Search Results (152)

Machine learning techniques have revolutionized physical layer security (PLS) and provided opportunities for optimizing the performance and security of modern communication systems. In this study, we propose the first machine learning-assisted random communication system (ML-RCS). It comprises a pretrained decision tree (DT)-based receiver that extracts binary information from the transmitted random noise carrier signals. The ML-RCS employs skewed alpha-stable ($\alpha$-stable) noise as a random carrier to encode the incoming binary bits securely. The DT model is pretrained on an extensively developed dataset encompassing all the selected parameter combinations to generate and detect the $\alpha$-stable noise signals. The legitimate receiver leverages the pretrained DT and a predetermined key, specifically the pulse length of a single binary information bit, to securely decode the hidden binary bits. The performance evaluations included the single-bit transmission, confusion matrices, and a bit error rate (BER) analysis via Monte Carlo simulations. The fact that the BER reached 10⁻³ confirms the ability of the proposed system to establish successful secure communication between a transmitter and legitimate receiver. Additionally, the ML-RCS provides an increased data rate compared to previous random communication systems. From the perspective of security, the confusion matrices and computed false negative rate of 50.2% demonstrate the failure of an eavesdropper to decode the binary bits without access to the predetermined key and the private dataset. These findings highlight the potential ability of unconventional ML-RCSs to promote the development of secure next-generation communication devices with built-in PLSs. Full article

Traditional 4-dimensional variational data assimilation methods have limitations due to the Gaussian distribution assumption of observation errors, and the gradient of the objective functional is vulnerable to observation noise and outliers. To address these issues, this paper proposes a non-Gaussian nonlinear data assimilation method called α-4DVar, based on Rényi entropy and the α-generalized Gaussian distribution. By incorporating the heavy-tailed property of Rényi entropy, the objective function and its gradient suitable for non-Gaussian errors are derived, and numerical experiments are conducted using the Lorenz-63 model. Experiments are conducted with Gaussian and non-Gaussian errors as well as different initial guesses to compare the assimilation effects of traditional 4DVar and α-4DVar. The results show that α-4DVar performs as well as traditional method without observational errors. Its analysis field is closer to the truth, with RMSE rapidly dropping to a low level and remaining stable, particularly under non-Gaussian errors. Under different initial guesses, the RMSE of both the background and analysis fields decreases quickly and stabilizes. In conclusion, the α-4DVar method demonstrates significant advantages in handling non-Gaussian observational errors, robustness against noise, and adaptability to various observational conditions, thus offering a more reliable and effective solution for data assimilation. Full article

The titanium matrix composites (TMCs) fabricated via Directed Energy Deposition (DED) effectively overcome the issue of coarse columnar grains typically observed in additively manufactured titanium alloys. In this study, systematic annealing heat treatments were applied to in situ (TiB + TiC)/Ti-6Al-4V composites to refine the microstructure and tailor mechanical properties. The results reveal that the plate-like α phase in the as-deposited composites gradually transforms into an equiaxed morphology with increasing annealing temperature and holding time. Notably, when the annealing temperature exceeds 1000 °C, significant coarsening of the TiC phase is observed, while the TiB phase remains morphologically stable. Annealing promotes decomposition of acicular martensite and stress relaxation, leading to a reduction in hardness compared to the as-deposited state. However, the reticulated distribution of the TiB and TiC reinforcement phases contributes to enhanced tensile performance. Specifically, the as-deposited composite achieves a tensile strength of 1109 MPa in the XOY direction, representing a 21.6% improvement over the as-cast counterpart, while maintaining a ductility of 2.47%. These findings demonstrate that post-deposition annealing is an effective strategy to regulate microstructure and achieve a desirable balance between strength and ductility in DED-fabricated titanium matrix composites. Full article

