Atmospheric and Oceanic Physics
Acceleration of horizontal numerical advection for atmospheric modeling through surrogate modeling with temporal coarse-graining
Manho Park, Christopher V. Rackauckas and Christopher W. Tessum
Machine-learned surrogate modeling of advection may accelerate geoscientific models, but existing approaches have either achieved limited speedup or have sacrificed spatial resolution compared to the model they are trained to emulate. We developed a machine-learned solver that speeds up advection simulations without sacrificing spatial resolution through the use of temporal coarse-graining, where the model is trained to take larger integration steps than dictated by the Courant-Friedrich-Lewy (CFL) condition. Our solver framework includes a convolutional neural network that takes concentrations and CFL numbers as inputs and outputs mass flux. Our solvers emulate 10-day ground-level horizontal advection simulations with r$^2$ values against the baseline ranging from 0.60–0.98 with temporal coarsening factors of 4 to 32 times the baseline integration time step. Speed increases and accuracy decreases with increased coarsening, with $r^2 = 0.24$ in accuracy lost for every factor of 10 gained in speed, reaching a maximum 92$\times$ speedup while maintaining $r^2 = 0.60$. We deliberately trained our solvers only on January ground-level wind data to examine their ability to generalize across seasons and vertical heights. The 4$\times$-coarsened learned solver successfully reproduces simulations over 72 vertical levels. The 8$\times$–16$\times$ solvers (but not 32$\times$) emulate most vertical levels. The learned solvers also generalize well across seasons, except for instabilities in June and October. With additional fine-tuning, these learned solvers could be appropriate for operational use where trading accuracy for speed could be advantageous, such as in screening tools, in ensemble simulations, or with data assimilation.
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Fluid Dynamics · Cross-listed from cond-mat.soft
Time-dependent pore-network modelling of Ostwald ripening in porous media
Ademola Isaac Adebimpe, Sajjad Foroughi, Branko Bijeljic et al. (+1 more)
We present a time-dependent pore-network model that couples transient mass transfer in the aqueous phase, capillary pressure heterogeneity, and realistic pore-throat geometries to capture the dynamic
evolution of gas clusters during Ostwald ripening in porous media. The model is applied to Bentheimer sandstone to study Ostwald ripening after imbibition to residual gas saturation. Both imbibition (shrinkage) and drainage (growth) events occur as the local capillary pressure in trapped gas clusters approaches
equilibrium. The model tracks event statistics, capillary pressure equilibration, cluster volume distributions, and spatial saturation profiles over 48 hours. While the volume-weighted average capillary pressure is constant, there is a rapid initial decline in average number-weighted cluster pressure and a shift in cluster size distributions toward fewer, larger ganglia, consistent with pore-scale imaging studies. Pore and throat occupancy analysis reveal persistent gas trapping in larger pore spaces. Since growth is by drainage, the pore-scale configuration of fluid is different from that predicted by an
equilibrium percolation-without-trapping model that only allows imbibition events. The model reproduces displacement and ganglion rearrangement during time-limited laboratory experiments, and can then provide predictions of trapped saturation, relative permeability and capillary pressure under field-scale conditions with application to hydrogen, natural gas and carbon dioxide storage in the subsurface.
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All authors Ademola Isaac Adebimpe, Sajjad Foroughi, Branko Bijeljic, Martin J. Blunt
Geophysics
Parameter-Efficient Adaptation of Pre-Trained Vision Foundation Models for Active and Passive Seismic Data Denoising
Jiahua Zhao, Umair bin Waheed, Jing Sun et al. (+3 more)
The demand for high-resolution subsurface imaging and continuous Earth monitoring has driven rapid growth in active and passive seismic data from dense geophone deployments, distributed acoustic sensing (DAS) arrays, and large-scale 2D and 3D surveys. This expansion makes complex noise suppression increasingly challenging, especially when signal fidelity must be preserved. Conventional supervised deep learning methods are often task-specific, require large paired
datasets, and can suffer from domain shift under new acquisition conditions. Foundation models offer a promising alternative, but pre-training seismic foundation models from scratch requires massive domain-specific data and substantial computation. We propose an efficient framework that repurposes general-purpose
Vision Foundation Models (VFMs) for geophysical tasks through Parameter-Efficient Fine-Tuning. The architecture uses a pre-trained VFM, a DINOv3 encoder, adapted with Low-Rank Adaptation (LoRA) to enable effective feature adaptation with few additional parameters. To improve robustness under unseen field conditions without ground truth, we introduce a kurtosis-guided unsupervised test-time adaptation module that updates only LoRA parameters during inference. This module self-calibrates the model to site-specific noise by identifying information-rich regions via kurtosis and performing self-training without labeled data. Experiments on public exploration seismic images and DAS vertical seismic profiling data from the Utah FORGE site show that the framework matches or outperforms domain-specific models. Tests on unseen cross-site data from a land survey in China and the Groß Schönebeck geothermal site in Germany further demonstrate strong generalization and effective signal-noise separation. These results highlight the potential of adapting pre-trained VFMs to data-intensive problems in exploration seismology.
