Area Contraction Research Articles

Mathematical Models on Mechanics of Biofluids

In this work, we study the mathematical models of flows for some biofluids. In biomechanics, peristaltic flow plays an important role in which the motion generated in the fluid contained in a distensible tube when a progressive wave of area contraction and expansion travels along the wall of the tube. We consider the effect of elasticity of the tube wall in the flow through the progressive wave travelling along its length without its direct calculation. Since the no – slip condition has used on a moving undulating wall surface, it determines the sinusoidal boundary conditions on the upper and lower wall of the tube. The wide occurrence of peristaltic motion gives its result physiologically from neuro-muscular properties of any tubular smooth muscle.

Barley vulnerability to climate change: perspectives for cultivation in South America.

Barley (Hordeum vulgare) is a globally significant cereal crop, widely used in both food production and brewing. However, it is particularly vulnerable to climate change, especially extreme temperature fluctuations, which can severely reduce yields. To address this challenge, a detailed climate zoning study was conducted to assess the suitability of barley production areas across South America, considering both current conditions and future climate scenarios from the Intergovernmental Panel on Climate Change (IPCC). The study utilized historical climate data along with projections from the CMIP6 IPSL-CM6A-LR model for the period 2021-2100. Several indices, such as evapotranspiration, were calculated, and factors like soil composition and topography were integrated into the classification of regions based on their agricultural potential. Critical variables in this assessment included temperature, precipitation, and water or thermal excess. The results showed that 6.59% of South America's territory is currently suitable for barley cultivation without additional irrigation, with these regions concentrated primarily in temperate southern areas. In contrast, 18.62% of the region is already unsuitable due to excessive heat. Projections under future climate scenarios indicate a shrinking of suitable areas, alongside an expansion of unsuitable regions. In the worst-case scenario, only 1.48% of the territory would remain viable for barley farming. These findings emphasize the crop's vulnerability to climate change, underscoring the urgency of developing agricultural adaptation strategies. The predicted contraction in suitable barley cultivation areas demonstrates the profound impact of climate change on agriculture and highlights the need for proactive measures to ensure sustainable barley production in South America.

Differences in left ventricular contraction in left bundle branch block with preserved and reduced ejection fraction: an evaluation using 2-dimensional speckle tracking echocardiography

Abstract Background Left ventricular (LV) contraction in left bundle branch block (LBBB) is characterized by early septal contraction and delayed contraction of the lateral wall, but the process may differ depending on myocardial contractility in addition to the degree of conduction block. Purpose This study aimed to evaluate LV contraction in patients with LBBB by analysis of longitudinal strain (LS) and to compare it between patients with preserved LV ejection fraction (pEF: EF>50%) and reduced LV EF (rEF: EF<40%). Methods We studied 87 patients with LBBB. Fifty had pEF (EF 59±7%) with a mean QRS duration of 144±12ms, and 38 had rEF (EF: 29±4%) with a mean QRS duration of 147±12ms (p=0.32 vs. pEF). We also studied 43 patients without conduction block (Narrow-QRS; pEF, n=23; rEF, n=20). Patients with a heart rate less than 60 or greater than 80 beats/min during echocardiography or with a history of myocardial infarction were excluded. Three standard apical images were recorded, and the LS of one heartbeat starting at the beginning of the QRS was evaluated in 18 LV segments. When the strain waveform showed a negative peak during the pre-ejection period, it was identified as early systolic contraction (ESC), and the first negative peak that appeared after aortic valve opening (AVO) was identified as late systolic contraction (LSC). The time from the beginning of QRS to the peak of the LSC (Q-Peak) and the strain value at the end of the QRS were measured in each segment. Results In patients with LBBB, the septum contracted early, and ESC was seen mainly in the early contracted area. The lateral wall contraction was delayed, and the difference between the maximum and minimum Q-Peak was greater than the Narrow-QRS in the same EF category. Patients with rEF and LBBB had a larger number of segments with ESC and a smaller minimum Q-Peak than those with pEF. The difference between the maximum and minimum Q-Peak was greater for patients with rEF than for patients with pEF. Conclusions Although patients with LBBB had significant dyssynchrony due to conduction block even those with pEF, LV contractile properties were altered in patients with rEF and associated with further increased dyssynchrony.

