Objectives To evaluate whether a modified sleep stage sequence (SSS) method based on a single epoch immediately preceding each rapid eye movement (REM) sleep period during nocturnal polysomnography (nPSG) could help identify candidates for further narcolepsy workup. Methods This study retrospectively analyzed 204 participants: 39 with narcolepsy type 1 (NT1), 63 with narcolepsy type 2 (NT2), 62 with idiopathic hypersomnia (IH), and 40 healthy controls (HC). In nPSG, REM periods were classified by the single 30-s epoch immediately preceding their onset, excluding sleep-onset REM periods (SOREMPs). The participant-level SSS(W/N1) ratio was the proportion of remaining REM periods preceded by wakefulness or N1. Decision trees distinguished NT1/NT2 from IH/HC using REM sleep latency (REML) alone or with this ratio, with 50 stratified 70/30 hold-out splits for internal validation. Results In pooled multiple sleep latency test SOREMPs, the proposed method showed the same between-group ordering as conventional SSS. In pooled nocturnal REM periods excluding SOREMPs, the frequency of SSS(W/N1) was highest in NT1 and showed a stepwise numerical gradient across NT1, NT2, IH, and HC. Adding the SSS(W/N1) ratio to REML increased the median validation area under the receiver operating characteristic curve from 0.64 [interquartile range, 0.63–0.67] to 0.70 [0.68–0.74]. Two rounded high-specificity rules were derived: Rule A (REML-based), REML < 40 min; and Rule B (SSS-enhanced), SSS(W/N1) ratio ≥ 0.4 with REML < 125 min. Median sensitivity/specificity were 23%/98% and 37%/97%, respectively. Conclusions A modified pre-REM SSS measure derived from routine nPSG may help prioritize patients for further narcolepsy workup.
Accelerated corrosion tests qualify protective coatings for steel bridges, yet their quantitative correspondence to field exposure is poorly established, especially for localized degradation at coating defects. We use 3D laser profilometry to quantify coating blistering over time and the terminal substrate corrosion of defective painted steel in four environments, comprising two field sites (Choshi, Pacific-coast; Miyakojima, subtropical marine) and two accelerated tests (ISO 16539 Method B and a composite cyclic test), for four coating systems. The acceleration factor (accelerated/field blister volume at comparable exposure) is large (≈13–200×), strongly coating-dependent, and site-dependent; the composite cyclic test far exceeds ISO 16539, and both greatly exceed the field. The coating ranking is preserved across environments, but accelerated tests inflate the spread between best and worst coatings, so a single acceleration factor cannot serve for quantitative life prediction. Cumulative time-of-wetness only weakly explains field degradation, and the two sites do not share a common dose–response curve; adding measured airborne sea-salt (≈1.8× higher at Miyakojima) as a second driver improves the fit and explains much of the inter-site difference. By contrast, the non-destructive blister volume predicts the post-blast substrate corrosion through a single transferable power law (corrosion volume is proportional to blister volume^0.60, R2 = 0.89; corrosion depth, R2 = 0.80) holding across all environments and the three coatings with measurable corrosion. The blister–corrosion mechanism is thus consistent across the environments studied though the rate is not, giving a non-destructive basis for estimating hidden corrosion beneath intact coatings and a foundation for data-driven cross-environment prediction.
This paper investigates Neumann initial-boundary value problems for nonlinear fractional partial differential equations in multidimensional, unbounded domains, with a focus on the fractional Ginzburg-Landau equation posed in hyperoctants. These problems are highly relevant in modeling nonlocal transport, anomalous diffusion, and interface dynamics in computational physics and engineering. The nonlocal nature of the fractional Laplacian, combined with the singular geometry of the hyperoctant and the intrinsic non-uniqueness of Neumann boundary conditions, presents deep analytical and numerical challenges. We establish the well-posedness of the problem and derive the necessary compatibility conditions between initial and boundary data to ensure solvability. Classical techniques-such as reflection principles and Laplace transforms-fail in this context due to the global influence of fractional operators and the complex boundary structure. To overcome these difficulties, we develop a novel analytical framework based on the Riemann-Hilbert method, which systematically captures nonlocal dynamics and boundary singularities in high-dimensional settings. The resulting theory provides sharp asymptotic estimates and explicit error bounds, offering a rigorous foundation for numerical simulation. These results have direct applications to the design, validation, and refinement of computational schemes for fractional PDEs in truncated domains, with implications for modeling time-dependent processes in superconductivity, nonlinear media, and diffusion-driven systems.
Topology optimization has been widely applied to thermal–fluid design, particularly for channel-based systems. However, many conventional approaches rely on implicit density-field representations, making it difficult to preserve geometrically interpretable channel features and directly obtain editable CAD models. This study develops a geometry-driven topology optimization framework for cooling-system design based on a three-dimensional loft-based channel representation. Each channel is parameterized by a B-spline centerline and spatially varying cross-sectional profiles, enabling simultaneous control of its trajectory and sectional shape. The resulting geometry is mapped onto a fixed background mesh through a distance-field-based explicit–implicit formulation for thermal–fluid analysis. A predominantly analytical sensitivity scheme is developed for the geometry-to-field mapping, with finite-difference evaluation restricted to the computationally inexpensive rotation-minimizing-frame term. The local nature of the mapping is further exploited through narrow-band evaluation to improve computational efficiency. Curvature, domain-feasibility, adhesion, and self-support constraints are incorporated to preserve design intent and additive manufacturability. Numerical examples demonstrate that the method can generate complex two- and three-dimensional channels while retaining explicit geometric control, computationally efficient gradient evaluation, and direct reconstruction of editable CAD geometries.
hand side of NLS equation behave as subcritical for large time. We transform the equation by integrating by parts with respect to time, thereby obtaining a new formulation with higher-order nonlinearities that exhibit improved decay properties for large time in the supercritical regime. We assume that the initial data u0 admit small analytic extensions in a suitable sector of the complex plane. Under these assumptions, we find the large-time asymptotics of the global solution. (c) 2026 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
