Average Variation Research Articles

Associations of long-term exposure to temperature with coronary artery calcification risk among middle-aged adults: The Coronary Artery Risk Development in Young Adults (CARDIA) study.

The impact of ambient temperature on population health has drawn increasing attention as climate change drives more extreme temperatures globally. However, little research has investigated its connection to subclinical cardiovascular diseases. This study aims to examine the impact of long-term exposure to temperature on coronary artery calcification (CAC) among middle-aged Black and White adults in four U.S. areas with varying climate and weather conditions. This study compiled long-term environmental temperature data and individual coronary artery Agatston score (0 vs. >0) from the Coronary Artery Risk Development in Young Adults study. It employed logistic regression and examined the influences of multiple temperature metrics, including average temperature and variation in the summer, winter, or during the year. Subgroup analyses by sex and race were also conducted. Increased average temperatures were associated with lower odds in the presence of CAC (winter average: odds ratio, 0.988 [95% CI, 0.979-0.998]; yearly average: 0.981 [0.964-0.999]), and yearly variation in temperatures was positively related to individuals' CAC risk (1.031 [1.005-1.057]). With statistical adjustment, female participants' CAC risk was significantly related to winter and yearly average temperatures (0.964 [0.932-0.998] and 0.943 [0.891-0.999], respectively), and White participants' CAC risk would increase with greater annual temperature variations (1.181 [1.023-1.363]). This study appears to be the first to examine the impact of long-term exposure to ambient temperature on subclinical cardiovascular diseases. Increased risks of CAC are linked to decreased average winter/yearly temperatures among females and greater yearly temperature variations among White adults.

Warming reduces bacterial diversity and stability in Lake Bosten.

Understanding the effects of warming on bacterial communities is essential for predicting microbial responses to climate change in aquatic ecosystems. However, the mechanisms through which warming influences bacterial diversity and stability in lake ecosystems remain poorly understood. To address this gap, we conducted a mesocosm experiment in Lake Bosten, a climate change hotspot, with three temperature scenarios (26°C, 29°C, and 32°C), and investigated bacterial diversity, community composition, potential functions, and stability. Our findings revealed that temperature, time, and their interactions significantly reduced bacterial α-diversity (two-way ANOVA: P<0.05). Warming altered bacterial potential metabolic functions, with decreases in methanotrophy and methylotrophy and increases in phototrophy and photoheterotrophy. Warming also increased species replacement within bacterial communities, indicating a dynamic shift in community composition. Network analysis indicated heightened complexity under higher temperatures but also a decrease in bacterial stability, evidenced by higher average variation degree (AVD), increased vulnerability, and reduced robustness. Overall, our study highlights the profound effects of warming on the ecological dynamics of lake bacterial communities, underscoring the need for further research to understand and mitigate the impacts of global climate change on aquatic ecosystems.

An Experimental Pilot Approach to Evaluate the Infrastructure Accessibility and Level of Service at Metro Station Platforms

Metro stations are essential for daily commuting, but overcrowding due to increased demand can severely impact infrastructure quality and passenger experience. The Level of Service (LOS), a key indicator of congestion, is influenced by factors such as density, flow, and speed, and poor LOS leads to issues like longer boarding times, overcrowded platforms, and reduced accessibility, especially for vulnerable populations. To address these challenges, the study explores innovative solutions to improve platform design infrastructure for better accessibility and LOS, aligning sustainable development goals to create safer, more inclusive transport systems. This study presents two strategies designed to reduce passenger congestion at Francia station on the Valparaíso metro platform infrastructures. The strategies, tested in experimental scenarios, showed minimal differences in boarding and alighting times, with less than a one-second average variation between the two. However, survey results revealed that passengers preferred the strategy “let passengers alight before boarding the train”, as it provided greater comfort and accessibility, reducing the number of passengers per door and improving the LOS from level C to B. Despite the minimal intervention in the experiments, the results suggest potential operational improvements. Future research will focus on measuring passengers’ emotional responses using psychophysiological data to further evaluate the suitability of the proposed strategies.

