Evolutionary Patterns Research Articles

Exploration of the covariation signal between cortical bone and dentine volumes across the upper limb bones and anterior teeth in modern humans and relevance to evolutionary anthropology.

Cortical bone and dentine are two mineralized tissues sharing a common embryological origin, developmental, and genetic background, distinct from those of enamel. Understanding their relationship is crucial to decipher the factors acting on their postnatal development, and shedding light on the evolutionary patterns of tissue proportions. Here, we investigate the coordinated variation between cortical bone and dentine volumes measured from arm and forearm bones (humeri, ulnae, radii) and upper anterior teeth (central incisors, lateral incisors, canines) of modern humans. Given the shared characteristics of cortical bone and dentine, we expect similarities in their postnatal development, which may lead to covariation between their volumes. The degree of bone-dentine covariation may be influenced by the physiological response of upper limb bones to mechanical loading. No such covariation is expected with enamel volumes, due to the greater developmental independence of bone and enamel. Our sample includes 55 adults of African and European ancestries from South African osteological collections. Principal component analysis of cortical thickness variation along the shafts of paired humeri, ulnae, and radii is used to assess asymmetry. Bone regions with bilateral asymmetry in cortical bone thickness are considered sensitive to functional loads, while regions with minimal bilateral variation likely reflect genetic influences during bone postnatal development. Statistical analyses reveal strong positive correlations between cortical bone and dentine volumes across all bones and teeth, and weaker correlations between cortical bone and enamel. We outline a complex pattern of bone-dentine covariation that varies by skeletal location and tooth type. Contrary to our expectations, the presumed functional sensitivity of bone regions does not influence the covariation signal. Additionally, the strength of the covariation appears to align with the developmental sequence of the anterior teeth, with the upper canines showing the strongest correlation with cortical bone volumes, followed by lateral and central incisors. These results provide insights into the functional and biological factors influencing the coordinated variation of cortical bone and dentine volumes during postnatal development. Further research on the cortical bone-dentine covariation across different skeletal parts, including lower limb elements, would enhance our understanding of the effects of both endogenous and exogenous factors on the development of the mineralized tissues.

Research Progress on the GP3 Protein of Porcine Reproductive and Respiratory Syndrome Virus

Porcine reproductive and respiratory syndrome (PRRS) is a highly contagious immunosuppressive disease caused by the porcine reproductive and respiratory syndrome virus (PRRSV) that is characterized by a highly variable gene sequence and a high rate of recombination, thereby contributing to difficulties in the clinical prevention and control of this virus. Glycosylated protein 3 (GP3) is the most glycosylated protein in PRRSV, and is closely associated with the composition of PRRSV virus particles, infection, and immune evasion. This review summarizes the structural features, genetic evolutionary patterns, glycosylation of GP3 and its interactions with other PRRSV and host proteins, associations with PRRSV infection and virulence, and immunomodulatory roles. Additionally, it provides an overview of research progress on monoclonal antibodies and vaccines targeting GP3. This study aims to provide a theoretical foundation for better understanding the structure and function of GP3, of the mechanisms of PRRSV infection, and the development of novel vaccines.

Regional Space–time Differences and Dynamic Evolution Law of Real Estate Financial Risk in China

Abstract This study develops a framework to evaluate real estate financial risk from three perspectives: internal risk factors, external risk factors, and interconnected risk factors, examining regional space–time differences and dynamic evolution laws across 30 provinces in China. The research finds that (1) interconnected risk factors are key contributors to real estate financial risk. (2) Significant regional differences in real estate financial risks exist across China. The western and northeastern regions are hotspots for risk, while the eastern region exhibits the most pronounced market stratification and polarization. (3) There is significant spatial autocorrelation in China’s real estate financial risks, with most provinces showing high–high (HH) and low–low (LL) clustering. HH clusters are primarily located in the western and northeastern regions, while LL clusters are more prevalent in the central and eastern regions. (4) The distribution of real estate financial risks follows a single-peak evolutionary pattern, characterized by the dynamic transition of weakening LL clusters and strengthening HH clusters. (5) The dynamic evolution of China’s real estate financial risks exhibits strong “spatial stickiness” and “positive reinforcement.” Over time, the probability of regions transitioning to higher-risk types increases, demonstrating a trend toward escalating risk levels.