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All authors Jiahua Zhao, Umair bin Waheed, Jing Sun, Yang Cui, Nikos Savva, Eric Verschuur
Optics · Cross-listed from cond-mat.mtrl-sci
Homogenization of one-dimensional periodic rod networks as special Cosserat rods
Vinayak and Ajeet Kumar
One-dimensional periodic rod networks are the structures that are obtained by periodically assembling its microstructural unit, a network of rods itself, in just one direction. In this work, we present a scheme for obtaining the nonlinear constitutive response of such structures when homogenized macroscopically as a continuum rod. To accurately capture arbitrary and large deformations, the geometrically exact special Cosserat rod theory is used for modeling the rod at both micro- and macroscales. By assuming the periodic structure to be strained uniformly, at macroscale, along its arc length, the full structure problem is reduced to just that of its microstructural unit but subjected to helically periodic boundary condition. The microscale problem, consisting of a network of rods and formulated in a variational setting, is solved in the presence of rod-joint constraints and helically periodic boundary conditions. The expressions for the macroscale rod's stress resultants, i.e. internal contact force and moment, and stiffnesses are then obtained. Finally, several numerical examples having different microstructural units are presented to demonstrate our method. First, the results corresponding to simpler square and cross microstructural units are presented and validated with the existing literature. Square microstructural units having helical constituent rods are then taken up which have application as artificial muscle fiber material. Eventually, homogenization of auxetic tubular metamaterials is performed. It is shown how various design parameters of these microstructural units can be tuned to obtain the desired macroscopic response.
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Atmospheric and Oceanic Physics
Overturning instability in forced ageostrophic oceanic flows
Laur Ferris and Donglai Gong
The subpolar oceans are characterized by intense storm forcing and complex littoral topography. Submesoscale frontal instabilities are significant sources of turbulent kinetic energy (TKE) in these regions. However, criteria for identifying and parameterizing these instabilities in regional models have predominantly relied on a geostrophic framework that neglects generalized ageostrophic shear. We derive criteria for overturning instability that account for stabilizing and destabilizing effects of ageostrophic shear on mechanically forced boundaries, deviating from the geostrophically derived potential vorticity (PV) criterion, $qf < 0$. Ageostrophic forcing modifies stability from that implied by the vertical PV structure underlying bulk surface boundary layer diagnostics, which may limit the applicability of such bulk criteria in strongly forced regimes and motivate the need for layer-resolved measures. We demonstrate their application using a feature model of a wind-forced jet, as well as a 1-km Regional Ocean Modeling System (ROMS) hindcast of the high North Atlantic, and assess the importance of forced ageostrophic overturning instability (AOI) in intense frontal zones. In the feature model, ageostrophic shear increases overturning instability by up to 20%, compared to a strictly geostrophic framework.
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Instrumentation and Detectors
Ion-Optical Tuning of the Large Acceptance Spectrometer for Improved Angular Resolution and Acceptance
Taichi Miyagawa, Junki Tanaka, Shinsuke Ota et al. (+8 more)
The trade-off between angular resolution and acceptance in scattering-angle measurements with a
magnetic spectrometer is quantitatively evaluated for the Large Acceptance Spectrometer (LAS). The dependence on the multipole magnet field strength is investigated. Third-order transfer
matrices were calculated with GICOSY, and particle transport was simulated with MOCADI. The vertical angular resolution is defined as the standard deviation between reconstructed and true angles, while the acceptance is determined from the transport efficiency within an elliptical gate in target angle space. The resolution improves with increasing field strength, reaching $\sigma_b \sim 5.5$ mrad at +20%, consistent with $5.43 \pm 0.20$ mrad. In contrast, stronger fields reduce the vertical acceptance and solid angle. These results demonstrate a trade-off between resolution and acceptance. Enhanced vertical focusing shifts the focal condition away from the nominal focal plane, enabling high-precision reconstruction.
