Search Results (861)

Unsteady laminar pipe flows, prevalent in oscillating liquid columns, physiological pulsatile systems, and hydraulic transients, exhibit instantaneous velocity distributions that deviate significantly from the classical Hagen–Poiseuille parabolic profile. This deviation is governed by the interaction of inertial effects, viscous diffusion, phase lags, and localized flow reversal. Despite extensive documentation of these phenomena, a systematic framework for quantifying such morphological deviations remains largely undeveloped. This study proposes a suite of physically grounded indicators to quantify velocity profile distortion. These metrics characterize complementary aspects of non-Poiseuillean behavior, specifically: centerline curvature variation, profile flattening, energetic divergence, radial peak migration, reverse-flow fraction, and the emergence of inflection points. The methodology employs an analytical reconstruction of the local velocity field through a generalized Fourier–Bessel solution of the linearized Navier–Stokes equations, calibrated against experimental free-surface motion in a vertical U-tube undergoing damped oscillations. The application of these indicators demonstrates consistent correlations between geometric, energetic, and topological features during acceleration, deceleration, and flow-reversal phases. The findings indicate that no single parameter adequately captures the complexity of unsteady fields, but the integrated framework provides a robust classification of instantaneous flow regimes. This approach delineates the limitations of Poiseuille-based assumptions and establishes a quantitative foundation for advanced unsteady friction models. Full article

The quantitative characterization of microscopic pore structure has long been a challenge in reservoir evaluation for igneous reservoirs, owing to their pronounced heterogeneity and complex pore geometry. In this study, thin-section casting, X-ray diffraction, high-pressure mercury intrusion, nuclear magnetic resonance, and fractal theory were employed to investigate the reservoir-space types, pore-structure characteristics, and fractal features of the igneous rocks both quantitatively and qualitatively. The relationships among reservoir petrophysical properties, pore structure, movable-fluid saturation, and fractal dimension were examined. The results indicate that the reservoirs in the study area are characterized by medium-to-low porosity and medium-to-low permeability, with mean values of 6.57% and 2.06 mD, respectively; the storage performance of andesite was found to exceed that of tuff. Based on the morphology of the mercury intrusion curves and the petrophysical parameters, the reservoirs were classified into three categories. From Class I to Class III, the displacement pressure increased progressively, the movable-fluid saturation declined from 9.65% to 8.54%, and the heterogeneity was markedly enhanced. The fractal analysis revealed that the reservoirs exhibit distinct piecewise fractal behavior with a well-defined inflection point, allowing two fractal intervals to be distinguished: large pore-throats (D₁) and small pore-throats (D₂). The mean total fractal dimension was 2.8996, and the large pore-throat fractal dimension (mean = 2.9607) exceeded that of the small pore-throats (mean = 2.3863), indicating that large pore-throats serve not only as the principal contributor to reservoir space but also as the dominant control on heterogeneity. Correlation analysis demonstrated that D₁ is significantly negatively correlated with both porosity and permeability, making it a key indicator for evaluating reservoir flow capacity, whereas D₂ is positively correlated with petrophysical properties, reflecting the role of fine throats in improving the connectivity of isolated pores. Notably, the large-pore-throat fractal dimension (D₁) of these igneous reservoirs generally exceeds that of tight sandstone, whereas the small-pore-throat fractal dimension (D₂) is positively correlated with petrophysical properties rather than negatively, in contrast to sandstone reservoirs; this indicates that the pore-structure behavior of igneous reservoirs is distinct from that of conventional clastic reservoirs. This study offers a new perspective on the quantitative characterization of pore structure in igneous reservoirs and provides a scientific basis for reservoir evaluation and exploration-and-development efforts in the study area. Full article