Spatio-temporal evolution characteristics and influencing factors of environmental welfare performance in Chinese cities

BackgroundIn the process of China’s urbanization, issues such as air pollution, water pollution, soil pollution, and noise pollution have become increasingly prominent, severely constraining the sustainable development of cities. The resultant decline in environmental welfare performance (EWP) not only affects residents’ quality of life but may also lead to public health issues, increasing healthcare costs, and subsequently impacting social stability and economic development.MethodsThis paper incorporates factors closely related to environmental pollution, such as residents’ health and social welfare, into the analytical framework of environmental welfare performance. Using the Hybrid-Network-DEA model, we measure the EWP of 240 cities in China, and then investigate the spatial distribution characteristics and spatio-temporal evolution patterns of EWP. Finally, empirical testing of the factors influencing EWP is conducted using spatial econometric methods.ResultsThe overall level of EWP in 240 Chinese cities from 2004 to 2019 is relatively low, but it generally shows a wavy upward trend. Meanwhile, notable regional disparities exist in EWP, with the highest average performance in the east, followed by the west, and the lowest in the central. The main source of regional differences in EWP lies in inter-regional disparities. The greatest internal disparities are found in the east, while the largest inter-regional disparities are between the east and the west. A pronounced positive spatial autocorrelation is observed in the EWP among Chinese cities. Economic development, opening-up, financial development, digital infrastructure, and population density significantly promote the local EWP, whereas the industrial structure and transportation structure have exerted opposite effects. Additionally, the enhancement of EWP in neighboring regions is also notably facilitated by economic development, opening-up, financial development, and digital infrastructure. Within the three major regions, the direct and indirect effects of various influencing factors exhibit significant differences.ConclusionBased on these insights, we suggest comprehensively improving environmental welfare efficiency, narrowing regional disparities, strengthening spatial agglomeration effects, optimizing industrial structure, and strengthening financial support and digital infrastructure construction.

Analysis of the Spatiotemporal Evolution Patterns and Driving Factors of Various Planting Structures in Henan Province Based on Mixed-Pixel Decomposition Methods

Understanding the spatiotemporal evolution patterns and drivers of cropping structures is crucial for adjusting cropping structure policies, ensuring the sustainability of land resources, and safeguarding food security. However, existing research lacks sub-pixel scale data on planting structure, where planted area data are mainly derived from manual counting results. In this study, remote sensing technology was combined with geostatistical methods to realize the spatiotemporal evolution of crop planting structure at sub-pixel scale. Firstly, the spatial distribution of the multiple cropping structure in Henan Province was extracted based on a mixed-pixel decomposition model, and spatiotemporal evolution of the crop planting structure was analyzed using a combination of Sen’s slope estimator and Mann–Kendall trend analysis, as well as centroid migration. Then, Pearson correlation coefficients were calculated to explore the contribution of driving factors. The results indicate the following: (1) from 2001 to 2022, the cropping structure in Henan Province shows a slightly obvious increase. (2) The centroid of different cropping structures migrates to the main production areas as a whole. (3) Among the driving factors, there was a positive correlation with the labor force and a negative correlation with the urbanization rate. This study provides new insights into the evolution of large-scale crop planting structures and offers significant theoretical and practical value for sustainable agricultural development and the optimization of agricultural planting structures.

Correlations of gene expression, codon usage bias, and evolutionary rates of the mitochondrial genome show tissue differentiation in Ophioglossum vulgatum.