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All authors Taichi Miyagawa, Junki Tanaka, Shinsuke Ota, Masanori Dozono, Nobuyuki Kobayashi, Lakmin Wickremasinghe, Fumiya Furukawa, Daichi Ishii, Sho Nishioka, Kota Takahashi, Erika Ukai
Biological Physics
Statistical analysis of virion-cell interactions mediated by peptide nanofibrils and peptide amphiphiles using STEM tomography
Philipp Rieder, Julia La Roche, Orkun Furat et al. (+8 more)
Peptide nanofibrils (PNFs) and peptide amphiphiles (PAs) are promising tools for enhancing viral transduction and gene transfer. However, quantitative insight into how their supramolecular architecture governs virion-
cell interactions is limited. Here, we introduce a framework for the acquisition, processing, and statistical analysis of scanning transmission electron microscopy (STEM) tomograms to objectively quantify peptide-virion-
cell interactions. Using four transduction-enhancing peptides (D4, Vectofusin-1, palmitic acid-PA (pal-PA), and eicosapentaenoic-PA (eic-PA)), peptide aggregate morphology, interfacial contact areas, and the spatial organization of virions with respect to peptides and
cells were analyzed using advanced
geometric descriptors. All peptides efficiently captured virions, resulting in few free virions, but they differ in how strictly virions were spatially confined near the
cell surface. These differences reflect alternative spatial organization strategies, which are likely crucial factors influencing transduction-enhancing efficacy. Our approach provides a novel, generalizable method to evaluate infection-enhancing nanomaterials and guides the rational design of next-generation peptide assemblies for therapeutic viral delivery.
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All authors Philipp Rieder, Julia La Roche, Orkun Furat, Annalena Kuhn, Lena Rauch-Wirth, Kübra Kaygisiz, Fabian Zech, Jan Münch, Clarissa Read, Rüdiger Groß, Volker Schmidt
Chemical Physics
A class and home problem on electrolyte transport: constant electric field implies electroneutrality, but electroneutrality does not imply a constant electric field
Ankur Gupta
We present a class and home problem in graduate transport phenomena and electrochemical engineering that clarifies a common misconception: electroneutrality implies the electric field is constant. Starting with one-dimensional Poisson–Nernst–Planck equations for a silver electroplating
cell, students obtain concentration and potential profiles. A companion home problem with added background electrolyte introduces a new dimensionless ratio and admits a closed-form solution. Students conclude that electroneutrality is necessary but not sufficient for a constant electric field.
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Applied Physics
Programmable Integrated Magnonic Meshes
Piero Florio, Matteo Vitali, Valerio Levati et al. (+9 more)
Integrated
circuits are a cornerstone of modern information technology, and analog wave-based architectures could enable fast and efficient processing beyond conventional charge electronics. In magnonics,
spin waves provide a highly tunable, compact and energy-efficient medium for on-chip microwave signal transport and processing. However, progress has been limited to isolated elements or short devices, severely limiting the overall functional complexity and scalability. Here we realize the key elements of universal magnonic circuitry, using a single-step direct
laser writing process in yttrium iron garnet, and monolithically cascade them in multi-stage programmable devices and networks. Using magneto-optical Kerr effect microscopy, we show efficient
spin-wave propagation and preserved phase coherence in waveguide structures for hundreds of wavelengths. In coupled waveguides, we observe complete and periodic power transfer over several coupling lengths, and in phase shifters we achieve arbitrary, tunable phase delays. By cascading these elements, we realize programmable splitters, frequency demultiplexers, and phase-controlled 2x2 routers, where output power and relative phase can be programmed on demand via external fields. Finally, we realize programmable magnonic interferometric meshes for on-chip
radio-frequency signal routing, with up to six magnonic inputs and outputs and seven cascaded stages, without the need for intermediate amplification. These direct-write cascaded networks bridge a long-standing gap in magnonic scalability, offering a viable pathway toward integrated, large-scale architectures for both classical and
quantum processing.
