Biological Physics
Simulating Mono-and Multi-Protein Phosphorylation within Nanoclusters
Olivier Destaing and Bertrand Fourcade
Protein nanoclustering is a characteristic feature of their activated state and is essential for forming numerous subcellular structures. The formation of these nanoclusters is highly dependent on a series of post-translational modifications, such as mono-and multi-phosphorylation and dephosphorylation of residues. We theoretically simulate how a
protein can be either mono-or multi-phosphorylated on several residues in functional nanoclusters, depending on effective biophysical parameters (
diffusion, dwell time, etc.). Moving beyond a binary view of phosphorylation, this approach highlights the interplay between mono-and multi-phosphorylation, the cooperative effects generally associated with multi-phosphorylation networks, and stresses the role of phosphatases in transforming graded phosphorylation signals into almost switch-like responses. The results are discussed in light of experiments that probe the distribution of phospho-residues.
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Medical Physics
Evaluating the Impact of Partial Volume Correction on FDG PET Radiomics Reproducibility in Lymphoma Lesions
Setareh Hasanabadi, Mohammad Saber Azimi, Mehrdad Bakhshayesh Karam et al. (+1 more)
To evaluate how partial volume correction (PVC) affects the reproducibility of 18F-FDG PET radiomic features in lymphoma lesions, with respect to lesion volume and tissue type. This single-center retrospective study included 131 newly diagnosed lymphoma patients who underwent baseline 18F-FDG PET/CT. In total, 1,603 lesions (1,302 lymph nodes, 117 spleen/liver, 150 bone, and 34 bone/soft-tissue) were semi-automatically segmented and grouped by volume (<3, 3-10, 10-30, >30 mL) and tissue type. 93 radiomic features were extracted from non-PVC and PVC images processed with the Richardson-Lucy (RL) and Reblurred Van Cittert (RVC)
algorithms following IBSI guidelines. Reproducibility was quantified using the coefficient of variation (CoV) and the intraclass correlation coefficient (ICC2, absolute agreement), with statistical comparisons performed via Mann-Whitney U tests and false-discovery-rate (FDR) correction. PVC significantly improved feature reproducibility, particularly for large lesions (>30 mL), with median ICC2>0.90 across most feature categories. Small lesions (<3 mL) showed lower stability (ICC2=0.84-0.94) and higher CoV (0.09-0.21). First-Order and GLCM features were the most robust overall (ICC2=0.92-0.99; CoV=0.07-0.11). Bone and spleen lesions exhibited the highest reproducibility (median ICC2 approx 0.95), whereas lymph-node and liver features were more variable. All volume- and tissue-dependent differences remained significant after FDR correction (p<0.05). PVC using RL and RVC markedly enhances FDG-PET radiomic reproducibility in lymphoma, particularly for larger and structurally uniform lesions. Robust features such as First-Order and GLCM can support standardized radiomics workflows and the development of reliable biomarkers for prognosis and personalized therapy. Multicenter validation is warranted to confirm generalizability beyond a single-center setting.
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All authors Setareh Hasanabadi, Mohammad Saber Azimi, Mehrdad Bakhshayesh Karam, Hossein Arabi
Optics
3D printed microfiber waveguide in C-shaped fiber for temperature and air pressure measurement
Qipeng Huang, Shanmei Zeng, Jingxian Cui et al. (+4 more)
In this study, we propose a microfiber waveguide for temperature and air pressure measurement. To improve mechanical strength of the sensor, a C-shaped fiber is sandwiches between two single mode fibers (SMFs) by fusion splice. The microfiber waveguide is 3D printed between two SMFs to connect two fiber cores by two-
photon polymerization technology. Due to multimode property of this printed waveguide, a Mach-Zehnder interferometer (MZI) is obtained. This sensor exhibits a high temperature sensitivity of 361 pm/{\deg}C at 25{\deg}C to 45{\deg}C and a high air pressure sensitivity of 55 pm/kPa from 300hpa to 1000hpa. The MZI sensor features significant advantages such as small size, high stability, and easy fabrication, without the need for complex post-processing, showing great potential and broad application prospects in many sensing applications.