The effects of SGLT2 inhibitors on right ventricle functions in heart failure patients: update meta-analysis of the current literature

Abstract Background There is some discrepancy in the present studies concerning the effect of sodium-glucose cotransporter type 2 (SGLT2) inhibitors on right ventricular (RV) functions in heart failure (HF) patients. The current meta-analysis was focused on determining the impact of SGLT2 inhibitors on RV functions in such individuals. Methods Two independent investigators searched PubMed, Google Scholar, and the Cochrane Library for articles of interest. To analyze heterogeneity, Higgins' I2 as well as prediction intervals and Egger's test were utilized to assess heterogeneity. The Newcastle-Ottawa standard ratings approach was used to assess the quality of observational studies. The Robin-I risk of bias algorithm was used to assess the bias risks of randomized studies. Results This meta-analysis evaluated 8 studies in total. Over the follow-up time frame, patients who used SGLT-2 inhibitors had substantially lower systolic pulmonary artery pressure (sPAP) and higher TAPSE values (mean difference (MD) = 1.30 [0.78;1.82], p =0.002 and MD =-5.39 [-7.88; -2.89], p=0.003, respectively). There was no significant difference in RVS’ values between follow-up and baseline (MD=1.38 [-1.35;3.80], p=0.169). However, as compared to the baseline period, fractional area contraction (FAC) values were substantially larger at the end of the follow-up period (MD=5.40 [3.74;7.07], p=0.015). Conclusion To the best of our knowledge, this is the first meta-analysis assessing the impact of SGLT2 inhibitors on RV function in HF patients. Our findings suggest that SGLT2 inhibitors may improve RV performance in HF patients.

Bio-inspired circular soft actuators for simulating defecation process of human rectum.

Soft robots have found extensive applications in the medical field, particularly in rehabilitation exercises, assisted grasping, and artificial organs. Despite significant advancements in simulating various components of the digestive system, the rectum has been largely neglected due to societal stigma. This study seeks to address this gap by developing soft circular muscle actuators (CMAs) and rectum models to replicate the defecation process. Using soft materials, both the rectum and the actuators were fabricated to enable seamless integration and attachment. We designed, fabricated, and tested three types of CMAs and compared them to the simulated results. A pneumatic system was employed to control the actuators, and simulated stool was synthesized using sodium alginate and calcium chloride. Experimental results indicated that the third type of actuator exhibited superior performance in pressure generation, enabling the area contraction to reach a maximum value of 1. The successful simulation of the defecation process highlights the potential of these soft actuators in biomedical applications, providing a foundation for further research and development in the field of soft robotics.

Economic analysis of shipping route planning in deep-sea mining operations under uncertain shipping market

Deep-sea mining is an emerging interdisciplinary and cross-domain research topic. As commercialization of deep-sea mining advances, economic analysis of the maritime transportation of minerals is critical to forming sound commercial plans. This paper proposes an approach for the economic analysis of shipping route planning in deep-sea mining operations, considering the varying capacities of the proposed mobile offshore minerals units (MOMUs) and the limited capacity. Capital expense (CAPEX), operational expense (OPEX), and voyage expense (VOYEX) are taken into account according to the arrangement of mineral transportation vessels (MTVs) with different capacities of MOMUs and fluctuating shipping prices. Monte Carlo Simulation is used to analyze the uncertainties of the total cost for MTVs with respect to CAPEX, OPEX, and VOYEX. A case study of the shipping route from the Chinese contract area in the Clarion-Clipperton Zone to Ningbo-Zhoushan Port is presented to interpret the proposed approach. The derived results demonstrate that 120,000 tons is the most economically viable MOMU size, saving at least 1.9 % of the total cost. These savings are mainly due to better scheduling, speed, and resilience to market prices. The proposed approach can support economic feasibility for deep-sea mining projects and provide investors with more specific operational measures to make well-informed decisions.

Near-Infrared Stimuli-Responsive Hydrogel Promotes Cell Migration for Accelerated Diabetic Wound Healing.

