Physics and Society
Towards an LLM-based method for quantifying the sexual content in song lyrics
Ignacio M. Sticco
Reggaeton is one of the most widely consumed music genres in the world, and its lyrics are commonly regarded as highly sexualized. This claim rests mostly on qualitative studies and on small-scale quantitative ones. This paper has two goals. First, we present a reproducible method that uses a large
language model to quantify thematic content in song lyrics along several independent dimensions. The method is not restricted to sexual content. Second, we apply it to a corpus of 1,259 songs by 12 reggaeton artists released between 2002 and 2025. The analysis covers four topics: a
dataset characterization, a per-artist comparison, an analysis of how the dimensions change over time, and a comparison between our sexual-explicitness score and Spotify's own explicit flag. We release the data collection code, the scoring
prompt, and the corpus, so that other researchers can replicate the approach or apply it to their own lyrics
datasets.
Read the full abstract ▾
Medical Physics · Cross-listed from eess.SY
Preview-Based Relative-Motion Control of an Insertion Tool for Neural-Thread Placement in Pulsating Tissue
Yongyan Cao and Xiaobo Li
Flexible neural electrode threads must be placed at a prescribed depth while the cortical surface moves with cardiac and respiratory pulsation. A controller tracking a fixed point in the laboratory frame cannot distinguish commanded insertion from tissue motion; the error appears as both a depth offset and relative tip–tissue velocity during contact. This paper formulates thread insertion in tissue-relative coordinates: a harmonic observer predicts delayed cortical-surface motion over the control horizon, a constrained MPC regulates the tip relative to that prediction while limiting actuator effort and lateral relative velocity, and an augmented disturbance state removes the steady offset from persistent contact force and model mismatch. In a 1-DOF MuJoCo
benchmark, the controller reaches RMS relative-placement errors of 12.0\um\ free-space and 1.9\um\ in contact, versus 18.3/176.8\um\ for delayed-feedback impedance and 286.1/275.5\um\ for laboratory-frame PD – the lower contact offset costs more peak contact force (3.43 vs.\ 2.00~mN), since it drives to commanded depth rather than yielding to tissue. A 3-DOF extension reduces lateral shear velocity from 1.34 to 0.50~mm/s at 2.1\um\ lateral placement error, and a feasibility-restoring soft-slack formulation keeps the shear constraint solvable under degraded sensing where a matched hard-constraint controller fails. A two-vertex Lyapunov certificate for the finite-horizon gain holds over $-40\%/{+}50\%$ reflected-mass mismatch, and the 1-DOF QP solves in under 0.4~ms at the 95th percentile. These results are a simulation-based control
benchmark, not a clinical safety claim: the modeled tip is a rigid contact point, and flexible-thread mechanics, a validated force constraint, biological damage thresholds, and hardware-realistic sensing and timing remain necessary before deployment.
Read the full abstract ▾
Space Physics · Cross-listed from cs.CR
Treating Statewide CORS Networks as Spatially Distributed Sensors for GNSS Integrity Monitoring under Unintentional and Deliberate Threats
Minhaj Uddin Ahmad, Sagar Dasgupta, Muhammad Sami Irfan et al. (+3 more)
State departments of transportation (DOTs) in the United States increasingly rely on statewide continuously operating reference station (CORS) networks to support high-precision Global
Navigation Satellite System (GNSS)-based positioning and timing for intelligent transportation systems. These networks also provide continuous observations that can support regional GNSS integrity monitoring. This study develops and demonstrates a framework that treats a statewide CORS network as a spatially distributed sensor system for identifying unintentional (environmental) and intentional (cyber) interference when GNSS measurements deviate from expected spatial patterns. We develop a graph-based Network Consistency Framework (NCF) that evaluates each station against its spatial neighborhood using four metrics: neighborhood residual, spatial gradient, residual, and graph smoothness. These metrics are combined into a Network Consistency Index (NCI). The framework is demonstrated using two consecutive days of four-constellation observations from 50 stations in the Alabama DOT-maintained CORS network, using changes in vertical total electron content ({\Delta}VTEC) and the Rate of TEC Index (ROTI) as spatially coherent observables. The framework quantified network-wide spatial consistency and identified localized anomalies. Detected anomalies indicate stations whose observations deviated from the surrounding regional network, signaling potential integrity issues. Determining whether anomalies result from receiver faults, localized interference, spoofing, or other causes requires further investigation. This study introduces statewide CORS networks as regional GNSS integrity observatories and presents the NCF and NCI for graph-based spatial integrity monitoring. Transportation agencies can implement the framework using existing CORS observations to monitor network integrity and identify localized anomalies.