Mitochondria are crucial for energy production in plant tissues, but their quantity and activity vary in different tissues and developmental processes. Determining the factors underlying differential molecular evolutionary rates has long been a central question in evolutionary biology, with expression level emerging as the prime predictor. Although we have previously observed an anti-correlation between expression level (E) and evolutionary rate (R) in chloroplast genes, it remains unclear whether such an anti-correlation exists in plant mitochondrial genes. Ophioglossum vulgatum is a typical plant belonging to the Ophioglossaceae, characterized by its unique morphology with only a single leaf above ground. It holds significant scientific and medicinal value. Using the mitochondrial genome and transcriptome data of O. vulgatum, we first analyzed the correlation between mitochondrial gene expression, codon usage bias, and evolutionary rates in different tissues. Our findings indicated that mitochondrial gene expression level was the strongest between stem and leaf, while the weakest was between sporangium and root. Kruskal-Wallis tests revealed significant differences across various tissue types. Codon usage bias was influenced by both mutation and selection, with selection exerting a greater impact. The Spearman's rank correlation coefficients between codon adaptation index and expression levels of sporangium, stem, leaf, and root were 0.1178, 0.3926, 0.4463, and 0.2945, respectively, with significance in stem and leaf (P < 0.05). The correlation coefficients between the nonsynonymous substitution rate (dN) and expression levels in sporangium, stem, leaf, and root were -0.0840, -0.1786, -0.1714, and -0.0857, respectively, yet none are statistically significant. The correlation coefficient between the synonymous substitution rate (dS) and expression levels in sporangium was negative, whereas those between dS and the stem, leaf, and root were positive, although they were not significant. The dN/dS ratio exhibited a significant negative correlation with expression levels in both leaf and root (P < 0.05). For the first time, our study revealed differences in the correlation between mitochondrial gene expression and codon usage bias, as well as evolutionary rates, across various tissues of O. vulgatum. Moreover, we also provide novel insights into understanding the effects of plant mitochondrial gene expression on evolutionary patterns.

Rural transformation and the future of China's "granary": A perspective on livelihood trajectories

Recent research demonstrates that the core features of agricultural and rural transformation in grain-dependent areas of the newly industrializing countries in East and Southeast Asia do not fully align with classical theories and paradigms. However, there is a lack of a theoretical model that illustrates the general patterns of rural evolution and transformation in these areas during structural transformation and outlines their future trajectories. Through case studies of a well-known grain base in China, this paper explores this issue using an analytical framework consisting of the trajectory of agricultural transformation associated with rural residents' livelihood changes and the trajectory of rural community restructuring induced by these livelihood changes. The results show that, since structural transformation, the grain-dependent countryside of China has roughly undergone an evolution from a stage of relative isolation and self-sufficiency, marked by agricultural involution, to a stage of accelerating factor flows between cities and the countryside, marked by part-time livelihoods, and finally to the current stage of accumulating "potential energies" for rural restructuring, marked by population aging. Meanwhile, challenges to the further transformation of the countryside are rooted in the socioeconomic characteristics of the middle-income period, which underscores the significance of overcoming the middle-income trap. Finally, we propose theoretical patterns for the future trajectories of China's grain-dependent countryside through the scenario analysis based on overcoming the middle-income trap and discuss the implications for rural revitalization in these areas.

Sexual size dimorphism as a determinant of biting performance dimorphism in Anolis lizards.

