Geophysics
pDSurfTomo: A High-Performance Parallel Computing Package for Direct Surface Wave Tomography
Shaohang Zhu, Junlun Li, Guoyi Chen et al. (+2 more)
Surface wave
tomography is essential for investigating the shear-wave velocity structure of the crust and upper mantle. The direct surface wave
tomography method, DSurfTomo, has become one of the most widely adopted packages due to its ability to account for ray path bending in complex media to increase subsurface characterization accuracy. However, its inherent serial architecture lacks effective support for multicore CPUs and GPUs. Furthermore, its built-in solver is computationally expensive when solving large-scale linear systems. Consequently, the software struggles to meet current demands for large-scale, high-resolution surface wave
tomography. To address these limitations, we propose pDSurfTomo, a highly optimized package utilizing hybrid CPU-GPU acceleration. First, it overcomes the scalability bottleneck in sensitivity kernel computation through a refined parallel design; also, it uses vectorization techniques to accelerate the modeling of surface wave dispersion, achieving efficient computation of the sensitivity kernel. Second, it implements parallelization of the serial fast marching method using OpenMP, significantly reducing computation time for surface wave traveltimes. Finally, it incorporates GPU acceleration to efficiently solve large-scale sparse linear least-squares problems. To streamline the workflow, we provide a cross-platform GUI with remote server connectivity, allowing users to execute and visualize inversion tasks locally while seamlessly utilizing remote computing clusters. Application to an observed dispersion
dataset from 229 stations in North China demonstrates that pDSurfTomo reduces computation time by more than an order of magnitude while maintaining a negligible discrepancy compared to the original DSurfTomo. It is expected that pDSurfTomo will provide a highly efficient and accessible solution for large-scale, high-resolution surface wave
tomography.
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All authors Shaohang Zhu, Junlun Li, Guoyi Chen, Hongjian Fang, Huajian Yao
Fluid Dynamics
Generalised least squares approach for estimation of the log-law parameters of turbulent boundary layers
M. Aguiar Ferreira and B. Ganapathisubramani
Uncertainty in estimating the log-law parameters is arguably the greatest obstacle to establishing definitive conclusions regarding their numerical values and universality. This challenge is exacerbated by the limited number of studies that provide thorough uncertainty analyses of experimental data and fitting procedures, and those that do often adopt different approaches, undermining direct comparisons. The present study applies the generalised least squares (GLS) principle to the log-law velocity profile to establish a standardised, comprehensive framework for quantifying uncertainty in the log-law parameters across
datasets. GLS contrasts with ordinary least squares (OLS) and weighted least squares (WLS), which do not account for correlation in errors across measured quantities, as well as with alternative heuristic methods that independently sample primitive variables. Instead, it incorporates a full covariance
matrix of the residuals, propagated from the uncertainties in the primitive variables and consistent with the experimental methods employed. The study presents a systematic analysis of the response of the log-law regression model using synthetic data, emulating measurements from a hot-wire anemometer mounted on a linear traverse. This analysis serves as a predictive tool for experimental design, identifying a priori the dominant sources of uncertainty in the log-law parameters and potential mitigation strategies. The study also provides new insights into the correlation between the log-law parameters and proposes a new fitting procedure that eliminates the need to prescribe the location and extent of the log region. The open-source Python implementation of the log-law regression model is available for download on GitHub at https://github.com/ma2ferreira/gls_loglaw.git.
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Fluid Dynamics
RAPRAL v1.0: RAdiation Prediction using RAy tracing and Line-by-line methods for hypersonic air flows
Yuzhe Zhang, Qizhen Hong, Xiaoyong Wang et al. (+1 more)
A new radiation solver, RAPRAL (RAdiation Prediction based on RAy tracing and Line-by-line) implemented in C++, is developed for simulating high-temperature thermochemical nonequilibrium radiative processes. RAPRAL integrates detailed line-by-line spectral modeling with a ray-tracing solution of the radiative transfer equation, enabling accurate resolution of both spectral features and spatial radiation transport. The adopted methods and their implementation are described in detail. To assess the overall capability and accuracy of RAPRAL, we first focus on the computation of atomic and molecular bulk spectral coefficients. Through comparison with the established code in the literature, RAPRAL demonstrates its ability to accurately capture key spectral features across a wide range of conditions. Moreover, RAPRAL is applied to predict afterbody radiative heating in the Fire II flight experiment, based on a two-temperature, 11-species air flowfield. The results demonstrate that the present approach provides reliable predictions of radiative heat flux and effectively captures the dominant radiation mechanisms. Overall, the presented results demonstrate that RAPRAL is a robust tool for simulating radiative processes in hypersonic air flows, and future versions will extend its capabilities to include species relevant to planetary atmospheres.
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All authors Yuzhe Zhang, Qizhen Hong, Xiaoyong Wang, Quanhua Sun
Optics · Cross-listed from cond-mat.mtrl-sci
Surface-enhanced Raman scattering and density functional theory study of selected-lanthanide-citrate complexes (lanthanide: Tb, Dy, Ho, Er, Tm, Yb and Lu)
Hao Jin and Yuko S. Yamamoto
In this study, surface-enhanced Raman scattering (SERS) and density functional theory (DFT) calculations were combined to investigate the SERS spectra of Ln-citrate complexes (Ln: Tb, Dy, Ho, Er, Tm, Yb, and Lu) under 488 and 532 nm excitation. Peak assignment was supported by simulated SERS spectra calculated with an optimized DFT method using large-core effective core potentials. The main bands near 935, 1060, 1315, and 1485 cm-1 were assigned to (C-COO-) + (CH2), (CH2) + (C-O – Ln), sym(COO-) + (CH2), and asym(COO-) + (CH2), respectively. Relative peak intensities were evaluated by normalizing the bands near 935, 1060, and 1485 cm-1 to that near 1315 cm-1. The ratios I_935/I_1315 and I_1485/I_1315 generally increased from Dy-citrate to Lu-citrate, whereas the I_1060/I_1315 ratio decreased. These trends were observed under both excitation wavelengths. The decrease in relative SERS peak intensity of the 1060 cm-1 band is attributed to stronger Ln-O interaction and reduced polarizability change, whereas the increases of the 935 and 1485 cm-1 bands are likely related to changes in local electronic distribution and effective
symmetry sensitivity.