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All authors Piero Florio, Matteo Vitali, Valerio Levati, Rasheed M. Ishola, Luca Ciaccarini Mavilla, Nora Lecis, Carsten Dubs, Riccardo Bertacco, Marco Madami, Silvia Tacchi, Daniela Petti, Edoardo Albisetti
Atomic Physics · Cross-listed from quant-ph
Unified approach to time-resolved x-ray and electron diffraction imaging
Mingrui Yuan and Nikolay V. Golubev
Time-resolved x-ray diffraction (TR-XRD) and ultrafast electron diffraction (TR-UED) are emerging tools for probing ultrafast
quantum dynamics. From a theoretical perspective, they are commonly described within different frameworks and modeled using distinct approximations. Here, we present a unified
quantum-field-based description of ultrafast diffraction imaging that permits consistent consideration of TR-XRD and TR-UED within a common theoretical formalism. Our approach elucidates the correspondence between TR-XRD and TR-UED and allows their similarities and differences to be systematically disentangled. The developed formalism is sufficiently general to consistently and straightforwardly incorporate additional physical effects of interest, such as relativistic charge-current and current-current couplings. We apply our approach to simulate diffraction measurements of
laser-driven electron dynamics in
graphene, demonstrating the unique capabilities of diffraction imaging to unravel intricate
quantum processes in matter.
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Fluid Dynamics
Frequency spreading of internal wave energy by balanced flows in two dimensions
Nicholas DeFilippis, Oliver Bühler and K. Shafer Smith
Interactions between inertia-
gravity waves and balanced flows lead to a spectral
diffusion of wave action. Prior work has established that this
diffusion is weak across constant frequency surfaces in three-dimensional settings, but can be significant in two dimensions with a non-stationary balanced flow. We investigate the two-dimensional setting through numerical simulations that simultaneously evolve a turbulent quasigeostrophic balanced flow and advect rotating shallow water wave packets. In contrast to earlier predictions based on the synthetic flows used by Dong et al. (J. Fluid Mech., 2020, vol. 905, R3), we find that frequency spreading from wave mean-flow interactions is weaker for realistic turbulent flows. We derive a timescale for frequency
diffusion and show that frequency spreading with a realistic background flow is an order of magnitude smaller than with the synthetic flow. We narrow the discrepancy between the two- and three-dimensional induced
diffusion theories, which suggests other mechanisms are responsible for the broadband frequency spectra seen in the atmosphere and ocean.
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Medical Physics
Resolution-Noise Characteristics of Common FDK Filter Kernels: A Practical Reference for Preclinical Cone-Beam Micro-CT
Falk L Wiegmann and Nancy L Ford
The ramp filter kernel and cutoff frequency are fundamental parameters of the Feldkamp-Davis-Kress (FDK)
algorithm that determine the resolution and noise characteristics of the reconstructed image. Despite their importance, systematic evaluations of their combined effect on task-based image quality in preclinical micro-CT are scarce, and many studies do not report the filter configuration used. We reconstruct identical data from a GE eXplore CT 120 scanner using four filter kernels (ramp, Shepp-Logan, cosine, Hamming) at four cutoff frequencies (1.0, 0.8, 0.6, and $0.379\times$ Nyquist, matched to the detector-to-voxel size ratio) and evaluate each of the sixteen configurations using the modulation transfer function (MTF), noise power spectrum (NPS), and non-prewhitening detectability index (NPW $d'$). Qualitative assessment is performed on a mouse lung specimen. Across the sixteen configurations, $\mathrm{MTF}_{10}$ ranges from 0.93 to 2.35 lp/mm, integrated NPS from 75,670 to 13,259 $\mathrm{HU}^2$, and the Rose criterion crossing diameter from 2.86 to 0.93 mm at $\Delta C = 500$ HU and from 7.74 to 3.62 mm at 100 HU. This note presents the data as a concise visual and quantitative reference for groups selecting FDK filter parameters for preclinical cone-beam CT.
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Classical Physics
A revisited time domain formulation of boundary integral equations for two-dimensional elastodynamics
Domenico Capuani
A boundary integral equation (BIE) formulation for 2-D transient elastic wave propagation problems is presented. On the basis of the three-dimensional integral identity, the time-dependent kernels for the two-dimensional boundary integral equation are obtained. A linear time variation of displacements and tractions is assumed over each time step and an implicit time marching scheme is deduced. The formulation is used to obtain an analytical solution for the cylindrical cavity under transient pressure at the boundary surface.