Diabetic wound healing including diabetic foot ulcers is a major clinical challenge, which could bring an increased level of mortality and morbidity. However, conventional wound dressings exhibit limited healing efficacy due to their lack of active modulation for the healing process. Here, a near-infrared (NIR) stimuli-responsive composite hydrogel dressing with the synergistic effect of both mechanical contraction and epithelial-mesenchymal transition (EMT) was developed to facilitate cell migration and vascularization for diabetic wound healing. In the methacrylated gelatin-based composite hydrogel, N-isopropylacrylamide and polydopamine nanoparticles were incorporated to endow the composite hydrogel with thermosensitive and photothermal properties. Linagliptin (LIN) was loaded into the composite hydrogel, and the drug release rate could be controlled by NIR laser irradiation. NIR-triggered on-demand active contraction of wound area and LIN release for biological stimulation were potentially realized in this responsive system due to the thermally induced sol-gel transition of the composite hydrogel. The release of loaded LIN could effectively promote cell migration by activating EMT and enhancing angiogenesis. In the full-thickness skin defect model, the LIN-loaded composite hydrogel with NIR laser irradiation had the highest wound closure rate as compared with the pure hydrogel and LIN-loaded hydrogel groups. Therefore, this composite hydrogel can serve as an excellent platform for promoting wound healing and will find more practical value in clinical treatment.

GERENCIAMENTO DE RISCOS NO PLANEJAMENTO DAS LICITAÇÕES E CONTRATOS PÚBLICOS

Recent legislative changes in the area of public bidding and contracts, especially the guidelines implemented by Normative Instruction SEGES/MPDG Nº. 05/2017, established a new regime for contracting outsourced services in the Brazilian legal system. This new instrument aims to expand the dispute, in compliance with the principle of competitiveness, resulting in the expansion of the supplier market. IN Nº. 05/2017 establishes the rules and guidelines for the procedure for contracting services under the indirect execution regime within the scope of the Direct, autarchic and foundational Federal Public Administration. The regulation establishes innovative phases: Contracting Planning; Supplier Selection; and Contract Management. The Planning phase consists, according to the IN, of 3 stages: Preliminary Studies; Risk Management; and Terms of Reference or Basic Design. This paper aims to present a Risk Management Plan, developed in the planning phase of contracting a bidding process in the Electronic Auction for Price Registration modality. According to the PMBOK® Guide Sixth Edition p. 395, project risk management includes the processes of conducting planning, identification, analysis, response planning, implementation of responses and monitoring of risks in a project. The objective is to maximize exposure to positive events and minimize exposure to negative events. In this context, through causes, consequences, categories and SWOT analysis, 75 risks were identified. Risk management processes were used in accordance with the PMBOK® doctrine and the Pareto Principle to prioritize 25 risks.

Towards a sustainable future in the age of polycrisis

Our generation lives in an age of polycrisis. Polycrisis is a phenomenon where various single crises interact in ways that lead to an overall negative impact that is more significant than the sum of each issue. The age of polycrisis poses a considerable threat to humanity. Since the age of polycrisis results from human actions, humans are responsible for addressing it. As such, an ultimate roadmap and in-depth sustainability transformations are needed across all sectors. This raises a quest for a unified social contract that can engage everybody to promote the well-being of people and the planet locally, regionally, and globally. Our paper explores a holistic picture of a social transformation process to address the challenges of the age of polycrisis. We put together a new social contract, different actors (civic society, private sector, public sector, decision-makers), and specific focus areas of actors to implement the goals of Agenda 2030. Each societal sector has a unique role to play in this transformation. The private sector can drive innovation and investment, the public sector can provide governance and regulation, civic society can advocate for change and hold other sectors accountable, and decision-makers can provide leadership and coordination. A new social contract called “Society’s Commitment to Sustainable Development” can foster societal transformation towards sustainability with the involvement of these different societal sectors. The widespread commitment of public and private sectors as well as civil society can be an effective driver when implementing Agenda 2030 goals to build a more sustainable future. We, the current generation, have power to make a difference regarding international collaboration, national decision-making, industries, households – even down to the choices we make in our everyday lives. The future is shaped by the decisions we make today.