Read the full abstract ▾
All authors Minhaj Uddin Ahmad, Sagar Dasgupta, Muhammad Sami Irfan, Mizanur Rahman, Mashrur Chowdhury, Thejesh Bandi
Applied Physics · Cross-listed from cond-mat.mes-hall
Time-Reversal-Invariant Altermagnetic Acoustic Crystals
Tianzhi Xia, Han-Rong Xia, Jinglin Liu et al. (+3 more)
Altermagnets have emerged as a new class of
magnetic materials that combine
spin-split electronic bands with zero net magnetization. Extending this paradigm to classical-wave systems has, however, been fundamentally challenging because conventional realizations require broken time-reversal
symmetry (TRS). Here, we overcome this limitation by introducing two pseudospin degrees of freedom and constructing a pseudo-time-reversal operator that faithfully reproduces the action of its physical counterpart while preserving actual TRS. Building on this framework, we theoretically propose and experimentally realize the first time-reversal-invariant altermagnetic acoustic
crystal. Acoustic measurements directly reveal pseudospin-dependent band splitting–a defining hallmark of altermagnetism–under strictly TRS-preserving conditions. Moreover, the altermagnetic acoustic
crystal exhibits sublattice-pseudospin locking, enabling flexible control over acoustic pseudospin splitting and filtering. Our work establishes acoustic
crystals as a versatile platform for exploring altermagnetic physics and opens new avenues for
spin-inspired wave manipulation in nonmagnetic devices.
Read the full abstract ▾
All authors Tianzhi Xia, Han-Rong Xia, Jinglin Liu, Xiying Fan, Zebin Zhu, Zhen Gao
Medical Physics · Cross-listed from cs.CV
MRI super-resolution in ten sampling steps using a diffusion bridge model
Mojtaba Safari, Hang Yu, Zach Eidex et al. (+10 more)
Objective. MRI provides excellent soft-tissue contrast, but long acquisition times can cause patient discomfort and lead to motion artifacts, forcing a trade-off between spatial resolution and scan time.
Diffusion-based super-resolution (SR) reconstructs high-resolution (HR) images from low-resolution (LR) inputs, but typically needs many sampling steps and initializes from a Gaussian prior ill-suited to image restoration. We developed an efficient
diffusion framework that reconstructs HR MRI directly from LR data. Approach. We propose super-resolution
diffusion bridge model (SR-DBM), a super-resolution
diffusion bridge model that casts SR as a
stochastic transport between the LR and HR image distributions. Through a Doob's h-transform of a mean-reverting
stochastic differential equation, SR-DBM pins the process to the paired HR and LR images at its endpoints, initializing reconstruction from the measured anatomy rather than from Gaussian noise. The HR image is recovered by a deterministic reverse trajectory in which a network predicts the clean image at each of only ten sampling steps. We evaluated SR-DBM on ultra-high-field 7T
brain T1 MP2RAGE maps and pelvic T2-weighted prostate images against nine comparison methods using PSNR, SSIM, GMSD, and LPIPS. Main results. SR-DBM attained the highest PSNR and SSIM and the lowest GMSD on both
datasets (
brain: 27.66+-1.52 dB, 0.96+-0.02, 7.96+-1.86$; prostate: 27.87+-2.29 dB, 0.80+-0.05, 8.38+- 1.44), with statistically significant gains over every comparison method (two-sided Wilcoxon signed-rank test with Holm correction, p<0.05). The strongest baseline, SR-EMamba, ranked second. Qualitatively, SR-DBM produced the smallest residual errors and best preserved fine structures and lesions.
Read the full abstract ▾
All authors Mojtaba Safari, Hang Yu, Zach Eidex, Mingzhe Hu, Ryan J. Sanford, Alexandru Florea, Shansong Wang, Chih-Wei Chang, Erik H Middlebrooks, Aditya Juloori, Stanley L. Liauw, Ralph Weichselbaum, Xiaofeng Yang
Biological Physics
Optimal concentration and gradient sensing by perfect monitors
Farshid Jafarpour
Cells often estimate chemical concentrations from only a few diffusing molecules, whose
stochastic motion limits sensing precision. We consider a perfect monitoring instrument that records the instantaneous molecular density throughout a finite region without perturbing the concentration field or distinguishing molecular identities. The standard Berg-Purcell
estimator weights all positions uniformly. Here we derive the optimal spatial weighting within a large class of unbiased
estimators for both concentration and gradient sensing. Variance minimization maps to an electrostatic problem. Surprisingly, although the instrument monitors the entire volume, the optimal
estimator assigns all weight to its boundary, reducing the uncertainty in both concentration and gradient sensing. We extend the results to arbitrary geometries and spatial dimensions.
Read the full abstract ▾
Chemical Physics
Self-consistent double-hybrid density functional theory via one-body second-order Møller-Plesset perturbation theory and projection-based embedding
Huy Gia Bui and Lan Nguyen Tran
We present the development of self-consistent one-body double-hybrid (OBDH) density functional theory (DFT). In this approach, the one-body second-order Møller-Plesset (OBMP2) perturbation potential is embedded directly in the generalized Kohn-Sham framework, allowing orbitals to be optimized in the presence of MP2-level dynamic correlation. Unlike existing orbital-optimized double hybrids, OBDH requires neither the optimized effective potential nor perturbative orbital relaxation corrections. The energy functional combines a semilocal exchange-correlation functional, exact exchange, and OBMP2 correlation, from which the effective
Hamiltonian and self-consistent-field equations are systematically derived. To reduce computational cost, projector-based
embedding with concentric localization truncation is applied to the OBMP2 component, termed sub-OBDH. OBDH and sub-OBDH are benchmarked on diatomic potential energy curves, self-interaction errors, dihedral torsions of organic molecules, and interaction energies in non-covalent charged systems. Across all systems, OBDH consistently outperforms standard DFT, demonstrating its potential for accurate and practical electronic structure calculations.
