquake-induced stresses may last more than eighty years until the surface deformation is less than 1 mm/yr, that is, below the resolution of the modern geodetic method. We further study the stress interactions between the Tangshan fault and neighboring active crustal faults.

Because a high signal-to-noise ratio (SNR) is critical in enhancing the accuracy of subsequent processing, noise reduction remains a pivotal challenge in seismic signal processing, especially for complex noise interference scenarios. To address this, we propose a novel network termed MSARDNet for seismic signal denoising, with its novelty in a multi-level feature processing architecture integrating innovative modules. Specifically, the architecture comprises an encoder module, a ResDC module, and a decoder module. The encoder integrates depthwise separable convolution to efficiently extract local features with reduced parameters and improved computational efficiency. Prior to pooling, an enhanced channel attention mechanism is incorporated to adaptively emphasize critical features and suppress noise based on their importance, further boosting denoising efficacy. The ResDC module combines dilated convolutions for multi-scale receptive field expansion and residual connections for gradient optimization, ensuring feature integrity and facilitating joint extraction of multi-scale features and global context. This design effectively mitigates information loss, preserves useful signals, and enhances SNR by filtering complex noise. Through comparative experiments on synthetic and field data using denoising methods such as U-Net, DnCNN, and DeepDenoiser, MSARDNet achieved signal-to-noise ratio improvements of + 15.94 dB, + 12.03 dB, and + 4.83 dB over these methods, respectively. The results demonstrate that MSARDNet outperforms existing methods in eliminating complex background noise and holds broad application prospects in seismic data processing.

High-resolution above-ground biomass (AGB) data play a critical role in advancing low-carbon development strategies across cities. However, research on urban trees’ AGB largely relies on high-accuracy field measurements, which limits the feasibility of conducting cross-regional studies. In contrast, existing remote-sensing-based AGB products provide extensive coverage while lacking the spatial resolution required for precise city-scale analysis. To address the dilemma of achieving both high spatial resolution and broad coverage, this study integrated 149 feature variables derived from multi-source datasets and implemented quality-control procedures to select high-quality samples from two globally representative AGB products (GEDI AGB and CCI AGB). This strategy substantially improved the performance of the random forest model and generated 10 m resolution urban trees’ AGB maps for 51 C40 cities across Eurasia continent. The results indicate that: (1) after applying quality control to the target variables, the mean R2 of ten-fold cross validation improved from 0.37 to 0.75, and the MAE decreased substantially from 47.02 Mg/ha to 17.48 Mg/ha; (2) by enhancing the spatial resolution of AGB maps to 10 m, the resulting products exhibit superior spatial detail, better capture local variations, and maintain greater spatial continuity compared with the CCI AGB and GEDI AGB datasets; (3) the mean AGB density across the Eurasian continent was 39.44 Mg/ha, with total urban tree s’ AGB reaching 83.83 × 106 t. Comparison with previous single-city C40 studies shows that our estimated AGB density and total AGB closely align with previously reported values. The above data implies that cities carry an undeniable amount of carbon storage, both in terms of carbon density and total amount. This study provides a robust foundation for accurately assessing the potential of urban carbon sinks and optimizing the path to achieving carbon neutrality.

BackgroundConsidering the heavy burden on healthcare resources owing to HBV infection and the broad feasibility of transient elastography techniques in China, we aimed to construct and corroborate a liver stiffness measure (LSM)-dictated prediction model concerning hepatocellular carcinoma (HCC) development among CHB patients.MethodsA retrospective cohort study was conducted, involving 713 consecutive patients with CHB. These patients were randomly assigned to the derivation (n = 534) and internal validation (n = 179) cohorts, respectively. Variable selection was optimized using the least absolute shrinkage and selection operator (LASSO) regression and subsequent multivariate Cox regression analysis. A corresponding nomogram was built and compared regarding discrimination, calibration, and risk stratification across the whole population. To further verify the generalizability of the predictive model, we integrated data from multiple external centers to construct two external validation cohorts for evaluation (n = 1084 and n = 623).ResultsDuring a median follow-up duration of 57 months, 48 (8.99%) patients in the derivation cohort and 18 (10.06%) patients in the internal validation cohort developed HCC. Following the LASSO alongside Cox regression analyses, 5 variables were retained and constituted the LEAST model (LSM, age, albumin, sex, and platelet) and resulting nomogram. Our proposed model demonstrated sufficiently discriminative abilities to predict cumulative HCC development, as indicated by a time-dependent area under the curve (tdAUC) of 0.838 (95% CI 0.752–0.925), 0.898 (95% CI 0.851–0.944), and 0.907 (95% CI 0.856–0.959) over 3, 5, and 8 years, respectively. Nomogram-derived risk strata can appropriately identify patients at high risk of developing HCC. Our prediction model exhibited numerically the highest AUC compared to several previous scores. Moreover, the validity and generalizability of the LEAST model were verified in 2 independent external validation cohorts, confirmed in the calibration and stratification performance.ConclusionsThe LEAST model could predict HCC development in CHB patients, facilitating the identification of high-risk patients who might benefit from enhanced surveillance or early therapy.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12916-025-04430-2.