Particle composition-based water classification method for estimating chlorophyll-a in coastal waters from OLCI images

The complex composition of seawater presents significant challenges for accurately estimating biogeochemical data through optical measurements, both in situ and via satellite data. To address the regional applicability of single bio-optical or remote sensing algorithms caused by these challenges, we explored a water optical classification method based on inherent optical properties and particle composition. The ratio of organic particulate matter to total suspended particulate matter concentration (POM/SPM) serves as an optical discriminator of water bodies based on the proportions of organic and mineral particles. The boundary value is determined by the relationship between the particulate backscattering coefficient bbp(λ) and POM/SPM. By analyzing in situ data collected from the coastal waters of Qinhuangdao in the Bohai Sea, China, we developed empirical algorithms to estimate both the POM/SPM ratio and chlorophyll-a (Chl-a) concentration, the latter being a key parameter derived from current ocean remote sensing that indicates phytoplankton abundance. The evaluation of our algorithms demonstrates that accounting for POM/SPM variations significantly improves Chl-a estimate accuracy across the optically-complex coastal waters near Qinhuangdao compared to algorithms that do not consider changes in particle composition, such as the well-known OC4Me algorithm. Furthermore, we determined the distribution of monthly averaged Chl-a concentration and POM/SPM ratio on the coast of Qinhuangdao, Bohai Sea, in 2023. Our results show, for the first time, that the monthly average variations of the POM/SPM ratio in the Bohai Sea and Chl-a concentrations exhibit pronounced seasonal fluctuations.

Spatio-temporal analysis of litterfall load in the lower reaches of Qarqan and Tarim rivers using BP neural networks

Litterfall load is crucial in maintaining ecosystem health, controlling wildfires, and estimating carbon stock in arid regions. However, there is a lack of spatiotemporal analysis of litterfall in arid riparian forests. This study aims to estimate Litterfall load using a BP neural network based on vegetation indices from Landsat 5 and 8 satellite images, litterfall inventory data, slope, and distance to major river tributaries. It also aims to analyze the spatiotemporal distribution pattern of litter in the research area by estimating and analyzing the spatiotemporal pattern of litterfall along the desert riparian forests of the lower Qarqan and Tarim Rivers from 2001 to 2021. The results show that the initiation of the ecological water transfer project has facilitated the decomposition of litterfall, leading to an initial decline. Subsequently, the vegetation gradually recovered, leading to an increase in leaf litter input. Since 2001, litterfall initially decreased until reaching its lowest value of 4.39 × 109 kg in 2005, followed by a subsequent increase, reaching its highest value of 12.5 × 109 kg in 2021. The study concludes that ecological water conveyance promotes both the decomposition and increase of litterfall. Initially, it accelerates litterfall decomposition, while later stages foster an increase in Litterfall load. Meanwhile, due to the ecological water transfer project and the higher vegetation cover along the Tarim River compared to the Qarqan River, the Tarim River basin experiences higher average Litterfall load and variation.

Investigation of the Sensitivity of Acoustic Emission to the Differentiation Between Mode I, II, and III Fracture in Bulk Polymer Materials

There is very limited research in the literature investigating the way acoustic emission signals change when polymer materials are undergoing different fracture modes. This study investigates the capability of acoustic emission to recognize the fracture mode through acoustic emission parameter analysis, and can be considered the first-ever study which examines the impact of different loading conditions, i.e., fracture mode I, mode II, and mode III, on the acoustic emission parameters in polymer materials. To accomplish this, prism-like pre-cracked polymer specimens were tested under the three different fracture modes. Acoustic emission parameters appeared sensitive to the different loading conditions of the pre-cracked specimens, indicating that acoustic emission can be used to distinguish the three fracture modes in polymer materials. Both frequency and time parameters reflect changes in the stress states at the crack tip. The duration and rise time of the waveforms were found to be the most sensitive acoustic emission parameters for identifying the fracture mode, while the average frequency variation can be employed to differentiate between in-plane and out-of-plane fracture modes. In order to interpret the experimental results in relation to wave mechanics, numerical wave propagation simulations for longitudinal and shear excitations were performed to simulate tensile and shear fracture modes and the corresponding emitted waves. An interesting correlation between the experimental and numerical results exists, showcasing acoustic emission’s potential for fracture identification.