Read the full abstract ▾
Fluid Dynamics
Turbulence anisotropy in a bubbly vertical channel flow with topological change
Arturo A. Arosemena, Davide Procacci, Simone Di Giorgio et al. (+2 more)
High-fidelity numerical simulations of bubble-laden, vertical channel flow in the upward configuration, where the bubbles undergo topological changes (breakup and coalescence), were performed with the purpose of exploring the effect of the surface tension on the
turbulence anisotropy in the carrier phase. A qualitative analysis shows that velocity fluctuations are enhanced in the wake of large bubbles. Moreover, as shown by the velocity spectra, these structures seem to scale with bubble size and interact with those closer to the wall. Finally, a barycentric map and other indicators of
turbulence anisotropy clarify that, except at the core of the channel where the largest bubbles reside, the multiphase flow cases are actually more isotropic than the single-phase flow at a matching friction Reynolds number. This unexpected behavior is attributed to a better redistribution of energy due to an enhancement of sweep events (high-speed fluid towards the wall) in the presence of large bubbles.
Read the full abstract ▾
All authors Arturo A. Arosemena, Davide Procacci, Simone Di Giorgio, Jannike Solsvik, Shahab Mirjalili
Accelerator Physics · Cross-listed from hep-ph
Comment on "Regarding the Rotational Unruh Effect"
S. R. Mane
We comment on various statements in a recent document (A.~Deur, S.~J.~Brodsky, C.~D.~Roberts and B.~Terzić, Regarding the Rotational Unruh Effect, arXiv:2607.25004v1 [hep.ph], (2026)). The examples cited treat electrons (or positrons) circulating and emitting
photons in high-energy storage rings. The topic is also of interest in astrophysics, for electrons orbiting in
magnetic fields around
neutron stars.
Read the full abstract ▾
Chemical Physics
Analytical Nuclear Gradients and Hessians on Quantum Hardware via Orbital-Optimized VQE with Error Mitigation
Renato Olarte Hernandez, Karl Michael Ziems, Erik Kjellgren et al. (+3 more)
Nuclear gradients and Hessians are fundamental quantities in computational chemistry, essential for a wide range of applications including geometry optimization, vibrational spectroscopy, and molecular property calculations. In this work, we present their analytical implementation on
quantum hardware. The methodology is formulated within an active-space framework combining orbital optimization and linear-response theory. On the
quantum-computing side, the approach employs the tiled
unitary product state (tUPS) ansatz to directly evaluate the tensor elements required for solving the response equations. Moreover, the expectation values are corrected using an adapted confusion-
matrix error-mitigation scheme in combination with post-selection criteria. The resulting workflow is assessed on molecular hydrogen and on water through the calculation of potential energy surfaces,
nuclear gradients, Hessians, and vibrational frequencies, enabling the evaluation of both its capabilities and current limitations. The results demonstrate good performance for the hydrogen molecule, whereas the water molecule provides a more demanding test of
quantum-hardware resources and highlights the trade-offs associated with error-mitigation strategies. The quantified analysis of the results identify the main sources of errors, suggesting improvement directions for more accurate
quantum computer applications.
Read the full abstract ▾
All authors Renato Olarte Hernandez, Karl Michael Ziems, Erik Kjellgren, Jacob Kongsted, Sonia Coriani, Stephan P. A. Sauer
Fluid Dynamics
Deformation dynamics of Oldroyd B drop in alternating electric field
Sarika Shivaji Bangar and Gaurav Tomar
The deformation of viscoelastic drops in alternating electric fields is relevant to electrohydrodynamic applications such as microfluidics, inkjet printing, and drop manipulation. We investigate the dynamics of a neutrally buoyant Oldroyd-B drop subjected to a uniform alternating electric field using asymptotic analysis and direct numerical simulations with the open-source solver Basilisk. An analytical solution is derived for small deformation and weak elasticity for an Oldroyd-B drop suspended in an Oldroyd-B medium, with both fluids modeled as leaky dielectrics under axisymmetric Stokes flow. Depending on the conductivity and permittivity ratios, six electrohydrodynamic regions are identified, characterized by distinct deformation modes, flow directions, and nonlinear responses; while some exhibit stable spheroidal deformation, others undergo pointed-tip, multi-lobed, or oblate breakup beyond a critical electric capillary number. Across high-, intermediate-, and low-frequency regimes, the deformation oscillates at twice the applied field frequency, with its mean and amplitude governed by the field frequency and viscoelasticity. For cases that produce prolate deformation under a steady field, the drop remains prolate at high frequency, exhibits brief oblate excursions at intermediate frequency, and undergoes large-amplitude oscillations between near-spherical and highly deformed states at low frequency. The mean deformation varies monotonically or non-monotonically with $De$, depending on frequency and electrical property ratios. For cases producing oblate deformation under a steady field, the drop remains oblate at high frequency, develops dimples at intermediate frequency, and breaks up at low frequency for sufficiently large $De$ and $Ca_E$; the mean deformation increases monotonically with $De$.