Gastric cancer (GC) is a severe malignancy characterized by late diagnosis, poor prognosis, and low survival rates. Its progression is often linked to chronic non-atrophic gastritis (CNAG) and chronic atrophic gastritis (CAG), which show atypical symptoms. Identifying biomarkers for CNAG, CAG, and GC progression is crucial for earlier diagnosis and prevention. This study conducted non-targeted metabolomics on 81 clinical samples (17 controls; 23, 23, and 18 from CNAG, CAG, and GC patients, respectively) using ultra-high-performance Liquid chromatography and high-resolution mass spectrometry. A total of 763 metabolites were identified, of which eight metabolic pathways were in dysregulation at different disease stages. Disease progression showed pronounced disruptions in amino acid, Lipid, and microbial metabolism. Targeted metabolomics identified 56 metabolites, with significant differences in O-(4,8-dimethylnonanoyl) carnitine and dehydroepiandrosterone sulfate (DHEAS). DHEAS and L-threonic acid (L-TA) were validated as biomarkers, with detection methods developed and applied to confirm their clinical significance. These findings enhance understanding of CNAG, CAG, and GC progression and provide validated biomarkers for potential clinical application in GC diagnosis and treatment.

In order to solve the problems of low accuracy of seismic precursor anomaly data detection method and long-term reliance on manual observation and calculation to identify precursor anomalous data, this paper proposes a precursor anomaly data identification method with improved Reverse Selection Algorithm, which uses the seismic precursor data provided by the China Earthquake Network as the input index, and uses the particle swarm optimization PSO optimization Reverse Selection Algorithm to train the dimensionally reduced data, so as to achieve the purpose of identifying abnormal data. It solves the problem that the traditional Reverse Selection Algorithm can only be set artificially and cannot independently determine the self-radius Rs, and the algorithm anomaly recognition rate is improved. Compared with other anomaly data detection algorithms such as traditional Reverse Selection Algorithm and support vector machine algorithm, the running speed, global search ability, stability of operation, and prediction rate of abnormal data recognition rate of the system are improved.

The South Caspian Basin contains one of the thickest accumulated sedimentary sequences on earth with accumulated sedimentary sequences over 20 km overlying thin oceanic crust. The basin represents an enigmatic aseismic “block” within the Arabia-Eurasia collision, which moves relative to both Iran and Eurasia. To understand the nature and evolution of the South Caspian basin, a model of the tectonic motion of the basin has been built. The model integrates subsurface interpretation in the Caspian Basin with active tectonics studies from outcrops. The study is based on significant database including the results of geologic and geodetic studies, field-based and remote-sensing study of active faults, and the interpretation of offshore seismic reflection data in the central and southern parts of Caspian to examine the timings and styles of deformation in its interior and periphery.The relative plate movements and faulting in the eastern Caspian lowlands on the eastern shores of the Caspian have been studied. The study has revealed several domains of folding and faulting within the South Caspian that are likely related to “thick skinned” faulting, based on their wavelength and asymmetry, as opposed to the thin-skinned deformation observed in the deeper basin, which is more likely related to movement within the mobile Maykop deposits. The thick-skinned structures of the Absheron Ridge in the central Caspian started to grow at 1.8 Ma and is related to onset of the present-day tectonic regime. The structures in the proximal offshore Kura domain are interpreted as the result of strike-slip deformation that can be traced onshore to structures that display prominent right-lateral displacement in Holocene age deposits. The anticlines started to form at 1.8 Ma with the folding and then replaced by faulting that continues to the present-day.The results of the study refine our understanding of the present-day kinematics of the South Caspian Basin, and of the factors that may have helped cause an evolution in the tectonic configuration through time.

