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An approximate factor model of high dimension has two key features. First, the idiosyncratic errors are correlated and heteroskedastic over both the cross-section and time dimensions; the correlations and heteroskedasticities are of unknown forms. Second, the number of variables is comparable or even greater than the sample size. Thus, a large number of parameters exist under a high-dimensional approximate factor model. Most widely used approaches to estimation are principal component based. This paper considers the maximum likelihood-based estimation of the model. Consistency, rate of convergence, and limiting distributions are obtained under various identification restrictions. Monte Carlo simulations show that the likelihood method is easy to implement and has good finite sample properties.

This paper considers the maximum likelihood estimation of factor models of high dimension, where the number of variables (N) is comparable with or even greater than the number of observations (T). An inferential theory is developed. We establish not only consistency but also the rate of convergence and the limiting distributions. Five different sets of identification conditions are considered. We show that the distributions of the MLE estimators depend on the identification restrictions. Unlike the principal components approach, the maximum likelihood estimator explicitly allows heteroskedasticities, which are jointly estimated with other parameters. Efficiency of MLE relative to the principal components method is also considered.

Assembly of a high-quality genome is important for downstream comparative and functional genomic studies. However, most tools for genome assembly assessment only give qualitative reports, which do not pinpoint assembly errors at specific regions. Here, we develop a new reference-free tool, Clipping information for Revealing Assembly Quality (CRAQ), which maps raw reads back to assembled sequences to identify regional and structural assembly errors based on effective clipped alignment information. Error counts are transformed into corresponding assembly evaluation indexes to reflect the assembly quality at single-nucleotide resolution. Notably, CRAQ distinguishes assembly errors from heterozygous sites or structural differences between haplotypes. This tool can clearly indicate low-quality regions and potential structural error breakpoints; thus, it can identify misjoined regions that should be split for further scaffold building and improvement of the assembly. We have benchmarked CRAQ on multiple genomes assembled using different strategies, and demonstrated the misjoin correction for improving the constructed pseudomolecules. A high-quality genome assembly is essential for various genomic studies in life sciences. Here the authors develop CRAQ, a reference-free method that facilitates the evaluation and improvement of any de novo genome assembly with single nucleotide resolution.

The incorporation of mineral admixtures plays a crucial role in enhancing the performance and sustainability of geopolymer systems. This study evaluates the influence of fly ash (FA), silica fume (SF), and metakaolin (MK) as typical mineral admixtures on slag–Yellow River sediment geopolymer eco-cementitious materials. The impact of varying replacement ratios of these admixtures for slag on setting time, workability, reaction kinetics, and strength development were thoroughly investigated. To understand the underlying mechanisms, microstructural analysis was conducted using thermogravimetric–differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy–energy dispersive spectroscopy (SEM-EDS), and mercury intrusion porosimetry (MIP). The results indicate that the incorporation of FA, SF, and metakaolin delayed the initial reaction, prolonged the induction period, and reduced the acceleration rate. These effects hindered early strength development. At 30% FA content, the matrix exhibited excellent flowability and sustained heat release. The 28-day splitting tensile strength increased by 42.40%, while compressive strength decreased by 2.85%. In contrast, 20% SF significantly improved compressive strength, increasing the 28-day compressive and splitting tensile strengths by 11.19% and 6.16%, respectively. At 15% metakaolin, the strength improvement was intermediate, with 28-day compressive and splitting tensile strengths increasing by 3.55% and 10.59%, respectively. However, dosages exceeding 20% for SF and metakaolin significantly reduced workability. The incorporation of FA, SF, and metakaolin did not interfere with the slag’s alkali-activation reaction. The newly formed N-A-S-H and C-S-H gels integrated with the original C-A-S-H gels, optimizing the pore structure and reducing pores larger than 1 µm, enhancing the matrix compactness and microstructural reinforcement. This study provides practical guidance for optimizing the use of sustainable mineral admixtures in geopolymer systems.

Understanding the effect of acid rain to landslides is crucial for a better landslide risk assessment. This work aims to reveal the unsuspected but key role of acid rain in Panzhihua airport landslide, China. Firstly, we propose a hypothesis that acid rain may aggravate the slaking behavior of mudstone at weak interlayer and make it more fragmented, eventually further reducing its shear strength and predisposing the Panzhihua airport landslide. Subsequently, mudstone samples are subjected to slaking durability test, respectively, using water with a pH of 7 and two dilute hydrochloric acid solution with pH of 5 and 3. Slaking durability index ( I dn ) is adopted aiming to quantitatively evaluate the impact of acid rain on the slaking. Moreover, the mechanisms of acid rain affecting the slaking behavior of mudstone are revealed by (1) analyzing cation compositions changes in different pH slaking fluid and (2) observing micro-structure change of mudstone-chip before and after acid rain treatment. Finally, three works are conducted as evidences to prove that acid rain indeed plays a key role in the occurrence of Panzhihua airport landslide, including (1) analysis of the link between the slaking behavior of mudstone and its shear strength, (2) comparison of cations between spring water at the edge of the toe of landslide and acid rain, and (3) comparison of mineral contents of mudstone samples collected from different locations. These findings have implications for comprehensively analyzing the formation mechanism of landslide in acid rain area (such as Europe, North America, and China).