Identification of Tree-Related High-Impedance Earth Faults Based on Long-Term Fluctuations in Zero-Sequence Current

To address the challenge of accurately identifying tree-related high-impedance earth faults (THIEFs), a method based on long-term fluctuations in zero-sequence current is proposed. The analysis of the recorded data from staged tests in a real test network reveals the development patterns of THIEFs and their zero-sequence characteristics during the fault process. It was found that, over an extended duration, the fluctuation characteristics of the zero-sequence current RMS value curves for THIEFs differ significantly from those of the other types of high-impedance earth faults (HIEFs). By applying approximate arc length parameterization, the RMS value curve is standardized. The curvature standard deviation, the average curvature variation rate, and its standard deviation are used as feature parameters. An identification method based on an improved grey wolf optimization probabilistic neural network is constructed. Validation with staged test results demonstrates that the proposed method achieves a success rate of 97.5%, accurately distinguishing THIEFs from other types of HIEF.

The inter-trial and inter-session reliability of Theia3D-derived markerless gait analysis in tight versus loose clothing

Background Gait analysis is traditionally conducted using marker-based methods yet markerless motion capture is emerging as an alternative. Initial studies have begun to evaluate the reliability of markerless motion capture yet the evaluation of different clothing conditions across sessions and complete evaluation of the lower limb and pelvis reliability have yet to be considered. The aim of this study was to evaluate the inter-trial, inter-session and inter-session-clothing variation and root mean square differences between tight- or loose-fitting clothing during walking. Method Twenty-two healthy adult participants walked along an indoor walkway whilst eight video cameras recorded their gait in either tight- or loose-fitting clothing. A commercial markerless motion capture system (Theia3D) provided gait kinematics for evaluation. Results Reliability results showed average inter-trial variation of &lt;2°, inter-session variation of &lt;3° and inter-session-clothing variation &lt;3.5°. Root mean square differences (RMSD) between clothing conditions were &lt;2°. Discussion Pelvis variations were smaller than those at the hip, knee and ankle. Our results showed smaller variation than in previous studies which may be due to updates to software. The demonstration of the reliability of markerless motion capture for gait analysis in healthy adults should prompt further evaluation in clinical conditions and reconsideration of multi-assessor marker-based gait analysis protocols, where variation is highest.

Winter-spring droughts exacerbated PM2.5-O3 compound pollution? Evidence from China.

With the impact of global climate change, drought events are becoming more frequent, making it critically important to quantitatively evaluate the effects of these events on air pollution. This study uses the augmented synthetic control method and the mediation effect model to quantitatively evaluate the impact effect of the winter-spring drought of 2023 on PM2.5-O3 compound pollution and its driving factors with Chinese prefecture-level city data. This study indicates that: firstly, compared to non-drought periods, both the monthly averaged and diurnal variations pattern of PM2.5 and O3 significantly increased during drought periods. Secondly, the winter-spring drought of 2023 led to an average increase of 101.05μg/m3(28.14%) for PM2.5 and 153.74μg/m3(13.32%) for O3 in Yunnan Province, while the average increases in Guizhou Province were 25.71μg/m3(11.59%) and 23.95μg/m3(4.09%), respectively. Thirdly, the increase in temperature and the decrease in precipitation and relative humidity during the winter-spring drought were among the main driving factors for the increased risk of "double-high" PM2.5-O3 compound pollution. The article expands the research on the impact of abnormal weather events on atmospheric compound pollution, providing new insights for preventing compound pollution events in the context of abnormal weather.

