Search Results (878)

Scientifically assessing ecosystem health and optimizing ecological source areas (ESAs) are essential for effective environmental management, particularly in ecologically strategic mountain barrier regions. However, existing studies face challenges in identifying and optimizing ESAs. To address these limitations, this study integrated the contribution–vigor–organization–resilience (CVOR)-based ecosystem health framework, a genetic algorithm (GA), and circuit theory to assess ecosystem health, optimize ESAs, and identify ecological corridors (EC) and restoration priorities in the Daiyun Mountain Rim. The results demonstrate the following: (1) a significant ecosystem health decline from 2012 to 2022, evidenced by a 38.97% to 21.09% reduction in high-priority ecological zones accompanied by increased landscape fragmentation; (2) delineation of 90 GA-optimized ESA and 248 EC (2164.71 km), forming an interconnected ecological network; (3) enhanced connectivity metrics through GA optimization, showing α-index improvements of 0.15–0.23 and β-index gains of 0.05–0.08 compared to the traditional large-patch and morphological spatial pattern analysis (MSPA)-based ESA selection methods; (4) development of a tiered spatial strategy featuring primary/secondary restoration clusters and a “three-belt–one area–multiple clusters” framework for adaptive landscape governance. Although uncertainties remain due to the selected study period, parameter settings, and lack of field-based validation, this framework provides a useful reference for ecological planning, restoration prioritization, and ecosystem management in similar mountainous ecological barrier regions. Full article

The rapid advancement of high-performance computing has spurred growing demand for miniaturized, high-density, high-power, and highly reliable electronic packaging. Through-silicon via (TSV), as a pivotal technology enabling high-density integrated packaging, achieves vertical interconnection that reduces signal latency and power consumption while substantially improving system integration. However, inherent challenges persist due to coefficient of thermal expansion mismatches among heterogeneous materials in TSV and parasitic effects introduced by high-density TSV arrays, leading to critical concerns regarding thermomechanical reliability and signal integrity. This study focuses on TSV structures, investigating their thermomechanical reliability and electrical performance. First, the macro–micro model of 2.5D package structure was established to address cross-scale challenges based on Representative Volume Element (RVE) homogenization and sub-model technique. Then, an equivalent circuit model integrating transmission line network theory was developed and validated through full-wave electromagnetic simulations using S-parameter analysis to analyze signal transmission characteristics. Finally, by introducing an improved multi-objective grasshopper algorithm, the structural parameters of TSV are co-optimized using a genetic algorithm back propagation network (GA-BP) and an improved multi-objective grasshopper algorithm (IMOGOA) to enhance both thermomechanical reliability and electrical characteristics simultaneously. The proposed approach offers a practical and effective solution for improving the reliability and performance of high-density integrated packaging, providing valuable insights for future packaging design and optimization. Full article

Purpose: In 2024, the University of the West Indies transitioned from discipline-specific final examinations to a unified medical exit examination. This study evaluates the feasibility and psychometric performance of this unified format, focusing on written item discrimination and the comparability of multiple Objective Structured Clinical Examination (OSCE) circuits. Methods: A retrospective analysis of de-identified results from all candidates sitting the unified examination at the St Augustine Campus in May/June 2025 was conducted. The assessment comprised a 320-item single best answer paper and a 17-station OSCE delivered concurrently across seven circuits. Inter-circuit differences were tested with one-way analysis of variance (ANOVA). Reliability was estimated using Cronbach’s alpha and Generalizability Theory (G- and phi coefficients). Decision-study modelling estimated the number of OSCE stations required for high-stakes reliability. Pearson’s correlation assessed the relationship between written and OSCE performance. Results: Scores from 157 candidates were analysed. Of 320 MCQs, 163 (50.9%) demonstrated acceptable discrimination with a point-biserial correlation coefficient (PBSC ≥ 0.20) and 26 (8.1%) showed negative discrimination, indicating the need for post-examination item review. Although 16 of 18 OSCE stations showed statistically significant inter-circuit differences, these variances were substantially attenuated upon aggregation; total OSCE scores showed only minor but statistically significant difference in total OSCE scores between circuits. Overall OSCE reliability was moderate (Cronbach’s alpha 0.72; G-coefficient 0.72; phi coefficient 0.69). Decision-study modelling indicated that approximately 20 stations would be required to achieve reliability suitable for high-stakes decisions. Written and OSCE scores correlated positively (r = 0.70, p < 0.001). Conclusions: A unified final exit examination is feasible and psychometrically defensible in large cohorts, but requires adequate OSCE station sampling to support high-stakes decisions. Full article