Rensch's rule describes a pattern of interspecific allometry in which sexual size dimorphism (SSD) increases with size among closely related species (i.e., among a group of related species, the largest ones tend to show more male-biased SSD). Sexual selection is often invoked to explain Rensch's rule, as larger male body size is assumed to be favoured by sexual selection for increased fighting performance in contests for mating opportunities. Often, however, the correlation between size and performance is not well described. We studied a sexually selected performance trait, bite force in Anolis lizards, to determine whether patterns of SSD are linked to size-associated patterns of performance dimorphism at the macroevolutionary level, as expected under the sexual selection hypothesis for Rensch's rule. Additionally, we tested whether allometric patterns of performance dimorphism differ between mainland and island species, as the latter have likely evolved under a stronger sexual selection regime. We found that SSD overwhelmingly explains the relationship between performance dimorphism and size in anoles, as expected under a sexual selection model for Rensch's rule. However, residual performance dimorphism was higher in island than in mainland species, suggesting that these groups differ in performance dimorphism for reasons unrelated to size. Head size dimorphism was associated with residual performance dimorphism, but did not fully explain the difference in performance dimorphism between island and mainland species. Together, these findings highlight the need to interpret Rensch's rule patterns of body size evolution cautiously, as allometric patterns of performance dimorphism and size dimorphism might not be equivalent.

Discussion on pore-to-field scale evolution of invasive pattern in immiscible two-phase flow with pseudoplastic behavior in porous media

The immiscible two-phase flow with non-Newtonian behavior presents many challenges for geoscience engineering applications. Due to the non-Darcy flow with pseudoplasticity in bitumen or heavy oil reservoir, the variable and velocity-affected viscous force leads to unstable and unpredictable evolution of invasive patterns in porous media. Primarily, drainage experiments, computational fluid dynamics, and analytical model analyses were conducted to track morphological variations of invasive interface, revealing the evolution mechanisms of invasive patterns with pseudoplasticity. Subsequently, the field-scale two-phase flow simulation, established by the blocked-centered finite difference method, quantitively investigates the impact of invasive patterns on the extraction of pseudoplastic oil. Ultimately, given previous methods for evaluation of invasive patterns, capillary number, and mobility ratio play a communicating role in the pore-scale and the field-scale study. Through the dual-scale framework, the capillary number and mobility ratio, serving as driving force and resistance, respectively, predictably improve the evolutionary diagram pore-scale invasive patterns and accurately evaluate the field-scale potential of pseudoplastic oil extraction. From both pore and field perspectives, our work holds promising application for optimizing invasive patterns by injection operation in the pseudoplastic oil reservoirs.

Evolution and migration patterns of sediments in an earthquake-affected catchment in Wenchuan, Sichuan Province, China

Evolution and migration patterns of sediments in an earthquake-affected catchment in Wenchuan, Sichuan Province, China

AmChi7, an AmWRKY59 - Activated chitinase, was involved in the adaption to winter climate in Ammopiptanthusmongolicus.

Chitinases are enzymes that hydrolyze β-1,4-glycosidic bonds in chitin. Previous studies have shown that several chitinases accumulated significantly in A. mongolicus, suggesting that chitinases might participate in the adaptation to winter climate in Ammopiptanthus mongolicus. Here, we analyzed the evolution and expression patterns of the chitinase gene family in A. mongolicus and investigated the function and regulatory mechanisms of the AmChi7 gene in response to abiotic stress. The chitinase gene family in A. mongolicus comprises 27 members, many of which arose through formed by tandem and segmental duplication. Several chitinase genes, including AmChi7 gene, were significantly upregulated in winter. Overexpression of AmChi7 gene enhanced the tolerance of yeast to freeze-thaw cycle and osmotic stress, and enhanced the tolerance of transgenic Arabidopsis to low-temperature and drought stress. Furthermore, AmWRKY59, a MeJA-induced transcription factor, bound to the W box element in the AmChi7 gene promoter, activating its expression in winter. It is speculated that chitinase AmChi7 accumulation in winter enhances adaptation to temperate winter climates in A. mongolicus. This study expands our understanding of the biological functions of chitinases and provides insights into the molecular mechanisms underlying winter climate adaptation in A. mongolicus.

Genetic Epidemiology of Porcine Epidemic Diarrhea Virus Circulating in China From 2010 to 2024: Characterization of Phylogenetic and Genetic Diversity of S1-Based Genes.