Time-frequency analysis (TFA) technology is an important tool for analyzing non-Gaussian mechanical fault vibration signals. In the complex background of infinite variance process noise and Gaussian colored noise, it is difficult for traditional methods to obtain the highly concentrated time-frequency representation (TFR) of fault vibration signals. Based on the insensitive property of fractional low-order statistics for infinite variance and Gaussian processes, robust fractional lower order adaptive linear chirplet transform (FLOACT) and fractional lower order adaptive scaling chirplet transform (FLOASCT) methods are proposed to suppress the mixed complex noise in this paper. The calculation steps and processes of the algorithms are summarized and deduced in detail. The experimental simulation results show that the improved FLOACT and FLOASCT methods have good effects on multi-component signals with short frequency intervals in the time-frequency domain and even cross-frequency trajectories in the strong impulse background noise environment. Finally, the proposed methods are applied to the feature analysis and extraction of the mechanical outer race fault vibration signals in complex background environments, and the results show that they have good estimation accuracy and effectiveness in lower MSNR, which indicate their robustness and adaptability. Full article

Background/Objectives: To date, there are no validated tools that assess children’s performance in connected text dictation tasks in European Portuguese using automated analysis. International studies were identified, but these primarily involved word dictation tasks and did not use automatic scoring tools. The present study aims to assess the reliability of the Dita.te (internal consistency and inter-rater reliability), a written assessment test based on a dictation task with automatic spreadsheet analysis, and establish normative data for text dictation tasks for children from 3rd to 6th grade. Methods: This study included 315 European Portuguese-speaking children from the 3rd to 6th grades. The Dita.te tool was used to assess orthographic errors based on phonological, morphological, and prosodic criteria. Descriptive statistics, percentiles, the inter-rater reliability and internal consistency were analyzed. Non-parametric tests compared performance by gender and school year due to a non-normal data distribution. Results: The Dita.te had excellent internal consistency (α = 0.929). The correlation between items scored highly (Intraclass Correlation Coefficient = 0.925). The number of errors decreased as the school year progressed, with errors affecting the syllable nucleus being the most frequent across all school years. These were followed by orthographic substitution errors, with grapheme omission being the most prevalent. Conclusions: Our findings suggest that orthographic competence is mostly stable before the 3rd grade, and the mismatches found in children with typical development show residual error in their orthographic performance. Full article

Sarcopenia and sarcopenic obesity (SO) represent significant age-related muscular disorders. Their specific biomarkers and pathophysiological mechanisms remain insufficiently elucidated. This study aims to identify differential and shared biomarkers between these conditions to reveal distinct pathophysiological processes, providing a foundation for precision diagnostics and targeted interventions. We conducted a systematic review and meta-analysis of studies examining biomarkers related to sarcopenia and SO in adults aged 45 and older. Electronic and manual searches were performed in PubMed, Web of Science, Cochrane Library, and Embase up to December 2024. The quality of each study was assessed using the National Institutes of Health Quality Assessment Tool. Meta-analysis was performed when at least three studies investigated the same biomarkers in frailty and sarcopenia, calculating the pooled effect size based on the standard mean difference using a random effects model. In total, 80 studies (64 on sarcopenia and 16 on SO) were included, encompassing 36,680 older adults (aged 45 and above) from 16 countries with varying levels of development. Participants were categorized based on their setting, age, and gender distribution. Sarcopenia is characterized by lower serum triglycerides and stable HDL/LDL ratios, while SO presents with higher triglycerides and disrupted cholesterol correlation, indicating distinct metabolic interactions. Analysis of inflammatory profiles revealed significantly elevated CRP levels in SO, with WBC as a specific marker, while TNF-α was associated with sarcopenia, suggesting a subtype-specific role of chronic inflammation. Vitamin D deficiency is prevalent in both conditions and may represent a potential therapeutic target. Subgroup analyses indicated an increased risk of muscle function decline in high-risk communities in developing regions, underscoring the urgent need for early intervention. A set of shared metabolic, hematologic, and inflammatory biomarkers was identified in sarcopenia and SO. These findings address a knowledge gap in biomarker research and highlight the distinct mechanisms involved in the development of both conditions. Developing biomarker-based diagnostic algorithms is essential for optimizing personalized treatment. Subgroup analyses have also identified high-risk populations, underscoring the need for early intervention. Full article

