U-shaped Distribution Research Articles

Gender trends in orthopedic surgical residency programs in Canada over 20 years.

Gender disparities exist in several surgical specialties, particularly in orthopedic surgery. The purpose of this study was to determine the current trends in gender diversity among orthopedic surgical residents in Canada over the last 20 years. We analyzed gender distribution data for orthopedic trainees from the Canadian Resident Matching Service (CaRMS) for 2013-2022 and the Canadian Post-MD Education Registry for 2000-2022 using linear and quadratic regressions. More male (4.7%) than female medical students (1.9%) applied to an orthopedics program (p < 0.001). The proportion of male applicants entering CaRMS who applied to orthopedics followed a quadratic (U-shaped) distribution over time (p = 0.01). The proportion of female applicants remained unchanged from 2013 to 2022 (p > 0.9). However, for matching results, among the applicants who applied to orthopedic surgery, there was no gender effect (men 56.1% matched, women 50.3% matched; p = 0.3). The proportion of residency spots offered to female applicants remained at around 30%, without significant changes over time (p = 0.1). The number of female orthopedic graduates increased linearly from 2000 to 2021 (p < 0.001), projected to reach gender equalization (at 50%) by 2060. Female residents experienced higher attrition in residency (3.4%) than male residents (2.1%; p = 0.05), and this gender difference is decreasing over time (p = 0.03). Over 2 decades, women have shown consistently lower rates of application to orthopedic surgery programs than their male colleagues. Women who matched experienced higher attrition rates than men, although this appears to be improving over time.

A Local Adversarial Attack with a Maximum Aggregated Region Sparseness Strategy for 3D Objects.

The increasing reliance on deep neural network-based object detection models in various applications has raised significant security concerns due to their vulnerability to adversarial attacks. In physical 3D environments, existing adversarial attacks that target object detection (3D-AE) face significant challenges. These attacks often require large and dispersed modifications to objects, making them easily noticeable and reducing their effectiveness in real-world scenarios. To maximize the attack effectiveness, large and dispersed attack camouflages are often employed, which makes the camouflages overly conspicuous and reduces their visual stealth. The core issue is how to use minimal and concentrated camouflage to maximize the attack effect. Addressing this, our research focuses on developing more subtle and efficient attack methods that can better evade detection in practical settings. Based on these principles, this paper proposes a local 3D attack method driven by a Maximum Aggregated Region Sparseness (MARS) strategy. In simpler terms, our approach strategically concentrates the attack modifications to specific areas to enhance effectiveness while maintaining stealth. To maximize the aggregation of attack-camouflaged regions, an aggregation regularization term is designed to constrain the mask aggregation matrix based on the face-adjacency relationships. To minimize the attack camouflage regions, a sparseness regularization is designed to make the mask weights tend toward a U-shaped distribution and limit extreme values. Additionally, neural rendering is used to obtain gradient-propagating multi-angle augmented data and suppress the model's detection to locate universal critical decision regions from multiple angles. These technical strategies ensure that the adversarial modifications remain effective across different viewpoints and conditions. We test the attack effectiveness of different region selection strategies. On the CARLA dataset, the average attack efficiency of attacking the YOLOv3 and v5 series networks reaches 1.724, which represents an improvement of 0.986 (134%) compared to baseline methods. These results demonstrate a significant enhancement in attack performance, highlighting the potential risks to real-world object detection systems. The experimental results demonstrate that our attack method achieves both stealth and aggressiveness from different viewpoints. Furthermore, we explore the transferability of the decision regions. The results indicate that our method can be effectively combined with different texture optimization methods, with the average precision decreasing by 0.488 and 0.662 across different networks, which indicates a strong attack effectiveness.

Hemogram-Based Phenotypes of the Immune Response and Coagulopathy in Blunt Thoracic Trauma.