Understanding the spatiotemporal relationship between agricultural inputs and crop production is essential for sustainable agricultural management. Using provincial panel data from China from 2000 to 2022, this study integrates spatiotemporal analysis with the XGBoost-SHAP model to examine the nonlinear effects of agricultural machinery, fertilizers, pesticides, and plastic films on soybean, cereal, and tuber yields. The results show that China’s agricultural input system shifted around 2015 from input-intensive growth toward green transformation, with fertilizer, pesticide, and plastic-film use declining after this inflection point. Spatially, agricultural inputs and crop production show clear agglomeration and path dependence: machinery is concentrated in northern China, fertilizers and pesticides in eastern intensive farming regions, and plastic-film use in arid and cold regions, while soybean, cereal, and tuber production are mainly concentrated in Northeast China, the Northeast-Huang-Huai-Hai region, and Southwest China, respectively. The SHAP results reveal distinct crop-specific importance rankings and nonlinear threshold patterns. For soybean yield prediction, agricultural plastic film use contributes most strongly to the model output, followed by fertilizer application, pesticide use, and machinery power; its SHAP contribution turns negative beyond approximately 112.4 thousand tons. For cereal yield prediction, machinery power ranks first, followed by fertilizer application, pesticide use, and plastic-film use; its contribution becomes positive beyond approximately 28.34 million kW and then gradually levels off. For tuber yield prediction, fertilizer application is the dominant predictor, followed by pesticide use, machinery power, and plastic-film use; its contribution turns negative beyond approximately 1.35 million tons. These findings indicate that agricultural inputs have crop-specific nonlinear effects, and that input regulation should prioritize the most influential factors for each crop while considering their threshold ranges. The study provides a scientific basis for differentiated, crop-specific, and regionally adaptive agricultural input management. Full article

Postharvest quality deterioration of Korla fragrant pear (Pyrus sinkiangensis Yu) severely constrains its market value, yet the regulatory role of preharvest soil management in shaping postharvest performance remains poorly understood. Although green manure is widely adopted to ameliorate orchard soil degradation, species-specific modulation of postharvest storage trajectories and the quantitative fidelity of soil-to-fruit nutrient transmission have rarely been resolved for climacteric pear species. This study investigated how green manure species modulate fruit quality at harvest and during postharvest storage life and their underlying soil–fruit linkages. Three preharvest treatments were imposed, as follows: control (CK), sweet clover (CM), and alfalfa (MX). Fruits were harvested and stored at 4 °C, with samplings at 1, 5, 10, 15, and 20 d. A critical quality transition was identified at 15 d, characterized by the concurrent peaking of soluble sugars, organic acids, vitamin C, and anthocyanins alongside an optimal sugar–acid ratio. Beyond this inflection point, CM and MX diverged markedly: CM enhanced soluble sugar accumulation, anthocyanin retention, and ester volatile production—most notably hexyl acetate, which increased over 14.4-fold—thereby generating a pronounced fruity aroma bouquet. Conversely, MX sustained higher amino acid and vitamin C levels and conferred superior late-storage stability, evidenced by a three-fold lower coefficient of variation in the sugar–acid ratio relative to CK. Partial-least-squares structural equation modeling (PLS–SEM) revealed soil fertility as the principal exploratory associative factor of fruit quality, but the fidelity of soil-to-fruit transmission was species-dependent. MX exhibited the highest observed associative strength (R² = 0.971), whereas CM exhibited attenuated transmission fidelity (R² = 0.777), with network analysis further indicating that CM exhibited divergent associative patterns of key soil–fruit correlations. These findings suggest that green manure identity is linked to postharvest quality through divergent soil–fruit coupling pathways: alfalfa shows nutrient transmission efficiency and stabilizes nutritional quality, whereas sweet clover promotes sugar-aroma accumulation at the cost of reduced soil–fruit conversion fidelity. Species-specific green manure selection thus offers a viable strategy for targeted modulation of postharvest traits in Korla fragrant pear. Full article

