Search Results (3,695)

Unsteady flow-induced pressure fluctuations and the consequent dynamic stresses in pump-turbines are critical determinants of their operational reliability and fatigue resistance. This investigation systematically examines the spatiotemporal propagation of Rotor–Stator Interaction (RSI)-induced pressure pulsations and evaluates the corresponding dynamic stress mechanisms based on a phase-resolved fluid–structure interaction strategy. The results reveal a significant hydrodynamic duality: RSI pressure waves manifest as convective traveling waves on the pressure side but as modal standing waves on the suction side. Crucially, a severe spanwise phase mismatch is identified between the hub and shroud streamlines, which induces a periodic hydrodynamic torsional moment on the blade. Due to the rigid constraint at the blade–crown junction, this torsional tendency is restricted, resulting in high-amplitude constrained tensile stresses at the root. This explains why the stress concentration at the crown inlet is significantly higher than in other regions. Additionally, the stress spectrum shows strong load dependence, characterized by low-frequency modulations on the suction side under high-load conditions. Full article

The energy transition stands as the central focus of Indonesia’s national energy policy, as outlined in the National Energy General Plan (RUEN). This study aims to analyze the extent to which RUEN has accommodated the principle of Heffron’s Energy Justice Framework, both from the perspective of intergenerational and intragenerational justice. Using qualitative policy analysis, the paper assesses distributive, procedural, and recognition justice within RUEN and identifies structural gaps in implementation. The study highlights that although the RUEN has established measures to support the energy transition, significant barriers remain to ensuring a fair and sustainable distribution of energy, particularly unequal energy access, limited stakeholder participation, and a slow reduction in fossil fuel dependence. The results of this study are expected to yield more inclusive and equitable policy recommendations to support the energy transition, while also enhancing RUEN’s effectiveness in achieving energy resilience, sustainability, and justice in Indonesia. Full article

Wildfire is a dominant ecological force in Mediterranean pine forests, and post-fire silvicultural practices can substantially alter their recovery trajectories. In this study, we examined how natural regeneration and artificial plantations influence the composition, structure, and functional roles of medium and large-sized mammal communities in burned Pinus brutia forests of southwestern Türkiye. Camera trap data were combined with linear mixed-effects models, functional diversity metrics, and indicator species analysis to assess community responses. Mammalian assemblages showed marked shifts across treatments: generalist carnivores such as Vulpes vulpes and Canis aureus dominated burned areas, whereas higher-trophic specialists like Caracal caracal were restricted to unburned forests. Functional richness was consistently higher in unburned stands, while artificial plantations reduced both richness and evenness. Natural regeneration partly mitigated these declines by sustaining more balanced community structures. Indicator species analysis confirmed these patterns, with Lepus europaeus strongly associated with burned sites and C. caracal with unburned forests. Overall, findings demonstrate that post-fire silvicultural practices strongly shape mammalian community assembly and functional diversity. Natural regeneration preserves structural heterogeneity and supports functionally diverse assemblages, whereas artificial plantations promote homogenization. Effective restoration strategies should therefore integrate wildlife responses with vegetation recovery to strengthen ecosystem resilience and maintain the ecological roles of mammals. Full article

The Spanish conquest of the Inca empire in the early 16th century stands as one of the most striking examples of asymmetric historical collapse. In this paper, a simplified mathematical formulation is developed being inspired by Lotka–Volterra dynamics to describe, in a stylized quantitative manner, the interactions between the Inca state and the invading Spanish forces. The model is not intended to explain the historical events in a causal or predictive sense, but rather to capture and represent key mechanisms commonly identified in historical analyses. These include the demographic and political weakening caused by smallpox epidemics prior to direct contact, the internal fragmentation produced by the civil war and the introduction of external shocks such as the capture of Atahualpa and the fall of Cusco. Although intentionally minimalistic, the framework provides a dynamical illustration of how combined internal and external pressures can destabilize a complex society. This descriptive perspective situates the Inca collapse within the broader conceptual language of complex systems, emphasizing how nonlinear interactions, feedback and structural asymmetry shape trajectories of resilience and failure. Full article

This paper presents an integrated study on the design, simulation, manufacturing, and experimental testing of a three-blade tritoroidal propeller compared to a conventional two-blade configuration for small UAVs. The aerodynamic analysis was performed in ANSYS Fluent 2022 R1 using the k–ω SST turbulence model at 6000 rpm, while structural integrity was assessed through FEM simulations in ANSYS Mechanical 2022 R1. Both propellers were fabricated via SLA additive manufacturing using Rigid 4000 resin and evaluated on an RCbenchmark 1585 test stand. The CFD results revealed smoother flow attachment and reduced tip vortex intensity for the tritoroidal geometry, while FEM analyses confirmed lower deformation and a more uniform stress distribution. Experimental tests showed that the tritoroidal propeller produces thrust comparable to the conventional one (within 1%) but at a 58% higher torque, resulting in slightly lower efficiency. However, vibration amplitude decreased by up to 70%, and the SPL was reduced by 0.1–6.2 dB at low and moderate speeds. These results validate the tritoroidal concept as a structurally robust and acoustically efficient alternative, with strong potential for optimization in low-noise UAV propulsion systems. Full article