Background: Blunt thoracic trauma possesses unique physiopathological traits due to the complex interaction of immune and coagulation systems in the lung tissue. Hemogram-based ratios such as neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR), neutrophil-to-lymphocyte × platelet (NLPR) ratios have been studied as proxies for immune dysregulation and survival in trauma. We hypothesized that blunt thoracic trauma patients exhibit distinct patterns of coagulation and inflammation abnormalities identifiable by the use of readily available hemogram-derived markers. Methods: The present study represents a retrospective observational analysis that included 86 patients with blunt thoracic trauma from a single high-volume level one trauma center. The primary outcome was mortality prediction in blunt thoracic trauma patients using these derived biomarkers. Secondary outcomes included phenotypes of the immune response and coagulopathy and the prediction of non-fatal adverse events. Results: A U-shaped distribution of mortality was found, with high rates of early deaths in patients with an NLPR value of <3.1 and high rates of late deaths in patients with NLPR > 9.5. A subgroup of blunt thoracic trauma patients expressing moderate inflammation and inflammation-induced hypercoagulation objectified as NLPR between 3.1 and 9.5 may have a survival benefit (p < 0.0001). The NLPR cut-off for predicting early deaths and the need for massive transfusion was 3.1 (sensitivity = 80.00% and specificity = 71.05%). Conclusions: These findings suggest that blunt thoracic trauma patients exhibit distinct phenotypes of the immune response and coagulopathy from the early stages. A controlled, balanced interaction of immune, coagulation, and fibrinolytic systems might effectively achieve tissue repair and increase survival in thoracic trauma patients and should be subject to further research.

Does obesity matter in patients receiving venoarterial extracorporeal membrane oxygenation? The U-shaped relationship between body mass index and mortality after extracorporeal cardiopulmonary resuscitation

BackgroundThe impact of obesity on the prognosis of patients receiving venoarterial extracorporeal membrane oxygenation remains unclear. This study examines the association between body mass index and in-hospital mortality among patients on venoarterial extracorporeal membrane oxygenation support. MethodsThis retrospective study enrolled adult patients who received venoarterial extracorporeal membrane oxygenation support, which included extracorporeal cardiopulmonary resuscitation, at National Taiwan University Hospital between 2010 and 2021. Patients were classified as follows: underweight (body mass index <18.5), normal weight (18.5≤ body mass index <24), overweight (24≤ body mass index <27), class I obesity (27≤ body mass index <30), class II obesity (30≤ body mass index <35), and class III obesity (body mass index ≥35). Multivariable Cox regression with spline models was employed. ResultsThe study included 1,329 patients; of these, 670 underwent extracorporeal cardiopulmonary resuscitation, and the overall mortality rate was 61.6%. Multivariable Cox regression revealed that class III obesity was significantly associated with higher mortality (hazard ratio 2.11, 95% confidence interval 1.48–3.02, P = .001), particularly in the extracorporeal cardiopulmonary resuscitation subgroup (hazard ratio 2.71, 95% confidence interval 1.71–4.29, P < .001). No significant association was observed in the non–extracorporeal cardiopulmonary resuscitation subgroup (hazard ratio 1.29, 95% confidence interval 0.70–2.36, P = .415). Although underweight patients initially exhibited higher mortality (hazard ratio 1.77, 95% confidence interval 1.12–2.80, P = .015), this effect was attenuated after adjusting the confounders (hazard ratio 1.46, 95% confidence interval 0.91–2.35, P = .119). Kaplan-Meier analysis indicated that class III obesity was associated with the highest in-hospital mortality, followed by the underweight group (log-rank P = .009). ConclusionObesity increased mortality in patients who underwent venoarterial extracorporeal membrane oxygenation, but this was primarily due to a nonlinear U-shaped distribution between body mass index and in-hospital mortality observed in patients receiving extracorporeal cardiopulmonary resuscitation. Further studies are needed to clarify the causal factors underlying these associations.

Initial blood pressure and adverse cardiac events following acute ischaemic stroke: An individual patient data pooled analysis from the VISTA database.