As a porcine alphacoronavirus, porcine epidemic diarrhea virus (PEDV) frequently undergoes mutations that significantly reduce the effectiveness of current prevention and control strategies, leading to recurrent outbreaks in China. This study investigates the genetic evolution and mutation patterns of the S1 protein to characterize PEDV variation in China. Genetic evolutionary analysis of 804 PEDV S1 genes, including 620 Chinese PEDV strains, revealed that 78.06% of the Chinese PEDV strains belong to the G2a-subgroup, further divided into seven branches (G2a-Clade 1-7), with the predominant strains from 2020 to 2024 being in G2a-Clade 4 (68.00%). From 2021 to 2024, 32 novel substitutions, 25 deletions, and 8 insertions were identified in the S1 protein of Chinese strains compared to those from 2010 to 2011. Notably, complete mutations were observed at amino acid sites N139D, H189Y, L229P, I287M, F345L, A361T, T499I, and A520S. Moreover, protein homology modeling analysis displayed that these deletion-insertion mutations significantly altered the surface structure of the S protein, particularly in the N-terminal domain (NTD) and receptor-binding domain (RBD) regions of S1 protein. The predictive analysis using AlphaFold3 indicated that deletion-insertion mutations in the S1-RBD region notably affected the binding affinity of the S protein to porcine DC-SIGN. These findings enhance our understanding of the genetic evolution of PEDV in China.

Molecular Evolutionary Analyses of the RNA-Dependent RNA Polymerase (RdRp) Region and VP1 Gene in Sapovirus GI.1 and GI.2

Human sapovirus (HuSaV) is a significant cause of gastroenteritis. This study aims to analyze the evolutionary dynamics of the RNA-dependent RNA polymerase (RdRp) and capsid (VP1) genes of the HuSaV GI.1 and GI.2 genotypes between 1976 and 2020. Using bioinformatics tools such as the Bayesian phylogenetics software BEAST 2 package (v.2.7.6), we constructed time-scale evolutionary trees based on the gene sequences. Most of the recent common ancestors (MRCAs) of the RdRp region and VP1 gene in the present HuSaV GI.1 diverged around 1930 and 1933, respectively. The trees of the HuSaV GI.1 RdRp region and VP1 gene were divided into two clusters. Further, the MRCAs of the RdRp region and VP1 gene in HuSaV GI.2 diverged in 1960 and 1943, respectively. The evolutionary rates were higher for VP1 gene in HuSaV GI.1 than that in HuSaV GI.2, furthermore, were higher in GI.1 Cluster B than GI.1 Cluster A. In addition, a steep increase was observed in the time-scaled genome population size of the HuSaV GI.1 Cluster B. These results indicate that the HuSaV GI.1 Cluster B may be evolving more actively than other genotypes. The conformational B-cell epitopes were predicted with a higher probability in RdRp for GI.1 and in VP1 for GI.2, respectively. These results suggest that the RdRp region and VP1 gene in HuSaV GI.1 and GI.2 evolved uniquely. These findings suggest unique evolutionary patterns in the RdRp region and VP1 gene of HuSaV GI.1 and GI.2, emphasizing the need for a ‘One Health’ approach to better understand and combat this pathogen.

Anatomy of the Critically-Endangered Anji Salamander (Hynobius amjiensis) Provides New Insights Into Morphological Evolution of Salamanders.

The Anji Salamander (Hynobius amjiensis) is a critically-endangered amphibian endemic to the Tianmushan Mountain area in southeastern China. As most of its congeneric species in the ancestral salamander family Hynobiidae, the osteology of H. amjiensis has remained essentially unknown and has hampered efforts in understanding morphological evolutionary patterns of early salamanders. Here, we investigate the skeletal anatomy of H. amjiensis based on microcomputed tomography scans of post-metamorphosed juvenile and adult specimens. Our results reveal Hynobiidae has more early-tetrapod-like plesiomorphic characters than expected, as H. amjiensis has a stapedial foramen in the middle ear and two centralia and a centrale-radius contact in the limb. We demonstrate that Hynobius amjiensis is the first known living salamander species with a stapedial foramen whose absence was believed to unite salamanders and anurans, and hence opens major questions on the evolution of the middle ear in modern amphibians: if some salamanders and caecilians had a stapedial foramen inherited from their common ancestor, when and how many times was the foramen lost independently in modern amphibians, and how did this structural loss impact the phylogenetic evolution of salamander clades? Our findings of hyper-ossified pectoral and pelvic girdles and loss of postminimus in the pes in H. amjiensis demonstrate that functional morphological features in hynobiids are potentially informative in phylogeny and ontogeny of early salamanders.