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All authors Qipeng Huang, Shanmei Zeng, Jingxian Cui, Lin Htein, Hwa-Yaw Tam, Xuehao Hu, Hang Qu
Classical Physics · Cross-listed from math.NA
A surrogate-based approach to accelerate the design and build phases of reinforced concrete bridges
Mouhammed Achhab, Pierre Jehel and Fabrice Gatuingt
Integrating uncertainties in the design process of reinforced concrete rail bridges, in a fully probabilistic framework, makes their design more complex and challenging. To propagate these uncertainties and convey their influence on the performance of the engineering system, a high-dimensional design space is supposed to be explored. A great challenge to be considered here lies in the computational burden as conducting such an exploration campaign requires substantial calls to computationally expensive finite element simulations. To address this challenge, a surrogate model mapping the design space to the reinforced concrete bridge performance functions is developed in the context of an active learning
algorithm. The importance of this model lies in its ability to explore as many design scenarios as possible with minimal computational resources and classify the design scenarios into failure and safe scenarios. This work considers a 4-span reinforced concrete bridge deck. A multi-fiber finite element model of this beam is developed in Cast3m to generate the required design of experiments for the surrogate model. A performance comparison is undertaken to evaluate the Kriging surrogate model effectiveness with and without active learning while the reliability of Kriging predictions is also assessed in comparison to PC-Kriging.
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Physics and Society
Urban Complexity through Vision Intelligence: Variance, Gradients, and Correlations across Six Italian Cities
Mirko Degli Esposti, Armando Bazzani, Chiara Dellacasa et al. (+3 more)
This paper introduces a scalable methodology for the objective analysis of quality metrics across six major Italian metropolitan areas: Rome, Bologna, Florence, Milan, Naples, and Palermo. Leveraging georeferenced Street View imagery and an advanced Urban
Vision Intelligence system, we systematically classify the visual environment, focusing on key metrics such as the Pavement Condition Index (PCI) and the Façade Degradation Score (FDS). The findings quantify Structural Heterogeneity (Spatial Variance), revealing significant quality dispersion (e.g., Milan $\sigma^2_{\mathrm{PCI}}=1.52$), and confirm that the classical Urban Gradient – quality variation as a function of distance from the core – is consistently weak across all sampled cities ($R^2 < 0.03$), suggesting a complex, polycentric, and fragmented morphology. In addition, a Cross-Metric Correlation Analysis highlights stable but modest interdependencies among visual dimensions, most notably a consistent positive association between façade quality and greenery ($\rho \approx 0.35$), demonstrating that structural and contextual urban qualities co-vary in weak yet interpretable ways. Together, these results underscore the diagnostic potential of
Vision Intelligence for capturing the integrated spatial and morphological structure of Italian cities and motivate a large national-scale analysis.
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All authors Mirko Degli Esposti, Armando Bazzani, Chiara Dellacasa, Matteo Falcioni, Mario Massimon, Martino Pietropoli
Atmospheric and Oceanic Physics · Cross-listed from math-ph
Acoustic pulse propagation in a non-ideal shallow-water model
Aleksandr Kaplun and Boris Katsnelson
This study develops a theoretical framework for modeling acoustic pulse propagation in a non-ideal shallow-water waveguide. We derive an {\epsilon}-pseudodifferential operator ({\epsilon}-PDO) formulation from the general three-dimensional wave equation, that accounts for vertical stratification, bottom interaction, and slow horizontal inhomogeneity. Using the operator separation of variables method and the WKB-ansatz, we obtain single-mode equations describing the
evolution of amplitude and phase along rays. The approach incorporates non-self-adjoint operators to model energy leakage through the bottom and introduces a
Hamiltonian formalism for eikonal and transport equations, enabling the computation of amplitude, time, and phase fronts. Analytical and numerical examples are provided for different boundary conditions, including Neumann (ideal), self-adjoint, and partially reflecting interfaces. The results extend previous semiclassical and ray-based theories of wave propagation by including dissipative effects and improving the physical realism of shallow-water acoustic modeling.
