bluuebunny/crossref_metadata_2025 huggingface dataset:
Conditioning of the solar corona due to large flares
Authors: Thalmann J.K. , Gupta M. , Veronig A.M. , Liu Y.
Published: January 2025

We aim to better characterize the conditions of the solar corona, especially with respect to the occurrence of confined and eruptive flares. In this work, we model the coronal evolution around 231 large flares observed during solar cycle 24. Using Helioseismic and Magnetic Imager vector magnetic field data around each event, we employed nonlinear force-free field extrapolations to approximate the coronal energy and helicity budgets of the solar source regions. A superposed epoch analysis and dynamical time warping applied to the time series of selected photospheric and coronal quantities were used to pin down the characteristics of the pre- and postflare time evolution, as well as to assess flare-related changes. During the 24 hours leading up to a major flare, the total magnetic energy and unsigned magnetic flux were seen to evolve closely with respect to each other, irrespective of the flare type. Prior to confined flares, the free energy evolves in a way that exhibits more of a similarity with the unsigned flux than the helicity of the current-carrying field, while the opposite trend is seen prior to eruptive flares. Furthermore, the flare type can be predicted correctly in more than 90% of major flares when combining measures of the active regions nonpotentiality and local stability. The coronal energy and helicity budgets return to preflare levels within ≈,6 to 12 hours after eruptive major M-class flares, while the impact of eruptive X-flares lasts considerably longer. Finally, the postflare replenishment times of ≳12 hours after eruptive X-class flares may serve as a partial explanation for the rare observation of eruptive X-class flares within a time frame of a few hours.
Comparative Analysis of Diabetes Prediction Models Using the Pima Indian Diabetes Database
Authors: Zhao Yize
Published: January 2025

This study provides an in-depth review and comparison of diabetes prediction models using the Pima Indian Diabetes database. The main aim is to contrast and evaluate the performance of two distinct predictive models: K-means clustering and Random Forest. The research begins by introducing the significance of accurate diabetes prediction and the methodologies used in the analysis. The K-means model operates by grouping data points into separate clusters according to their characteristics, achieving an accuracy of 90.04% in diabetes prediction. In comparison, the random forest model, which builds multiple decision trees (DT) to do their predictions, demonstrates superior performance over several widely used algorithms such as K-Nearest Neighbours (KNN), Logistic Regression (LR), DT, Support Vector Machines (SVM), and Gradient Boosting (GB). The study reveals that while both models are effective, the Random Forest model provides enhanced predictive accuracy. These findings underscore these models’ potential for use in real-world medical diagnosis, where they can assist in identifying people at risk of diagnosing diabetes and starting early prevention. Future research directions include further refinement of these models and their application to larger and more diverse datasets to improve prediction accuracy and generalizability.
Evaluation of Natural Image Generation and Reconstruction Capabilities Based on the β-VAE Model
Authors: Zhang Honghao
Published: January 2025

Natural image generation models are crucial in computer vision. However, the Variational Autoencoder (VAE) has limitations in image quality and diversity, while β-VAE achieves a balance between the decoupling of latent space and generative quality by adjusting the coefficient β. This article evaluates the performance of β-VAE in natural image generation and reconstruction tasks, comparing it with Conditional VAE and Information VAE. Train the model on the CelebA dataset, using three metrics: Mean Squared Error (MSE), Structural Similarity Index (SSIM), and Fréchet Inception Distance (FID) for matrix evaluation, to analyze the generation quality and reconstruction capability of each model. The results indicate that β-VAE performs well in reconstruction tasks, but due to the strong constraints of the latent space, the realism of the images is lower in generation tasks. Conditional VAE and Info VAE perform more balanced in terms of generation quality and task balance. This article suggests optimizing β-VAE by introducing adversarial training and flexible latent space modeling to enhance its generative capabilities. Future research can further validate the potential of β-VAE in different application scenarios.
Characterization of Lipophilicity and Blood Partitioning of Pyrrolizidine Alkaloids and Their N-Oxides In Vitro and In Silico for Toxicokinetic Modeling
Authors: Lehmann Anja , Haas Manuel , These Anja , Hethey Christoph , Taenzer Julian , Hamscher Gerd , Kloft Charlotte
Published: January 2025

Lipophilicity and blood partitioning are important determinants for predicting toxicokinetics using physiologically-based toxicokinetic modeling. In this study, the logarithm of the n-octanol : water partition coefficient and the blood-to-plasma concentration ratio were, for the first time, experimentally determined for the pyrrolizidine alkaloids intermedine, lasiocarpine, monocrotaline, retrorsine, and their N-oxides. Validated in vitro assays for determination of the n-octanol : water partition coefficient (miniaturized shake-flask method) and the blood-to-plasma conentration ratio (LC-MS/MS-based depletion assay) were compared to an ensemble of in silico models. The experimentally determined octanol : water partition coefficient indicates a higher affinity of pyrrolizidine alkaloids and their N-oxides to the aqueous compared to the organic phase. Depending on the method, in silico determined n-octanol : water partition
coefficients overpredicted the experimental values by ≥ 1 log unit for three out of four pyrrolizidine alkaloids (SPARC), four out of six (CLOGP), five out of eight (KowWIN), and three out of eight (S+logP) pyrrolizidine alkaloids and their N-oxides. The blood-to-plasma concentration ratio obtained in vitro suggested a low binding affinity of pyrrolizidine alkaloids and their N-oxides towards red blood cells. For all eight pyrrolizidine alkaloids and their N-oxides, in silico predicted blood-to-plasma ratios deviated from experimental values by less than 50%. In conclusion, for physiologically-based toxicokinetic modeling of pyrrolizidine alkaloids and their N-oxides, the experimental octanol : water partition coefficient should be preferred, while the blood-to-plasma concentration ratio predicted by the acid/base classification model is a suitable surrogate for experimental data.
Local switching of states in inhomogeneous HTS materials
Authors: Kulik I. I. , Balkashin O. P.
Published: January 2025