Stable Soil Biota Network Enhances Soil Multifunctionality in Agroecosystems.

Unraveling how agricultural management practices affect soil biota network complexity and stability and how these changes relate to soil processes and functions is critical for the development of sustainable agriculture. However, our understanding of these knowledge still remains unclear. Here, we explored the effects of soil management intensity on soil biota network complexity, stability, and soil multifunctionality, as well as the relationships among these factors. Four typical land use types representing a gradient of disturbance intensity were selected in calcareous and red soils in southwest China. The four land use types with increasing disturbance intensity included pasture, sugarcane farmland, rice paddy fields, and maize cropland. The network cohesion, the network topological features (e.g., average degree, average clustering coefficient, average path length, network diameter, graph density, and modularity), and the average variation degree were used to evaluate the strength of interactions between species, soil biota network complexity, and the network stability, respectively. The results showed that intensive soil management increased species competition and soil biota network complexity but decreased soil biota network stability. Soil microfauna (e.g., nematode, protozoa, and arthropoda) stabilized the entire soil biota network through top-down control. Soil biota network stability rather than soil biota network complexity or soil biodiversity predicted the dynamics of soil multifunctionality. Specifically, stable soil communities, in both the entire soil biota network and selected soil organism groups (e.g., archaea, bacteria, fungi, arthropoda, nematode, protozoa, viridiplantae, and viruses), support high soil multifunctionality. In particular, soil microfauna stability had more contributions to soil multifunctionality than the stability of soil microbial communities. This result was further supported by network analysis, which showed that modules 1 and 4 had greater numbers of soil microfauna species and explained more variation of soil multifunctionality. Our study highlights that soil biota network stability should be considered a key factor in improving agricultural sustainability and crop productivity in the context of increasing global agricultural intensification.

Analysis of Climate Change Impacts on Water Resources in Harirod-Murghab River Basin

Climate change represents one of the paramount challenges confronting humanity today. The profound impacts of phenomena such as changes in precipitation patterns, global warming, polar ice melt, floods, and the onset of untimely and extreme temperatures worldwide have instilled a sense of urgency and concern. This critical issue has been placed at the forefront of climate change. To understand the ramifications of climate change on water resources within the Harirud-Marghab River basin, an analysis of average precipitation and temperature variations (including minimum, maximum, and average values) across different time frames (annual, monthly, seasonal, and during wet and dry seasons) has been conducted using data from hydrometeorological stations in the catchment area from 1979 to 2022. the non-parametric Mann-Kendall and PCI methods were chosen as the analytical tools. The findings reveal a notable decline in annual rainfall within the Harirud-Marghab River basin, with a pronounced reduction during the winter, the basin's primary water season. Conversely, an increase in seasonal rainfall has been observed in summer and autumn. Overall, rainfall in this river basin tends to be intense, occurring on limited days throughout the year. Furthermore, a significant rise in the annual average temperature has been documented, alongside fluctuations and changes in water flow across most stations within the basin. Consequently, the surface water resources of the Harirud-Marghab River basin have experienced a substantial decrease, amounting to approximately 29% of its capacity, equivalent to a reduction of 0.98 billion cubic meters of water.

Efficacy of tranexamic acid solution versus vitamin C solution after micro-needling in treatment of persistent post acne erythema: a split face clinical and 3DAntera camera comparative study.