Adverse cardiac events following ischaemic stroke (stroke-heart syndrome, SHS) pose a clinical challenge. We investigated the association between initial blood pressure at stroke presentation and the risk of SHS. We utilised data from the Virtual International Stroke Trials Archive (VISTA). We defined SHS as the incidence of cardiac complications within 30 days post-ischaemic stroke. These presentations included acute coronary syndrome encompassing myocardial injury, heart failure/left ventricular dysfunction, atrial fibrillation/flutter, other arrhythmia/electrocardiogram abnormalities, and cardiorespiratory arrest. Using Cox proportional hazards models, we assessed the risk trajectories for developing SHS and its presentations associated with initial blood pressure. We also explored the risk trajectories for 90-day mortality related to initial blood pressure. From 16,095 patients with acute ischaemic stroke, 14,965 (mean age 69 ± 12 years; 55% male) were analysed. Of these, 1774 (11.8%) developed SHS. The risk of SHS and initial blood pressure showed a U-shaped relationship. The lowest blood pressures (⩽130 mmHg systolic and ⩽55 mmHg diastolic) were associated with the highest risks (adjusted hazard ratio [95%confidence interval]: 1.40 [1.21-1.63]; p < 0.001, 1.71 [1.39-2.10]; p < 0.001, respectively, compared to referential blood pressure range).Cardiorespiratory arrest posed the greatest risk at higher blood pressure levels (2.34 [1.16-4.73]; p = 0.017 for systolic blood pressure >190 mmHg), whereas other presentations exhibited the highest risk at lower pressures. The 90-day mortality risk also followed a U-shaped distribution, with greater risks observed at high blood pressure thresholds. There is a U-shaped relationship between initial blood pressure at ischaemic stroke presentation and the risk of subsequent SHS.

Characteristics and Drivers of Soil Carbon, Nitrogen, and Phosphorus Ecological Stoichiometry at the Heavy Degradation Stage of the Alpine Meadow

An in-depth understanding of the soil nutrient status and balance relationship can help the effective recovery and management of alpine degraded meadows. In order to study the balance relationship among soil carbon, nitrogen, and phosphorus nutrients during the heavy degradation stage of meadows, field sampling and investigation, indoor analysis, and mathematical statistics were used to explore the characteristics and driving factors of changes in soil carbon, nitrogen, and phosphorus content, storage, and ecological stoichiometry during the heavy degradation stage of alpine meadows in the Sanjiangyuan region. The results showed that in the heavy degradation stage, miscellaneous grass plants occupied absolute dominance, soil C∶N∶P was approximately 32.83∶3.87∶0.67, and there was certain nitrogen limitation. The coefficients of variation of soil carbon, nitrogen, and phosphorus content were in the following order： organic carbon （1.09） &gt; total nitrogen （0.63） &gt; total phosphorus （0.29）. The organic carbon content and the carbon and nitrogen ratio showed a significant linear decreasing trend with the increase in the grassland degradation index （GDI）, while the total phosphorus content and organic carbon storage showed a significant non-linear change, in which the total phosphorus content showed a significant gentle U-shaped distribution, and the organic carbon storage decreased more gently at the beginning of the heavy degradation stage and then decreased sharply when the GDI was 57.9. The results of Mantel correlation analysis showed that the soil carbon to nitrogen ratio, carbon to phosphorus ratio, and nitrogen to phosphorus ratio showed significant correlation with organic carbon content and storage and total nitrogen storage. The results of structural equation modeling indicated that soil water content had direct effects as well as indirect through vegetation factors, soil carbon, nitrogen, and phosphorus ecological stoichiometry ratios, and soil water content and vegetation factors （height, cover, and biomass） were key environmental factors affecting soil ecological stoichiometry. The research results can provide scientific basis and practical guidance for the restoration of heavily degraded grassland in alpine meadows.

U-Shaped Distribution Guided Sign Language Emotion Recognition With Semantic and Movement Features

U-Shaped Distribution Guided Sign Language Emotion Recognition With Semantic and Movement Features

A METHOD OF SIMULATING SEAT LOAD FOR NUMERICAL ANALYSIS OF WOOD CHAIR STRUCTURE

This study aimed to investigate the characteristic values of the human-seat interface in a normal sitting posture, and to numerically mode the load on the chair seat for the structural design of chairs. The stress distributions and the characteristic values of seat were measured under normal sitting posture by using a human body pressure distribution measurement system considering the effects of gender and body mass index (BMI). The stress distribution on the seat was then numerically modeled using three modeling methods. The observed results and the numerical analysisresults were compared. The results showed that an inverted U-shaped pressure distribution was observed in normal sitting posture. The stress was concentrated on the ischial tuberosity with a maximum value of 0.066 MPa. The ratio of the load on the seat to the gravity of the human body weight was about 65.3%. The numerical model established using the body pressure mapping method was superior to those of the uniform load method and the standard loading pad method in terms of stress distribution, maximum stress, and contact area.