A systematic investigation of current (voltage) jumps and hysteresis singularities in IVC of various types of contacts with Bi-based HTS compounds has been carried out. Measurements were made over a wide range of temperatures (1.6–200 K) and rf radiation frequencies (0–80 GHz). The obtained results are explained by using the thermal model.
Two-scale electron structure of copper-oxide superconductors and superconducting pairing mechanism
Authors: Ratner A. M.
Published: January 2025

An acceptor impurity distributed in a crystallographic plane parallel to the superconducting CuO2 plane produces a Coulomb potential in this plane with a large characteristic range. The bottom of the conduction band distorted by this potential plays the role of a secondary potential relief which is manifested in anisotropy of the conductivity and in Raman scattering anomalies. Van der Waals attraction sufficient for the formation of a superconducting gap with a width of tens of millielectronvolts takes place between the holes localized at the secondary relief minima. These phenomena are considered for the YBa2Cu3O6+x superconductor. The experimental data confirm the relation between the superconductivity mechanism and the secondary potential relief.
Kinetics of critical currents, superconducting transition temperature, and electrical conductivity of normal state for photoelectric irradiation of an epitaxial film of YBa2Cu3O6+x
Authors: Dmitriev V. M. , Eremenko V. V. , Kachur I. S. , Piryatinskaya V. G. , Prikhod’ko O. R. , Ratner A. M. , Khristenko E. V. , Shapiro V. V.
Published: January 2025

Time dependences of the critical current Ic, superconducting transition temperature Tc, and the normal conductivity σ are measured in an epitaxial superconducting metaloxide film of YBa2Cu3O6.5 during detailed irradiation. It is shown that the kinetics of σ, Tc, and Ic are formed by two processes whose time constants differ by an order of magnitude. The rapid process is associated with increasing number of hole carriers, while the slow process is associated with the ordering of oxygen in the CuOx plane for a constant number of carriers. This process affects the movement of carriers in the CuO2 plane through the potential relief produced in it by the impurity charges from the CuOx plane. Only the slow process is manifested in the kinetics of the critical temperature Tc, which explains the direct connection between the high-temperature superconductivity and the potential relief. It is shown that the basic mechanism of confinement of critical current in YBa2Cu3O6+x films is connected with weak bonds formed in the region with a reduced electric transparency.
Anomalous size effect in the conductivity of thin Bi films
Authors: Anopchenko A. S. , Kashirin V. Yu. , Komnik Yu. F.
Published: January 2025

The kinetic properties (conductivity, magnetoresistance, and Hall coefficient) of Bi films with a thickness of 100−500 Å are investigated at helium temperature. Thin Bi films exhibit anomalous size effect, i.e., an increase in the conductivity with decreasing thickness, as well as clearly manifested quantum interference effects, i.e., weak localization of electrons and enhancement of electron– electron interaction in a disordered system. The data obtained on the kinetic properties of the films are used for determining the nature of variation of the concentration and mobility of electrons and holes upon a decrease in the film thickness. The isotropy of the properties in the plane of the film associated with the axial texture has made it possible to use equations for a conductor with two types of charge carriers. The analysis of the kinetic characteristics is carried out taking into account the contribution of quantum corrections associated with quantum interference. It is found that the charge carrier concentration increases noticeably (up to two orders of magnitude) as the film thickness decreases to 100 Å, which determines the anomalous size effect in the conductivity of the films.
Peculiarities in dissipative properties of quasi-two-dimensional superconductors in the region of strong phase fluctuations of the order parameter
Authors: Genenko Yu. A. , Krivoruchko V. N. , Medvedev Yu. V.
Published: January 2025

A “paramagnetic” mechanism is proposed for resistive losses in layered superconductors due to magnetic polarization of fluctuation vortex loops by the field of a moving Josephson vortex. This mechanism is significant for the temperature range in which the layered structure of the system becomes a decisive factor, and high-intensity quasi-two-dimensional fluctuations in the form of vortex–antivortex pairs determine the superconducting properties of the system.
Kinetics of isotopic phase separation and diffusion processes in a solid 3He–4He mixture
Authors: Shvarts V. A. , Mikhin N. P. , Rudavskiĭ É. Ya. , Usenko A. M. , Tokar’ Yu. A. , Mikheev V. A.
Published: January 2025

