Double perovskite oxides have drawn considerable attention owing to their chemical stability, structural flexibility, and highly tunable physical properties, making them attractive candidates for a wide range of optoelectronic and energy-related applications. In this study, ab initio investigations are performed to explore the structural, electronic, optical, and elastic properties of Ca₂InSbO₆, Sr₂InSbO₆, and Ba₂InSbO₆ double perovskite oxides. The calculations were performed within the framework of density functional theory using the full-potential linearized augmented plane-wave (FP-LAPW) method, in conjunction with the Tran–Blaha-modified Becke–Johnson (TB-mBJ) potential, as implemented in the WIEN2k package. Despite previous experimental reports and a limited number of theoretical studies, a comprehensive description of their combined structural, electronic, optical, and elastic properties remains incomplete. The obtained results provide detailed insights into the structural stability, electronic, linear optical response and elastic behavior of the investigated compounds. Overall, these findings indicate that the investigated double perovskites are promising candidates for UV optoelectronic devices and photovoltaic energy conversion. This work contributes to filling the existing gap in theoretical data and provides a reliable reference for future experimental and computational studies.
The development of compact and efficient nonlinear photonic devices is essential for applications in optical signal processing, wavelength conversion, and integrated photonic circuits. In this study, we model a cadmium sulfide (CdS) nanobelt as an infinite-width slab waveguide and optimize its structure to enhance second harmonic generation (SHG) efficiency by achieving both phase matching between the fundamental and second harmonic waves and maximizing mode overlap. Through theoretical analysis and finite-difference time-domain (FDTD) simulations, we identify the optimal crystallographic axis alignment and waveguide thickness that maximize SHG efficiency. Our results show that the highest normalized SHG efficiency of ≈ 3× 10^-11 μm/μW is achieved at a waveguide thickness of 0.29 μ m with the crystallographic axis aligned along the x-axis, demonstrating the effectiveness of modal phase matching in subwavelength-scale nonlinear waveguides. The simulations confirm that under these optimal conditions, SHG intensity increases quadratically with propagation distance, producing constructive SH buildup in a bare dielectric waveguide without resonant or plasmonic enhancement. These findings indicate that CdS slab waveguides are potentially useful for compact nonlinear photonic functions such as on-chip wavelength conversion.
Vaccination is one of the most effective strategies for mitigating infectious diseases, but vaccine protection is often imperfect. Combined with heterogeneous social interactions, imperfect vaccination considerably complicates epidemic spreading on complex networks. Moreover, epidemic dynamics on quenched networks are strongly influenced by dynamic correlations between connected nodes, making the accurate prediction of epidemic thresholds a longstanding theoretical challenge. We investigate the susceptible–vaccinated–infected–susceptible (SVIS) epidemic model on quenched complex networks and derive an epidemic threshold beyond the conventional mean-field level. By combining heterogeneous mean-field theory with the effective degree method, we explicitly incorporate dynamic correlations induced by fixed network structures and imperfect vaccination, and find that the basic reproduction number is governed by the network structural factor (⟨ k^2⟩ -⟨ k⟩ )/⟨ k⟩ , in contrast to the conventional mean-field result ⟨ k^2⟩ /⟨ k⟩ . The derived threshold shows excellent agreement with extensive Monte Carlo simulations on quenched random and scale-free networks. Our results demonstrate that dynamic correlations play a crucial role in determining epidemic outbreaks and that ordinary mean-field approaches substantially underestimate the effects of network heterogeneity and vaccination dynamics.
We observe a rare occurrence of multiple caloric effects in the multiferroic YCrO _4 compound having a zircon-type crystal structure. The significant magnetocaloric entropy change of ∼ 11.5 J kg ^-1 K ^-1 is observed for a magnetic field change of 0–50 kOe at the paramagnetic to ferromagnetic transition ( T_C ∼ 9 K). On the other hand, the electrocaloric entropy is also found to be considerable as ∼ 1.6 J m ^-3 K ^-1 for a small electric-field change of 0–100 kV/m at the ferroelectric transition temperature ( T_FE ∼ 100 K). The presence of the magnetocaloric and electrocaloric effects in YCrO _4 at two different temperatures attracts the community for practical applications.