An Actively Homing Insertion Element in a Phage Methylase Contains a Hidden HNH Endonuclease

Background/Objectives: The ShiLan domain was previously identified as an insertion sequence in a phage DNA methylase gene that exhibited similar evolutionary patterns to that of an active intein or self-splicing intron but could not be identified as either. It produces no internal stop codons when read in frame with its host methylase gene, leading to the thought that it may not be an intron and rather be an abnormal type of intein. However, the sequence has no detectable self-splicing domains, which are essential for intein persistence, as preventing an intein from successfully splicing is often detrimental to proper host protein function. Methods: The analysis of alternate open reading frames for the full nucleotide sequence of this insertion element revealed the insertion to be an out-of-frame histidine-asparagine-histidine (HNH) endonuclease. A GTG start codon is located 18 bp into the insertion, and a TAA stop codon within the last four bases of the insertion (TAAC). When this frame is read, an HNH endonuclease is revealed. In-depth computational analysis could not retrieve support for this element being any known type of self-splicing element, neither intein nor intron. When read in-frame with the methylase gene, this insertion is predicted to take on a looping structure that may be able to avoid interference with the DNA methylase activity. We performed searches for sequences similar in nature to the inserted out-of-frame HNH and found several in other phages and prokaryotes. We present our survey of these out-of-frame endonuclease insertion elements as well as some speculation on how these endonucleases are getting translated to facilitate their homing activity. Conclusions: These findings expand our understanding of the possible arrangements for and prevalence of unorthodox mobile genetic elements and overlapping open reading frames in phages.

Impact of Paleocene–Eocene tectonic and climatic forcing on Arctic sediment transfer variability: SW Barents Sea, Norway

During the Paleocene and Eocene, many Arctic basins experienced multiple, yet synchronous periods of increased sedimentation rates. Several causal factors have been suggested including major volcanic events, tectonic plate reorganization and plate break-up, as well as widespread uplift along with contemporaneous and short-lived hyperthermal events. However, the significance of and relation between tectonic and climatic forcing on Arctic sediment transfer during the early Paleogene is poorly understood. In this case study from the Barents Shelf margin in the Norwegian Arctic, we present previously unpublished cores combined with exploration wells, and new high-resolution 3D seismic data to investigate sedimentary stacking patterns and geomorphological features in the Sørvestsnaget Basin. Our integrated investigations reveal the development of climate-controlled and tectonically-driven submarine fans. The PETM fans display an individual fan as a result of single depositional event compared to the middle Eocene fans that show stacked submarine fans probably deposited during multi-phase events. Our Stratigraphic Forward Modelling analysis indicates that regional-scale tectonically induced uplift significantly increased the amount of sand delivered to the basin as documented by a thickening of the basin fill succession. The climatic component contributes to sand transport variability to the basin, and thus the temporal evolution pattern of sand is much varied. Finally, we discuss our findings with the tectonic and climatic forcing factors in a circum-Arctic perspective.