Read the full abstract ▾
Chemical Physics · Cross-listed from quant-ph
What solvable models reveal about Born-Oppenheimer, Born-Huang, and exact factorization
Stephen Wiggins
The Born-Oppenheimer (BO) and single-surface Born-Huang (BH) approximations replace the full molecular problem by
nuclear motion associated with one clamped electronic state, whereas the full BH expansion and exact factorization (EF) are exact representations. We use two analytically transparent models to identify what controls one-surface error. For Fernández's bilinearly coupled oscillators, the Brattsev ground-state bracket was already known; we derive closed-form differences proving strictness for every positive
nuclear mass and nonzero stable coupling. Using Hunter's conditional-amplitude construction, we place the closed-form ground-state EF potential alongside BO and single-surface BH. Exact excited-state calculations show that the bracket does not extend through the spectrum. The diagonal BH correction is the
quantum-metric coefficient of the retained electronic state divided by twice the
nuclear mass. Fernández's sixth-order expansion shows that the next omitted correction contains the same derivative couplings, an additional inverse electronic-energy separation, and a factor depending on the
nuclear state. We therefore add a two-state model with a position-dependent gap. Decreasing its minimum separation makes the metric higher and narrower while leaving the total Fubini-Study length equal to pi/2. The exact EF, BO, and BH potentials can differ visibly even when their
nuclear ground-state amplitudes are nearly identical. The two models show that one-surface accuracy depends on
nuclear mass, electronic-state variation, energy separation from omitted states, and the
nuclear wavefunction.
Read the full abstract ▾
Classical Physics
Critical damping in linear system with two degrees of freedom: surprises and pitfalls
Maxim D. Arnold, Oleg V. Gendelman and Vadim Zharnitsky
In this Brief Communication, we establish the notion of critical damping for generic two-degree-of-freedom system. For given set of masses and stiffnesses, the critical damping corresponds to the real
eigenvalue with maximal multiplicity, equal to minus geometrical mean of the eigenfrequencies. This case corresponds to the fastest possible asymptotic decay rate for generic initial conditions. The damping
matrix for the critical case is unique up to reflection of one modal coordinate and, generically, non-diagonal. Quite surprisingly, for large difference of the eigenfrequencies, it is also not positive definite. Therefore, physical realization of the critical case will require active elements that provide negative effective damping.
Read the full abstract ▾
Plasma Physics
Transitional evolution of the wave dispersion relation during helicon discharge ignition: an analytical theory from vacuum to steady operation
Lei Chang
The dispersion relations of the helicon and Trivelpiece–Gould (TG) waves in a steady, fully developed magnetised
plasma column are well established, but the discharge does not begin in that state. During ignition the electron density rises through five to seven orders of magnitude and the electron–neutral collision frequency falls by two to three, so the dispersion relation is itself a time-dependent object whose very existence must be justified. This paper develops a closed analytical theory of that transition for a cylindrical column in a uniform axial field, using a cold, collisional, two-species description that remains regular in the
vacuum limit. Three structural results emerge. First, the
vacuum limit is a degenerate double root of the quartic governing the perpendicular wavenumber; the helicon and TG branches are not independent modes that appear at some threshold but the two lobes of a single
vacuum root, split by the gyrotropic and anisotropic parts of the dielectric tensor. The leading-order contribution to the discriminant cancels identically, so the branches separate linearly in density rather than with the square-root behaviour generic to a perturbed repeated root; the separation is correspondingly suppressed, and the helicon root remains pinned at its
vacuum value until the electron density reaches about 10$^{15}$ m$^{-3}$ while the TG root departs immediately.
Read the full abstract ▾
Optics
Low optical loss electrical isolation for multi-section monolithic GaSb-based photonic circuits
Md Ajwaad Zaman Quashef, Nouman Zia, Jukka Viheriälä et al. (+1 more)
Monolithic photonic integrated
circuits (PICs) platforms exploiting III-V materials combine passive and active waveguide structures in multi-section optoelectronic device architectures. Their operation requires high electrical isolation between adjacent functional sections without compromising the optical signal. This fundamental requirement is addressed for GaSb-based waveguides, which are known to exhibit high conductivity of p-type layers reducing the electrical isolation capability. To this end, a co-designed electrical-optical isolation strategy based on using deeply etched strip waveguides combined with adiabatic ridge-to-strip waveguide tapers in GaSb-based multiple-
quantum-well
heterostructures is proposed. While deep etching alone enables isolation resistances of up to 40 k-ohm, it severely degrades optical propagation. By introducing optimized adiabatic tapers, we demonstrate good optical performance as single-mode continuous-wave lasing in a two-section device with integrated absorber, while maintaining an isolation resistance of 17.3 k-ohm; this corresponds to an approximately 17-fold improvement over previously reported GaSb two-section devices. The approach establishes a critical building block for the development of monolithic GaSb-based PICs operating above 2 um.