This study investigates charged anisotropic compact stellar configurations within the framework of modified Rastall f(Q) gravity, where Q denotes the non-metricity scalar. By applying the Karmarkar condition, a connection between the metric potentials is obtained, allowing the corresponding field equations to be solved. The corresponding field equations are formulated and the behavior of the h(Q) function is analyzed for two different cases. In the first case, a linear equation of state in hybrid form is applied, from which h(Q) is derived. In the second case, the same hybrid form of f(Q) is retained but h(Q) is considered in a logarithmic form. In both cases, the parameters η and ζ are varied to explore different theoretical models of gravity such as hybrid, power law, and exponential forms. We discuss several key physical aspects, such as matter variables, anisotropy, pressure and density gradients, equation of state parameter, mass function, energy conditions, and stability to assess the physical viability of the model. The observed mass and radius values of the pulsar PSR J1416-2230 are taken into account in this analysis. It is found that the obtained solutions exhibit stable behavior and satisfy the necessary physical acceptability conditions throughout the study.
Polycrystalline Ba₂BiRO₆ (R = La, Pr, Nd, and Sm) compounds were prepared by the conventional solid-state reaction technique, and their structural, impedance, and electrical characteristics were systematically examined. X-ray diffraction analysis confirmed that all samples crystallized in a centrosymmetric monoclinic structure belonging to the I2/m space group, with no detectable secondary phases. Impedance and ac conductivity measurements were performed over the temperature range 30 °C–550 °C and frequency range 100 Hz–1 MHz for all compounds. The temperature-dependent real part of impedance showed that the insulating behaviour of the materials diminished as the temperature increased. The grain and grain-boundary resistances were extracted by modelling the Nyquist plots with a two-RC parallel circuit model. The temperature-dependent grain resistance followed the Arrhenius equation. Furthermore, the magnitude of the semicircular arcs decreased with increasing temperature. The frequency dependence of ac conductivity followed Jonscher’s universal power law for all the compounds. Among the investigated samples above 300 °C, the ac conductivity was lowest for the R = Sm compound, followed by R = Nd, La and Pr compounds. These findings provide valuable insights into the insulating characteristics of Ba2BiRO6 (R = La, Pr, Nd, and Sm) compounds.
Traditional definition of effective temperature relies on quasi-equilibrium assumptions based on the matching of total internal energy, which fails to accurately describe non-equilibrium states containing quantum coherence. To address this problem, an effective temperature definition based on the passive state is proposed. For a quantum system, its ergotropy is first extracted, transforming the system into the passive state. Then, a Gibbs state is introduced whose internal energy is equal to that of the passive state, and the effective temperature of the non-equilibrium system is defined as the temperature 1/β of the Gibbs state. Several essential properties of this definition are analyzed, including positivity, consistency with Gibbs temperature, and recoverability in the classical limitation. This definition naturally excludes the influence of quantum coherent work on the temperature, ensuring that the temperature only reflects the thermal properties of the system. Finally, an example is presented to demonstrate the explicit calculation procedure.
The scrutiny of heat and mass transfer efficiency in power-law nanofluid boundary layer flow holds significant importance in various industries, such as oil engineering, pharmaceuticals, textiles, and food production. The present analysis concerns heat and mass transfer in a chemically reactive power-law nanofluid modelled by the Buongiorno framework, over a stretched surface in the presence of thermal radiation and magnetic field, with the account of suction/injection and convective heating. The similarity solutions of complex nonlinear self-similar equations are achieved with the assistance of shifted Chebyshev collocation and Keller box methods. The effects of several generalized flow governing factors on velocity, temperature, and concentration are presented graphically for pseudoplastic, Newtonian, and dilatant fluids. The profiles of velocity, temperature, and concentration of pseudoplastic fluids attain greater values in comparison with Newtonian and dilatant fluids. Further, the quantitative finding of local Nusselt and Sherwood numbers for these fluids is expressed in tabular form, and the results are found in good accordance with published work. The Nusselt and Sherwood numbers attain the peak values for dilatant fluids and the least for pseudoplastic fluids, but the skin friction shows opposite characteristics. The increasing suction/injection factor leads to a thinner boundary layer and improves the transport rate. The velocity, temperature, and concentration of pseudoplastic fluids attain greater values in comparison with Newtonian and dilatant fluids.