Post acne erythema (PAE) is a common sequela of acne inflammation, and it refers to telangiectasia and erythematous lesions remaining after the acne treatment. Although some PAE may improve over time, persisting PAE might be esthetically undesirable for patients. The efficacy of various treatment options for PAE has been investigated in many studies but there exists no gold standard treatment modality. This current split face comparative study aimed to assess and compare the therapeutic efficacy of vitamin c solution 10% with microneedling versus Tranexamic acid solution (TXA) (50mg/ml) with microneedling in treating patients with PAE. Four sessions were held, two weeks apart. The assessment was done 2 weeks after the last session via change in Clinical Erythema Assessment (CEA) score, Antera 3D camera parameter changes (average hemoglobin level and hemoglobin variation), and patient satisfaction scale. Also, side effects were documented. Our study showed that both topical vitamin C and TXA solutions after microneedling showed significant decrease in hemi-CEA score and Antera camera measures of both Hb variations and average Hb levels. However, TXA treated side showed superior improvement than the side treated with vitamin c. Also, there was great patient satisfaction on both treated sides. The side effects reported were transient and minimal. Microneedling with TXA solution is a safe, effective and readily available modality of PAE treatment and showed superior results over vitamin C solution. Antera 3D camera is an excellent objective tool for assessing even minimal changes in Hb level and variation.

Technology for Pre-sowing Encapsulation of Ears Using Biodegradable Polymer Materials

The paper highlights that for enhancing technological processes in grain crop breeding, a method for protecting seed material was proposed, accompanied by the development of a device for sowing seeds with unthreshed ears. This approach improves labor productivity during sowing and ensures varietal purity. However, challenges, such as ear jamming in seeder mechanisms and reduced seed productivity per ear were identified. To address these issues, the use of biodegradable polymeric materials, including polyvinyl alcohol and polylactide, is proposed for encapsulating ears sown with a spikelet seeder. (Research purpose) The paper examines the impact of encapsulating Rima wheat ears with biodegradable materials on the quality of sowing using a spikelet seeder and on seed productivity indicators. (Materials and methods) Sowing quality was evaluated using the coefficient of variation of distances between adjacent ears. Seed productivity was evaluated based on stem growth and development using the laboratory-vegetative method, as well as by analyzing the dynamics of plant biochemical composition with infrared spectroscopy. (Results and discussion) The study found that the average variation coefficient during seeding with a spikelet seeder was 15.5 percent for untreated control samples, 11.3 percent, for ears treated with polyvinyl alcohol, and 9.7 percent for those treated with polylactide. For manual seeding, the variation coefficient of control samples averaged 13.1 percent. By the 19th day, plants grown from ear seeds treated with polyvinyl alcohol exhibited growth indices 7 percent higher than the control samples, while those treated with polylactide showed a 13 percent decrease. Biochemical analysis revealed that plants grown from seeds of ears treated with polyvinyl alcohol showed a 19.3 percent increase in water content, a 42.9 percent increase in fats, a 57.2 percent increase in carbohydrates, and a 21.6 percent decrease in protein content compared to the control samples. For plants grown from seeds of ears treated with polylactide, fat content increased by 44.5 percent and carbohydrates by 60.3 percent, while water content decreased by 59.7percent and proteins by 9.3%, compared to the control samples. (Conclusions) The study demonstrates that encapsulating ears with biodegradable materials such as polyvinyl alcohol and polylactide is a promising solution for enhancing the sowing and yield qualities of seeds in grain crop breeding. This technology reduces the coefficient of variation in adjacent ear spacing during sowing, increases plant height, and improves nutrient content. Among the materials studied, polyvinyl alcohol proved to be the most effective for seed breeding due to its superior properties