Effect of hydrocolloid-nitric oxide wound dressings on wound healing in dogs.

To determine the rates of wound healing in surgically created wounds between nitric oxide releasing wound dressings and control wound dressings. Prospective, controlled, randomized experimental study. Purpose-bred, adult, male Beagles (n = 6). Four 2 × 2 cm wounds were surgically created on the trunk of each dog with each wound randomized to treatment with a nitric oxide wound pad (NP), nitric oxide wound gel (NG), plain hydrocolloid wound dressing (HC), or Telfa pad (T). Wound images were taken daily for 8 days then every other day until day 21 with images masked and randomized for evaluation. Total wound area, contraction percentage, and days until granulation were calculated. Time to first appearance of granulation tissue was significantly shorter for NP (3.2 days) than for NG (4 days; p = .023), HC (4.5 days; p = .001), and T (5.2 days; p < .0001). There were significant differences in total wound area and contraction percentage between sites and treatments (p < .001). Total wound area for NG was lower than treatment T (0.7 ± 0.1 cm3; p < .001), HC (0.9 ± 0.1 cm3, p < .001), and NP (0.6 ± 0.1 cm3, p < .001). Use of a nitric oxide wound dressing resulted in faster wound healing as evidenced by lower total wound area and higher contraction in the NG group and faster time to granulation tissue development in the NP group. Nitric oxide wound dressings are innovative and inexpensive products that can significantly decrease the amount of time and cost necessary for open or second intention wound resolution in dogs.

Spatio-temporal Pattern of Ecosystem Service Value Evolution in the Yihe River Basin in the Context of Land Use Change

In this study, the modified equivalent factor method was applied to account for the long time series ecosystem service value （ESV） of the Yihe River Basin from 1975 to 2020 in the context of land use change, and the cold hot spot analysis and topographic position analysis methods were introduced to explore the characteristics of its spatial pattern. The results showed that： ① From 1975 to 2020, the land use type of the Yihe River Basin was dominated by arable land, and the land use changes were characterized by the rapid decrease of arable land and the continuous expansion of construction land, a slight increase in the area of forest land and grassland, a contraction of the water body area, and little change in the area of unused land. ② The modified equivalent factor method was more suitable for accounting for the ESV in the basin. From 1975 to 2020, the overall ESV of the basin showed an upward spiral trend （33.369-33.816 billion CNY）, dominated by the regulating services. The ESV of arable land was the highest with a decreasing trend, whereas the ESV of unused land was the lowest. ③ In the horizontal spatial pattern, the hot spot of ESV was near mountains and reservoirs, and the cold spot of ESV was near urban areas. In terms of vertical spatial patterns, with growing topographic gradient, vertical changes in ESV for all land use types showed an increasing trend followed by a decreasing trend. The results of the study revealed the spatial and temporal patterns of ecosystem service values in the Yihe River Basin in the context of land use change and provide a scientific basis for optimizing the land use structure and spatial pattern and enhancing ecosystem services.

Changing Pattern and Drivers of Land Use and Land Cover in Bagmati Province of Nepal

Land use and land cover (LULC) represents the physical component of the Earth's environment, and often changes as a result of natural and anthropogenic activities. This study carried out changing patterns and orientations of LULC types of Bagmati province of Nepal by using satellite images between 1996 and 2016. The study applied a classification scheme through support vector machines (SVM) for the period from 1996 to 2006, and 2006 to 2016. Our study explored that built-up area expansion was the major change witnessed which increased from 85.25 km2 in 1996 and sharply increased and labeled 250.06 km2 in 2016. Similarly, the forest land of the province increased by 329.02 km2 between 1996 and 2016. The status of cultivated land was found slightly decreasing trend, which was noted at 6113.50 km2 in 1996 and labeled at 5725.82 km2 in 2016. The shrubland of the province declined by 272.03 km2 from 1851.67 km2 in 1996 to 1579.64 km2 in 2016. However, the status of snow/ ice cover found at fluctuated form, which was noted 774.27 km2 in 1996, 1297.43 km2 in 2006, and 828.92 km2 in 2016. The increasing population trend is the main driver of the high rate of built-up area expansion and contraction of the cultivated land. Community forestry programs highly supported the expansion of forest cover. The proper implementation and improvement of the existing policy are the major concerns for sustainable LULC management in the province.