Background: Incarcerated men experience disproportionately high levels of health inequities shaped by social determinants, including poverty, violence, family adversity, trauma, and limited access to healthcare. These long-standing disadvantages, added to the adverse conditions experienced in prisons, may be associated with elevated rates of suicidality in this population. This study examined the prevalence of suicidal ideation and lifetime suicide attempts among men deprived of liberty in Southern Brazil and investigated the role of cumulative adversities and current protective factors in these outcomes. Methods: A cross-sectional study was conducted with 496 incarcerated men. Participants completed a sociodemographic and background questionnaire assessing lifetime adversity (e.g., hunger, homelessness, sexual abuse, domestic violence, family substance dependence) and current protective factors in prison (e.g., family visits, education, leisure, physical activity, religion, positive self-perception). Cumulative adversity and protective factors were operationalized as composite indices. Logistic regression models tested whether cumulative adversities and protective factors were independently associated with suicidal ideation and suicide attempts. Results: Lifetime prevalence was 9.6% for suicidal ideation and 10.8% for suicide attempts. Cumulative adversities were associated with higher odds of both suicidal ideation (OR = 1.43; 95% CI = 1.11–1.84; p = 0.006) and suicide attempts (OR = 1.94; 95% CI = 1.50–2.52; p < 0.001). Protective factors were associated with lower likelihood of suicidal ideation (OR = 0.74; 95% CI = 0.58–0.96; p = 0.020) but were not significantly associated with suicide attempts. No significant interaction effects were observed, indicating that protective factors did not moderate the impact of adversity. Conclusions: Suicidal tendencies among incarcerated men were associated with cumulative structural and psychosocial adversities. Protective factors in prison were associated with lower odds of ideation but not attempts. These associations may inform person-centered and equity-oriented approaches and are consistent with the relevance of social determinants to mental health, although causal inferences are not supported by this project. Full article

This paper presents the activities carried out to improve the quality of certain composite structures by manufacturing them with the assistance of an ultrasonic field. As many composite materials use epoxy resins as base materials, an important problem was noted, namely their high curing time, as well as the problems of lack of adhesion and delamination, which are also known and experienced in the case of composite structures made with metallic materials as a support. The application of an ultrasonic field can successfully solve both problems. To demonstrate this improvement, the manufacturing of cylinders used in braking stands in the automotive industry was considered the main application. The proposed technology will be then extended to conveyor belts or to the manufacturing of other high-adhesion surfaces. This article presents the traditional method and the new ultrasonic field deposition technology. The design of the ultrasonic system is presented based on an analytical calculation, FEM modal analysis, followed by the construction of the ultrasonic system, as well as by bending tests and infrared thermography to demonstrate the advantages of presented method. Full article

Accurate modeling of stem taper is essential for forest management decisions, including the definition of cutting cycles, the feasibility of annual harvesting, assortment classification, size and volume estimation, and ensuring sustainable production continuity. This study modeled the stem taper of Araucaria angustifolia (Bertol.) Kuntze stands in southern Brazil using Kozak’s variable-exponent model fitted with nonlinear mixed-effects techniques. Both fixed- and mixed-effects models showed high predictive performance, regardless of calibration. An unstructured (UN) covariance structure was required to reduce autocorrelation. The mixed-effects model improved predictive accuracy by up to 22%, achieved R² values above 0.99 with RMSE < 0.74 cm, and significantly reduced residual autocorrelation in diameter estimates. The most effective calibration of random effects was achieved using diameter measurements taken at heights between 0.3 and 6.3 m above ground (approximately between 1.3% and 28.3% of the total height, considering the tallest tree as a reference). This research improves the accuracy of volume estimation and the definition of timber assortments for A. angustifolia, thereby supporting forest management decision-making in southern Brazil. Full article

In the context of the ongoing climate crisis, the health and sustainability of forest ecosystems in peri-urban areas play a crucial role in alleviating the adverse impacts of climate change on urban populations, particularly in cities with limited green spaces. This study explores the biodiversity and ecological values of an old-growth forest in the peri-urban area, Thessaloniki, northern Greece, the Kouri Forest. These types of forest ecosystems, except for their high ecological values, provide a lot of benefits to the city residents and the surrounding areas, and to achieve that they should have appropriate composition, structure and function to be able to provide high-level ecosystem services. The research was based on collecting analytical field data, including field sampling plots, and a series of tree cores for tree age determination and tree growth analysis. Data analysis demonstrates the unique characteristics of this forest, which was found to be an old-growth forest dominated by deciduous oak species, aged over 180 years. The high biodiversity of the forest and the rich composition and the multistorey stand structure, in combination with the long age of the trees, suggests that the forest is an old-growth (ancient) forest, and set the forest as an important biogenetic reserve, despite its small area, proximity to the city of Thessaloniki, and the pressures subjected. Accordingly, special management measures are suggested to aim at the sustainable use of peri-urban natural resources. Full article