The growth kinetics of the bcc 3He phase in the phase separation of a hexagonal close-packed 3He–4He mixture with an initial concentration of 3.18% 3He at a pressure of 3.7 MPa is investigated by low-frequency pulsed NMR. The characteristic separation time τ of the mixture during stepped cooldown into the metastable range is measured. It is shown that τ decreases monotonically as the temperature decreases and with a corresponding decrease in the equilibrium concentration of 3He in the hep phase. Possible causes of the effect, in particular, the role of mass quantum diffusion, are discussed.
Electronic structure of TI2Ba2Can−1CunO2n+4 (n = 1,2) thin films
Authors: Dubrovskiĭ O. I. , Kurganskiĭ S. I. , Maksimova E. I. , Shchekotov A. Yu.
Published: January 2025

The energy spectra of electrons in Tl2Ba2CuO6 and Tl2Ba2CaCu2O8 thin films are calculated by the method of linearized augmented plane waves. The results of energy band computations for each film are used to calculate the total and local densities of electron states and to carry out a theoretical analysis of the x-ray emission OKα and CuLα spectra. The dependence of the electronic structure and x-ray emission spectra on the number of CuO2 layers in the unit cells of the films is discussed.
Electromagnetic field frequency at which the ohmic resistance of HTS materials is independent of temperature
Authors: Dmitriev V. M. , Ofitserov M. N. , Prentslau N. N. , Rogacki K. , Sadowski V.
Published: January 2025

The singularity in the temperature-frequency dependence of the ohmic resistance R of HTS materials, which is manifested in the sign reversal of the derivative ∂R/∂T at a certain frequency fc, is studied. It is shown that the value of fc correlates with the value of (∂ρ/∂T)/ρ0, where ρ0 is the dc resistivity of the sample at the temperature T0 corresponding to the beginning of the linear dependence ρ(T). It is found experimentally that fc is a function of both |∂ρ/∂T| and ρ0. A relation between the quantities under investigation is derived.
Ultralow-temperature spin–lattice relaxation of a nuclear spin system with dipole–dipole interaction
Authors: Buishvili L. L. , Giorgadze N. P. , Lepsveridze R. L.
Published: January 2025

Ultralow-temperature spin–lattice relaxation of a nuclear spin system with dipole–dipole interaction, associated with two-level systems, is considered along with relaxation due to energy exchange between nuclear spins and phonons with a simultaneous virtual flip–flop of the electron spin of a paramagnetic impurity. The expressions obtained for the relaxation rate show that the most effective mechanism is connected with resonance energy exchange between nuclear spins and two-level systems.
Scattering and capture of electrons by dislocation dipoles
Authors: Feldman È. P. , Fursova T. N.
Published: January 2025

The energy spectrum of an electron in the field of a dislocation dipole consists of a finite number of level series concentrated at the edge of the continuous spectrum with an infinite number of energy levels in each series. It is shown that the small-angle scattering of electrons by the dipole makes a relatively small contribution to the total cross section for scattering at large angles. It is found that dislocation dipoles suppress magnetic susceptibility oscillations at low temperatures (de Haas–van Alphen effect) much more weakly than solitary dislocations.
Nuclear demagnetization refrigerator with automatic control, data collection and processing system
Authors: Golub A. A. , Goncharov V. A. , Litvinov V. R. , Mikheev V. A. , Rudavskiĭ È. Ya. , Tokar’ Yu. A. , Usenko A. M. , Shvarts V. A.
Published: January 2025

A nuclear demagnetization refrigerator with automatic control, data collection and processing system, intended for various physical investigations at ultralow temperatures, is developed. The design of the main units and the characteristics of the refrigerator and the automatic system are described. The possibility of operation in various regimes are analyzed for NMR studies of helium quantum crystals.
Effect of neon impurity on low-temperature plasticity of n-H2
Authors: Alekseeva L. A. , Strzhemechny M. A. , Shcherbakov G. N.
Published: January 2025

The results of plasticity studies for dilute solutions of Ne in normal hydrogen under axial extension at liquid helium temperatures for the neon concentrations 0.01 and 0.001% are reported. Stress–strain curves are plotted, and the values of yield stress are determined. A pronounced plastifying effect of neon impurities is observed.
Thermo- and hydrodynamics of the B-phase of a superfluid Fermi liquid
Authors: Kovalevskiĭ M. Yu. , Rozhkov A. A.
Published: January 2025

Hydro- and thermodynamics of the B-phase of a superfluid Fermi liquid are described using the Fermi-liquid approach. The spectra of natural oscillations of the system are obtained and analyzed. The Cartan form and the superfluid momentum are expressed in terms of the order parameters. An expression connecting the fluxes of physical quantities in the local equilibrium state is derived. The hydro- and thermodynamic equations are presented in the Galilean and relativistic forms.
Vortices in the cone phase of a classical quasi-two-dimensional ferromagnet
Authors: Ivanov B. A. , Sheka D. D.
Published: January 2025