Background: Respiratory failure (RF) is a frequently fatal complication of chronic liver disease (CLD), yet population-level data on RF-related mortality trends among adults with CLD are lacking. This study characterized temporal trends and demographic disparities in RF-related mortality among U.S. adults with CLD from 1999 to 2024. Methods: Death certificate data were obtained from the CDC WONDER database for adults aged ≥25 years with both RF (ICD-10: J96) and CLD (ICD-10: K70–K76) listed as an underlying or contributing cause of death. Age-adjusted mortality rates (AAMRs) per 100,000 were calculated using the 2000 U.S. standard population. Joinpoint regression identified temporal inflection points and annual percentage change (APC). Results: Among 241,075 deaths, the overall AAMR increased 3.2-fold from 2.237 (1999) to 7.162 (2021) per 100,000, then declined to 6.132 by 2024. Joinpoint analysis identified four segments: moderate increase (1999–2006; APC +2.40%), accelerated increase (2006–2018; APC +5.37%), late acceleration period (2018–2021; APC +13.10%), and post-pandemic decline (2021–2024; APC −4.32%; all p < 0.001). The 2024 AAMR remained 174.2% above baseline. The male-to-female rate ratio narrowed from 2.02 to 1.50, with females showing steeper acceleration (+14.38% vs. +12.36%). American Indian or Alaska Native individuals had the highest AAMRs and the most dramatic surge (APC +26.90%). Rural areas surpassed urban AAMRs by 2020, with steeper post-2007 acceleration (+8.74% vs. +5.51%). The Western U.S. consistently had the highest regional rates. Younger adults aged 25–34 and 35–44 showed 2.96-fold and 2.37-fold increases in crude mortality rates, respectively. Approximately 80% of deaths occurred in inpatient settings. Conclusions: RF-related mortality among U.S. adults with CLD increased more than threefold from 1999 to 2021, with a dramatic surge followed by incomplete decline. Persistent disparities by sex, race/ethnicity, urbanization, and region highlight the need for targeted interventions, including expanded screening for alcohol-associated and metabolic liver disease and improved access to hepatology services in underserved communities. Full article

Planar linkage mechanisms remain a cornerstone of motion generation and trajectory control, yet the geometric tools that desRcribe their instantaneous behavior, namely centrodes and Bresse’s circles, have been developed almost exclusively for mechanisms with entirely revolute joints, where a sliding pair fundamentally alters the velocity and acceleration fields and disrupts the symmetries on which classical curvature theory relies. This paper presents a comprehensive higher-order kinematic analysis of a planar six-link, single-degree-of-freedom mechanism in which a slider-crank stage and a rocker stage are coupled through a shared prismatic joint that acts simultaneously as output and input. Using vector algebra and a matrix-based loop-closure formulation, the position, velocity, and acceleration analyses are derived in closed form, yielding angular velocity ratios, the instantaneous centers of rotation and acceleration of both coupler links, and their inflection and stationarity circles. The analysis reveals a distinctive geometric constraint on the slider-side coupler’s instantaneous center, a decoupling of the curvature loci of the two couplers, and degenerate configurations, linked to coupler instantaneous-stop and rocker dead-point conditions, that arise at joint-invariant crank angles. Implemented as a computational algorithm and demonstrated on a carton flap-closing mechanism and cross-validated against independent multibody simulation, the framework confirms favorable transmission and dead-point clearance behavior, extending curvature-theory tools to linkages containing sliding pairs. Full article

Background/Objectives: Rapid and accurate ketone detection is clinically valuable for both diabetic and non-diabetic individuals. Breath acetone represents an attractive non-invasive and real-time alternative for monitoring ketones. This study aimed to explore the correlation between breath acetone measured by proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) and ketone bodies in blood and urine in individuals with normoglycemia, prediabetes and diabetes. Methods: A total of 4000 participants were recruited. Urinary ketone levels, blood β-hydroxybutyrate (βHB) concentrations, and breath acetone (measured by PTR-TOF-MS) were assessed. Participants were classified into urine ketone-negative and urine ketone-positive groups. They were further divided according to the semiquantitative degree of urinary ketone (−, +, ++, +++ and ++++). Spearman rank correlation analysis was performed to evaluate the relationship between breath acetone and blood βHB. Receiver operating characteristic (ROC) curve analysis was conducted to determine the preliminary thresholds of breath acetone for detecting blood βHB positivity. Multiple linear regression, including a quadratic term for blood βHB, was performed, and the inflection point of the curve was calculated. Results: Blood βHB and breath acetone were significantly higher in the urine ketone-positive group than in the urine ketone-negative group (p < 0.001). A progressive elevation in blood βHB and exhaled breath acetone concentrations was observed with increasing urinary ketone levels (p < 0.001). The Spearman rank correlation coefficient between breath acetone and blood βHB was 0.493, 0.522, 0.379, and 0.636 in the general population, normoglycemia, prediabetes, and diabetes groups, respectively (all p < 0.001). The preliminary thresholds of breath acetone concentration for detecting blood βHB positivity were 2.37 ppmv in diabetes, 1.10 ppmv in prediabetes, and 2.05 ppmv in normoglycemia, respectively. Blood βHB exhibited a significant quadratic association with breath acetone in the general population, normoglycemia, and diabetes (B = −1.698, −1.409, and −16.070, respectively; p < 0.001), with inflection points of the quadratic curves at 2.73 mmol/L, 3.28 mmol/L and 1.61 mmol/L, respectively, whereas in prediabetes, the relationship did not significantly deviate from linearity. Conclusions: In normoglycemia and diabetes, breath acetone based on PTR-TOF-MS exhibited an inverted U-shaped relationship with blood βHB, while in prediabetes, breath acetone showed a linear positive correlation with blood βHB. In populations where blood βHB is below the quadratic inflection point, breath acetone measured by PTR-TOF-MS holds promise as a non-invasive ketone-monitoring tool. Full article