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Atomic Physics · Cross-listed from quant-ph
Many-Body Super- and Subradiance in Ordered Atomic Arrays
Alec Douglas, Lin Su, Michal Szurek et al. (+7 more)
When
quantum emitters couple indistinguishably to light, they can synchronize into a collective light matter system with radiative properties profoundly different from those of independent particles. To date, the resulting collective effects have largely been confined to point like or homogeneous ensembles. Here, we open access to a qualitatively new collective regime by realizing geometrically ordered, spatially extended atom arrays with subwavelength spacing. This establishes a fundamentally new platform in which collective emission is no longer confined to a single Dicke mode but instead emerges from an ordered network of
photon mediated interactions. We find that 2D atom arrays undergo strong super and subradiant emission. Despite subwavelength spacing, we achieve site resolved imaging and directly observe the buildup of spatial correlations, demonstrating the transformation of cooperative decay into a strongly correlated many-body process. We observe extensive scaling of superradiance, uncover superradiant revivals, and reveal the
ferromagnetic nature of superradiance and the
antiferromagnetic nature of subradiance. Our results realize a novel programmable platform for exploring and utilizing dissipative many-body
quantum physics, opening new possibilities for
photon capture, storage, and atom
photon entanglement.
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All authors Alec Douglas, Lin Su, Michal Szurek, Robin Groth, Sandra Brandstetter, Ognjen Marković, Oriol Rubies-Bigorda, Stefan Ostermann, Susanne F. Yelin, Markus Greiner
Atomic Physics
Extraction of Effective Electromagnetic Material Properties for Rydberg Electrometer Vapor Cells from 10-300 MHz
D. Richardson, J. Dee, J. Yaeger et al. (+7 more)
Quantum sensors often consist of packaging, such as dielectric-based vapor
cells and metallic electrodes, that reduces and spatially alters the locally observed electromagnetic fields. These effects have been well studied in the optical regime, and even in the RF regime over a few GHz. However, there have been few studies in the electrically small regime below 1 GHz. In order to account for or remove the effects of the packaging, more studies are needed across a broad range of frequencies. This paper reports on the complex permittivity and conductivity of several commercially available vapor
cells used for Rydberg electric field sensing from 10-300 MHz. A new method using a stripline transmission measurement was performed and full wave electromagnetics modeling was used to extract the effective dielectric constitutive parameters from the vapor
cells. Additionally, the field reduction inside the vapor
cell is reported, and published atomic measurements of the electric field are used to further validate the results presented here. Several observations were made from the measurements, such as the frequency dependencies of the RF dispersion and absorption. Applications of this technique include making precise numerical field corrections or physically designing a more optimal vapor
cell via coatings, material changes, or
geometric changes to improve field strength and uniformity.
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All authors D. Richardson, J. Dee, J. Yaeger, M. Viray, J. Marsh, B. Kayim, B. C. Sawyer, D. S. La Mantia, R. Wyllie, R. S. Westafer
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Multiple spiking functionalities in annealing-optimized Ag/Hf$_{0.5}$Zr$_{0.5}$O$_2$-based memristive neurons
Nikita Zhidkov, Andrei Zenkevich and Anton Khanas
Rapid progress of artificial neural network applications in recent years has led to the issue of an unprecedented energy consumption. It can be solved by the implementation of energy efficient hardware based on non-von-Neumann architectures, which requires the development of electronic components emulating the behavior of synapses and
neurons. While research of synaptic elements is vast, the technology for fabrication of scalable and highly reproducible neuronal elements is far less developed. In this paper, we demonstrate an artificial
neuron with multiple functionalities based on filamentary switching Ag/Hf$_{0.5}$Zr$_{0.5}$O$_2$ (HZO) memristors. To improve the parameters of memristors, we propose a two-step annealing method, which allows for better control of the crystallization of the functional dielectric layer (HZO) as well as of the
diffusion of active electrode (Ag) atoms. Furthermore, we demonstrate the leaky integrate-and-fire (LIF) neuronal behavior in multiple spiking modes: time-to-first-spike (TTFS), number of spikes and firing rate coding. Moreover, the
neuron operation does not require the additional electronic overhead and is supported solely by a Ag/HZO memristor with a current limiting resistor connected in series. The presented results pave the way for the creation of next generation energy efficient neuromorphic hardware operating on the principles of spiking neural networks.