Stock market participation is considered as an indicator of consumer financial well-being. This study examined the association between financial literacy overconfidence and stock market participation. Financial literacy overconfidence was measured by the difference between an individual's subjective and objective financial literacy scores. Data from the 2012 Chinese Survey of Consumer Finance was analyzed. The results showed that financial literacy overconfidence is positively correlated with stock market participation. On the other hand, under-confidence is negatively correlated to stock market participation. This study contributes to the existing literature by relating a unique factor, financial literacy overconfidence, to stock market participation.

Severe osteoporotic vertebral compression fractures (OVCFs) were considered as relative or even absolute contraindication for vertebroplasty and kyphoplasty and these relevant reports are very limited. This study aimed to evaluate and compare the efficacy of vertebroplasty with high-viscosity cement and conventional kyphoplasty in managing severe OVCFs. 37 patients of severe OVCFs experiencing vertebroplasty or kyphoplasty were reviewed and divided into two groups, according to the procedural technique, 18 in high-viscosity cement percutaneous vertebroplasty (hPVP) group and 19 in conventional percutaneous kyphoplasty (cPKP) group. The operative time, and injected bone cement volume were recorded. Anterior vertebral height (AVH), Cobb angle and cement leakage were also evaluated in the radiograph. The rate of cement leakage was lower in hPVP group, compared with cPKP group (16.7% vs 47.4%, P  = 0.046). The patients in cPKP group achieved more improvement in AVH and Cobb angle than those in hPVP group postoperatively (37.2 ± 7.9% vs 43.0 ± 8.9% for AVH, P  = 0.044; 15.5 ± 4.7 vs 12.7 ± 3.3, for Cobb angle, P  = 0.042). At one year postoperatively, there was difference observed in AVH between two groups (34.1 ± 7.4 vs 40.5 ± 8.7 for hPVP and cPKP groups, P  = 0.021), but no difference was found in Cobb angle (16.6 ± 5.0 vs 13.8 ± 3.8, P  = 0.068). Similar cement volume was injected in two groups (2.9 ± 0.5 ml vs 2.8 ± 0.6 ml, P  = 0.511). However, the operative time was 37.8 ± 6.8 min in the hPVP group, which was shorter than that in the cPKP group (43.8 ± 8.2 min, P  = 0.021). In conclusion, conventional PKP achieved better in restoring anterior vertebral height and improving kyphotic angle, but PVP with high-viscosity cement had lower rate of cement leakage and shorter operative time with similar volume of injected cement.

To investigate the effect of isolation piles on surface subsidence induced by excavation and to explore the influence of isolation pile layout parameters on the subsidence behind the piles, this study employs a combined approach of theoretical calculation and model testing to systematically analyze the control effect of isolation piles on excavation-induced deformation. Based on a three-stage analysis method, the Kerr three-parameter foundation model is first introduced to solve the deflection differential equation and calculate the lateral deformation of the underground continuous wall induced by excavation. The boundary element method is then used to compute the additional stress near the isolation piles caused by the wall displacement, considering the shielding effect of pile groups. The lateral deformation of the isolation piles due to excavation is calculated, and the boundary element method is applied again to determine the additional stress induced by the pile displacement. Finally, the Mindlin solution is employed to compute the surface subsidence behind the isolation piles. Laboratory-scale experiments on subsidence control using isolation piles are conducted, and the results are compared with theoretical calculations to verify the validity of the theory. The results show that, compared to the condition without isolation piles, the presence of isolation piles reduces the surface subsidence by 0.099 mm. Increasing the diameter, elastic modulus, or pile-to-wall distance of the isolation piles, as well as reducing the spacing between isolation piles, helps reduce both the lateral deformation of the isolation piles and the surface subsidence behind the piles. Under the parameters used in this study, the reduction in lateral deformation of the underground continuous wall reaches 0.112 mm, 0.054 mm, 0.147 mm, and 0.172 mm, while the reduction in subsidence reaches 0.07 mm, 0.027 mm, 0.094 mm, and 0.124 mm, demonstrating significant deformation control effects. The conclusions derived from this study can be directly applied to practical foundation pit engineering. They offer valuable insights for optimizing the selection and arrangement of isolation piles, thereby providing effective guidance for controlling ground subsidence induced by excavation activities on site.

In this study, densified wood was prepared by hot pressing after partial lignin and hemicellulose were removed through alkaline solution cooking. The tensile strength and elastic modulus of densified wood were improved up to 398.5 MPa and 22.5 GPa as compared with the original wood, and the characterization of its supramolecular structures showed that the crystal plane spacing of the densified wood decreased, the crystallite size increased, and the maximum crystallinity (CI) of cellulose increased by 15.05%; outstandingly, the content of O(6)H⋯O(3′) intermolecular H-bonds increased by approximately one-fold at most. It was found that the intermolecular H-bond content was significantly positively correlated with the tensile strength and elastic modulus, and accordingly, their Pearson correlation coefficients were 0.952 (p < 0.01) and 0.822 (p < 0.05), respectively. This work provides a supramolecular explanation for the enhancement of tensile strength of densified wood.

We propose an efficient isogeometric boundary element method to address the coupling of heat conduction and radiation in homogeneous or inhomogeneous materials. The isogeometric boundary element method is used to construct irregular 2D models, which eliminate errors in model construction. The physical unknowns in the governing equations for heat conduction and radiation are discretized using an interpolation approximation, and the integral equations are finally solved by Newton–Raphson iteration; it is noteworthy that we use the radial integration method to convert the domain integrals to boundary integrals, and we combine the numerical schemes for heat conduction and radiation. The results of the three numerical cases show that the adopted algorithm can improve the computational accuracy and efficiency.