Vortex phenomenology is developed for the Berezinskii–Kosterlitz–Thouless topological spin transition in a classical weakly anisotropic Heisenberg easy-plane ferromagnet in the so-called cone phase in an external magnetic field directed along its hard axis. A field-induced decrease in the transition temperature is predicted. The structure of static vortices in the applied field is calculated. It is shown that the field produces different effects on oppositely polarized vortices and significantly affects the form of the components of the dynamic structural factor of the magnet.
The trick to controlling the notched stick’s rotation
Authors: Lange Katherine De
Published: January 2025

A model that considers the forces on the nail supporting the propeller demonstrates the working principles of the notched stick
The physics of phase transition phenomena enhanced by nanoparticles
Authors: Yang Liu , Tian Jialu , Ding Yulong , Alagumalai Avinash , Selimefendigil Fatih , Aghbashlo Mortaza , Tabatabaei Meisam , Asirvatham L. Godson , Wongwises Somchai , Sherif S. A. , Michaelides Efstathios E. , Markides Christos N. , Mahian Omid
Published: January 2025

Phase transitions are fundamental phenomena in physics that have been extensively studied owing to their applications across diverse industrial sectors, including energy, power, healthcare, and the environment. An example of such applications in the energy sector is thermal energy storage using phase change materials. In such systems, and indeed in many other thermal systems, an emerging and promising approach involves the use of nanoparticles, which have been extensively studied for their potential to enhance the performance of thermal systems. However, conducting thermodynamic analyses of thermal systems in the presence of nanoparticles proves to be complex and resource-consuming because of the involvement of many parameters, including (i) temperature, molecular structure, and composition of the host fluid in which nanoparticles are either dispersed or in physical contact; (ii) nanoparticle morphology, size, type, and concentration; and (iii) complex interactions between the nanoparticles and the base fluid. This article reviews recent studies on the role of nanoparticles in phase transition processes such as freezing, melting, boiling, evaporation, and condensation. It begins with an overview of phase transition phenomena without nanoparticles, emphasizing the most important controlling parameters, and then examines the underlying physics of nanoparticle-involved phase transitions, critically examining their impact on process speed (transport rates). The article also explores physical phenomena, such as Brownian motion, thermophoresis, microconvection, and nanoparticle agglomeration, and considers their contribution to rate control (enhancement or reduction). Finally, the article presents challenges, research gaps, and suggestions for future exploration, aimed at offering a comprehensive understanding of the complex interplay between the presence of nanoparticles and the phase transition processes.
Direct calibration of microwave amplification chain on an axion cavity haloscope
Authors: Chang Hsin , Liu Han-Wen , Doan Hien Thi , Chen Yung-Fu
Published: January 2025

In an axion haloscope, the weak photon signal, theoretically converted from axions, is captured by a detection cavity. The signal from the cavity is too weak to be acquired by a signal receiver. The amplification chain assists the signal acquisition by amplifying the signal and requires accurate gain calibration. Typically, the readout line is calibrated using the Y-factor method, involving a switch that directs either the detection line or the calibration line to the amplification chain. The detection and calibration lines may have different transmissions, which leads to the calibration results being less accurate. In response, we propose a calibration method that eliminates the need for a switch. In this approach, the cavity temperature is decoupled from its incoming noise source and can be controlled, resulting in excess or deficiency of the noise spectrum near its resonance frequency. The experimental result shows that the gain of the amplification chain can be calibrated directly using the temperature-varied cavity radiation.
The improvement of self-excited small current breaking of SE-DCCB by magnetic field reconstruction based on the evolution mechanism of arc root transition
Authors: Li Jing , Yin Yue , Peng Shidong , Liu Shuxin , Fu Yue , Yu Longbin
Published: January 2025

Self-excited DC air circuit breaker (SE-DCCB) is widely used in urban rail transit and ship propulsion due to its excellent stability and reliability. However, the arc re-strike and small current breaking failure sometimes occur in SE-DCCB. An experimental platform of self-excited breaking was built in this work, based on which the arc root evolution during small current breaking in SE-DCCB was recorded by a high-speed camera. The magneto-hydro-dynamic model was coupled with the time-varying and non-uniformly distributed magnetic field model to investigate small current breaking in SE-DCCB, and the temperature, current density, and magnetic force of the arc were analyzed. The results show that the insufficient magnetic force of the self-excited coil and the arc root stagnation caused by the airflow vortices are the main reasons for arc re-strike, which results in the small current breaking failure in SE-DCCB. Increasing the coil turns can only reduce the arc duration; however, arc root stagnation remained unresolved. Based on the simulation results, the magnetic field in the arc chamber was reconstructed. The self-excited coil and permanent magnet was implemented to strengthen the magnetic force acting on the arc root during the last stage of small current breaking in the SE-DCCB. This approach mitigated arc root stagnation and reduced the risk of arc re-strike. This work presents reasons and influencing factors of small current breaking failure in SE-DCCB. By reconstructing the magnetic field, the small current breaking capability of SE-DCCB has been enhanced, and this work offers guidance for the optimal design of such devices.
A wide-spectrum mid-infrared electro-optic intensity modulator employing a two-point coupled lithium niobate racetrack resonator
Authors: Hwang Hyeon , Ko Kiyoung , Nurrahman Mohamad Reza , Moon Kiwon , Ju Jung Jin , Han Sang-Wook , Jung Hojoong , Seo Min-Kyo , Lee Hansuek
Published: January 2025