Evaluation of the environmental factors influencing the quality of Astragalus membranaceus var. mongholicus based on HPLC and the Maxent model

BackgroundIn recent years, global climate change in tandem with increased human activity has resulted in habitat degradation or the migration of rare medicinal plants, potentially impacting the quality of medicinal herbs. Astragalus membranaceus var. mongholicus is a valuable bulk medicinal material in Northwest China. As the demand for this medicinal herb continues to increase in both domestic and international markets, ensuring the sustainable development of high-quality Astragali Radix is important. In this study, the maximum entropy (Maxent) model was applied, thereby incorporating 136 distribution records, along with 39 environmental factors of A. membranaceus var. mongholicus, to assess the quality zonation and potential distribution of this species in China under climate change.ResultsThe results showed that the elevation, annual mean temperature, precipitation of wettest month, solar radiation in June, and mean temperature of warmest quarter were the critical environmental factors influencing the accumulation of astragaloside IV and Astragalus polysaccharide in A. membranaceus var. mongholicus. Among the twelve main environmental variables, annual mean temperature, elevation, precipitation of the wettest month, and solar radiation in November were the four most important factors influencing the distribution of A. membranaceus var. mongholicus. In addition, ecological niche modelling revealed that highly suitable habitats were mainly located in central and western Gansu, eastern Qinghai, northern Shaanxi, southern Ningxia, central Inner Mongolia, central Shanxi, and northern Hebei. However, the future projections under climate change suggested a contraction of these suitable areas, shifting towards northeastern high-latitude and high-elevation mountains.ConclusionsThe findings provide essential insights for developing adaptive strategies for A. membranaceus var. mongholicus cultivation in response to climate change and can inform future research on this species. By considering the identified environmental factors and the potential impacts of the predicted climate changes, we can visualize the regional distribution of high-quality Radix Astragali and develop conservation strategies to protect and restore its suitable habitats.

Major clinical results of orthognatic surgery in obstructive sleep apnea syndrome: a systematic review

Introduction: Obstructive sleep apnea involves obstruction or narrowing of an individual's airways during sleep and is associated with several comorbidities. Management can be surgical or non-surgical, and Phase II of the Stanford Protocol for surgical management involves maxillomandibular advancement. Objective: To conduct a concise systematic review to present the main considerations and clinical results of orthognathic surgery in obstructive sleep apnea syndrome. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from April to June 2024 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: 110 articles were found, 41 articles were evaluated and 23 were included in this systematic review. Considering the Cochrane tool for risk of bias, the global assessment resulted in 28 studies with a high risk of bias and 28 studies that did not meet GRADE. Most studies showed homogeneity in their results, with X2 =88.5% &gt;50%. Maxillomandibular advancement surgery is a successful treatment for obstructive sleep apnea, but there are still concerns about cosmetic results due to the major advances involved. Bimaxillary advancement osteotomy significantly increases oropharyngeal volume and contracted superficial areas, which remain stable between 6 months and 1 year postoperatively.

Global climate change-driven impacts on the Asian distribution of Limassolla leafhoppers, with implications for biological and environmental conservation.

Knowing the impacts of global climate change on the habitat suitability distribution of Limassolla leafhoppers contributes to understanding the feedback of organisms on climate change from a macroecological perspective, and provides important scientific basis for protecting the ecological environment and biodiversity. However, there is limited knowledge on this aspect. Thus, our study aimed to address this gap by analyzing Asian habitat suitability and centroid shifts of Limassolla based on 19 bioclimatic variables and occurrence records. Selecting five ecological niche models with the outstanding predictive performance (Maxlike, generalized linear model, generalized additive model, random forest, and maximum entropy) along with their ensemble model from 12 models, the current habitat suitability of Limassolla and its future habitat suitability under two Shared Socio-economic Pathways (SSP1-2.6 and SSP5-8.5) in the 2050s and 2090s were predicted. The results showed that the prediction results of the five models are generally consistent. Based on ensemble model, 11 potential biodiversity hotspots with high suitability were identified. With climate change, the suitable range of Limassolla will experience both expansion and contraction. In SSP5-8.52050s, the expansion area is 118.56 × 104 km2, while the contraction area is 25.40 × 104 km2; in SSP1-2.62090s, the expansion area is 91.71 × 104 km2, and the contraction area is 26.54 × 104 km2. Furthermore, the distribution core of Limassolla will shift toward higher latitudes in the northeast direction, and the precipitation of warmest quarter was found to have the greatest impact on the distribution of Limassolla. Our research results supported our four hypotheses. Finally, this research suggests establishing ecological reserves in identified contraction to prevent habitat loss, enhancing the protection of biodiversity hotspots, and pursuing a sustainable development path with reduced emissions.