Study on Phenotypic Variation in Wild Populations of Prunella vulgaris

Objective: This study aimed to clarify the variation law of phenotypic traits such as the stem, leaf, flower, main branch ear and seed of Prunella vulgaris Linnaeus. (P. vulgaris), providing provide basic data support for protecting its wild germplasm resources. The phenotypic traits of stems, leaves, flowers, main branch ears and seeds of different wild populations of P. vulgaris were measured to reveal the phenotypic variation among and within populations of P. vulgaris, and to provide a scientific basis for the protection, utilization and collection of wild P. vulgaris germplasm resources. Methods: Variance analysis, coefficient of variation analysis, multiple comparison analysis, cluster analysis and principal component analysis were used to study the phenotypic traits of nine wild P. vulgaris populations in different regions of China. Results: The average phenotypic differentiation coefficient of nine traits was 52.04%. Inter-population variation was the main source of phenotypic variation of P. vulgaris. The average variation coefficient of each trait in the population was 21.25%, and the variation range was 15.02–28.94%. Pearson correlation analysis showed that there was a strong autocorrelation between phenotypic traits of wild P. vulgaris, and spikes and stems were greatly affected by environmental factors. According to the diameter of the stem and ear, nine wild P. vulgaris from different geographical populations could be divided into three groups. Group III (AHHS, JXFY) had the best phenotypic traits, and the traits of stem height, stem diameter, leaf length, leaf width and main branch ear length were the largest. The contribution rate of the three principal components screened by principal component analysis was 85.78%. Conclusions: We believe that the phenotypic differentiation among wild populations of P. vulgaris is at a medium level, and the variation within the population is smaller than that between populations, which may be an important reason for the sharp decline in the wild resources of P. vulgaris.

The Microfungal Communities in Deep-Sea Sediments from the Equatorial Atlantic

Microfungi of deep-sea sediments, and especially those several meters below the water–sediment interface, are poorly studied. In this work, for the first time, microfungal communities isolated by cultivation from deep-sea sediments of the eastern part of the Equatorial Atlantic (the Romanche and Chain Fracture Zones) were investigated. Fungi were isolated from sediments sampled at each of 12 stations from horizons 1.0–4.7 m below the sediment–water interface. To study microscopic fungi, one sediment horizon was isolated from each core. The fungal abundances were within the range of 0.0–3300.0 CFU g-1 sediment dry weight. A total of 19 fungal taxa from the phyla Ascomycota (18) and Basidiomycota (1) were identified, and Mycelia sterilia 1 strain was also isolated. Seven fungal species were encountered only once. In this case, the maximum similarity of species composition, in terms of the Bray – Curtis coefficient, was 57.14% (horizons 1.0 and 3.6 m, four common species). A comparison of the taxonomic structures of fungal communities from the study area was made with those from sediments of the Indian and Pacific Oceans and other areas of the Atlantic. The fungal communities from sediments in the study area were compared with those from the Indian and Pacific Oceans and other areas of the Atlantic. From the literature data and present study results, a list of fungal species with 180 names was compiled. The fungi belonged to 97 genera, 57 families, 32 orders and 13 classes of the phyla Ascomycota, Basidiomycota, and Mucoromycota. The diversity of fungal communities was assessed using indicators of taxonomic richness (number of taxa from different ranks), proportions (genera/families, species/families, species/genera), Average Taxonomic Distinctness index (AvTD, Δ+) and Variation in Taxonomic Distinctness index (VarTD, Λ+). Four and twelve fungal classes were identified in sediments in the Eastern Equatorial Atlantic and the Indian Ocean, respectively. The species/genera proportions in the communities varied from 1.33 (Indian Ocean) to 3.8 (other areas of the Atlantic Ocean). For the fungal communities of the Eastern Equatorial Atlantic, the AvTD index value was minimal (Δ+ = 50.19), the VarTD index was maximal (Λ+ = 945.38), and they were beyond the 95% confidence interval. This was due to the small number of the fungal classes and vertical and horizontal unevenness of species distribution along taxonomic branches, which was manifested in the dominance of species of the family Aspergillaceae (78.9% of the species in the class Saccharomycetes and Eurotiomycetes), only two species belonging to the classes Sordariomycetes and one species belonging to the class Microbotryomycetes (phylum Basidiomycota). Consequently, statistically significant differences were found between the taxonomic structures of the fungal communities of the Eastern Equatorial Atlantic and the other regions of the World Ocean, which are due to the insufficient amount of data obtained on the species composition of fungi in the sediments of this area. The study did not reveal any pattern in the change in the number of fungal species and their abundance in relation to the water characteristics (temperature, pH, and salinity), horizon depth in the sediment core, sediment type, or sampling station location in the Romanche and Chain Fracture Zones.