Read the full abstract ▾
All authors Md Ajwaad Zaman Quashef, Nouman Zia, Jukka Viheriälä, Mircea Guina
Optics
Degenerate four-wave mixing in a CPT-symmetric coupler with intermodal dispersion
Nguyen Duc Anh Quan, Do Duc Tho, Marek Trippenbach et al. (+3 more)
Four-wave mixing provides a simple setting in which dispersion, nonlinearity, and non-Hermiticity compete to select resonant energy-transfer channels. We study degenerate four-wave mixing in a Kerr dual-core coupler with balanced gain and loss and frequency-dependent intercore coupling. The dispersive coupling changes the
symmetry from conventional $\mathcal{PT}$
symmetry to a combined $\mathcal{CPT}$
symmetry and reshapes the two-branch linear spectrum. We determine the unbroken-$\mathcal{CPT}$ domain and classify the branch configurations that can satisfy the degenerate phase-matching condition. In the parameter ranges examined, three resonant channels persist over broad regions, whereas a same-branch channel appears only close to the
symmetry-breaking threshold. In this near-threshold regime, a single pump can simultaneously satisfy two distinct nonzero sideband resonances. Direct pulse simulations confirm the predicted resonances and reveal secondary-wave generation and multifrequency cascades near eigenmode coalescence. A reduced three-wave model captures the initial dynamics away from the exceptional point but loses accuracy as the modal basis becomes ill-conditioned. These results show how dispersive coupling reorganizes resonances, group-velocity mismatch, and nonlinear energy exchange in a non-Hermitian wave system, and they identify the exceptional-point region as a regime where a few-mode description can break down.
Read the full abstract ▾
All authors Nguyen Duc Anh Quan, Do Duc Tho, Marek Trippenbach, Nguyen Thi Dung, Tran Thi Hai, Nguyen Viet Hung
Biological Physics · Cross-listed from math.AP
Asymptotic Analysis of the Narrow Escape and Berg-Purcell problems on general three-dimensional domains with reactive boundary patches
A. E. Lindsay, A.J. Bernoff, D.S. Grebenkov et al. (+2 more)
We present an asymptotic analysis of two diffusive capture problems in general smooth closed three-dimensional geometries with multiple small reactive boundary patches of arbitrary shapes. (i) The narrow escape problem seeks to determine the escape rate of Brownian particles from an enclosed region through small boundary windows. (ii) The related Berg-Purcell (or narrow entrance) problem seeks to resolve the capture rate for signaling molecules diffusing outside the
cell and entering through localized reactions at membrane-bound receptors. We obtain matched asymptotic solutions of these two problems and thus address the long-standing challenge of describing the role that
curvature and local reactivities play in modulating diffusive capture rates. Our explicit expansions quantify local effects on diffusive capture through the sizes, shapes, and reactivities of the patches together with the principal
curvatures of the
manifold at each patch. In turn, we examine global effects on diffusive capture such as the spatial configuration of patches on the
manifold, as encloded by the associated surface Neumann Green's function and its regular part. The accuracy of our asymptotic formulas is validated against a full numerical solution for an ellipsoidal domain. Overall, our results yield new insights on how geometry and stochasticity combine to shape the dynamics of various biological processes.
Read the full abstract ▾
All authors A. E. Lindsay, A.J. Bernoff, D.S. Grebenkov, J.G. Hoskins, M.J. Ward
Optics
Geometric phase-space nonseparability triggers giant optical shifts
Kaiqi Zhu, Yonglei Liu, Yao Zhao et al. (+8 more)
Nonseparability among multiple degrees of freedom has enabled fundamental advances in structured light and related applications. Here we unveil a previously overlooked form of nonseparability in phase space, which we term
geometric phase-space nonseparability. The latter arises solely from the wavefront
curvature of a conventional wave packet, such as a fundamental Gaussian beam. This phase-space structure manifests as a position-dependent transverse-momentum distribution across the beam profile leading to the
giant spatial and angular beam shifts upon reflection at a planar interface that we predict analytically and observe experimentally. Remarkably, the
curvature-induced phase-space correlation remains robust against spatial-coherence degradation, allowing the
giant shifts to persist even in the nearly incoherent regime. Our results establish wavefront
curvature as a general mechanism for engineering beam shifts across optical, acoustic, and matter-wave systems.
Read the full abstract ▾
All authors Kaiqi Zhu, Yonglei Liu, Yao Zhao, Zhongyi Hu, Jiahui Shen, Yimeng Zhu, Lin Liu, Yangjian Cai, Fei Wang, Sergey A. Ponomarenko, Yahong Chen
Accelerator Physics
Terahertz-based longitudinal phase space diagnostics of laser wakefield accelerated electron beams
Zhihao Chen, Yu Fang, Ran Li et al. (+5 more)
Femtosecond relativistic electron beams are key probes of ultrafast dynamics, and their pulse duration directly limits the achievable temporal resolution.
Laser wakefield acceleration (LWFA) provides a compact source of such beams, but the injection-induced energy spread makes bunch compression sensitive to nonlinear longitudinal transport, motivating direct longitudinal phase space (LPS) measurements. Here, a terahertz transverse-deflecting cavity (THz-TDC) combined with a dipole magnet is used to reconstruct the nonlinear LPS of LWFA electron bunches compressed in a double-bend achromat (DBA), resolving a characteristic C-shaped distribution associated with higher-order longitudinal transport. At an average energy of approximately 4.55 MeV, the diagnostic achieves a temporal resolving power of 1.8 fs and an energy resolution of 6.0 keV, corresponding to a relative energy resolution of 0.13%. For comparable energy spreads of approximately 2.9%, shifting the transmitted energy-window center from 4.574 MeV to 4.532 MeV moves the selected beam away from a low-slope region of the nonlinear LPS and increases the root-mean-square bunch length from 26 fs to 42 fs; with the window center held near 4.553 MeV, increasing the energy spread from 2.0% to 4.4% lengthens the bunch from 27 fs to 44 fs. These results show that the final bunch duration is governed by both the position and width of the transmitted energy window within the nonlinear LPS, establishing an LPS-guided strategy for optimizing DBA-compressed LWFA electron bunches and providing a basis for future higher-order phase-space correction.