The COVID-19 pandemic highlighted critical issues in health services and public policy, particularly in long-term care facilities across Canada. Failures in these facilities revolving around chronic underfunding, staffing shortages, inadequate infection control, and inconsistent regulatory oversight, underscore the need to rethink health service interventions, especially considering varying implementation contexts among provinces. The Ontario Long-Term Care COVID-19 Commission Final Report pointed to long-standing systemic issues as the primary causes of the sector’s failures. To explore this issue, a narrative review was conducted with findings indicating that the long-term care crisis in Canada cannot be solved by more privatization, regulation or efficiency measures, as these have contributed to the problem’s root causes. Ontario’s long-term care crisis stems from systemic misalignments in policy, structure and stakeholder dynamics, requiring a shift toward systems thinking and resident-centered care to build an equitable and sustainable long-term care sector. Ultimately, governments must lead a policy redesign that reflects shared responsibility, stakeholder interdependence, and public involvement, offering a model for broader healthcare reform. Full article

Severe erosion persists in the red soil region of southern China despite dense vegetation. Stratified vegetation volume (SVV), which integrates horizontal and vertical vegetation density, better captures understory structure than fractional cover. Here, we established and surveyed 75 forest stands (10 m × 10 m) spanning an erosion-intensity gradient in Changting County, Fujian Province, China. Within each stand, soil was sampled by depth (0–20 cm), and living and dead vegetation volumes in the canopy, shrub–herb, and litter layers were quantified to derive SVV. Relative to slightly eroded soils, moderate and severe erosion reduced the soil water content by 38–41% and soil organic matter by 19–34%, while increasing bulk density by 25–30% and pH by 6–8%. Severe erosion increased the sand content by 20–31% and decreased the gravel content by ≤15%. SVV declined sharply with erosion, with the largest loss in the shrub–herb layer (66–97%). Erosion was most strongly associated with shrub–herb SVV, soil water content, organic matter, and bulk density (r = 0.5–0.6, p < 0.05). The shrub–herb layer was the key component resisting surface erosion. Overall, understory degradation accelerates erosion and soil coarsening, reinforcing a constrained vegetation–soil system; restoring native shrubs and grasses, coupled with targeted canopy thinning, may improve soil and water conservation. Full article

Vascular endothelial growth factor 165 (VEGF₁₆₅) stands out as a pivotal isoform of the VEGF-A protein and is critically involved in various angiogenesis-related diseases. Consequently, it has emerged as a promising target for diagnosing and treating such conditions. Structurally, VEGF₁₆₅ forms a homodimer, and each of its constituting monomers comprises a receptor-binding domain (RBD) and a heparin-binding domain (HBD). These two domains are linked by a flexible linker, and thus the overall structure of VEGF₁₆₅ remains incompletely understood. Aptamers are known as potent drugs that interact with VEGF₁₆₅, and dimeric aptamers that can simultaneously interact with two distant domains are frequently adopted to improve the potency. However, designing such aptamer dimers faces challenges in regard to determining the appropriate length of the linker connecting the two aptamer fragments. To gain insight into this distance information, we here employ biased molecular dynamics (MD) simulations with the umbrella sampling method, with the distance between the two HBDs serving as a reaction coordinate. Our simulations reveal an overall preference for compact conformations with HBD-HBD distances below 3 nm, with the minimum of the potential of mean force located at 1.1 nm. We find that VEGF₁₆₅ with the optimal HBD-HBD distance forms hydrogen bonds with its receptor VEGFR-2 that well match experimentally known key hydrogen bonds. We then try to computationally design aptamer homodimers consisting of two del5-1 aptamers connected by various linker lengths to target VEGF₁₆₅. Collectively, our findings may provide quantitative guidelines for rationally designing high-affinity aptamers for targeting VEGF₁₆₅. Full article