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Fluid Dynamics
Bicuspid Valve Closure and Backflow Prevention: Role of Leaflet Geometry
B. Kaoui, A. Bou Orm, P. Navet et al. (+2 more)
Bicuspid valves with crescent-shaped leaflets are found in lymphatic vessels and veins, where their primary function is to prevent reflux and ensure unidirectional flow toward the heart. These valves are passive, and their functionality emerges spontaneously from a complex interplay between the properties of the valve leaflets and the flow patterns developing within the vessel sinus region surrounding the valve. The main function of the valves is to limit retrograde flow, or reflux, but the optimal valve structure has not been well-characterized. Here we investigate numerically how the length of the leaflets affects the valve efficiency in preventing reflux. The valves are subjected to backward flow, akin to that imposed by
gravity. We report the flux through the valve orifice as a function of key parameters: valve length, leaflet length, and leaflet
rigidity. We monitor the transition in the flow regime - from reflux to complete flow blockage - by varying only the leaflet length. The transition threshold is found to depend strongly on the valve shape and stiffness. We captured these control parameters numerically to evaluate the ability of the valve to close and prevent reflux. This study allowed us to explain reflux observed experimentally in certain incompetent abnormal and immature valves, particularly those with shorter leaflets.
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All authors B. Kaoui, A. Bou Orm, P. Navet, J. Baish, L.L. Munn
Instrumentation and Detectors · Cross-listed from hep-ex
Neutron Reconstruction via Blips in Liquid Argon Time Projection Chambers
Miguel Hernandez Morquecho, Bryce Littlejohn, Paola Sala et al. (+1 more)
Neutrons are important final-state particles in
neutrino interactions, yet they are not considered or reconstructed in most current
neutrino LArTPC physics analyses. In this paper, we present a simulation-based proof-of-concept study of
neutron reconstruction in a generic LArTPC detector. Leveraging isolated, MeV-scale energy deposits, or blips, from
neutron inelastic scattering, and using realistic blip response from published experimental results, we demonstrate the capability to identify
neutrons and to reconstruct the direction and energy of the final-state
neutron system in sub-GeV
neutrino interactions. We then explore how
neutron-related blip attributes can be used to improve physics studies of
neutrino interactions, such as enhancing
neutrino-antineutrino separation in atmospheric
neutrinos and reverse-horn-current beam
neutrinos. This simple study provides an initial quantification of LArTPC
neutron reconstruction capabilities, which we expect to improve with future advancements in blip reconstruction, identification, and classification
algorithms, as well as the modeling of
neutrons.
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All authors Miguel Hernandez Morquecho, Bryce Littlejohn, Paola Sala, Linyan Wan
Fluid Dynamics
Shape-dependence of electrophoretic mobility: an AI-assisted derivation
Arkava Ganguly and Ankur Gupta
The electrophoretic mobility of a spherical particle is well understood, yet how particle shape modifies this mobility at arbitrary Debye length remains an open question. Here, we compute the electrophoretic mobility of a nearly spherical particle whose surface is described by $r_s(\theta) = a[1 + \varepsilon f(\theta)]$, with $\varepsilon \ll 1$, at arbitrary ratio of particle size to Debye length $\kappa a$. Using a volume-integral formulation combined with domain perturbation techniques, we derive a universal shape correction coefficient $\sigma_2(\kappa a)$ such that the mobility takes the compact form $C_\parallel = f_H(\kappa a)\,[1 + \varepsilon\,c_2\,\sigma_2(\kappa a)]$, where $f_H$ is Henry's function. We show that $\sigma_2$ interpolates between $+1/5$ in the thick-double-layer (Hückel) limit, governed solely by the Stokes drag correction, and zero in the thin-double-layer (Smoluchowski) limit, recovering the classical shape-independence
theorem. The perturbation theory agrees quantitatively with exact spheroid solutions for both prolate and oblate orientations. A key finding is that only the $P_2$ (quadrupolar) component of the particle shape affects the mobility at leading order; higher harmonics are electrophoretically silent due to angular selection rules governing the coupling between the dipolar applied field and the shape perturbation. The results in this paper were generated using Claude Code (Anthropic, Opus 4.6 model) with supervision from the authors. Our thoughts on the usage of AI for theoretical research, along with representative
prompts from the development process, are provided in the manuscript and Appendix.
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Optics
Self-Configuring Universal Multichannel and Multidimensional Integrated Photonic Processing Engine
Zengqi Chen, Wu Zhou, Hao Chen et al. (+8 more)
Arbitrary manipulation of light across multiple physical dimensions is essential for harnessing its parallelism in fundamental research and advanced applications, such as optical interconnects, computing, imaging, sensing, and
quantum networks. However, creating a universal device capable of arbitrary operations of multidimensional optical beams has been challenging, primarily due to their complex mutual interferences and dynamic transmission characteristics. In this study, we experimentally demonstrate a self-configuring integrated photonic processor designed for the arbitrary manipulations of multiple optical waves over their spatial and polarization dimensions. Despite the random nature of the input speckle, the photonic processor relies on an optical singular-value decomposition engine to sort all orthogonal input beams and implement arbitrary processing over both spatial and polarization dimensions precisely. Notably, the photonic processor can be self programmed in situ, enabling versatile functionalities such as beam shaping, optical switching, and reconfigurable optical add-drop multiplexing. Our findings advance the manipulation of multidimensional optical beams through a scalable, CMOS-compatible integration approach, paving the way for fully exploiting the parallelism of light in various applications.