Read the full abstract ▾
All authors Zhihao Chen, Yu Fang, Ran Li, Xiancong Yang, Tianliang Zhang, Jianfei Hua, Fei Li, Wei Lu
Biological Physics
A General Theory for Phenotypic Association in Biological Systems
Giuseppe Battaglia
Biological recognition rarely rests on one strong bond. It works by forming many weak ones at once, between crowded, deformable surfaces in water. This review develops that process as a problem in statistical mechanics. Counting the ways two multivalent objects can bind proves to be the classical monomer-dimer problem on a graph, with a rigorous consequence: the apparent switching of multivalent binding is always a smooth crossover, never a phase transition. Three constraints follow. A repulsive surface layer is obligatory rather than a design choice; bonds do not act independently; and since free energies enter rates exponentially, small changes in receptor number shift binding lifetimes by orders of magnitude. One set of equations then covers antibodies, lipoproteins, and T
cell recognition. In each, what decides the outcome is not the strength of any single bond but how a fixed total is spread over many: affinity is a property of a molecule, selectivity a property of an assembly.
Read the full abstract ▾
Fluid Dynamics · Cross-listed from cond-mat.soft
Heat and mass transport in a three-dimensional mesoscale odd fluid
Yuxing Jiao and Mingcheng Yang
Fluids with nonvanishing antisymmetric components of the transport coefficient tensor are named odd fluids. In our previous works, we proposed a mesoscale simulation model for isotropic two-dimensional odd fluids and then extended it to the three-dimensional case to model an anisotropic odd fluid with cylindrical
symmetry. The Navier-Stokes equation and the viscosity tensor of this three-dimensional mesoscale odd fluid were derived previously via a kinetic theory. Herein, we derive the heat conduction and self-
diffusion equations, along with the corresponding thermal conductivity and self-diffusivity tensors. These theoretical results are validated by simulations. We further investigate heat and mass transport behaviors of three-dimensional odd fluids in a confined geometry through our mesoscale model. In striking contrast to normal isotropic fluids, the steady-state temperature and density distributions of confined odd fluids are significantly deformed by the odd transport coefficients.
Read the full abstract ▾
Atmospheric and Oceanic Physics
Performance Evaluation of the WeatherEx Forecasting System (WFS) for Extreme Monsoon Rainfall over Kerala
Rashad P E and Akshay Sunil
Extreme monsoon rainfall over Kerala presents a major operational
forecasting challenge because of the interaction of Arabian Sea moisture transport, mesoscale convection, coastal convergence, and strong orographic forcing along the Western Ghats. Spatial analysis showed that WFS reproduced the principal Western-Ghats-aligned rainfall corridor and represented localized high-intensity rainfall structures more distinctly than the smoother global-model guidance examined for the event. The results demonstrate the complementary roles of operational regional guidance and higher-resolution diagnostic forecasts and highlight the importance of region-specific calibration, spatial verification, and continued evaluation across multiple monsoon events and forecast lead times.
Read the full abstract ▾
Accelerator Physics · Cross-listed from nucl-ex
High Precision Fundamental Physics Experiments at JLab with Spin-transparent Storage Rings of Low-energy Polarized Electron Beams
Vladimir Khachatryan, Riad Suleiman, Alberto Accardi et al. (+26 more)
A breakthrough in fundamental physics experiments measuring particle
spin precession may happen if
spin-transparent storage rings become adopted tools for such experiments. We present a new design of highly specialized table-sized storage rings, which use low-energy polarized electron beams and Mott polarimetry. Based on the
spin transparency ansatz, the
spin precession stemming from the
magnetic dipole moment is canceled at any beam energy after an electron's turn along the periodic orbit in the ring. Meanwhile, a
spin precession induced by the fundamental physics of interest, e.g., the electron's permanent electric dipole moment (EDM) and/or ultralight-dark-matter-mediated forces such as
axions, will accumulate. However, capitalizing on such types of rings is not only desirable for measurements of EDMs and
axion searches relevant to $CP$ violation and matter-antimatter asymmetry in the Universe, but may also find very promising applications in
quantum computing.