Force magnitude and distribution during impacts to the hip are affected differentially by body size and body composition

Hip fractures are a severe health concern among older adults. While anthropometric factors have been shown to influence hip fracture risk, the low fidelity of common body composition metrics (e.g. body mass index) reduces our ability to infer underlying mechanisms. While simulation approaches can be used to explore how body composition influences impact dynamics, there is value in experimental data with human volunteers to support the advancement of computational modeling efforts. Accordingly, the goal of this study was to use a novel combination of subject-specific clinical imaging and laboratory-based impact paradigms to assess potential relationships between high-fidelity body composition and impact dynamics metrics (including load magnitude and distribution and pelvis deflection) during sideways falls on the hip in human volunteers.Nineteen females (<35 years) participated. Body composition was assessed via DXA and ultrasound. Participants underwent low-energy (but clinically relevant) sideways falls on the hip during which impact kinetics (total peak force, contract area, peak pressure) and pelvis deformation were measured. Pearson correlations assessed potential relationships between body composition and impact characteristics.Peak force was more strongly correlated with total mass (r = 0.712) and lean mass indices (r = 0.510–0.713) than fat mass indices (r = 0.401–0.592). Peak deflection was positively correlated with indices of adiposity (all r > 0.7), but not of lean mass. Contact area and peak pressure were positively and negatively associated, respectively, with indices of adiposity (all r > 0.49). Trochanteric soft tissue thickness predicted 59 % of the variance in both variables, and was the single strongest correlate with peak pressure. In five-of-eight comparisons, hip-local (vs. whole body) anthropometrics were more highly associated with impact dynamics.In summary, fall-related impact dynamics were strongly associated with body composition, providing support for subject-specific lateral pelvis load prediction models that incorporate soft tissue characteristics. Integrating soft and skeletal tissue properties may have important implications for improving the biomechanical effectiveness of engineering-based protective products.

Inferring glacier mass balance from Sentinel-1 derived ice thickness changes using geoinformatics: A case study of Gangotri glacier, Uttarakhand, India

All glaciers respond to climatic changes by fluctuating their mass. Investigations of glacier dynamics are necessary for glacier monitoring. Himalayan glaciers make ongoing glacier observations challenging due to their location in a severe topographic environment and inhospitable terrain. Glacier area contraction or extension, together with a corresponding snout shift, can be linked to oscillations in glacier mass. Sentinel-1 dual-polarized datasets were used in this investigation to retrieve glacier surface velocity. Estimates of ice thickness were enhanced by segmenting the glacier into 100-m height intervals. Also, ice thickness variations between 2017 and 2022 have been used to compute glacier mass balance, and the results for several glacier zones have been briefly analyzed. The study revealed that the maximum surface velocity above Gangotri Glacier was approximately 0.33 m/day, with an estimated average of 0.09 m/day. Surface velocities of the central trunk have been seen to range from 0.12 m/day to 0.23 m/day. Additionally, between 2017 and 2022, the surface velocity was spotted between 0.19 m/day to 0.35 m/day. For the glacier, an average ice thickness of 189 ± 17.01 m was calculated. In the central parts, where the drag was least noticeable, thicknesses up to 587 ± 52.83 m were estimated. In the lower accumulation zone and middle reaches, the thickness was found to be decreasing between 2017 and 2022, which can be attributed to increased melting and glacier slowdown. Due to the increased glacier movement throughout time, the lower accumulation reaches over the main glacier body, and its tributaries have experienced mass balancing rates ranging from −1.3 m.w.e./year to −0.5 m.w.e./year (thickness change between −3 m/year and −0.6 m/year). With the help of previous research and existing data, the results were compared and validated. The suggested algorithm and findings can serve as inputs for satellite-based ice thickness measurements and as fundamental research for the forthcoming NISAR mission (expected by mid-2024) which will carry L- and S-band antennas.