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Optics
Percolation with coupled lasers: effect of non-linearities on the phase transition
Simon Mahler, Nikita Stroev, Mahmoud Abu Rmilah et al. (+2 more)
Controlled experimental studies of percolation are challenging due to difficulties in tuning site connectivity, isolating local interactions, and mitigating finite-size effects. In this work, we experimentally investigate percolation with a platform of coupled
lasers, where connectivity, interaction strength, and system size can be controlled. Using a square array of 100
lasers with astronomical number of possible cluster configurations, we show that the emergence of a percolating cluster corresponds to the onset of phase locking among the
lasers. We also show that the percolation probability undergoes a second-order alike transition as a function of the site-occupation probability, with a threshold consistent with classical theoretical predictions. Surprisingly, we find that at low pump level, amplified mode competition (nonlinear regime) alters the effective behavior of the lasing sites and modify the nature of the percolation transition. The experimental results are interpreted by the means of a theoretical toy model with connectivity rules to the classical percolation.
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All authors Simon Mahler, Nikita Stroev, Mahmoud Abu Rmilah, Asher Friesem, Nir Davidson
Chemical Physics · Cross-listed from cs.LG
CompleteRXN: Toward Completing Open Chemical Reaction Databases
Gabriel Vogel, Minouk Noordsij, Evgeny Pidko et al. (+1 more)
Chemical reaction
datasets such as USPTO suffer from substantial incompleteness, frequently missing byproducts, co-reactants, and stoichiometric coefficients. This limits their applicability and reliability in downstream applications. Here, we introduce CompleteRXN, a large-scale supervised
benchmark for reaction completion under realistic missing-data conditions. We construct a
dataset of aligned incomplete and atom-balanced reactions by mapping USPTO records to curated mechanistic reactions. We evaluate representative baselines, including a novel encoder-decoder reaction completion model with constrained decoding, the Constrained Reaction Balancer (CRB), and a recent algorithmic method, SynRBL. On our CompleteRXN
benchmark, the CRB achieves high performance across splits of increasing difficulty, reaching 99.20% equivalence accuracy on the random split and 91.12% on the extreme out-of-distribution split. SynRBL produces many balanced and chemically plausible completions, but with lower accuracy on the
benchmark test splits. Across all methods, performance degrades with increasing incompleteness. We observe a substantial drop when evaluating on reactions outside the
benchmark (full uncurated USPTO), highlighting the gap between
benchmark performance and practical robustness and motivating future work.
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All authors Gabriel Vogel, Minouk Noordsij, Evgeny Pidko, Jana M. Weber
Optics · Cross-listed from quant-ph
Generation of Tunable Entanglement from Thin-Film Lithium Niobate
Saniya Shinde, Maximilian A. Weissflog, Shaun Lung et al. (+7 more)
Entangled
photon pairs play a major role in various modern technologies such as
quantum imaging, communication, and computing. Conventional
photon-pair sources are often based on spontaneous parametric down-conversion in bulk nonlinear
crystals. Recent advances have also shown entangled
photon-pairs from transition metal dichalcogenide thin-films, however, these materials are not widely available and are not compatible with existing fabrication capabilities. We present a new thin-film lithium niobate source of polarization-entangled
photon pairs at the telecom wavelength that requires no additional optical elements for
entanglement generation and allows for easy application using the existing lithium niobate fabrication technologies. We demonstrate tunable
entanglement generation using the three-fold rotational
crystal symmetry of lithium niobate, allowing the generation of different maximally entangled Bell states or completely separable states depending on the polarization of the pump beam.
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All authors Saniya Shinde, Maximilian A. Weissflog, Shaun Lung, Elkin A. Santos, Jinyong Ma, Tongmiao Fan, Anna Fedotova, Sina Saravi, Andrey A. Sukhorukov, Frank Setzpfandt
Computational Physics · Cross-listed from math.OC
Structure-Preserving Optimal Control of Maxwell's Equations with Applications to Source Cloaking
Harbir Antil, Yaw Owusu-Agyemang, Rohit Khandelwal et al. (+2 more)
We develop a structure-preserving solution framework for the optimal control of the time-dependent Maxwell's equations. Building on a well-posedness theory for a weak form of the forward problem, we first analyze a forward solver that couples Nédélec and Raviart–Thomas finite elements with Crank–Nicolson time stepping. The solver preserves the de~Rham structure, enforces a discrete Gauss law, exactly satisfies a per-time-step energy balance, and converges to the weak solution under low regularity assumptions on the problem data, which are dictated by the optimal control setting. To control the Maxwell system, we add the curl of a space-time current density as a source to Ampére's law. The curl form yields charge conservation without auxiliary constraints. We prove the well-posedness and continuity of the control-to-state map, derive the adjoint system and a gradient representation for a tracking-type objective functional, and formulate a discrete optimization scheme that inherits structure preservation from the forward solver. Our discrete stationarity conditions are consistent with their continuous counterparts, and the discrete optimal controls converge, with mesh and time refinements, to the continuous optima. We demonstrate the merits of our optimal control formulation and the theoretical developments by numerically solving a series of source-cloaking model problems.