Against the backdrop of global warming and rapid urbanization, high-density central urban areas in valley cities face exacerbated ventilation deterioration and reduced pedestrian-level wind comfort due to topographic constraints and intensive development. This study investigates the coupling mechanism between spatial morphology and wind environment in Lanzhou’s Xiguan Cross area using a complex network model, CFD numerical simulation, and statistical analysis. A ventilation resistance surface was constructed using circuit theory and ArcGIS 10.8 to identify ventilation corridors. PHOENICS was used to simulate summer pedestrian-level (1.5 m) wind fields, while SPSS 2025 was employed for regression analysis of building density, enclosure degree, and dispersion degree against the mean wind velocity ratio. Results indicate: (1) wind velocities are higher at the periphery and lower in the interior; (2) building density and enclosure degree have a highly significant negative impact on the wind velocity ratio, whereas dispersion degree has a significant positive impact, with influence intensity ranked as enclosure degree > building density > dispersion degree. Based on these findings, three differentiated morphological optimization strategies are proposed and validated through simulation, effectively increasing the proportion of comfortable wind zones. This study provides a scientific basis for improving urban microclimate and pedestrian comfort through urban design. Full article

Neuronal excitability manifests itself mainly in the form of non-linear, self-regenerative waves of electricity moving along the surface of neuronal axons. These waves are commonly known as action potentials (APs). Theoretical and experimental investigations of the physical and functional characteristics of APs have broadly followed along the lines of the ionic hypothesis and the associated mathematical model introduced by Hodgkin and Huxley (HH). In the current form of this bioelectrical framework, adopted in mainstream physiology and other biological sciences, the axonal membrane is conceptualized as an electronic circuit where electric current is generated and propelled as a result of the time-dependent opening and closure of voltage-operated ion channel proteins, allowing passive flow of specific ions across and along the membrane, powered by their respective electrochemical gradients. Although representing mainstream research, the bioelectric perspective has been criticized for its narrow focus on the electrical characteristics of APs, whilst ignoring other physical manifestations of the nerve signal, particularly mechanical and thermal changes coinciding with AP propagation. As an alternative, a macroscopic thermodynamics-based acoustic theory has been outlined, in which all electric and non-electric manifestations of the nerve signal are considered as a result of a single density pulse in the axonal membrane carried by a reversible lipid membrane phase transition and momentum conservation. Representing a minority view, however, this unified, acoustic perspective on the physical nature of neuronal excitability is largely ignored by representatives of the bioelectric perspective. Here, we draw special attention to the philosophical dimension of the communication failure between the two communities of scientists. We argue that adherents of the bioelectric perspective favor a mechanist type of explanation, whilst supporters of the acoustic perspective are committed to so-called covering-law types of explanation. We conclude that it is this thus far unrecognized philosophical rift, rather than specific scientific differences in opinion, that blocks fruitful interdisciplinary cooperation necessary for building a comprehensive, fully integrated notion of the physical nature of neuronal excitability. Suggestions of how to bridge this conceptual gap are formulated. Full article

The problem of optimizing a causal objective function emerged in recent work, where the behavior of objects needs to be expressed in terms of interventional or counterfactual probabilities. A key example is the unit selection problem introduced by Li and Pearl, where the goal is to find the individuals who maximize a benefit function that scores their characteristics (called units) using counterfactual probabilities. Previous work on unit selection focused mainly on this specific objective function and on identifying its value using bounds. We complement this line of work by developing a theory that treats unit selection as a computational problem, assuming a fully specified causal model is available and a more general class of objective functions. At the core of our treatment is a novel reduction that transforms the computation of a broad class of causal objective functions into a classical associational probability on a meta-model called the objective model. Based on this reduction, we propose the first exact algorithm for finding the optimal units by applying Variable Elimination (VE) on the objective model. We then characterize the complexity of causal unit selection, showing that it is ${\mathrm{NP}}^{\mathrm{PP}}$-complete, and that the runtime of VE must be exponential in the constrained treewidth of the objective model, which is larger and denser than the original input model. To address this challenge, we compile the objective model into a special class of tractable arithmetic circuits, allowing the optimal units to be computed in time linear in the circuit size. Finally, we present experiments demonstrating the substantial speedup from the circuit-based method over the VE-based method, and the speedup from the VE-based method over a baseline search method, together with a case study on a real-world ecology problem. Full article