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All authors Zengqi Chen, Wu Zhou, Hao Chen, Kaihang Lu, Wenzhang Tian, Yiou Cui, Yuxiang Yin, Mingyuan Zhang, Xiaofu Pan, Jianqi Hu, Yeyu Tong
Medical Physics · Cross-listed from cs.CV
MosaicMRI: A Diverse Dataset and Benchmark for Raw Musculoskeletal MRI
Paula Arguello, Berk Tinaz, Mohammad Shahab Sepehri et al. (+2 more)
Deep learning underpins a wide range of applications in MRI, including reconstruction, artifact removal, and
segmentation. However, progress has been driven largely by public
datasets focused on
brain and knee imaging, shaping how models are trained and evaluated. As a result, careful studies of the reliability of these models across diverse anatomical settings remain limited. In this work, we introduce MosaicMRI, a large and diverse collection of fully sampled raw musculoskeletal (MSK) MR measurements designed for training and evaluating machine-learning–based methods. MosaicMRI is the largest open-source raw MSK MRI
dataset to date, comprising 3,150 volumes and 89,830 slices, including a 3,096-volume 1.5~T core
dataset and a 54-volume 0.55~T low-field set. The
dataset offers substantial diversity in volume orientation (e.g., axial, sagittal), imaging contrasts (e.g., PD, T1, T2), anatomies (e.g., spine, knee, hip, ankle, and others), numbers of acquisition coils, and field strengths. Using accelerated reconstruction as a testbed, we study scaling, robustness, and data selection under realistic MSK distribution shifts. Across E2E-VarNet, U-Net, and ViT baselines, mixed-anatomy training improves over anatomy-specific training, showing that the benefit of anatomical diversity is not architecture-specific. Zero-shot experiments on the 0.55~T low-field set highlight that using more training data improves average reconstruction under field-strength shift. Controlled subset experiments further suggest that these gains come from transferable cross-anatomy structure, rather than anatomy or contrast matching alone.
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All authors Paula Arguello, Berk Tinaz, Mohammad Shahab Sepehri, Maryam Soltanolkotabi, Mahdi Soltanolkotabi
Optics
Magnetic switching of self-hybridized exciton-polaritons in CrSBr photonic crystal slabs
T. D. Gorelkina, I. E. Kalantaevskii, A. N. Abramov et al. (+8 more)
Layered van der Waals antiferromagnet CrSBr supports strong light–matter coupling and formation of magnetically tunable
exciton-polaritons, yet active
magnetic control over polariton propagation direction has remained elusive. Here, we investigate self-hybridized
exciton-polaritons in photonic
crystal slabs fabricated from CrSBr flakes and their
evolution across the
antiferromagnetic-to-
ferromagnetic spin-flip transition induced by moderate in-plane
magnetic fields. Using angle-resolved reflectance and photoluminescence spectroscopy supported by modeling, we show that the polariton energy continuously tracks the layer-by-layer magnetization switching, revealing a gradual redistribution of oscillator strength from
antiferromagnetic to
ferromagnetic excitons near the critical field. Most notably, we demonstrate that the sign of the polariton group velocity can be reversed by a small change in the external
magnetic field of only 40 mT, resulting in complete switching of the polariton propagation direction. Our results establish CrSBr photonic
crystal slabs as a platform for magnetically controlled polariton transport, opening opportunities for active integrated photonic and polaritonic devices.
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All authors T. D. Gorelkina, I. E. Kalantaevskii, A. N. Abramov, K. A. Gasnikova, P. A. Alekseev, X. Zeng, D. Huang, T. Jiang, I. V. Iorsh, I. Y. Chestnov, V. Kravtsov
Fluid Dynamics
Schrödinger-Navier-Stokes equation for capillary fluids
Luca Salasnich, Simon Böhly, Sauro Succi et al. (+1 more)
We highlight some properties of the Schrödinger-Navier-Stokes (SNS) equation [Salasnich, Succi, and Tiribocchi (2024)] of potential relevance for microfluidics and soft matter. Specifically, we show that the SNS equation with generic parameters is formally equivalent to the Navier-Stokes-Korteweg equations for capillary fluids, with the equivalence established at the level of an action functional that decomposes naturally into a Korteweg conservative and a dissipative contribution. We derive the dispersion relation for sound modes, showing that the dispersive parameter controls capillary stiffness while the dissipative parameter controls viscous damping, and that the Bogoliubov dispersion relation is recovered in the
quantum limit. We also derive an effective one-dimensional SNS equation for a fluid confined in a narrow capillary tube.
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All authors Luca Salasnich, Simon Böhly, Sauro Succi, Adriano Tiribocchi
Fluid Dynamics
Data-driven oscillator model for turbulent flows with multiple dominant frequencies
Youngjae Kim, Koichiro Yawata, Hiroya Nakao et al. (+1 more)
The complex dynamics of high-dimensional oscillatory flows can be simplified using phase-reduction analysis, providing a deeper understanding of the flow response to external perturbations. Although phase-based modeling and analysis have been utilized in recent studies on oscillatory fluid flows, their usage is often limited to single-frequency flows due to difficulties in addressing chaotic characteristics, emerging from multiple dominant frequencies with broadband spectra in turbulent flows. In order to overcome this limitation, we propose a data-driven framework that models the dynamics of turbulent flows with multiple dominant frequencies based on a set of oscillators. The representative oscillators are extracted from the flow field data by training specially designed autoencoders. The oscillator dynamics are modeled through a machine-learning technique using neural networks to accurately predict the multi-frequency oscillatory behavior of turbulent flows. We verify the oscillator-based model of the oscillatory turbulent flows by applying the proposed data-driven method to the three-dimensional supersonic turbulent flow over a cavity. We show that the oscillators extracted from the spanwise-averaged pressure field represent the dominant large-scale flow features and reflect the physical characteristics of the turbulent cavity flow. The data-driven oscillator dynamics model with observation-based correction accurately forecasts the oscillatory behavior of the turbulent cavity flow for a long period. The proposed data-driven method for reduced-order modeling of turbulent flows with oscillators will enable deeper investigations of perturbation dynamics and control of turbulent flows.