Read the full abstract ▾
All authors Vladimir Khachatryan, Riad Suleiman, Alberto Accardi, Carlos Ayerbe Gayoso, Marco Battaglieri, Devesh Bhattarai, Silviu Covrig Dusa, Yaroslav Derbenev, Forrest Friesen, Joseph Grames, Paul Guèye, Tyler J. Hague, Ching Him Leung, Wenliang Li, Magno V.T. Machado, Preet Mann, Vasiliy Morozov, Son Nguyen, Michael Nycz, Howard Oh, Udit Raha, Mario Reig, Marco Schreck, Nathaniel Sherrill, Ye Tian, Zakia Tithi, Alexandre Vieira, Erik Wrightson, Zichen Yin
Fluid Dynamics
Data-Driven Surrogate Modeling for Micromixing of Non-Newtonian Fluids in Sinusoidal Converging-Diverging Microchannels
Kritagya Sharma and Bimalendu Mahapatra
Micromixing of non-Newtonian fluids remains challenging because laminar flow at microscales restricts transverse transport primarily to molecular
diffusion. In this study, we investigate the transport mechanisms governing passive micromixing of a Carreau–Yasuda fluid in two-dimensional sinusoidal converging–diverging microchannels and develop a surrogate-assisted framework for their multi-objective design. We perform high-fidelity finite-volume simulations by systematically varying the wall-amplitude ratio, phase offset, and wave count under creeping-flow conditions. The results show that successive contraction–expansion units enhance mixing through the combined effects of interface stretching, elevated shear rates, and shear-thinning-induced viscosity reduction. These mechanisms improve scalar transport but simultaneously increase pressure drop, creating an inherent trade-off between mixing performance and hydraulic resistance. To efficiently explore the multidimensional design space, we construct surrogate models from high-fidelity numerical simulations and identify Gaussian Process Regression (GPR) as the most accurate predictor of both the mixing index and pressure drop. Coupling the validated GPR surrogate with Non-dominated Sorting Genetic
Algorithm II (NSGA-II) accurately reproduces the Pareto front obtained from the high-fidelity simulations and identifies optimal microchannel geometries that balance mixing enhancement against pressure loss. The proposed machine learning framework provides a fast, accurate, and physically consistent strategy for the multi-objective design of passive micromixers for non-Newtonian fluids.
Read the full abstract ▾
Computational Physics · Cross-listed from cond-mat.stat-mech
Lee-Yang Theory Guided Force Field Refinement Based on Phase Diagrams
Bin Jin, Qijun Ye, Xinzheng Li et al. (+2 more)
We propose a general framework for automatic force field refinement guided by phase diagrams, grounded in Lee-Yang phase transition theory. The central idea is to directly use the partition function modulus as a phase-diagram-guided optimization target. Evaluating the modulus at points close to the real axis, where the Lee-Yang zeros are mostly associated with the phase transition, is more physically meaningful and avoids the numerical difficulty of explicitly solving for the zeros. This approach requires no system-specific order parameters or response properties for characterizing phase transition points, making it universal across various discontinuous phase transitions and material systems. We validate the method on refining parameters of a Lennard-Jones potential covering both gas-
liquid and solid-
liquid transitions, and a Cu embedded-atom method potential based on experimental melting curves. The refined force fields reproduce the target phase diagrams with significant improvement across all systems. For Cu, the refinement simultaneously improves predictions of enthalpy and heat capacity, which are observables beyond the optimization target. These results establish Lee-Yang theory as a practical tool for contemporary force field development.
Read the full abstract ▾
All authors Bin Jin, Qijun Ye, Xinzheng Li, Kuang Yu, Shenzhen Xu
Optics
Quasi-Sinusoidal Single Diamond Structure in Royal Jewel Butterfly: An Angle-Independent Photonic Structure
Yuanbo Li, Shuo Huang, Xi Wang et al. (+9 more)
Structural colouration with narrow spectral photonic bandwidth and high reflectivity is of critical importance for modern optical applications, including displays,
laser systems, and optical sensing, etc. Achieving such angle independent colouration typically relies on polycrystalline or inherent structural disorder. However, balancing angular uniformity with high brightness and strong colour contrast remains challenging. Herein, we uncover the structural origin of the spectacular bright, angle-independent blue colouration of Hypochrysops polycletus, a sapphire-like Royal Jewel butterfly. Three-dimensional (3D) electron microscopy reveals that the dorsal wing scale has a single diamond structure, a 3D photonic
crystal previously documented only in beetles and weevils. The
crystal domains form an extraordinary quasi sinusoidal surface geometry with a distinct template morphology-guided arrangement. Unlike typically thicker biophotonic structures that support multiple high
symmetry stopbands, this design contains only 3-4 unit
cells in the propagation direction. Its optical response is dominated by the fundamental stopband, with two dominant scattering mechanisms: specular reflection at the {111} inclined sidewalls of the hierarchical structure, and funnelling into localised quasi-normal modes enabled by a strongly anisotropic Bloch transport. By mimicking these features with two-
photon polymerisation, we artificially reproduced the optical response in the infrared region. The study opens a pathway towards bioinspired brilliant diffuse colouration and angle-robust photonic devices.
Read the full abstract ▾
All authors Yuanbo Li, Shuo Huang, Xi Wang, Congcong Cui, Hao Chen, Yuqin Xiong, Wang Zhang, Matthias Saba, Xueyan Feng, Bo Chen, Yuanyuan Cao, Lu Han
Fluid Dynamics
K41 Scaling in Bubble-Induced Turbulence Arises from Single-Bubble Wakes
Dabao Li, Zhilong Jin and Guangzhao Zhou
We use high-resolution, interface-resolved direct numerical simulations (DNS) to investigate the origin of Kolmogorov (K41) scaling in bubble-induced
turbulence (BIT). Region-wise velocity structure functions show that the 2/3 scaling appears only within bubble wake regions. Comparison with matched single-bubble DNS further indicates that the K41 scaling observed in the full BIT field arises from the superposition of individual bubble wakes. On this basis, we derive a scaling for the dissipation rate in dilute BIT that is consistent with experimental results from the literature.