Attention has become a central resource of contemporary political communication, yet existing accounts do not fully explain how visibility acquires social credibility and political force under platformised conditions. This article addresses that problem through the ritual model of communication and media rituals. It develops a theory-building framework linking attention, recognition, legitimacy, and participation within a platformised ritual circuit. Methodologically, it proceeds through conceptual synthesis and illustrative analytical reconstruction rather than causal testing. It reconstructs three public episode types centred on witnessing, conflict, and commemoration, using public artefacts, trace-based evidence, platform affordances, and reporting. The analysis argues that attention-based politics is a ritualised struggle over socially recognised salience. Visibility becomes politically consequential when publicly ratified through legible participation and when recognition traces are narrativised as claims to legitimacy. The article proposes a provisional comparative vocabulary for distinguishing dominant configurations of online political media rituals across concentrated witnessing, cyclical antagonism, and prolonged commemorative alignment. It concludes that platforms do not simply amplify visibility or host participation. They organise the recurring social forms through which visibility becomes usable in legitimacy claims. Full article

Large language models (LLMs) seem to demonstrate human-like understanding and generalization of language content. These arise from the capabilities of the models to memorize and generalize the training content. In this paper, we review the recent literature and theories on the mechanisms in self-attention neural networks. We also report three computational experiments that give insights into the underlying mechanisms and capabilities of the models. We also report three computational experiments showing that memorization capacity in compact transformers can be empirically linked to architectural parameters, that structured domain knowledge can be retained in small decoder-only models, and that in-context abstraction requires sufficient architectural depth. These findings suggest that the current models are superfluous for many specific applications, especially in on-edge use cases. A better understanding of application requirements and architecture details can be expected to help in building new LLM architectures that can be efficiently implemented on dedicated on-edge circuits. Full article

Responding to rapid urbanization, this study examines the trade-offs and synergies of ecosystem services (ESs) at the county scale in the Zhengzhou metropolitan area and constructs an ecological security pattern. Using the InVEST model, we quantified carbon storage (CS), soil conservation (SC), habitat quality (HQ), water yield (WY), and food production (FP). We then analyzed their trade-offs and synergies using the geographically weighted regression model, identified driving factors with an optimal parameter-based geographical detector model, detected ecosystem service bundles via a Self-organizing map model, and constructed an ecological security pattern based on circuit theory. The results showed that: (1) From 2003 to 2023, ES spatial distribution remained stable overall, with weak trade-offs and synergies. Locally, WY and HQ declined, while SC and FP increased. (2) Slope and DEM enhanced SC, whereas urban expansion consistently weakened CS, HQ, and FP. Moreover, slope played an increasingly prominent role in regulating WY. (3) Key synergistic bundles with stable spatiotemporal distribution were identified as ecological sources, leading to the construction of ecological security pattern characterized by “four districts, one corridor, and one belt.” This provides a framework for integrating ecological space protection and restoration into urban development. Full article

This paper presents a theoretical study on the electromechanical coupling response of piezoelectric–flexoelectric–semiconductor (PFS) nanocantilevers by adopting flexoelectric elasticity and semiconductor theory. A unified mechanical–electrical model is established to incorporate a strain gradient, the piezoelectric effect, semiconducting characteristics, and flexoelectricity at micro-/nanoscales. Analytical solutions for deflection, electric potential, and electron concentration are obtained under three types of electrical boundary conditions. Numerical results show that flexoelectricity significantly enhances the effective bending stiffness of the beam under open-circuit conditions with or without surface electrodes, especially in thinner structures. With a fixed external electric potential condition, the applied potential can effectively modulate the deflection by adjusting the polarization field. The induced electric potential, under the open-circuit condition with surface electrodes, exhibits a peak value at a critical thickness and flexoelectric coefficient due to the synergistic effect of the strain gradient and flexoelectricity. The electron screening effect induced by the high doping concentration is found to suppress the induced potential considerably. The present work provides a fundamental understanding of PFS coupling and provides guidance for the design of high-sensitivity micro–nano-electromechanical systems/devices. Full article

To investigate the influence of train operating speed on the transient characteristics of the pantograph–catenary arc, this paper establishes an integrated simulation model encompassing the traction network, electric locomotive, and arc. In this model, the traction network adopts a chain circuit model based on multi-conductor transmission line theory. The electric locomotive model considers the train body and the on-board transformer. For the pantograph–catenary offline arc, an improved Habedank model is employed, which takes the train operating speed and arc current as variables. Based on this model, this paper systematically investigates the variation patterns of arc electrical parameters and transient currents in each line of the traction network with train operating speed under pantograph–catenary offline. The simulation results indicate that as train speed increases, both the steady-state arc voltage and the maximum voltage at arc ignition rise, and the arc extinction time at current zero-crossing is prolonged. The peak arc currents on the contact wire, feeder, protective wire, and rails decrease, while the transient current on the ground wire increases. This study can provide a reference for the electromagnetic compatibility design, insulation coordination optimization, and electromagnetic protection of high-speed railway traction power supply systems. Full article