Despite substantial research on how environmental factors affect fungal diversity, the mechanisms shaping regional-scale diversity patterns remain poorly understood. This study employed ITS high-throughput sequencing to evaluate soil fungal diversity, community composition, and co-occurrence networks across alpine meadows, desert steppes, and alpine shrublands in the southwestern Tibetan Plateau. We found significantly higher fungal α-diversity in alpine meadows and desert steppes than in alpine shrublands. Random forest and CAP analyses identified the mean annual temperature (MAT) and normalized difference vegetation index (NDVI) as major ecological drivers. Mantel tests revealed that soil physicochemical properties explained more variation than climate, indicating an indirect climatic influence via soil characteristics. Distance–decay relationships suggested that environmental heterogeneity and species interactions drive community isolation. Structural equation modeling confirmed that the MAT and NDVI regulate soil pH and carbon/nitrogen availability, thereby influencing fungal richness. The highly modular fungal co-occurrence network depended on key nodes for connectivity. Vegetation coverage correlated positively with network structure, while soil pH strongly affected network stability. Spatial heterogeneity constrained stability and diversity through resource distribution and niche segregation, whereas stable networks concentrated resources among dominant species. These findings enhance our understanding of fungal assemblage processes at a regional scale, providing a scientific basis for the management of soil fungal resources in plateau ecosystems. Full article

The clover cutworm, Scotogramma trifolii Rottemberg (Lepidoptera: Noctuidae), is a globally distributed polyphagous pest causing significant economic losses to agricultural crops. RT-qPCR is a gold-standard technique for gene expression analysis, yet its accuracy depends critically on stable reference genes for data normalization. To address the lack of validated reference genes in S. trifolii, we evaluated six candidate genes (β-actin, RPL9, GAPDH, RPL10, EF1-α, and TUB) across four developmental stages (egg, larva, pupa, and adult) and six adult tissues (head, thorax, abdomen, wings, legs, and antennae) using geNorm, NormFinder, BestKeeper, and RefFinder algorithms. Stability analysis identified β-actin, RPL9, and GAPDH as the most reliable reference genes for developmental stage normalization, while RPL10, GAPDH, and TUB were validated for adult tissues. Functional validation using the odorant receptor gene StriOR20 revealed significant discrepancies in relative expression levels when normalized with unstable reference genes (TUB and RPL9), emphasizing the necessity of rigorous reference gene selection. This study establishes the first comprehensive reference gene panel for S. trifolii, providing a robust foundation for gene expression studies in this agriculturally important pest. Full article

Recent advances in designing multinuclear late transition metal catalysts for the oligo-/polymerization of olefins emphasize the great interest and promising approaches in the preparation and application of these catalytic systems. Accordingly, in this study, two dinuclear macrocyclic bis(iminopyridine) Fe- and Co-based complexes (FC and CC) were prepared at moderate yields through a one-pot template reaction. Upon activation by MMAO, not only did the catalysts show reasonable activities for the oligomerization of ethylene but also showed high selectivity for the production of tetramers (α-C₈). With respect to the catalyst structure, FC demonstrated higher catalyst activity (9.45 g mol⁻¹ Fe h⁻¹ × 10⁵ vs. 8.75 × 10⁵ g mol⁻¹ Co h⁻¹) along with higher selectivity for α-C₈ production compared to CC (96.6 vs. 96.1%). Both catalysts had thermal stability up to 70 °C, with FC being much more active and stable than CC under identical conditions. On the other hand, polymerization parameters had an influence on the catalyst performance and oligomer distribution. Moreover, molecular calculations were employed for geometry optimization and structural determination, which was consistent with the experimental results. Full article