Optical intensity modulators (OIMs) are essential for mid-infrared (mid-IR) photonics, enabling applications such as bond-selective molecular sensing, and free-space communications via atmospheric windows. Integrated photonics offers a compact and cost-effective solution, yet on-chip mid-IR OIMs significantly underperform compared to their near-IR counterparts. Furthermore, despite the potential benefits for system reconfiguration in accessing various communication frequencies and molecular absorption bands, developing a single OIM capable of operating across a broad spectral range remains a challenge. In this study, we introduce an on-chip OIM that operates over a wide wavelength range in the mid-IR, implemented using a racetrack resonator structure in thin film lithium niobate (TFLN). The modulator employs a two-point coupling scheme, allowing active control of the coupling strength to maintain critical coupling and thereby ensuring high modulation extinction across a wide spectral region. This approach not only achieves high modulation performance but also relaxes the design constraints and fabrication precision typically associated with resonator-based modulators, as confirmed through an analytic model. Implemented in TFLN having a wide transmission spectrum and strong electro-optic coefficient, the OIM demonstrates a modulation extinction ratio exceeding 20 dB with an electro-optic efficiency of 7.7 V cm over the wavelength range of 3.3–3.8 μm, which falls within the first atmospheric transmission widow in the mid-IR. This approach can be adapted to other spectral regions, providing a versatile solution for diverse photonic applications.
High-performance conditional-driving gate for Kerr parametric oscillator qubits
Authors: Chono Hiroomi , Goto Hayato
Published: January 2025

Kerr parametric oscillators (KPOs), two-photon driven Kerr-nonlinear resonators, can stably hold coherent states with opposite-sign amplitudes and are promising devices for quantum computing. Recently, we have theoretically proposed a two-qubit gate Rzz for highly detuned KPOs and called it a conditional-driving gate [Chono et al., Phys. Rev. Res. 4, 043054 (2022)]. In this study, analyzing its superconducting-circuit model and deriving a corresponding static model, we find that an AC-Zeeman shift due to the flux pulse for the gate operation largely affects the gate performance. This effect becomes a more aggravating factor with shorter gate times, leading to an increase in the error rate. We thus propose a method to cancel this undesirable effect. Furthermore, through the use of shortcuts to adiabaticity and the optimization of flux pulses, we numerically demonstrate a conditional-driving gate with average fidelity exceeding 99.9% twice faster than that without the proposed cancellation method and the shortcuts to adiabaticity.
Thermalization of a flexible microwave stripline measured by a superconducting qubit
Authors: Paluch Patrick , Spiecker Martin , Gosling Nicolas , Adam Viktor , Kammhuber Jakob , Vermeulen Kiefer , Bouman Daniël , Wernsdorfer Wolfgang , Pop Ioan M.
Published: January 2025

With the demand for scalable cryogenic microwave circuitry continuously rising, recently developed flexible microwave striplines offer the tantalizing perspective of increasing the cabling density by an order of magnitude without thermally overloading the cryostat. We use a superconducting quantum circuit to test the thermalization of input flex cables with integrated 60 dB of attenuation distributed at various temperature stages. From the measured decoherence rate of a superconducting fluxonium qubit, we estimate a residual population of the readout resonator of (2.2±0.9)×10−3 photons and we measure a 0.28 ms thermalization time for the flexible stripline attenuators. Furthermore, we confirm that the qubit reaches an effective temperature of 26.4 mK, close to the base temperature of the cryostat, practically the same as when using a conventional semi-rigid coaxial cable setup.
Efficient spintronic THz emitters without external magnetic field
Authors: Khan Amir , Beermann Nicolas Sylvester , Sharma Shalini , Schneider Tiago de Oliveira , Zhang Wentao , Turchinovich Dmitry , Meinert Markus
Published: January 2025

We investigate the performance of state-of-the-art spintronic THz emitters (W or Ta)/CoFeB/Pt with non-magnetic underlayer deposited using oblique angle deposition. The THz emission amplitude in the presence or absence of an external magnetic field remains the same and remarkably stable over time. This stability is attributed to the enhanced uniaxial magnetic anisotropy in the ferromagnetic layer, achieved by the oblique angle deposition of the underlying non-magnetic layer. Our findings could be used for the development of practical field-free emitters of linearly polarized THz radiation, potentially enabling applications in future THz technologies.
An electromagnetic logic metastructure realizing half addition and half subtraction operations based on a virtual polarizer
Authors: Zou Jia-Hao , Sui Jun-Yang , Zhang Hai-Feng
Published: January 2025