Fe49Co35Ti7Zr6B3 amorphous ribbons were fabricated by melt-spinning to investigate the effects of melt flow processing parameters on soft magnetic properties. The effects of nozzle diameter (D), nozzle-to-wheel gap distance (G), and wheel speed (V) on the structural, thermal, geometric, and magnetic properties were systematically examined while maintaining a fixed alloy composition. X-Ray diffraction analysis confirmed that all ribbons retained a fully amorphous structure regardless of processing conditions. Differential scanning calorimetry revealed only minor variations in the first crystallization temperature (TX1), suggesting that thermal stability was primarily associated with alloy composition, while the influence of processing parameters was relatively limited. In contrast, coercivity (HC) showed a strong dependence on melt-spinning conditions, whereas saturation magnetization (MS) remained nearly within a narrow range of 143–150 emu/g. The ribbon thickness increased with nozzle diameter and decreased with wheel speed, consistent with the qualitative trend predicted by the established melt-spinning scaling relation. Among the investigated parameters, nozzle diameter and gap distance exhibited the most significant influence on coercivity, which may be attributed to their influence on melt flow stability, internal stress, and structural homogeneity. Increasing the nozzle diameter from 0.4 to 0.8 mm reduced coercivity from 22.6 to 10.9 A/m. In contrast, variations in wheel speed resulted in relatively minor changes in coercivity within the investigated range. These results suggest that the magnetic softness of Fe–Co–Ti–Zr–B amorphous ribbons is highly sensitive to melt-spinning processing conditions, even when the alloy composition is kept constant. The present study highlights the importance of optimizing melt-spinning parameters to achieve low-coercivity amorphous soft magnetic materials.
Among cortical structures of various scales, macrocolumns are often proposed as the processing units that represent information or implement brain functions, according to the cell assembly theory. However, the precise role of macrocolumns in information processing remains unclear. In this study, we examine the firing properties of a cortical dynamics model to demonstrate how cortical blocks of a similar size to a macrocolumn serve as units that represent individual pieces of short-term memory information. Through analysis and simulations, we predict and observe the emergence of macrocolumn-sized activation clusters representing each piece of information in short-term memory. These clusters tend to remain in one place, much like a viscous substance, and spread out only minimally via short-range superficial connections. Instead, they can generate another activation that stores the same information in different locations via long-distance intercortical connections. These properties help to explain how the cerebrum can retain short-term memories for a long time—beyond the lifespan of activities maintained by recursive connections—and also why its capacity is severely limited as short-term memory.
The propagation of nonlinear dust-ion-acoustic waves in a three-component lunar dusty plasma consisting of warm positive ions, cold dust grains, and Maxwellian electrons is investigated. By employing the reductive perturbation technique, a Korteweg–de Vries (KdV) equation is derived to describe the weakly nonlinear evolution of the wave dynamics. The generalized Wronskian approach is then used to obtain positon, negaton, and positon-negaton interaction solutions, while the extended homogeneous balance method yields sinusoidal periodic, rational, kink-type, and explosive wave structures. The influences of the ion-to-dust mass ratio, ion-to-electron temperature ratio, electron-to-ion density ratio, and dust charge number on the phase velocity, nonlinearity coefficient, and nonlinear wave profiles are examined. The parametric analysis reveals that the amplitude and width of first-order negaton solitons increase with increasing ion-to-dust mass ratio and dust charge number, whereas enhanced electron-to-ion density ratio suppresses both characteristics. In contrast, higher ion-to-electron temperature ratio reduces the negaton amplitude. For second-order positons, growing ion-to-electron temperature and electron-to-ion density ratios lead to reductions in both wave amplitude and width. Furthermore, negaton solitons retain their essential characteristics after collisions with oscillatory singular structures, demonstrating their robustness during nonlinear interactions. The present findings contribute to the understanding of nonlinear dust-ion-acoustic structures and their interactions in lunar dusty plasma environments.
The body-centered tetragonal finite-difference time-domain (BCT-FDTD) method provides spatially collocated field components and reduced numerical-dispersion anisotropy relative to the standard Yee grid, but its original formulation assumes a uniform cell spacing that applies the same resolution everywhere in the domain. We extend BCT-FDTD to nonuniform grids by replacing the single per-axis spacing with cell-by-cell update coefficients c_i = Δ t / Δ x_i , where Δ x_i is the local cell size at index i. Smooth variation between fine and coarse regions is guaranteed by an automatic geometric transition zone that keeps the ratio of adjacent cell sizes below 1.1 per step, while constraining each transition to span an integer number of cells so that the domain can be sized exactly. We systematically study the spurious reflection introduced at the grid-transition boundary as a function of the coarse-to-fine cell-size ratio ρ and the number of transition cells d, treating the two-point (x) and four-point (z) BCT stencils separately. A near-abrupt interface produces measurable backscattering, which the geometric grading suppresses monotonically with d to below the numerical-dispersion floor at the automatically chosen width. The four-point z-direction reflects 30–40 dB more strongly than the two-point x-direction at matched parameters, so the two require independent treatment; at the automatic grading both stay below -60 dB for all ρ studied. The approach reduces the total cell count by a factor approaching ρ ^2 in the transverse plane relative to a uniform grid at the fine-region resolution, making BCT-FDTD practical for multiscale problems in nanophotonics and antenna design.