The location of alien chromatin in Xiaoyan 6 was identified using mc-GISH analysis, genetic mapping and whole genome re-sequencing, and its possible origin was discussed. As a founder parent, Xiaoyan 6 has played an important role in distant hybridization breeding in China. Although it came from the cross between common wheat and Thinopyrum ponticum (Podp.) Barkworth and D.R. Dewey, the location of its alien chromatin has not been determined using traditional genomic in situ hybridization (GISH). In the present study, chromosome variation in Xiaoyan 6 was discovered by multicolor GISH analysis. Four alien-specific markers were developed by specific-locus amplified fragment sequencing technique. Their amplified sequences were analyzed by basic local alignment search tool with the reference genome sequences of common wheat Chinese Spring (CS) and Th. elongatum, and the whole genome re-sequencing reads of Th. ponticum and CS. Furthermore, the four markers were mapped on three different chromosomes in two RIL populations. By dissecting the mapped reads depth of the whole genome re-sequencing of Xiaoyan 6, we found that the depth of nine chromosome regions was obviously lower than the average. Among these, three regions on 1A, 3A and 7B were demonstrated as the alien introgressions in Xiaoyan 6 by multiple methods. Finally, the genetic transmission of the alien chromatin was analyzed in a set of wheat-Th. ponticum introgression lines. Some stable QTLs for morphological and physiological traits have been mapped near the alien chromatin.

Based on life cycle cost analysis (LCCA), this paper constructs a framework for sustainable management of civil engineering cost, aiming at achieving the synergy between the optimal life cycle cost and the goal of sustainable development.The main innovations include the concept model of "three-dimensional sustainable cost": environmental cost (carbon emission, pollution control) and social cost (health impact, community effect) are brought into the scope of cost management, forming a multi-dimensional and dynamic cost evaluation system.A dynamic cost prediction equation including initial cost, operating cost, environmental cost and social cost is established, in which the discount rate is integrated with sustainable factors such as carbon price, which provides a scientific decision-making tool for civil engineering that takes into account economic, environmental and social benefits.Through the integrated design of BIM model, cost list, energy consumption simulation data, building materials carbon footprint database and operation and maintenance history big data, it provides full-cycle, structured and visual data input for LCCA model.Real-time monitoring of building energy consumption, indoor environmental quality and other data using Internet of Things (IoT) sensors, and regular input of LCCA model for comparative analysis, forming a closed-loop management, guiding long-term building management and optimization.The empirical study shows that: comparing the green scheme with the traditional scheme, although the initial construction cost of the green scheme is high, its significant savings in operation, environment and social costs reduce the total life cycle cost by 16.6%, which proves that the decision based on sustainable LCCA can achieve the best long-term comprehensive benefits.

The principle of the constant light speed was proposed by Einstein as a hypothesis in 1905. It is one of the cornerstones of the theory of special relativity. In the next 120 years, physicists have continuously discussed the reasons for the constant light speed, but their understanding of the causes of the constant light speed remains in Einstein’s initial hypothesis stage. From 2017 to 2022, Chinese scholar Song Guanyi, according to the analysis of the cosmic microwave background radiation data found by American radio astronomers Arnold Penzias and Robert Wilson in 1964, realized that the cosmic microwave background radiation is that the early strong radiation light quantum during the long distance traveling constantly loses energy (redshift), and evolves into a microwave (wavelength from 0.3 ~ 75cm). The observations prove that the light quantum is not previously understood as an independent, indivisible particle entity, and it should be composed of two parts: matter and energy. Based on the change of the structure of light quantum, this paper interprets the following concepts of physics related to light quantum a. The light quantum is composed of two parts: ground state matter (ground state photon) and energy (dynamic energy). When the ground state photon is excited by the dynamic energy, it turns into a light quantum. The light quantum is propagated in a continuous collision (elastic collision) manner between the light quantum and the ground state photon. The ground state photon is the medium particle of the light quantum propagation. A light quantum from any light source in the universe is new-born, and its propagation velocity (in a vacuum) has the same value C (whether it is emitted from a stationary or moving object). b. Interpretation of wave-particle duality. c. The existence state of ether (essentially the ground state photon) and its action. d. The difference between light wave and electromagnetic wave. e. The reason for the deviation when the starlight passes near the sun. f. The cause of the redshift of the galaxy spectral lines observed from the earth. g. The existence form and characteristics of dark matter (essentially ether). h. The existence morphology and characteristics of dark energy (essentially it is the energy carried by the light quantum and formed after the ground state photon (dark matter) is excited by the limited (one share by one share) dynamic energy).