Healthcare contact days for people with stage IV non-small cell lung cancer (NSCLC) in Ontario: A population-based study

BackgroundSurvival is limited with advanced NSCLC, and frequent healthcare visits can become all-consuming. We investigated patterns of contact days—days with any in-person healthcare contact as a measure of potential time toxicity—in a population-based sample. MethodsWe created a population-based, retrospective cohort with health administrative data from Ontario, Canada, of adults with stage IV NSCLC in 2014-2017, dying 2014-2019. The primary outcome was contact days assessed from diagnosis to death. We stratified analyses by receipt, type and lines of systemic therapy administered. We plotted and fitted with cubic splines the weekly percentage of contact days to obtain trajectories over the disease course. ResultsWe identified 5,785 stage IV NSCLC patients. The median (interquartile range [IQR]) survival was 108 days (49-426), and median percentage of contact days was 33.3%. Patients receiving systemic treatment had longer median survival (261 [152-420] vs. 66 [34-130] days) and lower median percentage of contact days (22.2% vs. 40.9%). Overall and for subgroups (systemic therapy vs. not; type and lines of therapy), trajectories followed a U-shaped distribution, with highest rates immediately following diagnosis and prior to death. The difference between the maximal peak and trough was greater in patients who received systemic therapy (peak 34.8% vs. trough 15.9%, ""deeper U"") vs. not (39.5% vs. 27.6%, ""shallower U""). ConclusionStage IV NSCLC patients spent a significant proportion of days alive with healthcare contact. These data serve as a call to recognize patient time burdens, improve care efficiency, and better support patients during periods of high burden.

Pattern and change of NDVI and their environmental influencing factors for 1986–2019 in the Qinling-Daba Mountains of central China

Previous studies have shown that climate change and human activities play an important role in the vegetation dynamics in the Qinling-Daba Mountains of central China. However, which environmental factors including climate, topography, soil and human activities play an important role in the vegetation dynamics and its spatial pattern in the Qinling-Daba Mountains remains to be further clarified. Based on the normalized difference vegetation index (NDVI) data of the growing season from 1986 to 2019 synthesized by Landsat series satellite data on Google Earth Engine, this study aimed to further investigate the spatial pattern of NDVI and its dynamics, and clarify its environmental controlling factors in the Qinling-Daba Mountains using the methods of spatial analysis and Geodetector. The results showed that: (1) the spatial pattern of NDVI in the study area had a U-shaped NDVI distribution in latitude, anti-U-shaped patterns in longitude and with increasing altitude. (2) 2005 was the year of NDVI breakthrough increase, and the vegetation dynamics was divided into two periods according to the result of MK mutation test: the slow increasing period with an increasing rate of 0.25%/a from 1986 to 2004 (R2 0.74), and the rapid increasing period with an increasing rate of 0.30%/a from 2005 to 2019 (R2 0.92). (3) Topography regulating local hydrothermal conditions and soil enriching nutritions played more important influence on NDVI spatial pattern than climate factors (temperature and precipitation) at the regional scale. The effect of land use on NDVI change was stronger than that of climate warming (temperature), and the climate warming in recent decades played a more important role than precipitation on the NDVI dynamics. Research on vegetation patterns, changes and their environmental influencing factors will help the government and other related agencies to formulate plans or policies for infrastructure development and land management, ecological restoration.

The age-related incidence of male genital lichen sclerosus is triphasic.

Male genital lichen sclerosus (MGLSc) is a chronic and acquired inflammatory dermatosis associated with substantial sexual dysfunction and urological morbidity and mortality. The age incidence of MGLSc is held to be biphasic, with a peak in infancy and another in adulthood. A recent review has implied two peaks in adulthood (making it triphasic overall); this triphasicity has been our emergent clinical impression from a voluminous practice. Furthermore, a link between MGLSc and smoking has been suggested, but this has not been our clinical impression. The primary objective was to clarify the age-specific incidence of adult men with GLSc; the secondary objective was to explore the relationship between MGLSc and smoking. We retrospectively reviewed the medical notes of 487 adult MGLSc patients from a large specialist male genital dermatology clinic. We abstracted data about the age of diagnosis and smoking history. A biphasic U-shaped age distribution was identified with two clear peaks at the end of the third decade and another in the sixth decade of life (Hartigan's dip-stat=0.03; p<0.01). Thirty-six percent of the patients had been smokers at some point in their lives. These findings confirm that MGLSc is biphasic in its adult incidence, confirming an earlier supposition; including the previously well-acknowledged paediatric peak, it is thus triphasic. The smoking data are probably unremarkable compared with the available data for smoking habits from the United Kingdom. These findings indirectly support what is postulated about the likely pathogenesis of MGLSc, that is, urinary micro-incontinence, occlusion and epithelial susceptibility.