An electromagnetic logic metastructure (ELM) based on the virtual polarizer, capable of realizing half addition and half subtraction operations, is presented in this work. A virtual polarizer can control the polarization state of electromagnetic waves by coherent perfect absorption. Electromagnetic waves display their distinctive propagation characteristics in diverse polarization directions through the utilization of anisotropic materials such as liquid crystal and plasma, enabling the ELM to fulfill the function of the virtual polarizer. Through changing the physical quantities regarded as inputs, a transmission peak or an absorption peak is formed in different polarization directions when the logical relation is met. The parallel solution of the AND logic and XOR logic operations is realized, and the function of half addition and half subtraction is achieved. The axial ratio proves that the calculation results can be quickly solved by observing the different polarization states of the waves. The ELM, based on the virtual polarizer, processes data faster and more accurately than traditional logic devices. Half addition and half subtraction operations realized based on different electromagnetic polarizations offer a novel approach to control the propagation of electromagnetic waves. It might have significant implications for the application of liquid crystal and other anisotropic materials.
Numerical algorithm for nonlinear flow response of soft brush beds based on the homotopy method
Authors: Sun Bo Hua , Li Meng , Pang Bo
Published: January 2025

Fuzzy flexible fibers attached to biological surfaces can reduce drag and influence fluid flow by altering their shape, an intriguing phenomenon that has garnered increasing attention. The complexity of fluid–structure interaction problems leads to highly nonlinear equations that describe this issue. Existing analytical solutions, such as perturbation methods and series expansion techniques, still do not perfectly align with experimental observations. To address this problem, this study explores numerical approaches. By introducing the method of homotopy transformation, we first tackle the convergence difficulties associated with the classical Newton–Raphson iterative method due to the a priori selection of initial values. Second, numerical results indicate that the proposed method aligns with experimental results across all velocity distributions, confirming previous conjectures regarding the −1/2 scaling rate at higher velocities. The developed homotopy numerical algorithm is compared with the shooting method provided by the MAPLE software, demonstrating superior convergence and computational results compared to existing numerical methods. Finally, we further investigate the deformation of elastic fibers under very large loads. The proposed method exhibits excellent convergence properties and can be utilized to explore numerical solutions for nonlinear equations, particularly in fluid–structure interaction problems, providing insights for future scientific exploration and engineering applications.
Comparative investigation of cavitating and non-cavitating flows around a two-dimensional hydrofoil using particle image velocimetry
Authors: Simanto R. I. A. , Jin Sion , Hong Ji-Woo , Ahn Byoung-Kwon
Published: January 2025

This study presents a thorough comparative analysis of non-cavitating and cavitating flows around a two-dimensional National Advisory Committee for Aeronautics airfoil (NACA) 0012 hydrofoil, focusing on flow behavior at different cavitation numbers while maintaining a constant Reynolds number. The experiments, conducted at Chungnam National University's cavitation tunnel, employ Particle Image Velocimetry to capture and analyze the flow dynamics under both regimes. The Reynolds number ranges from 5.8 × 105 to 7.2 × 105, with cavitation numbers (σ) ranging from 4.2 to 3.1 under cavitating conditions and 8.4 to 6.6 under non-cavitating conditions. The results indicated that cavitation substantially influences flow structures, forming re-entrant jets, intensifying shear zones, and increasing vortex shedding. As the cavitation length expands from 0.05 C to 0.4 C with decreasing σ, regions of heightened shear strain are observed between 0.2 and 0.65 C. The flow under non-cavitating conditions demonstrates smoother, more consistent behavior, with vortices concentrated near the trailing edge beyond 0.5 C. Detailed analyses of vector tracking, Q-criterion, and vorticity further clarify the complex interactions between cavitation and vortex dynamics, providing a comprehensive understanding of cavitating flows' turbulent behaviors and instabilities. This research offers new insights into the impact of cavitation on hydrofoil performance by maintaining a constant velocity while varying cavitation numbers. It contributes to a more profound understanding of cavitation phenomena and their implications for design and performance optimization in marine and industrial applications. These findings are essential for advancing mitigation strategies and enhancing the efficiency of hydrofoil-based systems in environments prone to cavitation.
Deep learning framework for velocity field reconstruction from low-cost particle image velocimetry measurements
Authors: Wei Li , Guo Xiaoxian
Published: January 2025

Particle image velocimetry (PIV) is a fundamental technique for flow field measurement in fluid mechanics, but its widespread application has been limited by the high costs of specialized equipment such as high-power lasers and sophisticated imaging systems. This paper presents an end-to-end deep learning model that enables velocity field reconstruction using low-cost laser emitters and conventional cameras, making PIV measurements more accessible. Based on a pyramid-structured autoencoder, the model processes particle image pairs captured under simplified experimental conditions. Experimental data were collected from flow around single and tandem cylinders under varying Reynolds numbers and gap ratios, with direct numerical simulation providing ground truth velocity fields. The proposed model achieves comparable accuracy to state-of-the-art models while significantly reducing computational costs and physical storage requirements. The model demonstrates robust performance with particle density variations from 0.8 to 1.2 and Gaussian noise levels below 10%. Transfer learning techniques were implemented to enhance model generalization, with fine-tuning of a pre-trained tandem-cylinders model yielding a 14.3% performance improvement and accelerated convergence in single-cylinder applications. Additionally, the model effectively addresses the common challenge of missing flow data in PIV experiments, successfully reconstructing high-resolution velocity fields with up to 10% missing data. Pre-masked training further improves the model's capability to handle partial data. This study validates the effectiveness of deep learning approaches in processing experimental PIV data and presents a practical solution for reducing PIV implementation costs while expanding its applicability.
Breakup characteristics of droplets induced by detonation waves under different diameters and Mach numbers
Authors: Yang Rui , Zhang Qibin , Xiao Qiang , Chen Qingyun , Jiang Yuguang , Fan Wei
Published: January 2025