Constrained optimization problems are commonly addressed by applying simulated annealing (SA) to a composite energy consisting of a main objective term and a penalty term that discourages constraint violations. Although simple and widely used, this approach is highly sensitive to the choice of the penalty weight assigned to the constraint term. Inspired by gradient gating in machine learning, we introduce a gated SA scheme in which the contribution of the penalty term to the Metropolis acceptance test is considered only when its energy change has the same sign as that of the main objective. As a result, the penalty term can reinforce objective-improving moves but cannot drive the search against the primary objective. To ensure convergence under hard equality constraints, the acceptance criterion is referenced to an anchor, defined as the lowest-violation state encountered so far. Constraint-violating detours are accepted only if they eventually return to the anchor violation level, at which point the penalty contribution cancels exactly. This mechanism makes the dynamics intrinsically robust to the penalty weight, eliminating the need for instance-specific parameter tuning. For cardinality-constrained quadratic binary optimization, the proposed method achieves performance comparable to that of conventionally tuned SA at its optimal penalty weight and consistently outperforms standard SA across the entire range of penalty weights.
We investigate intra-chain exciton energy transfer (EET) in a conjugated polymer using a reduced three-level donor–acceptor model that separates vertical excitations from vibrationally relaxed states. Population dynamics are obtained with the hierarchical equations of motion (HEOM), enabling a non-Markovian treatment of system–bath (S–B) interactions. Case studies on Donor–Acceptor (D–A) pairs with small and large energy gaps reveal competition among coherent hopping, vibrational relaxation, and Förster resonance energy transfer (FRET). Varying the hopping and the S–B relaxation rate highlights roles of exciton transfer, thermal relaxation, and dipole-mediated coupling. The results show that energy gap, hopping, and relaxation jointly control intrachain EET.
We investigate the coexistence of localized states and propagating one-dimensional (1D) modes in graphene moiré systems. We first show within a minimal model that a spatially varying scalar potential can confine localized states, while sign changes of a staggered potential generate 1D modes along the resulting domain walls. These two types of states can coexist within the same finite energy window and form a hybrid network. We then demonstrate a microscopic realization of this mechanism in twisted monolayer-rhombohedral N-layer graphene. Band structures, energy contours, and Bloch wave functions obtained in a realistic parameter regime reveal the coexistence of localized nearly flat-band states and propagating quasi-1D modes. Our results establish twisted monolayer-rhombohedral graphene as a promising platform for realizing hybrid electronic networks with coexisting states of distinct effective dimensionalities.
We report the observation of parametric resonance in cold ^133 Cs atoms confined in a dual-species magneto-optical trap (MOT) simultaneously trapping ^133 Cs and ^85 Rb atoms. By modulating the cooling-laser intensity at approximately twice the trap resonance frequency, the Cs atomic cloud separates into two oscillating clouds with a π -phase difference due to the nonlinear trapping potential, giving rise to finite-amplitude limit-cycle oscillations. This behavior is characteristic of parametrically driven nonlinear dynamics and is consistent with a Hopf bifurcation. The oscillation amplitudes were systematically measured while varying the modulation amplitude, magnetic-field gradient, and saturation parameter, and show good agreement with theoretical calculations based on a simple two-level Doppler-cooling model. We further investigate noise-induced switching between the two dynamical attractors by monitoring the temporal evolution of the atomic populations. An effective bias field is employed as a deterministic symmetry-breaking perturbation to prepare an imbalanced population, after which the relaxation dynamics are governed by noise-induced switching under the restored symmetric conditions. The observed nonlinear dynamical behaviors are in close agreement with those previously reported for parametrically driven ^85 Rb MOTs, showing quantitative similarities in phenomena such as parametric resonance, limit-cycle oscillations, Hopf bifurcations, and noise-induced switching.