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All authors Youngjae Kim, Koichiro Yawata, Hiroya Nakao, Kunihiko Taira
Biological Physics · Cross-listed from cond-mat.soft
An active soft condensed matter approach to the Physics of living systems
Nitin Kumar
This article aims to introduce the broad field of soft active matter physics and its relevance to the life sciences in simple, accessible
language. Although this area of research is relatively new, it has already demonstrated significant potential in providing a physical understanding of many biological processes. While several review articles by leading researchers exist, they can be difficult to grasp for undergraduate students and even early-career researchers who wish to enter this field. In this article, I cover the basics, introduce the origins of soft active matter physics, and explain how it differs from traditional
equilibrium condensed matter ideas at the fundamental level. For the most part, I will avoid mathematical equations and excessive technical precision in several statements. Instead, I will focus on communicating the core ideas and the overall spirit of the argument, using everyday examples to develop a physical intuition. The primary focus will be on the dynamical aspects of these systems. I will conclude by briefly discussing a published experimental study from our research group that examines universal features of the trajectories of homing and migrating organisms.
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Instrumentation and Detectors
Characterization of the 20-inch Photomultiplier Tubes for RENE Detector
Junkyo Oh, Byeongsu Yang, Cheong Heo et al. (+30 more)
To address the Reactor Antineutrino Anomaly (RAA) observed in
neutrino experiments, the Reactor Experiment for
Neutrino and Exotics (RENE) has been initiated using a
liquid scintillation detector. In this study, we investigate the characteristics of two 20-inch Hamamatsu R12860 photomultiplier tubes (PMTs) intended for installation in the RENE detector. The charge and timing responses of the PMTs were evaluated at both the nominal and target gains expected during actual operation. In particular, gain non-uniformity arising from the large-diameter photocathode with a box-and-line type dynode structure was examined, and the maximum gain variation was measured. The occurrence rate, timing, and charge distributions of late pulses and afterpulses were also investigated to characterize the specific response features of the R12860 PMT. The results reported in this study will aid in the interpretation of signals from the RENE detector and serve as a reference for estimating potential systematic uncertainties in RENE data. Furthermore, these findings are expected to provide valuable information for other experiments employing the same type of PMTs.
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All authors Junkyo Oh, Byeongsu Yang, Cheong Heo, Daeun Jung, Dong Ho Moon, Eungyu Yun, Hyun Woo Park, Jae Sik Lee, Jisu Park, Ji Young Choi, Kyung Kwang Joo, Ryeong Gyoon Park, Sang Yong Kim, Sunkyu Lee, Insung Yeo, Myoung Youl Pac, Jee-Seung Jang, Eun-Joo Kim, Hyunho Hwang, Junghwan Goh, Wonsang Hwang, Jiwon Ryu, Jungsic Park, Kyu Jung Bae, SeoBeom Hong, Hyunsoo Kim, Dojin Kim, Jonghee Yoo, Seunghwan Choi, Wonjun Lee, Jubin Park, Myung-Ki Cheoun, Intae Yu
Plasma Physics
Interaction of Strong Electromagnetic Waves with Unmagnetized Pair Plasmas
Navin Sridhar, Emanuele Sobacchi, Lorenzo Sironi et al. (+3 more)
We investigate analytically and numerically the interaction of strong electromagnetic waves with unmagnetized pair
plasmas. We show that the interaction is governed by a single nonlinearity parameter, $\varepsilon_{\rm p}$, defined as the ratio of the wave strength parameter to the wave frequency in units of the
plasma frequency (with both frequencies measured in the
plasma rest frame prior to the interaction). When $\varepsilon_{\rm p}<1$, the number of wavelengths that propagate through the
plasma without attenuation from induced Compton scattering is approximately $\varepsilon_{\rm p}^{-2/3}$. This attenuation can imprint sub-structures as narrow as a few wavelengths on the pulse profile. When $\varepsilon_{\rm p}>1$, the electromagnetic pulse acts as a relativistic piston and drives a shock into the
plasma. Our results establish a framework for the interaction of strong electromagnetic waves with pair
plasmas, a process relevant for intense
radio pulses from
neutron stars and for next-generation pair
plasma experiments at multi-petawatt
laser facilities.
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All authors Navin Sridhar, Emanuele Sobacchi, Lorenzo Sironi, Masanori Iwamoto, Daniel Grošelj, Brandon K. Russell
Plasma Physics
Gyrokinetic equilibria of high temperature superconducting magnetic mirrors
Maxwell H. Rosen, Manaure Francisquez, James Juno et al. (+3 more)
High-temperature superconducting (HTS) magnets and other advances have led to renewed interest in
magnetic mirrors for fusion energy. The non-Maxwellian nature of mirror
plasmas necessitates kinetic modeling to predict, optimize and design mirrors. Explicit gyrokinetic full-f codes can be used to study instabilities and turbulent transport in tokamaks and mirrors, but they have been prohibitively expensive to integrate directly over the very long time scales required to compute kinetic
plasma equilibrium. We demonstrate that these studies are now feasible thanks to novel multiscale methods delivering a 30,000X speed-up. The resulting kinetic
equilibrium, electrostatic potential, and ion confinement time are consistent with analytic theory. This transformative capability opens the door to a new way of obtaining
equilibria for mirrors, and we discuss how this technique may also accelerate calculations for tokamaks and stellarators. The models presented in this article address critical multiscale problems in modeling
magnetic mirrors, opening a new research avenue for
equilibrium studies using an explicit continuum gyrokinetic code.