Local Transition of Electron Pitch Angle Distribution within Flux Pileup Region behind Dipolarization Front

Dipolarization fronts (DFs), earthward-propagating magnetic transients with a strong magnetic field, are important regions favorable for energetic electron acceleration in the magnetotail. The DF-driven electron acceleration usually generates coherent pitch angle distributions (PADs) inside flux pileup regions (FPRs), i.e., strong magnetic field regions behind the DFs, such as pancake, butterfly, and cigar distributions, which dominate at different tail regions and often occur separately. Here we present unique observations of electron PAD evolution inside the FPR, showing that electron PAD underwent local transition from cigar distribution, to butterfly distribution, then toward pancake distribution, forming a U-shaped distribution. During the local transition, electron perpendicular flux (relative to the local magnetic field) is anticorrelated with magnetic field strength, contrary to traditional expectation. The unexpected feature of the electron U-shaped distribution is associated with multiple physical processes at different scales, including local expansion of flux tubes and pitch angle variation near the neutral sheet. These atypical observations can advance our current understanding of electron acceleration and transport in the magnetosphere.

Effects of pore characteristics on CO2 adsorption performance of coal slime with different metamorphic degrees

With the rapid development of Carbon Capture, Utilization and Storage (CCUS) technology, it is necessary to explore the feasibility of coal slime as a porous carbon material for CO2 capture. In this paper, scanning electron microscopy (SEM) was used to observe the morphological characteristics of coal slime samples with different metamorphic degrees, and the pore structure of coal slime was explored by low temperature N2 adsorption and low-pressure CO2 adsorption experiments. The pore distribution characteristics were analyzed, and the adsorption law of different metamorphic degrees were summarized through CO2 isothermal adsorption experiments. The results showed that: The specific surface area (SSA) and pore volume (PV) of the mesopores of the coal slime exhibited a U-shaped distribution with coal rank, and are much smaller than that of its micropores. Micropores less than 2 nm are the main adsorption space of coal slime, its PV accounted for 59%, 60%, 71%, and SSA accounted for 92%, 93%, 95%, obviously, which are dominant at all stages. The linear correlation fitting coefficients R2 between the limiting adsorbed amount a of CO2 and the micropores PV and the SSA were up to 0.830 and 0.887, respectively. The coal slime has good adsorption performance for CO2. Based on the Langmuir model to fit the limit adsorption amount, a-value can reach 41.774 cm3 g−1, 32.072 cm3 g−1, 38.457 cm3 g−1 at 303 K with the increase of Rmax. Studying the impact of coal slime on CO2 adsorption performance provides a theoretical basis for the subsequent preparation of energy storage materials and is of great significance for the safe, efficient and economic capture and sequestration of CO2, to alleviate the serious situation of the environment and realizing the dual-carbon goal.

Research on Water Ecological Resilience Measurement and Influencing Factors: A Case Study of the Yangtze River Economic Belt, China

Industrial development and population expansion has had serious negative impacts on the water ecological environment, and enhancing water ecological resilience (WER) has become a new sustainable development goal. Current research on WER is mostly about ecological resilience assessment including water systems. In order to explore the WER of the Yangtze River Economic Belt (YREB), ecological resilience and water ecology were combined to form the concept of WER. Based on the “social-ecological” resilience perspective, a DCSMI (Driving Force—Carrying Capacity—State—Management—Innovation) WER evaluation index system was constructed, which consists of five subsystems. The WER of the YREB from 2011 to 2022 was measured by using game-theoretic combination weights and the comprehensive evaluation method, which were then combined with the kernel density (KD) estimation, the Thiel index, and the center of gravity-standard deviation ellipse (SDE) method to reveal the WER differences and spatial evolution characteristics of the YREB. Finally, the key factors influencing WER were explored using the BP-DEMATEL model. It was found that (1) the average value of WER in the YREB has declined from 0.4562 to 0.4442, the polarization of WER is obvious, the overall gap is on a widening trend, and the gap between different basins is the main reason for the differences in WER in the YREB. (2) The WER of the YREB presents an asymmetric U-shaped distribution pattern with the downstream optimal, upstream medium, and midstream worst, and the spatial evolution presenting a northwestern–southeastern pattern. (3) The key factors of the top-ranked provinces in the WER index are concentrated in the layer of the State (S) indicators, the middle-ranked provinces and the back-ranked provinces are more influenced by the Driving Force (D) and the Carrying Capacity (C) indicators, respectively, and the Management (M) and Innovation (I) indicators are distributed in several provinces. These results can provide theoretical support for the construction of “resilient cities” and water ecology optimization in the YREB.