Clinical Characteristics of Patients With Proton Pump Inhibitor-refractory Globus.

Globus is often linked with gastroesophageal reflux disease, which influences its treatment strategies. This study aimed to investigate clinical characteristics of patients with refractory proton pump inhibitor (PPI) globus to better understand its etiology. Between 2017 and 2023, 123 out of 592 patients with Globus from the Samsung medical center outpatient clinic who were unresponsive to eight weeks of PPI treatment were analyzed. Patients underwent 24-hour esophageal pH monitoring and highresolution manometry (HRM). They were divided into acid reflux, non-acid reflux, and no reflux groups, with basal impedance (BI) measurements taken at 3, 9, and 15 cm along the esophagus. These values were compared against data of healthy volunteers to identify significant differences across groups. The acid reflux group displayed a median impedance of 1152 Ω at 3 cm, which was significantly lower than the median impedance of the non-acid reflux group (2644 Ω) and the no-reflux group (3083 Ω), highlighting varying degrees of reflux impact (P = 0.015). Most patients in non-acid reflux and no-reflux groups showed higher impedance levels at both 3 cm and 15 cm compared to the first quartile of healthy individuals with significant differences (P = 0.032 and P = 0.029, respectively). There was no notable difference in the average impedance variation between 3 cm and 15 cm in the no-reflux group (P = 0.540). Reduced proximal BI values compared to distal BI values suggest increased permeability in globus patients. Further studies with a larger cohort of refractory PPI patients and healthy volunteers are needed to explore these findings and their implications on globus etiology.

Study on the particle dynamic characteristics in a centrifugal pump based on an improved computational fluid dynamics-discrete element model

To accurately investigate the solid–liquid flow mechanisms within the pump, this study employs an improved Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach to examine the solid–liquid interactions in a centrifugal pump. First, the improved CFD-DEM is introduced, focusing on turbulence dissipation near the wall and velocity reconstruction. Then, a comparison is made between the CFD-DEM's performance before and after the enhancements. Finally, an analysis is conducted on how the dynamic characteristics of particles within the pump vary under different solid phase concentration conditions. The study revealed that the particle distribution from the corrected CFD-DEM aligns more closely with the experimental results. At a 2% concentration under the design conditions, the head error was reduced by 0.476%, while the efficiency error decreased by 0.076%. Additionally, as the solid phase concentration increased, there was a corresponding rise in the impact power loss of the particles, dissipative power loss, collision frequency, peak values of particle collisions, and the degree of overlap during these collisions. The comparison revealed that the pressure gradient force has the most significant impact on particle motion. As the pressure gradient force increases, the shear power dissipation of the particles also rises. For solid phase concentrations ranging from 1% to 4%, the average shear power variation during the computation period is between 4.28 × 10−6 W and 5.68 × 10−6 W. As the solid phase concentration increases, the volume fraction of the solid phase distribution on the component wall also gradually rises. These findings provide valuable insights for enhancing the accuracy of research on solid–liquid flow in centrifugal pumps.

The Dynamic Characteristics and Influencing Factors of Soil Respiration in Different Types of Grasslands in the Barkol Lake Basin