The growing interest of liquid-fueled detonation engines for the next-generation propulsion applications necessitates extensive understanding of the breakup physics of droplets induced by detonation waves. However, current knowledge of this topic still remains very limited. The breakup dynamics of water droplets induced by detonation waves under varying diameters and Mach numbers were experimentally investigated in the present study. High-speed schlieren imaging was used to capture the detailed breakup process of the droplets. Based on the experimentally observed flow instabilities, the detonation-induced droplet breakup can be classified into two stages dominated by the Kelvin–Helmholtz instability (KHI) and Rayleigh–Taylor instability (RTI), respectively. During the KHI-dominated phase, droplets of different Mach numbers and diameters exhibit nearly identical linear growth in non-dimensional cross-stream diameter with non-dimensional time. For the first time, significant differences in droplet acceleration between detonation waves and shock waves have been reported. The dimensionless droplet acceleration induced by shock waves is 11–17 times greater than that induced by detonation waves. Finally, theoretical analysis and experimental results show that decreasing droplet diameter and increasing Mach number can accelerate the instability development and shorten the absolute breakup time.
Spatially variable recruitment response to fire severity in golden-top wattle (Acacia mariae, family: Fabaceae), a thicket-forming shrub of semi-arid forests
Authors: Wright Boyd R. , Andrew Damien D. , Hewins Michael , Hewitt Claire , Fensham Roderick J.
Published: January 2025

Context Investigations into the life history strategies of organisms in ecosystems prone to fires are essential for effective fire impact management. In Australia, fire severity is expected to increase under anthropogenic climate change (ACC), therefore understanding plant responses to this fire regime element is essential for developing conservation-focused burning practices. Aims Assess the recruitment response of golden-top wattle (Acacia mariae) to varying fire severities (high, low and unburnt) in the semi-arid Pilliga forest in Northern Inland New South Wales. Investigate seedbank dynamics and germination biology to inform post-fire recruitment patterning. Methods Longitudinal seedbank studies were performed to understand seedbank dynamics and the associated influence on post-fire regeneration. A laboratory trial was conducted to assess the effects of heat shock and incubation temperature on seed germination. Field surveys were conducted at four sites to assess fire severity impacts and evaluate spatial variability in post-fire recruitment after the 2018 Gibbican Rd wildfire. Key results Recruitment varied among sites but was highest in shrubs burned by high-severity fire (5.8 seedlings/shrub), followed by low-severity fire (0.8 seedlings/shrub) and unburnt shrubs (0.1 seedlings/shrub). Over 5 years, seedbank densities fluctuated markedly, peaking in 2021 following a major seeding event but declined rapidly thereafter. Germination was optimised when seeds underwent heat shock at temperatures between 100 and 140°C and incubated at warm temperatures. Conclusions Acacia mariae germination is promoted by heat stimulation, explaining why high intensity burns with higher soil temperatures enhance recruitment. Differences in seedbank densities at the time of fire may account for varied recruitment across landscapes. Overall, A. mariae regenerates well after high-severity fires but poorly after low-severity fires, indicating that the species may be resilient to increased fire severity under ACC but struggle under current widespread low-severity prescribed management burning regimes.
The importance of off-river areas for fish in the mid- and lower Lachlan catchment of the Murray–Darling Basin, Australia: three case studies
Authors: Kerezsy Adam
Published: January 2025

Context There is increasing concern regarding the integrity of freshwater ecosystems at a global scale, and Australia’s Murray–Darling Basin is an area where the impacts of river regulation and invasive species are well-known and documented. However, broad-scale assessments have generally occurred in main-channel habitats. Aims The study considers endangered species and fish communities in off-river habitats in a specific Murray–Darling Basin catchment (the Lachlan) and aims to demonstrate that these wetlands and creeks may be important ecological areas in lowland river catchments. Methods The data are drawn from a large number of studies conducted since 2017; however, the fish-sampling methodology has remained constant throughout (large and small fyke nets set overnight). Key results Populations of endangered species such as olive perchlet (Ambassis agassizii) and freshwater catfish (Tandanus tandanus) persist at certain off-river locations within the Lachlan catchment, and large water storages appear to provide suitable habitat for sustaining resident populations of a broader range of native species. Conclusion Off-river areas play important roles within inland riverine systems, and research within and management of these often isolated habitats may pay ecological dividends, especially given the overall decline of freshwater systems worldwide.
The Duff Moisture Code and the limits of sustainable combustion: examining the evidence for a widely used threshold
Authors: Wotton Mike , Wheatley Melanie
Published: January 2025