Disease burden of stroke and its subtypes attributable to low dietary fiber in China, 1990–2019

This study aimed to assess the current status and changing trends of the disease burden of stroke and its subtypes due to low dietary fiber intake in China from 1990 to 2019. In cases of stroke and its subtypes attributable to low dietary fiber, deaths, disability-adjusted life-years (DALYs), age-standardized mortality rates (ASMR), age-standardized DALYs rates (ASDR), and percentage change were used to assess disease burden. Data were obtained from the 2019 global burden of disease study. Trends were assessed using Joinpoint regression and age-period-cohort analysis. Between 1990 and 2019, there was a declining trend in stroke and its subtypes, ASDR and ASMR, as well as the corresponding number of deaths and DALYs, due to low dietary fiber intake in China. Subarachnoid hemorrhage (SH) showed the greatest decrease, followed by intracerebral hemorrhage (IH) and ischemic stroke (IS). Local drift curves showed a U-shaped distribution of stroke, IS, and IH DALYs across the whole group and sex-based groups. For mortality, the overall and male trends were similar to those for DALYs, whereas female stroke, IH, and IS showed an upward trend. The DALYs for stroke and IH showed a clear bimodal distribution, IS showed an increasing risk with age. For mortality, the SH subtype showed a decreasing trend, whereas other subtypes showed an increasing risk with age. Both the period and cohort rates of stroke DALYs and motality due to low dietary fiber have declined. Males had a higher risk of DALYs and mortality associated with low fiber levels. The burden of stroke and its subtypes associated with a low-fiber diet in China has been declining over the past 30 years, with different patterns of change for different stroke subtypes and a higher burden for males, highlighting the differential impact of fiber intake on stroke and its subtypes.

Angle-of-attack characteristics of opposing jet for improving drag and heat reduction

While the opposing jet technique has the potential to achieve efficient drag and heat reduction, it can be severely affected by the incoming angle of attack. To analyze the angle-of-attack characteristics of opposing jet for improving drag and heat reduction, a three-dimensional blunt model was studied under various jet stagnation pressure ratios and angles of attack using the verified numerical method. The results showed that the enhanced reattachment shock on the windward side resulted in a higher pressure and temperature rise, which led to the deterioration of drag and heat reduction. Under the influence of the incoming angle of attack, the recirculation vortex transformed into a longitudinal vortex, resulting in a slanted U-shaped distribution of the surface pressure coefficient and Stanton number. Increasing the jet stagnation pressure ratio widened the coverage of the recirculation vortex on both the windward and leeward sides, which brought an improvement in drag and heat reduction. The interaction between the incoming angle of attack and the opposing jet caused a double-peak distribution of Stanton number due to the recirculation vortex reattachment and the compression of the incoming flow. The inclined opposing jet could reduce the peak values of pressure coefficient and Stanton number when subjected to the incoming flow with an angle of attack by spreading the recirculation vortex along the windward side. There should exist an optimal inclination angle that can effectively reduce the peak caused by the compression of the incoming flow without generating an excessive peak due to the recirculation vortex reattachment.