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All authors Harbir Antil, Yaw Owusu-Agyemang, Rohit Khandelwal, Jimmie Adriazola, Denis Ridzal
Data Analysis and Statistics
FitED: A User-Centric, Extensible Software Environment for Robust Peak-Profile and General Functional Data Fitting
Mustafa Mahmoud Aboulsaad
Reliable parameter extraction from experimental data is essential for quantitative analysis across spectroscopy, diffraction, photoluminescence, chromatography, microscopy, and time-resolved measurements. However, nonlinear fitting often remains difficult to reproduce, especially when complex models, correlated parameters, uncertain derived quantities, and user-dependent fitting choices are involved. We present FitED, a Python-based desktop application for nonlinear fitting of one-dimensional scientific data that combines an accessible graphical interface with a transparent and flexible numerical backend. FitED supports conventional peak profiles, including Gaussian, Lorentzian, Pseudo-Voigt, and exact area-normalized Voigt functions, as well as arbitrary user-defined analytical models for broader experimental applications. The software integrates local and global-search-assisted optimization strategies, automated model initialization, repeated stability testing, parameter-correlation analysis, and covariance-based propagation of uncertainty for derived quantities. By combining interactive usability with uncertainty-aware analysis and structured export of fitting results, FitED provides a practical platform for reproducible and interpretable fitting of experimental data. The software is intended to support both routine analysis and advanced model evaluation while preserving the parameter-level control required by experimental researchers.
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Fluid Dynamics
Curvature-corrected sloshing spectra for cylindrical tanks in microgravity
Gianni Cassoni
In microgravity, a partially filled cylindrical tank is generally bounded by a curved
equilibrium meniscus rather than by an almost flat free surface. This modifies both the bulk
liquid inertia and the capillary restoring force, so flat-interface sloshing frequencies can become inaccurate even in the linear regime. This effect matters once the Bond number is of order unity or smaller, precisely the regime relevant to capillarity-dominated propellant management. This study revisits the classical cylindrical curved-meniscus
eigenvalue problem for capillary-
gravity sloshing about axisymmetric Young-Laplace
equilibria. A semi-analytical boundary-operator formulation is derived that preserves the cylindrical Bessel structure and recovers the flat-interface limit exactly. Its main advantage lies in treating the bulk Dirichlet-Neumann operator and the linearised
curvature operator as distinct components, thereby making the physical origin of
curvature-induced frequency shifts explicit. The results show that
equilibrium curvature couples radial modes and alters the low-order spectrum once $Bo \lesssim 1$. Concave menisci lower the fundamental frequency, whereas convex menisci raise it while often lowering higher branches. The asymmetry between wetting and non-wetting configurations is found to be predominantly kinetic, being carried mainly by the Dirichlet-Neumann operator rather than by the capillary term. Curved menisci should therefore be treated as part of the leading-order model of cylindrical microgravity sloshing, not as a secondary correction, if reduced-order predictions are to capture the relevant dynamical scales for spacecraft applications.
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Atmospheric and Oceanic Physics · Cross-listed from cond-mat.dis-nn
Data-Driven Modelling to predict forest fire spread in the Patagonian region in Argentina
Lucas Becerra, Monica Malen Denham, Alejandro B. Kolton et al. (+1 more)
Wildfires are among the most severe disturbances affecting forest ecosystems, with over 50,000 hectares burned in Patagonia, Argentina, during 2025 alone. This study implements a Reaction-
Diffusion-Convection (RDC) model to simulate wildfire spread in the Steffen and Martin Lakes area, a region severely impacted by fires. By integrating high-resolution maps of slope, wind velocity, and vegetation, we conducted three computational experiments of increasing complexity to simulate fire propagation across heterogeneous landscapes. We employed a Genetic
Algorithm (GA) to recover reference model parameters by maximizing the spatial overlap between simulated and reference burned areas. Subsequently, parameter estimates were refined using XGBoost to improve accuracy. Results demonstrate that the GA accurately recovers reference parameters across all scenarios, while the XGBoost fine-tuning significantly enhances accuracy in simpler cases. This integrated framework offers a systematic approach for estimating difficult-to-measure wildfire parameters, demonstrating the potential of hybrid computational methods for wildfire modeling and forest management.