Driven by environmental concerns, the packaging industry is shifting toward high-performance and bio-based coating alternatives. In this research, poly(methylmethacrylate) (PMMA) and modified cellulose nanocrystal (m-CNC) were employed as reinforcing agents to develop sustainable poly (lactic acid)-based coatings for packaging applications. Various formulations, influenced by polymer matrix blends and m-CNC loadings (1–5%), were prepared using solvent and applied as protective coating on cardboard paper substrates. The grammage of polymeric coatings (CG) on paper was also investigated using various wet film thicknesses (i.e., 150–250 μm). Accordingly, key parameters including water contact angle, thermal behavior, mechanical performances and barrier properties were systematically evaluated to assess the effectiveness of the developed nanocomposite coatings. As a result, nonylphenol ethoxylate surfactant-modified cellulose nanocrystals exhibited good dispersion and stable suspension in chloroform for one hour, improving compatibility and interaction of polymer–CNC fillers. The water vapor permeability (WVP) of PLA-coated papers was significantly reduced by blending PMMA and increasing the content of m-CNC nanofillers. Furthermore, CNC incorporation enhanced the oil resistance of PLA/PMMA-coated cardboard. Pronounced improvements in barrier properties were observed for paper substrates coated with dry coat weight or CG of ~20 g/m² (corresponding to 250 μm wet film thickness). Coatings based on blended polymer—particularly those reinforced with nanofillers—markedly enhanced the hydrophobicity of the cardboard papers. SEM-microscopy confirmed the structural integrity and morphology of the nanocomposite coatings. Regarding mechanical properties, the upgraded nanocomposite copolymer (PLA-75%/PMMA-25%/m-CNC3%) exhibited the highest bending test and tensile strength, achieved on coated papers and free-standing polymeric films, respectively. Based on DSC analysis, the thermal characteristics of the PLA matrix were influenced to some extent by the presence of PMMA and m-CNC. Overall, PLA/PMMA blends with an optimal amount of CNC nanofillers offer promising sustainable coatings for the packaging applications. Full article

Industry 5.0 challenges higher education to adopt human-centred and sustainable uses of artificial intelligence, yet many current deployments still treat generative AI as a stand-alone tool, neurophysiological sensing as largely laboratory-bound, and governance as an external add-on rather than a design constraint. This article introduces Nested Learning as a neuro-adaptive ecosystem design in which generative-AI agents, IoT infrastructures and multimodal deep learning orchestrate instructional support while preserving student agency and a “pedagogy of hope”. We report an exploratory two-phase mixed-methods study as an initial empirical illustration. First, a neuro-experimental calibration with 18 undergraduate students used mobile EEG while they interacted with ChatGPT in problem-solving tasks structured as challenge–support–reflection micro-cycles. Second, a field implementation at a university in Madrid involved 380 participants (300 students and 80 lecturers), embedding the Nested Learning ecosystem into regular courses. Data sources included EEG (P300) signals, interaction logs, self-report measures of engagement, self-regulated learning and cognitive safety (with strong internal consistency; $\alpha /\omega \ge 0.82$), and open-ended responses capturing emotional experience and ethical concerns. In Phase 1, P300 dynamics aligned with key instructional micro-events, providing feasibility evidence that low-cost neuro-adaptive pipelines can be sensitive to pedagogical flow in ecologically relevant tasks. In Phase 2, participants reported high levels of perceived nested support and cognitive safety, and observed associations between perceived Nested Learning, perceived neuro-adaptive adjustments, engagement and self-regulation were moderate to strong ($r=0.41$–$0.63$, $p<0.001$). Qualitative data converged on themes of clarity, adaptive support and non-punitive error culture, alongside recurring concerns about privacy and cognitive sovereignty. We argue that, under robust ethical, data-protection and sustainability-by-design constraints, Nested Learning can strengthen academic resilience, learner autonomy and human-centred uses of AI in higher education. Full article

As the impacts of climate change intensify, water resource conflicts are escalating globally, particularly in regions with uneven water distribution, such as Central Asia. Long-standing disputes over water allocation persist between Kyrgyzstan and Uzbekistan. This paper aims to examine the conflicts and challenges in water allocation between the two countries and explore the potential of Decision Support Systems (DSSs) as a viable solution. The paper begins by reviewing the historical evolution of water allocation in Central Asia, analyzing upstream–downstream disputes and notable cooperation efforts, with a focus on key water agreements. It then outlines the definitions, development, and classifications of DSSs in the context of water allocation and presents two illustrative case studies—the Tarim River Basin in Xinjiang, China, and the Nile River Basin in Africa. These cases demonstrate the applicability of DSSs in water-scarce regions with similar socio-ecological dynamics and complex multi-country, cross-sectoral water demands. Building on these insights, the paper analyzes the key challenges to implementing DSSs for transboundary water allocation in Central Asia, including limited data availability and sharing, insufficient technical capacity, chronic funding shortages, socio-political complexities, climate change impacts, and the inherent difficulty of modeling complex systems. In response, a set of targeted pragmatic recommendations is proposed. While acknowledging its limitations, the paper argues that establishing a structured, system-based decision-making framework—namely DSSs—can help stakeholders enhance climate-informed strategic planning and foster cooperation, ultimately contributing to more equitable and sustainable water resource allocation in the region. Full article