The soybean yield per unit area in Xinjiang has reached a high level, with the crop maturing quickly because of the higher temperatures and levels of mechanization. However, environmental factors cause flowers and pods to shed easily, limiting yield potential. Efficient plant growth regulators (PGRs) used to increase crop yields have gained popularity, but their effectiveness in reducing flower and pod shedding, considering factors such as environment, crop variety, and time of spraying, remains unclear. This study investigated whether spraying several PGRs could reduce soybean flower and pod shedding. Field experiments were conducted from 2022 to 2024 in Ili, Xinjiang, China, using α-naphthaleneacetic acid (NAA), prohexadione-calcium (Pro-Ca), and iron chlorine e6 (ICE6) with foliar applications of 300, 450, and 45 g ha⁻¹ at the four-node stage (V4) and full pod stage (R4). All PGR treatments reduced flower and pod shedding over the years and resulted in an increase in the average flower and pod numbers compared to normal-growth-treated (CK) soybeans. The effective slowing of flower and pod shedding during the critical pod formation stage (R4) ensured a stable yield potential. The flower-to-pod conversion rate was higher after spraying plants with PGRs than for the CK group, and pod retention was higher at the beginning of maturity (R7). Our results demonstrated that spraying PGRs (NAA, Pro-Ca, and ICE6) effectively reduced soybean flower and pod shedding, optimized pod distribution, and increased soybean yield potential. The study findings provide a useful reference for global soybean growers to optimize planting methods. Full article

This study investigates the microstructural and corrosion properties of pure magnesium (Mg) and Mg-1.8Ca (at.%) alloy in both bulk and thin-film forms. Microstructure investigations showed that the addition of calcium (Ca) to Mg resulted in significant differences in microstructures. The bulk pure Mg exhibited coarse and elongated α-Mg grains, which were refined by Ca addition, together with the formation of a Mg₂Ca intermetallic phase distributed throughout the microstructure. In contrast, thin-film Mg-1.8Ca alloys displayed a refined single-phase microstructure with uniform nm-scale grains and no intermetallic formation. The electrochemical corrosion tests revealed that the bulk and thin-film pure Mg exhibited comparable corrosion rates, while a substantial difference between the corrosion resistance of bulk and thin-film Mg-1.8Ca (at.%) alloy was observed. The thin-film Mg-1.8Ca (at.%) alloy showed an exceptionally better corrosion resistance, attributed to the formation of a more stable surface film and the absence of a less noble Mg₂Ca intermetallic phase, ensuring a single-phase microstructure. This study highlights the importance of different manufacturing techniques and microstructural control in improving the performance of Mg alloys for high-tech applications. Full article

Monolepta signata are polyphagous pest widely distributed in China, and the damage as well as economic losses it caused were increasing in recent years. Knowledge of species diversity, population structure and habitat suitability could enhance the efforts of pest control. Here, we sampled the populations of M. signata in almost all of China’s major corn-producing regions. A total of 568 sequences were obtained from each gene. There were 48, 29, and 30 haplotypes of COI, ITS2 and EF-1α, respectively. The genetic distance between the HuangHuaiHai population and other populations was the largest. There were 61.90%, 71.43% and 61.90% of Nm values smaller than 1 in COI, ITS2 and EF-1α, respectively, which indicated that gene flow between most populations was weak. The degree of differentiation in most populations of M. signata was relatively high. The population of M. signata has also experienced rapid expansion. Population history dynamic analysis showed that the effective population size of M. signata remained relatively stable before 0.075 Ma. There was a slow contraction trend from 0.075 to 0.010 Ma. It has been rapidly and continuously expanding since 0.010 Ma. Among the investigated geographical populations, the “yellow-spot type” was only present in the populations of southern and southwestern regions, while the “two-spot type” and “four-spot type” were widely distributed in all other geographical populations. Predictions of the potential distribution areas of M. signata indicated that the northeast and north China regions will remain being the high suitability areas of M. signata in the future. Our results will not only facilitate studies on the phylogeography of M. signata but also benefit the effective monitoring and management of this agricultural pest. Full article