The paper deals with a finite element analysis (FEA) of the occurrence of an inflection point in the power loss vs. torque curve of permanent magnet synchronous machines (PMSM), related to optimal torque distribution in multi-motor all-wheel drive electric vehicles. Simplified, analytical power-loss models of the electric motor suggest that the power loss curve is convex, and consequently, the equal front/rear torque distribution is optimal. On the contrary, experimental studies usually point to a non-convex power loss curve containing an inflection point, which leads to more complex torque distribution laws. With the aim of explaining the experimentally observed effects, a first-principle, FEA approach is applied to PMSMs of different types (interior vs. surface permanent magnets, IPM vs. SPM) and different vector control strategies (maximum torque per ampere vs. maximum efficiency). Additionally, the impact of vehicle transmission losses on the power loss curve inflection point occurrence is analyzed. The results demonstrate that in the IPM motors, the inflection point occurs more readily than in the SPM motors due to the greater reluctance torque capabilities, which can strongly saturate the q-axis even under flux-weakening conditions, thus creating a highly nonlinear iron loss torque dependency. Also, the rising transmission efficiency vs. torque curve contributes to the occurrence of an inflection point. Full article

Mycotoxin contamination of cereal crops poses escalating food safety risks across the Central and Balkan European (CBE) corridor under climate change, yet no PRISMA 2020-compliant synthesis of remote sensing (RS) and machine learning (ML) evidence for this region exists. We conducted an AI-augmented systematic review applying a four-stage automated pipeline—PICO domain scoring, SBERT semantic deduplication, and Thompson-sampling reinforcement learning—to 36,038 corpus records (2010–2025), yielding 156 included studies (inter-rater κ = 0.81 (95% CI: 0.74–0.88)). Logistic growth modelling identified a 56-fold corpus expansion with inflection at t₀ = 2024.8 (R² = 0.981). Satellite multispectral imaging dominated the literature (91.7% of studies); random forest and gradient boosting models achieved R² = 0.74–0.80 for aflatoxin B1 and deoxynivalenol prediction in CBE maize and wheat when integrating vegetation indices, land surface temperature, and precipitation covariates. Deep learning surpassed classical ML in annual study count from 2021, reaching ~60% relative share by 2025, though the performance advantage narrows at field scale relative to laboratory hyperspectral benchmarks (98–99% accuracy). A five-percentage-point CBE–global performance gap is largely consistent with differences in sample size and multi-toxin design scope rather than algorithmic access. The country × mycotoxin gap matrix identifies zero eligible studies for four CBE nations and for T-2/HT-2 toxins across the Balkan states. Climate-driven satellite mycotoxin prediction emerges as the field’s active research frontier. Full article