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All authors Maxwell H. Rosen, Manaure Francisquez, James Juno, Benicio Terry-Mendoza, Ammar Hakim, Gregory W. Hammett
Optics
Anisotropic photonic time interfaces via isotropic spacetime modulations
Andrew M. Naylor and Victor Pacheco-Peña
The engineering of the optical properties of materials in space and time is opening further directions and possibilities to control wave propagation in four dimensions (x,y,z,t). A key example of such modulations are time interfaces where the permittivity of the medium is changed in time from isotropic to another isotropic value. Recently, isotropic-to-anisotropic time interfaces in a homogeneous, unbounded medium have also been proposed, demonstrating their potential for redirecting waves in real time. However, the challenge relies on accessing/creating permittivity tensors in time. To address this, here we propose isotropic-to-isotropic spacetime modulations inspired by spacetime effective media to emulate such isotropic-to-anisotropic time interfaces. Specifically, we consider that subwavelength spatially periodic multilayers, arranged either horizontally or vertically, are created in time using simultaneous isotropic-to-isotropic time interfaces applied in discrete spatial regions. The theory behind this approach is presented in detail demonstrating that, indeed, it is possible to change the direction of energy propagation in real time and emulate permittivity tensors. All the results are supported by numerical simulations, demonstrating the potential of the proposed spacetime approach to emulate photonics isotropic-to-anisotropic time interfaces.
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Fluid Dynamics
Influence of plume activity on thermal convection in a rectangular cell
Ambrish Pandey, Jörg Schumacher, Matteo Parsani et al. (+1 more)
We present three-dimensional direct numerical simulations of turbulent Rayleigh-Bénard convection in a closed rectangular box whose width $L_y$ and length $L_x$ are 0.8 and 2.4 times the height $H$, respectively. The Rayleigh number $Ra$ varies from $10^5$ to $10^{10}$, and the Prandtl number is unity. The advantages of the present configuration are: (a) A relatively stable unidirectional large-scale circulation, consisting of two counter-rotating rolls, fills the
cell and fixes the thermal plume ejection- and shear-dominated regions, in contrast to those in closed cylindrical
cells. (b) The regions of plume ejection are essentially independent of the sidewalls so that their autonomous existence can be studied. This is because there is some space, or "fetch", for the velocity and thermal boundary layers to develop along the length. (c) This geometry allows one to study the influence of locally thin and thick boundary layers (which follow larger or smaller plume activity) on the scaling of convection properties. In regions of larger plume activity (defined by an incessant movement of plumes), the temperature fluctuation as well as the normalised thermal and viscous dissipation rates decay more slowly with $Ra$ than in regions of lower activity. Both viscous and thermal boundary layers thin down rapidly with increasing distance from the plume ejection region. The local thicknesses of both boundary layers decline more rapidly with $Ra$ in the ejection region than in regions of impact and shear, where they are similar to each other. Despite these details, the global heat transport laws are practically the same as those in other configurations of low to moderate aspect ratios.
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All authors Ambrish Pandey, Jörg Schumacher, Matteo Parsani, Katepalli R. Sreenivasan
Data Analysis and Statistics · Cross-listed from cond-mat.mtrl-sci
A unified descriptor framework for hydrogen storage capacity and equilibrium pressure in interstitial hydrides
Seong-Hoon Jang, Di Zhang, Xue Jia et al. (+9 more)
Hydrogen is a promising energy carrier, yet its practical deployment is limited by the lack of storage materials that simultaneously achieve high storage capacity ($w$) and practical
equilibrium pressure at room temperature ($P_{\rm eq,RT}$). Interstitial metal hydrides offer fast kinetics and favorable thermodynamics (high $P_{\rm eq,RT}$) but suffer from intrinsically low w. Here, we establish a physically interpretable, data-driven framework to uncover descriptor-property relationships in interstitial hydrides using a curated database of pressure-composition-temperature measurements (Digital Hydrogen Platform, DigHyd) and white-box symbolic regression. Strikingly, the analysis reveals a clear separation of governing mechanisms, in which $w$ is governed by
geometric and
lattice conditions, captured by the average atomic radius ($\left\langle r_M \right\rangle$) and average thermal conductivity ($\left\langle\kappa\right\rangle$), with an optimal regime of $r_M \sim 1.47 \r{A}$ and relatively low $\left\langle\kappa\right\rangle$. In contrast, $P_{\rm eq,RT}$ is governed by elastic properties, captured by the average shear modulus ($\left\langle G \right\rangle$) and average Poisson's ratio ($\left\langle \nu \right\rangle$), reflecting the role of
lattice rigidity and mechanical compliance. These relationships are translated into compositional optimization pathways that follow the descriptor trends above, enabling the design of candidate materials with enhanced w under practical
equilibrium conditions ($P_{\rm eq,RT} \sim 0.1$ MPa). This work establishes a general, interpretable strategy for physics-informed design of energy materials systems.