Positron emission tomography/computed tomography (PET/CT) is widely used to diagnose lung cancer. Accurate segmentation of lung cancer lesions in PET/CT images is critical for diagnosis and treatment planning. However, Poisson–Gaussian noise generated during image acquisition degrades image quality, particularly at lesion edges, reducing segmentation accuracy. The median-modified Wiener filter (MMWF) effectively reduces noise while preserving structural details; however, its performance highly depends on kernel size. This study aims to optimize the MMWF algorithm kernel size and evaluate its usefulness in reducing noise and improving cancer segmentation performance in lung cancer PET/CT images. We added Poisson–Gaussian noise with standard deviation of 0.001, 0.002, and 0.004 to PET/CT images to simulate low-, moderate-, and high-noise conditions, respectively, and compared the MMWF algorithm against conventional median and Wiener filters as baselines. The MMWF algorithm was optimized by increasing the kernel size from 3 × 3 to 13 × 13 in 2 × 2 increments. Quantitative evaluation results showed that the 9 × 9 kernel size achieved the highest segmentation and image quality performance across all evaluation metrics and noise levels. Statistical analysis using linear mixed-effects models confirmed that the optimized MMWF 9 × 9 demonstrated significantly superior performance compared with both baseline filters across all metrics (all p < 0.001). In conclusion, the optimized MMWF kernel size effectively reduces noise and improves segmentation accuracy in PET/CT images, highlighting the potential applicability of the MMWF algorithm in PET/CT-based lung cancer analysis.
Coherent elastic neutrino–nucleus scattering (CEvNS) provides a sensitive probe of neutrino interactions at low momentum transfer, but its experimental observation is strongly constrained by detector-related effects such as energy threshold, resolution, electronics noise, trigger response, and event-selection criteria. In this work, we perform a detector-response benchmark assessment of CEvNS nuclear recoil observability for alternative target nuclei, with particular emphasis on how a common detector-response model reshapes the measurable recoil spectra. Using Geant4-based simulations, CEvNS interactions are modeled for boron, magnesium, titanium, and zirconium targets under identical neutrino source, geometry, response, and selection assumptions. The generated nuclear recoil distributions are propagated through a parametric detector-response chain incorporating quenching, energy-resolution smearing, noise-induced fluctuations, measured-energy threshold selection, trigger response, and veto rejection. We present a systematic comparison of normalized true recoil-energy spectra, measured recoil-energy spectra after detector response, target-by-target true-to-measured spectral distortions, combined response-level acceptance, and threshold-dependent acceptance variations. The results show that detector-response effects significantly modify the observable CEvNS signal, particularly in the near-threshold region where the recoil population is most sensitive to smearing, noise, and threshold assumptions. The threshold-variation study demonstrates that lighter targets such as B and Mg retain comparatively stronger robustness against increasing measured-energy thresholds, whereas heavier targets, especially Zr, are more strongly affected because of their larger low-energy recoil concentration. Rather than providing absolute event-rate predictions or experiment-specific sensitivity projections, this study focuses on relative spectral behavior and response-level target comparison under controlled benchmark assumptions. The results highlight that CEvNS target evaluation cannot rely solely on weak-charge scaling or generator-level recoil spectra; detector threshold, resolution, noise, trigger response, and veto selection must also be considered. The presented framework provides a consistent methodology for comparing prospective CEvNS target materials at the detector-response level and can be extended in future work to include experiment-specific flux models, backgrounds, exposures, and detector technologies.
Operating conditions for femtosecond pulse radiolysis were explored in the KAERI ultrafast electron diffraction (UED) beamline by adjusting the magnet settings without modifying the beamline layout. Three optimization scenarios were considered: maximum fluence at the sample position, minimum bunch duration under a fluence constraint, and maximum fluence under a bunch duration constraint. Under the maximum-fluence condition, the fluence increased with bunch charge, but the bunch duration also became longer because of stronger space-charge effects. For the 40 pC/mm2 fluence constraint, the shortest bunch duration was achieved at 0.4 pC, reaching 38.7 fs at the sample position. With a bunch duration constraint of 50 fs, the maximum fluence was achieved at 0.8 pC, reaching 106.1 pC/mm2. These results identify beam-dynamics conditions for delivering femtosecond electron bunches to an ultrathin liquid sheet sample and provide quantitative guidance for implementing pulse-radiolysis experiments in the present beamline.