Read the full abstract ▾
Chemical Physics
Bayesian Localization and Uncertainty Quantification of Trace Species in Two-Dimensional SIMS Imaging
Mengchi Wang, Binsheu Shieh, Ichiro Akai et al. (+4 more)
To enable accurate localization of trace species on material surfaces, we propose a
Bayesian framework for analyzing two-dimensional (2D) secondary ion mass spectrometry (SIMS) imaging data. SIMS is widely used in
semiconductor manufacturing, materials science, geology, environmental science, and life sciences because of its high sensitivity and excellent elemental and isotopic specificity. However, precise localization remains challenging because of primary ion beam broadening, overlap between neighboring ion distributions, and limited ion counts. The underlying distribution of trace species is modeled as a superposition of two-dimensional Gaussian peaks. To account for the
stochastic nature of low-count measurements, the detected ion counts are assumed to follow a Poisson likelihood within a
Bayesian framework. Posterior distributions of the peak parameters are estimated using replica-exchange Monte Carlo (REMC), enabling stable inference together with quantitative uncertainty estimation under low-count conditions. The proposed method is first validated using synthetic
datasets with known ground truth and is then applied to SIMS measurements of
semiconductor samples containing regularly arranged gold (Au) dots with diameters ranging from 0.4 to 2.0~$\mu$m, using scanning electron microscopy (SEM) images as the reference. Optimization of the measurement conditions reduced the relative localization error for 0.4~$\mu$m dots from 5.1$\%$ to 1.9$\%$. These results demonstrate accurate submicrometer localization with statistically rigorous uncertainty quantification in 2D SIMS imaging.
Read the full abstract ▾
All authors Mengchi Wang, Binsheu Shieh, Ichiro Akai, Masahiro Hara, Masao Yoshioka, Takeshi Hashishin, Toru Aonishi
Optics
Fundamental limits of hot-carrier and photothermal plasmonic solar chemistry
Seungwoo Lee
Plasmonic catalysts convert sunlight through direct metal–adsorbate excitation, nonequilibrium hot carriers and photothermal heating, yet these channels lack a common efficiency limit analogous to the Shockley-Queisser (SQ) limit. Here, we formulate a channel-resolved detailed-balance theory for plasmonic
solar chemistry. The theory enforces exclusive partition of absorbed power, microscopic reversibility, non-negative
entropy production, electromagnetic passivity and causality, and one physical nanostructure shared by all wavelengths and operating states. A reduced tightly coupled cycle obeys a chemical diode law with closed-form stall and maximum-power free energies. It recovers a 33.68% single-threshold radiative limit and the 30.58% ideal single-junction water-splitting limit at a 1.23-eV chemical load, whereas a Fowler hot-carrier kernel lowers the limit to 8.53%. Finite one-structure
benchmarks show that independent wavelength optimization overestimates shared-geometry performance by 6.6-33.8%, while cross-frequency correlations tighten semidefinite upper bounds by 21-56%. An exact multi-electron network yields a universal arrival-storage criterion and the low-flux scaling J_n\sim g^n\tau^{n-1}. A source-conditioned gold/p-type gallium nitride case study and a bias- and separation-complete ledger then distinguish enhanced product formation from net
solar-energy conversion. The resulting framework provides a thermodynamically closed
benchmark for hot-carrier and photothermal plasmonic chemistry.
Read the full abstract ▾
Atomic Physics
Multiple ionization and charge equilibration in slow, multiply charged $\mathrm{Ar^{q+} + Ar}$ collision studied via L-MM Auger-Meitner electron spectroscopy
Rohit Tyagi, L. C. Tribedi, M. K. Harbola et al. (+1 more)
We report energy and angle resolved absolute cross section measurements for LMM Auger-Meitner electron emission following collisions of hundred keV
protons and $\mathrm{Ar^{3+/6+}}$ ion with an atomic Ar target. The double differential cross section spectra show distinct contributions from target and projectile Auger-Meitner decay. The projectile emission exhibits the expected Doppler shift for various angles of electron emission, and the measured peak energies are in excellent agreement with kinematic calculations. The energy integrated cross sections show isotropic angular distribution for target and projectile species in their respective rest frames. The Auger-Meitner peak energy for target as well as projectile emission show significant difference in comparison to the characteristic L-MM Auger-Meitner energy peak from atomic Ar. The experimental measurements have been complimented with development of a theoretical model to calculate the transition probabilities corresponding to prominent L-MM Auger-Meitner transitions in neutral and multiply charged Ar atom. Comparison between measured and calculated spectra shows that the measured emission peak at approximately 150 eV originates from Auger-Meitner decay of $\mathrm{Ar^{4+}}$ ions. The peak energies for target and projectile emission are found to be equal, independent of the initial projectile charge state. This indicates that the decay occurs following extensive multiple ionization, charge exchange processes resulting in charge-state equilibration of the collision partners. The results demonstrate that collision-induced electronic rearrangement strongly modifies the Auger-Meitner spectra and provide evidence for an
equilibrium target-projectile charge state in low-energy $\mathrm{Ar^{q+} - Ar}$ collisions.
Read the full abstract ▾
All authors Rohit Tyagi, L. C. Tribedi, M. K. Harbola, A. H. Kelkar