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All authors Seong-Hoon Jang, Di Zhang, Xue Jia, Hung Ba Tran, Linda Zhang, Ryuhei Sato, Yusuke Hashimoto, Yusuke Ohashi, Toyoto Sato, Kiyoe Konno, Shin-ichi Orimo, Hao Li
Optics
High-Endurance, Low-loss Sb2Se3 Optical Switches on Silicon Nitride using Transparent Conductive Heaters
Xingshi Yu, Ipsita Chakraborty, Isaac Johnson et al. (+9 more)
We report an electrically actuated, low-loss non-volatile optical switch based on the phase-change material (PCM) Sb2Se3 integrated on a silicon nitride (Si3N4) platform. The device is fabricated using an 8-inch wafer-scale process flow, demonstrating the feasibility of scalable manufacturing for photonic integrated
circuits (PICs). By employing transparent indium tin
oxide (ITO) micro-heaters, reversible switching between the amorphous and crystalline states is achieved with an extinction ratio of 25~dB and an endurance exceeding 140 million switching cycles, establishing a new
benchmark for non-volatile integrated photonic
memory and reconfigurable architectures. Furthermore, multi-level operation beyond 6 bits can be repeatably demonstrated by tailoring the electrical pulse widths, enabling precise control of the optical phase. These results highlight a scalable and energy-efficient platform for high-density programmable and non-volatile photonic integrated systems.
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All authors Xingshi Yu, Ipsita Chakraborty, Isaac Johnson, Savvas I. Raptis, Qianbin Luo, Thalia Dominguez Bucio, Elliot Sandell, Chris Vagionas, Ioannis Zeimpekis, Amalia Miliou, Nikos Pleros, Frederic Gardes
Fluid Dynamics
From Sedimentation to Suspension: Critical Strain as a Predictor of Particle Resuspension Thresholds
Mohammadreza Mahmoudian, Simon A. Rogers and Parisa Mirbod
Viscous resuspension, the process by which sedimented particles are re-entrained into a fluid under flow, is central to numerous natural and industrial systems, including environmental contaminant transport, riverbed erosion, and biogeochemical cycling. Despite its ubiquity and importance, predicting when and how resuspension occurs remains challenging, particularly under oscillatory shear, where particle interactions are nonlinear, collective, and time-dependent. Here, we examine the resuspension dynamics of dense, non-Brownian suspensions under both steady and oscillatory shear using bulk rheometry and in situ rheo-microscopy over a broad range of particle volume fractions ({\phi}= 0.30 to 0.55). We demonstrate that strain is the key control parameter governing the transition from a sedimented bed to a fully suspended state. This strain-driven onset is mediated by effective interparticle collisions and collective particle motion. We develop a predictive model that captures the observed strain thresholds as a function of volume fraction, allowing for the construction of a new state diagram delineating sedimentation, resuspension, and full suspension regimes. These findings reveal a robust, strain-controlled resuspension mechanism and establish a unified framework for predicting suspension behavior across steady and oscillatory flows, offering new tools for managing particle-laden transport in geophysical, biological, and industrial environments.
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Optics
Long-wave infrared Fourier transform spectroscopy with enhanced and scalable sensitivity
Sergey Vasilyev, Roderik Krebbers, Dmitrii Konnov et al. (+7 more)
We report a broadband long-wave infrared
Fourier transform spectrometer with sensitivity exceeding that of previously reported direct-detection implementations. The system combines dual-comb spectroscopy with electro-optic sampling, multi-channel parallel near-infrared detection using InGaAs photodiodes, and real-time GPU-based computational corrections of multiple spectroscopy signals. Detection limits of 0.3 ppb for NH$_{3}$ and 2 ppb for C$_{2}$H$_{4}$ are achieved in 500 s, corresponding to 20x and 40x sensitivity improvements over earlier LWIR demonstrations, while maintaining high 0.0027 cm$^{-1}$ spectral resolution and broad spectral coverage. The architecture supports scalable sensitivity through increased detector count and enables rapid multispecies analysis of complex gas mixtures.
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All authors Sergey Vasilyev, Roderik Krebbers, Dmitrii Konnov, Mathieu Walsh, Igor Moskalev, Mike Mirov, Andrey Muraviev, Jerome Genest, Konstantin Vodopyanov, Simona M. Cristescu
Biological Physics
Dynamic Functional Connectivity Resolves Brain Integration-Segregation Trade-off Under Costly Links
Simachew Abebe Mengiste and Demian Battaglia
Dynamic functional connectivity (dFC) is ubiquitously observed in the
brain, but why functional networks should remain dynamic even at rest is unclear. We asked whether temporal reconfiguration becomes advantageous when keeping a functional link active is costly. Modeling resting-state dFC as a temporal communication network, we show that empirical dFC outperforms equal-cost static architectures by increasing the reach and speed of information spreading in sparse regimes. Unlike more randomized temporal null models, however, it also preserves strong local cohesiveness, temporal clustering, rapid return of information to its source, and high neighborhood retention. Empirical dFC therefore achieves a compromise between large-scale integration and transient local segregation. This compromise is not explained by generic temporal variability, nor by partially frozen null models with persistent templates. A connectome-based mean-field model reproduces several key features, including high spatial and temporal clustering and strong integrative and segregative performance, but remains more stable over time than the empirical data. Our results indicate that empirical dFC reflects a structured regime of controlled persistence and renewal, in which local neighborhoods are maintained long enough to support transient recirculation before broader network-wide spreading occurs. Dynamic functional connectivity thus appears to be a resource-efficient solution to competing communication demands.