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All authors Lucas Becerra, Monica Malen Denham, Alejandro B. Kolton, Karina Laneri
Accelerator Physics
Development of Ultra High Power Compact X-Band Pulse Compressor
Ankur Dhar, Mohamed A. K. Othman and Valery A. Dolgashev
We demonstrate a new 11.424 GHz SLED-type RF pulse compressor for powering high-gradient X-band photoinjectors with pulse lengths around 20 ns. RF pulse compression provides a practical path to higher peak power at the cost of pulse length for various applications such as RF deflectors for electron beam diagnostics on free electron
lasers. Our new compact pulse compressor uses spherical cavities supporting axially symmetric TE modes which have minimal electric fields on the cavity surfaces, intended to improve high-power robustness as compared to existing compact spherical SLEDs which use a TE dipole mode. We present the design of this pulse compressor composed of two spherical cavities and a waveguide hybrid. The two cavities and hybrid have TE01 circular waveguide ports. This pulse compressor was built and high power tested at SLAC. These tests demonstrated a peak power of 317 MW by compressing 52 MW, 1 $\mu$s pulses generated by a SLAC XL-4 klystron representing, to our knowledge, the highest peak power achieved from a single-stage compact SLED RF pulse compressor at X-band. The full-width at half-maximum of this compressed pulse was 27.1$\pm$1.1 ns. We
conjecture that this development demonstrates a viable route to reaching the high-gradient, short pulse regime for accelerating structures and RF photoinjectors.
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Plasma Physics
Characterization of ELM Pacing via Vertical Jogs on DIII-D
Kei Yasoda, Dario Panici, Andrew Oak Nelson et al. (+3 more)
Edge localized mode (ELM) pacing via vertical
plasma oscillations or jogging has been successfully demonstrated on DIII-D. Rapid vertical movement of the
plasma toward the X-point has been shown to effectively trigger ELMs. By vertically oscillating the
plasma at a rate of 10 Hz, the ELM frequency increased from $\sim$5~Hz, the natural ELM frequency in similar DIII-D discharges, to 10~Hz. Downward jogs have been observed to trigger multiple ELMs in one cycle. ELMs triggered at higher than natural frequencies lead to smaller decreases in stored energy, from ~10% to as little as below 1%. As a consequence, the peak heat flux to the divertor has been observed to be reduced by a factor of $\sim$2. In addition, a reduction in the carbon
impurity concentration has been observed. During downward jogs in the lower single null (LSN) configuration, the X-point movement is slower and smaller than the top of the
plasma. As a result, a reduction in the
plasma cross section and hence volume has been observed. To understand the mechanism of ELM triggering by jogging, a toy model of the edge toroidal current has been built and tested with DIII-D experiment data. The experimental data and model suggest that when the
plasma moves down towards the X-point, a net positive toroidal current is locally induced in the edge region. ELITE stability analysis suggests that this current pushes the
plasma state across the peeling side of the peeling-ballooning stability boundary into the unstable region triggering ELMs.
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All authors Kei Yasoda, Dario Panici, Andrew Oak Nelson, Florian M. Laggner, Sangkyeun Kim, Egemen Kolemen
Space Physics
Radial Dependency of ICME-associated Particle Acceleration Processes: Statistical Multipoint Observations from 2016-2023
Malik H. Walker, Robert C. Allen, George C. Ho et al. (+6 more)
During the propagation of interplanetary coronal mass ejections (ICMEs),
evolution of the ICME-driven shock along with interactions with other
solar wind structures, planetary bodies, and general changes to their morphology can alter particle acceleration efficiency and transport effects at their associated shocks. While the underlying mechanisms for these processes have been studied, the connection between the radial
evolution of the ICME-driven shock during propagation and resulting gradual
Solar Energetic Particle (SEP)and Energetic Storm Particle (ESP) intensities, composition, and acceleration has yet to be fully understood. The current distributed array of spacecraft at varying heliocentric distances provides a welcome opportunity to statistically analyze the radial dependency of particle populations and acceleration mechanisms present at ICME-driven shocks. We compile a database of 39 multipoint ICME events from 2016-2023, which are observed in situ by at least two of the following spacecraft: Parker
Solar Probe (PSP),
Solar Orbiter, ACE, Wind, and STEREO-A. Using the
magnetic field,
plasma, and ion compositional data provided by these spacecraft, we derive both local shock and ESP spectral shape parameters. By comparing the changes in these parameters at different stages of ICME propagation, we analyze the connection between the
evolution of the local shock conditions and the spectral shape. We find evidence to suggest a consistent increase in shock acceleration efficiency with heliocentric distance while the parent ICME is within 0.7 au, followed by a reduction in shock efficiency at further distances.