A common approach to simulating a Lévy process is to truncate its shot-noise representation. We focus on subordinators and introduce the remainder process, which represents the jumps that are removed by the truncation. We characterize when these processes are self-similar and show that, in the self-similar case, they can be indexed by a parameter $\alpha \in (-\infty ,1)$. When $\alpha \in (0,1)$, they correspond to $\alpha$-stable distributions, and when $\alpha =0$, they correspond to certain generalizations of the Dickman distribution. Thus, the Dickman distribution plays the role of a 0-stable distribution in this context. Full article

In this study, the impact of lentil hull soluble dietary fibers (SDFs) on colitis and behavioral deficits in mice was assessed. Structural characterizations of SDFs confirmed that cellulase-modified soluble dietary fiber exhibited better physicochemical properties: more porous microstructure; similar polysaccharide structure; more stable particle size distribution; higher crystallinity; better adsorption capacity; and lower viscosity. Additionally, we explored its potential cognitive benefits via the gut-brain axis by behavioral tests, histopathology, 16S rRNA sequencing, gas chromatography and metabolomics analysis. The results showed that SDFs significantly improved inflammatory symptoms in colon and brain and cognitive behaviors. LSDF had better efficacy than HSDF. LSDF intervention decreased the harmful bacteria abundance (Bacteroides, Flexispira and Escherichia, etc.) and increased beneficial bacteria abundance (Aggregatibacter and Helicobacter, etc.). LSDF also affected brain metabolites through the sphingolipid metabolism. Spearman correlation analysis showed that there was a positive correlation between harmful bacteria with inflammatory factors (LPS, IL-1β, IL-6, and TNF-α, etc.) and sphingolipid metabolites, while beneficial bacteria were positively correlated with brain-derived neurotrophic factor (BDNF), IL-10, and cognitive behavior. This study highlights the value of SDFs in future diet-based therapeutic strategies targeting gut-brain interactions. Full article

The evolution of coal’s pore structure is crucial to the efficient capture of carbon dioxide (CO₂) within coalbeds, as it provides both adsorption sites and seepage space for the adsorbed- and free-phase CO₂, respectively. However, the conventional single fractal method for characterizing pore structure fails to depict the intricacies and variations in coal pores. This study innovatively applies the low-temperature N₂/CO₂ sorption measurement and multifractal theory to investigate the evolution of the microporous structure of coals (e.g., from the Huainan coalfield) during the supercritical CO₂(ScCO₂)–water–rock interaction process. Firstly, we observed that the ScCO2–water–rock interaction does not significantly alter the coal’s pore morphology. Notably, taking the ZJ-8# sample as an example, low-temperature N₂ sorption testing displayed a stable pore volume following the reaction, accompanied by an increase in specific surface area. Within the CO₂ sorption testing range, the ZJ-8# sample’s pore volume remained unchanged, while the specific surface and pore width performed displayed a slight decrease. Secondly, by introducing key parameters from multifractal theory (such as D_q, α(q), τ(q), and f(α)), we assessed the heterogeneity characteristics of the coal’s pore structure before and after the ScCO2–water–rock reaction. The N₂ sorption analysis reveals an increase in pore heterogeneity for the ZJ-8# sample and a decrease for the GQ-13# sample within the sorption testing range. In the context of low-temperature CO₂ sorption analysis, the pore distribution complexity and heterogeneity of the GQ-11# and GQ-13# samples’ pores were escalated after ScCO2–water–rock interaction. The experimental and analysis results elucidated the dual roles of precipitation and dissolution exerted by the ScCO2–water–rock interaction on the micropores of coal reservoirs, underscoring the heterogeneous nature of the reaction’s influence on pore structures. The application of fractal theory offers a novel perspective compared to traditional pore characterization methods, significantly improving the precision and comprehensiveness of pore structure change descriptions. Full article