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Atmospheric and Oceanic Physics
A Regime Shift in Atlantic Surface Currents Reveals a Step-like Decline of the Meridional Overturning Circulation
Han Huang, Ningning Tao, Hongyu Wang et al. (+8 more)
The Atlantic surface currents associated with the Atlantic Meridional Overturning Circulation (AMOC) play a central role in regulating Earth's
climate, yet their large scale dynamical response to
climate variability remains poorly understood. Here we identify a previously unrecognized basin scale phase of Atlantic surface circulation, termed the Atlantic Convergence Divergence Mode (ACDM), characterized by a convergence divergence pattern in the North Atlantic and coherent meridional flows in the South Atlantic. We show that the ACDM experienced a pronounced regime shift in 2009, marked by weakened vertical water exchange and reduced meridional transport. This transition closely coincides with direct RAPID MOCHA AMOC observations and is driven by AMOC modulated multicale forcing: a low frequency oceanic thermal reorganization that preconditions the system, and episodic atmospheric shocks that trigger the shift. By identifying the ACDM variability as a sensitive and physically grounded proxy for interannual AMOC fluctuations, we reveal that the observed 2009 shift signifies a nonlinear, step like weakening of AMOC that triggered a fundamental basin scale reorganization of Atlantic surface currents. Our results offer a dynamical explanation for the AMOC's recent decline and demonstrate its inherently nonlinear nature, highlighting the need to account for step like transitions in assessing its stability and future
evolution.
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All authors Han Huang, Ningning Tao, Hongyu Wang, Teng Liu, Fei Xie, Xichen Li, Yongwen Zhang, Niklas Boers, Jingfang Fan, Deliang Chen, Xiaosong Chen
Physics Education
Multidimensional Profiles of Critical Thinking in Physics Labs: Latent Structure, Instructional Change, and Connections to Physics Identity
Marcus Kubsch, Natasha G. Holmes and Antti Lehtinen
The Physics Lab Inventory of Critical Thinking (PLIC) measures three components of students' critical thinking in physics labs: evaluating data, evaluating methods, and proposing next steps. Prior work has analyzed these components in isolation or as a composite score. In this study, we apply latent profile analysis (LPA) to the three PLIC scales using a large, multi-institutional
dataset of 5,513 matched pre/post student records to identify characteristic response patterns across the three components simultaneously. At both pre- and post-instruction, a two-profile solution best fit the data. Profile composition shifted substantially over instruction, with 48.4% of students in the lower-performing profile at pre-test transitioning to the higher-performing profile at post-test, while 43.6% of students moved in the opposite direction. Course type was statistically associated with profile membership at both timepoints, though the effect was small (Cramér's $V \approx 0.10$). To examine the relationship between profile transitions and students' affective development, we estimated cross-lagged panel models (CLPMs) linking profile membership to belonging, recognition, self-efficacy, and agency. Belonging emerged as the principal upstream predictor, prospectively predicting recognition, self-efficacy, agency, and higher-knowledge profile membership. Agency and self-efficacy formed a reciprocal but asymmetric loop, with the path from agency to later self-efficacy being stronger. Recognition functioned primarily as a downstream construct over this timescale. These results provide the first person-centered, multidimensional characterization of PLIC performance and demonstrate that epistemic and identity-related constructs are interlinked in physics lab learning.
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Instrumentation and Detectors
Mortality of ultra-thin LGADs and PiN diodes from high energy deposition
A. Tishelman-Charny, A. Buzzi, F. Capocasa et al. (+12 more)
Low Gain Avalanche Diodes are
prime candidates for high-resolution timing applications in High Energy Physics,
Nuclear science, and several other fields. Operating these devices in high-radiation environments presents various hazards, including the risk of their permanent degradation or destruction caused by effects such as Single Event Burnout. Studies using minimum ionizing particles found a greatly reduced Single Event Burnout risk by operating below a bias voltage corresponding to an average electric field of 12 V/$\mu$m - however, as high energy particle
colliders produce a wide energy spectrum of radiation, it is crucial to understand this phenomenon and other possible damage mechanisms at energy deposition levels greater than those of minimum ionizing particles. This was achieved by pre-irradiating LGADs and PiN diodes with active thicknesses of 20, 30, and 50 $\mu$m up to 1.5 $\times$ 10$^{15}$ $\mathrm{n_{eq}/cm^2}$, and exposing them to beams of
protons and heavy ions (C, O, Fe, Au) at the BNL Tandem van de Graaff accelerator. Several mortality categories were observed, defined by different electrical and mechanical damage signatures. This furthers our understanding of permanent radiation damage of silicon devices, crucial towards mitigating Single Event Burnout and other damage mechanisms to safely operate future detectors.
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All authors A. Tishelman-Charny, A. Buzzi, F. Capocasa, G. D'Amen, S. Diaw, D. Duan, M. H. Mohamed Farook, G. Giacomini, M. Kurth, D. Ponman, J. Roloff, E. Rossi, S. Stucci, A. Tricoli, H. Zhang
Physics and Society · Cross-listed from cs.CL
Phonological distances for linguistic typology and the origin of Indo-European languages
Marius Mavridis, Juan De Gregorio, Raul Toral et al. (+1 more)
We show that short-range phoneme dependencies encode large-scale patterns of linguistic relatedness, with direct implications for quantitative typology and evolutionary linguistics. Specifically, using an information-theoretic framework, we argue that phoneme sequences modeled as second-order Markov chains essentially capture the statistical correlations of a phonological system. This finding enables us to quantify distances among 67 modern
languages from a
multilingual parallel corpus employing a distance metric that incorporates articulatory features of phonemes. The resulting phonological distance
matrix recovers major
language families and reveals signatures of contact-induced convergence. Remarkably, we obtain a clear correlation with geographic distance, allowing us to constrain a plausible homeland region for the Indo-European family, consistent with the Steppe hypothesis.
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All authors Marius Mavridis, Juan De Gregorio, Raul Toral, David Sanchez