Money for operator: the impact of linked agricultural subsidy on incomes

The reform of China’s “three subsidies” has shifted the method of subsidization from payment based on the contracted area to payment based on the actual operational area. Within this context, studying the income-generating impact of the “three subsidies” holds significant practical relevance. Using data from the 2018 China Labor-force Dynamic Survey, this paper employs basic estimation, mediating effect, and moderating effect models to analyze the heterogeneity of agricultural subsidies’ impact on rural household income, the mediating effect of agricultural mechanization, and the moderating effect of operation scale. Our findings indicate that agricultural subsidies, known as the “three subsidies”, have increased total rural household income and agricultural income while decreasing wage income. However, they have shown no significant impact on business income. Notably, agricultural subsidies have significantly elevated the income of food-producing households, with agricultural mechanization partially mediating this effect. Operation scale positively moderates the impact of agricultural subsidies on rural household income and agricultural mechanization. Heterogeneity analysis indicates that agricultural subsidies have a more significant impact on rural household income among agricultural producers in the eastern region.

Characteristics of bare rocky land evolution in karst mountain areas of Southwest China based on socio-ecological system perspectives: The case study of Huajiang Canyon

Rock exposure is a prerequisite for the emergence of bare rocky land (BRL), a severe ecological and environmental problem in karst mountain areas (KMA) of Southwest China, severely restricting the region’s sustainable development. An in-depth analysis of the evolution of BRL in KMA of Southwest China based on socio-ecological perspectives is significant for promoting the region’s sustainable development. This paper firstly analyzes the evolution of the social-ecological system and BRL and the transition of human-land relations in KMA of Southwest China, then selects a typical KMA, Huajiang Canyon in Guizhou Province, for a case study and applies ArcGIS to analyze the dynamics of the BRL of Huajiang Canyon in the past 60 years from 1969 to 2020, and reveals the reasons for the evolution of BRL. The results show that: (1) The evolution of BRL in KMA of Southwest China is closely related to the changes in the local socio-ecological environment. (2) The number, spatial distribution, and landscape pattern of BRL in the Huajiang Canyon from 1969 to 2020 underwent significant changes, with the area of BRL transitioning from an expansion phase to an accelerated shrinking phase and with prominent spatial dispersion characteristics. (3) The transition of the BRL of the Huajiang Canyon into forest grassland and economic and fruity forest land, and the transition of land use from production to ecology and eco-economy, have proved the greening of the KMA of Southwest China from a microscopic perspective. (4) This paper shows that the expansion and contraction of BRL areas can reflect the human-land relations in KMA of Southwest China. Finally, the development path proposed in this paper has a certain positive effect on promoting the future sustainable development of the KMA of Southwest China and can also provide a reference for developing other mountainous areas with similar situations.

The influence of dynamic pitching on the aerodynamic performance of large horizontal axis wind turbines

To delve into the aerodynamic changes of wind turbines during pitching, this study employs the user-defined function (UDF) and dynamic mesh technique. The dynamic aerodynamic performance of a 3.3 MW turbine blade during variable pitch is investigated via numerical simulation. The results show that the optimal pitch angle increases with increasing incoming wind speed. At the initial and final stages of pitch change, the wind turbine experiences the influence of impact loads, leading to minor fluctuations in torque and thrust coefficients. Within the dynamic pitch change process, the pitch angle notably affects the aerodynamic performance of airfoils at blade x/ c = 0~0.6 c cross sections. The primary stress area of the airfoil contracts, with the blade root experiencing comparatively less impact. In the constant-wind-speed pitching scenario, the low-speed region in the immediate wake of the wind turbine diminishes, resulting in a 10.7% enhancement in the average wind speed at 2.5D wake.