Determining regional and global carbon cycles hinges on investigating the dynamic characteristics and influencing factors of soil respiration in various types of natural grasslands located in arid regions, and these characteristics are important indicators for assessing the structural and functional health of grassland ecosystems. Such investigations also provide theoretical support for carbon sink monitoring, energy conservation, emission reduction and low-carbon development in the western arid zone and are important for obtaining an in-depth understanding of the carbon cycle, as well as for ecosystem management, restoration and the reconstruction of arid areas. In this study, during the growing season (from May to October) of 2022, the LI-8100A automated soil CO2 flux system was used to measure the soil respiration rate (Rs), temperature from 1.5 m above the surface to depths of 5–25 cm (T, T5, T10, T15, T20 and T25) and the soil moisture content (SM) at a depth of 20 cm in four types of grasslands: lowland meadow, alpine meadow, temperate desert steppe and temperate steppe desert. Five replicates were established for each plot, and the responses of Rs to T and SM were fitted to construct the optimal regression model. The results revealed that (1) the daily average soil respiration was highest in the lowland meadow (0.07 to 5.76 μmol·m−2·s−1), followed by the alpine meadow (−0.57 to 0.95 μmol·m−2·s−1), the temperate desert steppe (−0.45 to 3.0 μmol·m−2·s−1) and the temperate steppe desert (−1.29 to 1.61 μmol·m−2·s−1); (2) the soil respiration rates of the four grassland types were significantly correlated with the temperature in the 5–15 cm soil layer, and the best model was an exponential function; the peak values generally appeared between 13:00 and 17:00 (h), with the minimum values at 2:00 or 8:00 (h); the maximum value was observed in July–August, and the minimum value was observed in October; and the soil respiration in the lowland meadow was higher than that in the other three types of grassland during the same period. The average variation intensities of the soil respiration from May to October were as follows: temperate steppe desert (91.78%) &gt; temperate desert steppe (76%) &gt; alpine meadow (58.77%) &gt; lowland meadow (43.93%). (3) The partial correlation analysis revealed that when soil temperature was used as a control, the correlation between SM and soil respiration in the four types of grasslands changed, and the coefficient of determination (R2) increased to varying degrees, explaining up to 80% of the variation in the soil respiration in the lowland meadows. The correlation between soil respiration and the SM normalized to 10 °C explained up to 93.8% of the variation in soil respiration; the two-factor fitting equations revealed that the model with soil temperature and SM was superior to the single-factor model with either soil temperature or SM.

Late holocene vegetation succession and climate change in the Central Plains of China: Evidence from a high-resolution pollen record

Late holocene vegetation succession and climate change in the Central Plains of China: Evidence from a high-resolution pollen record

Spatio-Temporal Generalization of VIS-NIR-SWIR Spectral Models for Nitrogen Prediction in Sugarcane Leaves

Nitrogen fertilization is a challenging task that usually requires intensive use of resources, such as fertilizers, management and water. This study explored the potential of VIS-NIR-SWIR remote sensing for quantifying leaf nitrogen content (LNC) in sugarcane from different regions and vegetative stages. Conducted in three regions of São Paulo, Brazil (Jaú, Piracicaba and Santa Maria), the research involved three experiments, one per location. The spectral data were obtained at 140, 170, 200, 230 and 260 days after cutting (DAC). From the hyperspectral data, clustering analysis was performed to identify the patterns between the spectral bands for each region where the spectral readings were made, using the Partitioning Around Medoids (PAM) algorithm. Then, the LNC values were used to generate spectral models using Partial Least Squares Regression (PLSR). Subsequently, the generalization of the models was tested with the leave-one-date-out cross-validation (LOOCV) technique. The results showed that although the variation in leaf N was small, the sensor demonstrated the ability to detect these variations. Furthermore, it was possible to determine the influence of N concentrations on the leaf spectra and how this impacted cluster formation. It was observed that the greater the average variation in N content in each cluster, the better defined and denser the groups formed were. The best time to quantify N concentrations was at 140 DAC (R2 = 0.90 and RMSE = 0.74 g kg−1). From LOOCV, the areas with sandier soil texture presented a lower model performance compared to areas with clayey soil, with R2 &lt; 0.54. The spatial generalization of the models recorded the best performance at 140 DAC (R2 = 0.69, RMSE = 1.18 g kg−1 and dr = 0.61), decreasing in accuracy at the crop-maturation stage (260 DAC), R2 of 0.05, RMSE of 1.73 g kg−1 and dr of 0.38. Although the technique needs further studies to be improved, our results demonstrated potential, which tends to provide support and benefits for the quantification of nutrients in sugarcane in the long term.