With the construction of transportation networks in mountainous areas under the Western Development Strategy, double-row pile foundations on slopes have been widely applied. However, due to the distortion of the soil stress field, their load distribution mechanism under bidirectional loading is extremely complex. To investigate the internal force distribution laws and deformation and failure modes, a systematic study was conducted utilizing theoretical derivation: 60 scale indoor physical model tests, and 3D refined finite element numerical simulations. The results show that the force distribution of double-row piles in slope environments differs significantly: the upper-row piles, affected by active earth pressure and sliding thrust, bear significantly higher load than the lower-row piles; meanwhile, the lower-row piles, constrained by stronger deep soil, can more fully utilize their vertical bearing capacity. Parametric analysis indicates that the terrain slope has a nonlinear amplification effect on the displacement difference at the pile top, with 50° being the critical mutation slope that triggers the failure of connection joints. In addition, the deformation mode of double-row piles undergoes a change when the pile spacing exceeds 5 times the pile diameter. Therefore, in practical engineering design, the traditional concept of symmetrical reinforcement should be abandoned in favor of differentiated bending reinforcement targeting the shallow surface layer of the upper-row piles and the deep inflection point of the lower-row piles. For working conditions with a slope greater than 50°, additional measures such as prestressed anchor cables must be applied to reduce the sliding load. Meanwhile, the row spacing should be strictly controlled within 5 times the pile diameter to fully ensure the diaphragm effect and the overall synergistic stability of the structure. Full article

Reservoir conformance control is a necessary production measure in the oil field, which significantly impacts the efficiency of enhanced oil recovery (EOR). Polymers, hydrophobic associating polymers (HAPs), polymer microgels (MGs), and preformed particle gel (PPG) are typical polymer/gel dispersion fluids that are widely used as conformance control agents. Currently, there is still no combined conformance control method to realize the equilibrium production of the reservoir. This paper first evaluates the reservoir adaptability of polymers, HAPs, and MGs by the three-parallel core displacement experiments. Then, the displacement equilibrium factor (DEF) was established by comprehensively considering the profile improvement, oil increment, and oil recovery to optimize the fluid switching time. Based on the above oil displacement experiments, a scatter plot of the DEF with respect to the ultimate recovery of each layer can be plotted, which has an inflection point when the DEF is 45%. When the DEF is lower than 45%, the difference in the oil displacement effect of each layer is enhanced. Therefore, the best time to switch the injection fluid is when the DEF is reduced to 45%. Finally, based on the above results, a graph guiding the combined conformance control method under different reservoir variation coefficients and reservoir median permeability was established, and an equilibrium production method for heterogeneous reservoirs was developed. The five-parallel core flooding experiments with the DEF < 45% as the switching guidance can increase the oil recovery by 17.79% based on association polymer flooding, which is 9.68% higher than that of the conventional conformance control method. This paper can provide theoretical and experimental support for the optimal design of conformance control in oilfields. Full article

Background: Cardiovascular disease and mortality are common outcomes of cardiovascular–kidney–metabolic (CKM) syndrome. The integrated role of metabolic dysfunction and frailty, quantified by the triglyceride–glucose–frailty index (TyG-FI), remains insufficiently explored. This study examined the association between TyG-FI and incident composite outcomes among participants with CKM stages 0–3. Methods: Data were obtained from two large cohort studies conducted in China and the United States. The analysis focused on participants classified as CKM stages 0–3. Cox proportional hazards models were used to estimate the relationship between TyG-FI and incident composite outcomes. Nonlinear associations were explored using spline functions. Additional analyses were performed across different subgroups and under varied assumptions. Model performance over time was also assessed. Results: Significant differences in outcome incidence were observed across TyG-FI levels. Higher quartiles showed a gradual increase in risk and displayed a dose–response pattern, with inflection points at 1.01 and 2.29. Associations were consistent across subgroups, and TyG-FI demonstrated moderate discrimination (AUCs 0.714 and 0.744). Conclusions: In the CHARLS and HRS cohorts, higher TyG-FI scores were independently associated with an increased risk of incident composite outcomes among participants with CKM stages 0–3, with a nonlinear relationship observed. Its discriminatory power was moderate, suggesting that TyG-FI may serve as a supplementary indicator for risk stratification in the early to mid-stages, although its clinical predictive value requires further validation. Full article