Signal response and energy evolution of separated sandstone

This study aims to establish a precise prediction system for strong rockbursts and mine earthquakes caused by high-hard roof fractures. A three-point bending test was conducted on separated sandstone (SS) to analyze deformation field changes under the influence of digital image correlation (DIC) and acoustic emission (AE) signals during rock fracture. Microscopic fracture modes and energy evolution patterns of SS are investigated using scanning electron microscopy and Particle Flow Code in 2 Dimension, revealing the internal mechanisms linking fracture modes, crack classifications, and energy evolution. The results show that the AE signals and DIC deformation fields are highly correlated. Tensile cracks are the primary indicator of damage to SS during the strong contact phase. Complete failure occurs at peak load, driven by a combination of tensile and shear cracks. Increasing the precast crack length (b) or the upper-to-lower rock layer thickness ratio (U/L) enhances tensile failure sensitivity, whereas simultaneous increases reduce it. Macroscopically, this is reflected in variations of AE peak frequency and the primary fracture's peak frequency. Microscopically, it appears as changes in fracture surface roughness and grain fracture morphology. Energetically, this is evident in changes to the ratios of strain energy and slip energy relative to total energy. Additionally, as b and U/L increase, the primary crack location and AE energy density concentration shift progressively from the lower to the upper rock layers. Meanwhile, total input energy decreases with increasing b or as U/L deviates from 1.

Climate and evolutionary history shape latitudinal patterns of angiosperm wood density

Climate and evolutionary history shape latitudinal patterns of angiosperm wood density

Study on the influence of working condition variation on lubrication characteristics of EHA internal pump

The operational characteristics of Electro-Hydraulic Actuator(EHA) result in the EHA internal pump facing complex conditions of variable speed, pressure and even direction, resulting in poor lubrication state of friction pairs. To study the evolution of lubrication states under varying working conditions, a joint simulation model using Simerics-MP+(Version: 5.2.13, https://www.simerics.com) and MATLAB(Version: R2020a, https://www.mathworks.com/products/matlab.html) was established, focusing on the gear ring/shell friction pair as the subject of study. The model was used to predict the micro-motion trajectory of the gear ring, and the results were validated through experimental measurements of dynamic changes. Results indicate that the simulation model can accurately predict oil film variations, with a calculation error of less than 7.6% for oil film thickness. The reduction in speed and the increase in load pressure will deteriorate the lubrication characteristics of the oil film in the friction pair. Under pump operating conditions, when the direction reversing rate increases from 20,000 rpm/s to 40,000 rpm/s, the average oil film thickness increases by 23.64%, while the fluctuation rate decrease by 2.57%. Similarly, when the direction reversing pressure decreases from 10 MPa to 5 MPa, the average oil film thickness increases by 22.39%, and the fluctuation rate decreases by 8.17%. During pump-motor working condition switching, an increase in the switching rate from 10,000 rpm/s to 40,000 rpm/s results in a 10.33% increase in average oil film thickness and a 20.9% decrease in fluctuation rate. This study significantly contributes to enhancing our comprehension of the evolutionary patterns of friction pairs in EHA internal pumps under varying operational conditions.

Forecasting the number of rural migrant workers in Chongqing using the optimized grey N_Verhulst model

Scientific prediction of migrant worker numbers provides decision-making references for resolving rural talent supply issues. Based on the evolutionary patterns and data features of Chongqing’s migrant workers, a new grey prediction model is constructed. The new model is constructed by introducing fractional-order operators in the real domain. In this way, the accumulating order of the traditional N_Verhulst model is optimized. It expands from 1 to all real numbers, thus enhancing its capacity to mine approximately saturated S-shaped time-series data. When the new N_Verhulst model is applied to simulate and predict migrant worker numbers, after optimizing the accumulating order, the mean relative simulation percentage error of the N_Verhulst model reduces from 3.66 to 2.93%, the mean relative forecasting percentage error from 8.02 to 2.18%, and the comprehensive mean relative percentage error from 4.53 to 2.78%. This shows that the optimization boosts the simulation and prediction performance of the N_Verhulst model. The prediction results show that the number of migrant workers in Chongqing will experience an orderly growth, rising from 2.41 million in 2023 to 2.85 million in 2028, with an increase of 18.26% and an average annual growth rate of 3.41%.