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All authors Malik H. Walker, Robert C. Allen, George C. Ho, Glenn M. Mason, Christina M. S. Cohen, Christina Lee, Christian Möstl, Emma E. Davies, Eva Weiler
Space Physics · Cross-listed from astro-ph.SR
EMBER: Machine-Learning Detection of Modulated Ion Acoustic Waves and Associated Core-Electron Heating in the Solar Wind with Parker Solar Probe
Argyro Sasli, Karish Seebaluck, Chris Colpitts et al. (+1 more)
Modulated ion acoustic waves (IAWs) – including triggered ion acoustic waves (TIAWs) and frequency-dispersed ion acoustic waves (FDIAWs) – are increasingly recognized as efficient drivers of electron heating in the
solar wind through nonlinear wave-particle interactions. Identification of these events in the Parker
Solar Probe (PSP) FIELDS burst-mode archive has so far relied on expert visual inspection and does not scale to the full mission. We present EMBER (Electron heating from Modulated Burst-mode Event Recognition), an open-source pipeline that converts PSP FIELDS Digital Burst
Memory (DBM) voltage bursts into log-scaled
Fourier spectrograms and applies a multi-detector, background-only anomaly detection suite. The suite combines physics-motivated detectors, classical outlier detectors, and deep learning detectors. The EMBER ensemble recovers 93% of the anomalous events at 1% FAR (1 false positive per 100 held-out backgrounds). Coincident SWEAP/SPAN diagnostics show that flagged intervals exhibit core perpendicular electron temperatures above the adiabatic cooling expectation and elevated Te/Ti, reproducing the preferential-heating phenomenology established by prior manual studies without any use of electron temperatures in the detection step.
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All authors Argyro Sasli, Karish Seebaluck, Chris Colpitts, Michael Coughlin
Atomic Physics · Cross-listed from quant-ph
Optically detected nuclear magnetic resonance of carbon-13 in bulk diamond
Maxwell D. Aiello, Janis Smits, Yaser Silani et al. (+13 more)
Precision measurements based on optically detected
nuclear magnetic resonance offer exquisite sensitivity to absolute shifts in
spin transition frequencies, with potential applications in fundamental physics experiments and inertial sensing. We investigate 13C
nuclear spins in diamond as a candidate system for solid-state implementations, which hold the promise for high-fidelity readout of large numbers of coherent
nuclear spins in millitesla or lower
magnetic fields. We demonstrate a technique that allows for both optical polarization and readout of large ensembles of ~10^{16} polarized
nuclear spins. Our method takes advantage of state-selective Landau-Zener transitions under microwave frequency sweeping, which bidirectionally transfer
spin polarization between Nitrogen-Vacancy (NV) electron
spins and remote 13C
nuclear spins. Using natural isotopic abundance diamonds with nitrogen densities of ~0.5-10 ppm, we perform optically-detected 13C Ramsey spectroscopy and realize a
nuclear-
spin-dependent fluorescence contrast exceeding 0.5% peak-to-peak. We observe
nuclear spin dephasing times T2*~2 ms that only modestly improve with homonuclear dipolar decoupling, indicating that they are limited by the longitudinal
spin relaxation of nearby NV electron
spins. We study the
magnetic field dependence of the optical readout and find comparable contrast and dephasing times for
magnetic fields in the range 8-20 mT. Our method can be interpreted as a type of repetitive readout, where each NV center optically reads out the
spin state of ~10^2
nuclei before
nuclear spins depolarize.
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All authors Maxwell D. Aiello, Janis Smits, Yaser Silani, Andris Berzins, David Lidsky, Bryan A. Richards, Amilcar Jeronimo Perez, Chandrasekhar Ramanathan, Sebastián C. Carrasco, Jabir Chathanathil, Michael Goerz, Vladimir S. Malinovsky, Dmitry Budker, Sean Lourette, Andrey Jarmola, Victor M. Acosta