Background Canadian fire managers rely on the value of the Duff Moisture Code (DMC) for estimating lightning ignition and sustained smouldering in ground fuels. A simple rule used widely operationally suggests that lightning does not ignite fires and smouldering is not sustainable until the DMC >20. Aims We examine the strength of evidence supporting this simple rule. Methods We used daily lightning, fire and weather data from 2000 to 2019 to estimate the probability of lightning fire ignition across a number of regions in Canada. We also examined datasets of forest floor consumption from experimental burns carried out in pine forests in Canada. Key results Neither the 20 years of lightning fire ignition data nor the observed forest floor consumption data reveal consistent signals of an ignition threshold at or around DMC = 20. Conclusions and Implications Increasing DMC is associated with increasing probability of ignition from lightning and the extent of forest floor consumption, but there is little to no evidence to support the existence of a meaningful threshold across Canada when DMC is ~20. Users of this simple rule, be it for lightning ignition or fire perimeter extinction, should be aware that the data do not support a meaningful threshold around this value.
Violence against women and girls research: Leveraging gains across disciplines
Authors: Falb Kathryn , Peterman Amber , Nordås Ragnhild , Field Anjalie , Porat Roni , Stark Lindsay
Published: January 2025

Violence against women and girls (VAWG) is a leading cause of mortality and morbidity worldwide, linked to numerous health, economic, and human rights outcomes. Target 5.2 of the Sustainable Development Goals calls for elimination of all forms of VAWG; however, progress toward achieving this goal has been inadequate. A lack of sufficient data and evidence has hindered global efforts to meet this target and hold governments accountable for action. While there have been substantial advancements in VAWG research methodology over the past three decades, researchers from diverse disciplines tend to work in silos, inhibiting progress in VAWG research. To address this challenge, we offer four key recommendations to support researchers in expanding transdisciplinary approaches: 1) leverage insights from a variety of VAWG data sources, 2) improve precision of VAWG definitions and outcomes, 3) create strategies to address underreporting, and 4) advance research ethics and equity. We conclude with a call to action for researchers, institutions, and donors to advance transdisciplinary research and foster collaboration, learning, and cross-fertilization across scientific fields to accelerate VAWG prevention efforts now and for future generations.
Molecular mechanism of ligand recognition and activation of lysophosphatidic acid receptor LPAR6
Authors: Duan Yaning , Xu Zhenmei , Hao Boyu , Zhang Anqi , Guo Changyou , He Yuanzheng
Published: January 2025

Lysophosphatidic acid (LPA) exerts its physiological roles through the endothelialdifferentiation gene (EDG) family LPA receptors (LPAR1-3) or the non-EDG family LPA receptors (LPAR4-6). LPAR6 plays crucial roles in hair loss and cancer progression, yet its structural information is very limited. Here, we report the cryoelectron microscopy structure of LPA-bound human LPAR6 in complex with a mini G
13
or G
q
protein. These structures reveal a distinct ligand binding and recognition mode that differs significantly from that of LPAR1. Specifically, LPA uses its charged head to form an extensive polar interaction network with key polar residues on the extracellular side of transmembrane helix 5-6 and the extracellular loop 2. Structural comparisons and homology analysis suggest that the EDG and non-EDG families use two distinct modes for LPA binding. The structural observations are validated through functional mutagenesis studies. We further uncover the mechanisms of LPAR6 activation and principles of G-protein coupling. The structural information revealed by our study lays the groundwork for understanding LPAR6 signaling and provides a rational basis for designing compounds targeting LPAR6.
Calcineurin governs baseline and homeostatic regulations of non–rapid eye movement sleep in mice
Authors: Yin Xin , Zhang Zihan , Zhou Rui , Zuo Peng , Sang Di , Zhou Shuang , Shi Bihan , Chen Lin , Wu Chongyang , Guo Ying , Wang Fengchao , Zhang Eric Erquan , Li Qi , Yanagisawa Masashi , Liu Qinghua
Published: January 2025

Sleep need accumulates during waking and dissipates during sleep to maintain sleep homeostasis (process S). Besides the regulation of daily (baseline) sleep amount, homeostatic sleep regulation commonly refers to the universal phenomenon that sleep deprivation (SD) causes an increase of sleep need, hence, the amount and intensity of subsequent recovery sleep. The central regulators and signaling pathways that govern the baseline and homeostatic sleep regulations in mammals remain unclear. Here, we report that enhanced activity of calcineurin Aα (CNAα)—a catalytic subunit of calcineurin—in the mouse brain neurons sharply increases the amount (to ~17-h/d) and delta power—a measure of intensity—of non–rapid eye movement sleep (NREMS). Knockout of the regulatory (
CnB1
) or catalytic (
CnAα
and
CnAβ
) subunits of calcineurin diminishes the amount (to ~4-h/d) and delta power of baseline NREMS, but also nearly abrogates the homeostatic recovery NREMS following SD. Accordingly, mathematical modeling of process S reveals an inability to accumulate sleep need during spontaneous or forced wakefulness in calcineurin deficient mice. Moreover, calcineurin promotes baseline NREMS by antagonizing wake-promoting protein kinase A and, in part, by activating sleep-promoting kinase SIK3. Together, these results indicate that calcineurin is an important regulator of sleep need and governs both baseline and homeostatic regulations of NREMS in mice.