Study on heat transfer characteristics and enhancement mechanism of supercritical carbon dioxide in adaptive channels

Supercritical CO2 power cycles have promising applications in many fields, the heat transfer of supercritical CO2 is critical to the efficiency and safe operation of cycle system. The adaptive channel was previously proposed by our group to improve heat transfer of supercritical CO2, the performance of heat exchanger with adaptive channel was experimentally studied. Whereas the effect of adaptive channel on heat transfer deterioration of supercritical CO2 and the mechanism remain unclear. In this study, the effect of adaptive channel on heat transfer deterioration of supercritical CO2 and the mechanism are analyzed numerically based on a single channel, the effect of structure on heat transfer is analyzed through the maximum wall temperature and average heat transfer coefficient under the same length and heat transfer area. The results reveal adaptive channel is effective at alleviating heat transfer deterioration with no local peak in wall temperature distribution. The channel variation length of adaptive channel need to be increased from 0.4 to 0.8 with the aggravation of heat transfer deterioration in order to eliminate local wall temperature peak. For the heat transfer deterioration conditions, the maximum wall temperature lowers first and then increases as channel variation length increases, there is a length that makes the maximum wall temperature lowest, which is lowered by more than 40 °C compared with straight channel. The average heat transfer coefficient can be increased by 1.1 ∼ 1.5 times as channel variation length increases. For the no heat transfer deterioration conditions, the maximum wall temperature increases about 30 °C whereas average heat transfer coefficient can be increased by 58 %∼76 % with channel variation length increasing. The mechanism of adaptive channel alleviating heat transfer deterioration is as follows: the fluid velocity always presents an inverted U-shaped distribution along the radial direction in adaptive channel, the radial density difference is less and buoyancy effects heat transfer weakly. The turbulent kinetic energy is kept at high, so the heat near the wall is transferred to the main flow timely.

&lt;Note&gt;Male chimpanzee age affects red colobus monkey hunting success

We used data collected from 1976 to 2010 in Mahale, Tanzania, to explore longitudinal changes in red colobus hunting throughout the life histories of individual male chimpanzees. The relative frequency (z-scores) of successful red colobus hunts by male chimpanzees exhibited an inverted U-shaped distribution with age. Hunting success increases when males are between 8–20 years old. Males in adulthood (20–35 years of age) made the highest number of kills. After 39 years of age, male chimpanzees were not observed to kill red colobus monkeys. These results were discussed in terms of their implications for understanding changes in the social status of male chimpanzees over time.

Measuring Public Preferences for Strategic Choices in an Era of Great Power Competition: Taiwan as a Case Study

As the U.S.–China relationship tilts toward competition and confrontation, scholars and policymakers have focused on the strategic choices faced by the citizens of small and medium-sized countries caught between the two great powers. However, methodological deficiencies remain in how public preferences for these strategic choices are measured. This paper attempts to fill this gap by developing a new means of measuring public opinion regarding strategic choices. Using survey data collected in Taiwan in March 2023, we demonstrate how this measure is constructed and why it aligns more closely with the theoretical concept of strategic choices. Our findings indicate that preferences for different strategies in Taiwan follow a U-shaped distribution that is centered either on hedging with the United States or with China. Multivariate analyses show that factors such as the threat of China, the U.S. security commitment to Taiwan, skepticism toward the United States, confidence in Taiwan’s military, and partisanship are all correlated with public preferences for different strategies. This paper helps us understand these preferences among citizens in small and medium-sized countries and contributes to the literature on public opinion, international relations theory, and policymaking.

A damage constitutive model of layered slate under the action of triaxial compression and water environment erosion

Based on the macroscopic structure control theory, The slate with a significant bedding plane is a composite rock mass composed of rock blocks containing microscopic defects, joint surface closure elements, and shear deformation elements. Considering the coupling damage effect of water erosion and triaxial compressive load on bedding structure plane, the transversely isotropic damage constitutive model of slate under triaxial compressive load is derived with the dip angle of bedding and confining pressure as the variable. Firstly, based on the statistical theory of continuous damage mechanics and the maximum tensile strain criterion, the transversely isotropic deformation constitutive model of rock block with micro-defects is given; Secondly, based on the phenomenological theory of closed deformation and shear-slip deformation mechanism of layered structural plane under the coupling action of water erosion and triaxial compression load, the calculation formula of axial deformation of layered structural plane under the coupling action is given; Finally, to verify the accuracy of the established constitutive model, triaxial compression tests are carried out to study the influence of dip angle and confining pressure on the macroscopic mechanical properties and mechanism of slate. The results show that: the established triaxial compression damage constitutive model of bedding slate can accurately describe the stress–strain relationship of bedding slate after water environment erosion. With the increase of bedding dip angle, the strength and deformation capacity of the bedding slate first decreases and then increases, showing a U-shaped distribution as a whole. There are three main types of failure: tension shear composite failure, shear slip failure, and splitting tension failure.