Rice production in flooded paddy systems must increasingly balance grain productivity with greenhouse gas (GHG) efficiency. This study evaluated two GroMore^® crop-protection program variants under two nitrogen input levels in a temperate Korean paddy field to determine whether these treatments could improve yield-scaled climate performance without compromising grain yield. Heading date was identical across all treatments, indicating that treatment effects were not attributable to phenological shifts. Grain yield ranged from 6.87 Mg ha⁻¹ in the conventional treatment to 9.88 Mg ha⁻¹ in GroMore-Duo N90. GroMore-Star N90 maintained high yield (9.05 Mg ha⁻¹) with the lowest greenhouse gas intensity (GHGI; 0.69 kg CO₂-eq kg⁻¹ grain) and reduced cumulative methane emission by 10.6% relative to the conventional treatment. Logistic analysis showed that the GroMore treatments reached the methane-accumulation inflection point earlier than the control and conventional treatments. GroMore-Duo N90 and GroMore-Star N90 reached this point at approximately 69 days after transplanting, whereas the control and conventional treatments reached it at 86 and 89 DAT, respectively. Overall, the GroMore programs were associated with differences in yield components and yield-scaled climate performance under flooded paddy conditions without changing crop phenology. Full article

Arid regions are ecologically fragile and occupy a substantial portion of the global terrestrial surface. In these regions, ecosystem services (ESs) are strongly constrained by water availability and, more importantly, by the balance between water supply and demand. However, the nonlinear responses and threshold mechanisms linking water supply–demand balance to ES dynamics remain unclear. Taking the Kubuqi Desert in the “Great Bend” of the Yellow River as the study area, this study quantified the Comprehensive Ecosystem Service Index (CESI) and the Water Supply–Demand Ratio (WSDR) by integrating the InVEST model, RWEQ model, the RUSLE model, Water Balance Method, and so on. The dual-constraint line method and elasticity coefficient approach were integrated to identify the constraint effects and critical thresholds of WSDR on CESI. Ecological management zones were further delineated by integrating the inflection-point intervals of the dual-constraint lines with the threshold intervals identified by elasticity coefficients. The results showed that CESI remained relatively low, with a maximum value of approximately 0.5, suggesting that the overall ES level was still limited, but exhibited a continuous increasing trend. The regional water supply–demand pattern gradually shifted from deficit toward relative balance, although agricultural water use still accounted for about three-quarters of total consumption. CESI showed a nonlinear threshold response to WSDR: mild water deficit suppressed CESI growth, whereas moderate water surplus promoted CESI recovery by alleviating water constraints and improving ecosystem functioning. Thresholds identified by elasticity coefficients mainly occurred near critical transitions between water deficit and surplus. Based on ES supply and threshold sensitivity, nine ecological management zones were identified, with priority enhancement areas accounting for approximately 75%. These findings provide a threshold-based basis for ecological zoning and differentiated restoration in arid regions. Full article

Background: Sepsis remains one of the leading causes of hospital morbidity and mortality worldwide. While its epidemiology has been extensively investigated, the chronobiology of sepsis—the temporal patterns underlying its occurrence and outcomes—has received comparatively little attention, despite its potential relevance for anticipating clinical demand and optimizing healthcare resource allocation. Objective: To analyze trends in the epidemiology and chronobiology of hospital admissions for sepsis across a large healthcare region in Spain over a 21-year period. Design: Retrospective observational study based on clinical–administrative records. We included all patients ≥ 18 years who had a principal diagnosis of sepsis or septic shock admitted between 2001 and 2021, identified through ICD-9-CM and ICD-10-CM coding in the Spanish National Hospital Discharge Records Database. Annual incidence, in-hospital mortality, and temporal distribution of admissions and deaths were assessed. Joinpoint regression was used to evaluate trends, Fourier spectral analysis to identify dominant rhythms, and multi-harmonic cosinor models to test for circannual rhythmicity. Results: We identified 39,622 sepsis admissions. Hospital incidence increased significantly over time (annual percent change [APC]: +9.6%; p < 0.001), with two inflection points (2008 and 2014). In-hospital mortality decreased linearly from 42.1% in 2001 to 31.9% in 2021 (p < 0.001), despite a progressive increase in patient age. Chronobiological analyses revealed no significant circannual rhythm in incidence or mortality (cosinor p = 0.14), although mortality was disproportionately clustered in winter months (p < 0.001). In multivariable analyses, clinical and epidemiological variables were independent predictors of in-hospital mortality. Conclusions: Over the last two decades, sepsis incidence has risen steadily, whereas hospital mortality has declined. Although no regular biological rhythm was demonstrated, excess winter mortality suggests extrinsic seasonal influences. This study provides novel evidence by jointly examining the epidemiology and chronobiology of sepsis, and supports their integration into healthcare planning strategies. Full article