Balancing ecological protection, carbon sinks, and development is a practical challenge in mountainous regions. Using Yunnan Province, China, as a case study, this paper develops a knowledge-guided probabilistic framework for carbon-oriented territorial zoning. The framework combines an indicator system, corridor analysis of pattern, risk and potential, knowledge-graph rule encoding, Bayesian mechanism calibration, and constrained posterior decoding on 11,853 effective planning cells. The results show a clear conservation–development gradient in the carbon sink priority surface: high-priority areas are concentrated in western and southwestern Yunnan, whereas low-priority areas cluster around major urban centers. Corridor analysis identifies a central resistance belt and several urban–rural bottlenecks, indicating that connectivity constraints are concentrated in a limited number of critical links. The final zoning assigns 35.4% of grids to integrated development, 25.9% to emergency intervention, 14.5% to long-term conservation, 13.8% to priority restoration, and 10.4% to risk control. Zone separability is generally strong, with one-versus-rest AUC values ranging from 0.777 to 0.995. Land use enrichment further supports the zoning results: integrated development contains 78.85% of built-up land and 45.93% of cropland, whereas Emergency intervention, priority restoration, and long-term conservation together contain 70.01% of forest area. Full article

This paper introduces a novel switching method called copolar switching, designed to maintain high power efficiency in CLLC bidirectional chargers across different modes of operation. The proposed method sets the switching frequency close to the resonance of the LC tank within the CLLC circuit, ensuring efficient power conversion in both the forward (charging) and reverse (discharging) modes. Using Fourier series analysis and circuit theory, the necessary duty cycle for achieving the target efficiency is derived and applied to the full bridge on the high-voltage side in reverse mode. Copolar switching ensures that the entire CLLC circuit operates at a single resonant frequency, addressing the conventional issue of unbalanced efficiency between forward and reverse power conversions. A prototype circuit was designed for power conversion between 400 V and 48 V. Experimental results demonstrate 1 kW power conversion with 97% efficiency in forward mode and 800 W conversion with the same efficiency in reverse mode. Additionally, the copolar switching method shows potential for applications requiring voltage output adjustments, such as converting between 400 V and 50 V. Full article

Constructing resilient Ecological Security Patterns (ESPs) in polycentric urban agglomerations is computationally challenging due to persistent scale mismatches between local planning and regional strategies. To address this, we developed a novel Proactive Integration Mechanism (PIM), a computational framework that dynamically optimizes ESPs by algorithmically fusing multi-source geospatial data. The PIM integrates three innovative components: (1) a Function–Structure–Policy data fusion approach that couples Self-Organizing Map clustering of ecosystem services with Morphological Spatial Pattern Analysis and policy data to identify ecological sources; (2) a Dual-Feedback Mechanism that hybridizes circuit theory with an Improved Ant Colony Optimization algorithm for dynamic corridor delineation; and (3) complex network analysis to derive targeted interventions from topological properties. Applied to a node city of the Chengdu-Chongqing Economic Circle, the PIM identified 22 integrated ecological sources and 37 corridors. The optimized network showed enhanced resilience: a deterministic 20.5% increase in circuit redundancy (α-index) and an 8.6% improvement in overall connectivity (γ-index), achieved through minimal topological modifications. Temporal validation (2000–2020) confirmed the high stability of the identified patterns. This study provides a potentially replicable and computationally robust framework that bridges spatial ecology with optimization algorithms, offering a promising paradigm for constructing ESPs in node cities within subtropical urban agglomerations. Full article

Could there be quantum superpositions of conscious states, as suggested by the Wigner’s friend thought experiment? Mathematical theories of consciousness, notably integrated information theory (IIT), make this question more precise by associating physical systems with both quantitative amounts of consciousness and structural characterizations of conscious states. Motivated by a recent proposal that ties wave-function collapse to integrated information, we construct a simple quantum circuit that would, on that proposal, place a minimal system—a feedback dyad—into a superposition of states that differ in their associated conscious states. This “Schrödinger’s dyad” provides a controlled setting for evaluating a central desideratum of consciousness-based collapse models: that collapse rates depend on how different the experiences in the superposition are. We prove a structural constraint on collapse dynamics of a standard (Lindblad) type: if collapse is governed by too few collapse operators, collapse rates cannot in general be made to depend solely on qualitative differences between conscious states. Avoiding this limitation requires introducing many commuting operators, leading to a rapid proliferation of collapse terms even for very simple systems. This proliferation bears directly on claims that IIT-based collapse theories may be especially experimentally tractable, since the required dynamics becomes highly complex. More generally, the difficulty is not specific to IIT: any Wigner-style collapse theory that distinguishes experiences using rich internal organization (such as neural connectivity in addition to neural state) will face a comparable explosion in dynamical complexity. Full article