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Biological Physics · Cross-listed from q-bio.NC
Characterizing sleep stages through the complexity–weighted-entropy plane in human intracranial data and in a whole-brain model
Helena Bordini de Lucas, Leonardo Dalla Porta, Alain Destexhe et al. (+4 more)
Approaches based on symbolic information, such as
entropy and complexity, have shown that sleep reorganizes the temporal structure of
brain activity. However, most of this evidence comes from scalp
EEG and group averages. In this work, we characterized sleep stages in intracranial recordings from 65 patients during wakefulness and the REM, N2, and N3 stages, using weighted permutation
entropy (WPE) and the statistical complexity measure (SCM). In the complexity–
entropy plane, the states formed a clear trajectory from wakefulness to REM, N2, and N3, with decreasing
entropy and increasing complexity as sleep deepened. This organization was observed individually in most patients and was recovered more consistently by WPE than by conventional permutation
entropy. The trajectory, however, was not the same throughout the cortex. All regions shifted in the same direction, but the occipital cortex followed a much shorter path than the parietal cortex. This result reflects the spatial heterogeneity of the
brain during sleep and shows that cortical regions differ not only in the position they occupy in the plane, but also in the path they follow between states. Finally, a whole-
brain model based on the human connectome showed that increasing neuronal adaptation shifts the simulated dynamics in the same direction observed in the empirical data, pointing to adaptation as one of the candidate mechanisms involved in this reorganization.
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All authors Helena Bordini de Lucas, Leonardo Dalla Porta, Alain Destexhe, Maria V. Sanchez-Vives, Osvaldo A. Rosso, Cláudio R. Mirasso, Fernanda Selingardi Matias
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Assessing Band Gap Stability of Organic Semiconductor Thin Films for Flexible Electronic Applications
Mahya Ghorab, Ayush K. Ranga, Arnulf Materny et al. (+2 more)
Integration of organic
semiconductors into flexible electronics requires that their optoelectronic properties remain stable under mechanical deformation. Among these, the optical band gap governs
exciton generation and limits photovoltaic voltage, making it a key parameter for strain-resilient design. In this work, we investigate band gap shifts in poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/P3HT thin films deposited on flexible poly(ethylene terephthalate) (PET) substrates under uniaxial tensile strain ranging from 1% to 10%. Samples were subjected to mechanical deformation and then characterized by ultraviolet–visible (UV–Vis) absorption spectroscopy. The optical band gaps extracted using a standardized Tauc analysis and statistically validated through equivalence testing and robust regression models. We find that up to 7% strain, the band gap shift ($\Delta E_g$) remains effectively invariant, independent of annealing condition or stack configuration, demonstrating electronic stability. However, at 10% strain, all groups exhibit a reproducible widening of $\sim$4–5~meV. This threshold-like behavior marks a transition from mechanical accommodation to electronic perturbation. These findings confirm that the optical band gap in semicrystalline P3HT-based thin films is robust under practical deformation, which provides clear strain thresholds to inform mechanical modeling and device-level simulation of flexible organic optoelectronic systems.
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All authors Mahya Ghorab, Ayush K. Ranga, Arnulf Materny, Veit Wagner, Mojtaba Joodaki
Fluid Dynamics
Effect of submerged vegetation on water surface geometry and air-water momentum transfer
Giulio Foggi Rota, Alessandro Chiarini and Marco Edoardo Rosti
Understanding how submerged vegetation modifies the water surface is crucial for modeling momentum exchange between shallow waters and the atmosphere. In particular, quantifying its impact on the equivalent aerodynamic roughness of the water surface is essential for improved boundary-layer parameterization in oceanic and atmospheric models. In this Letter, we present fully resolved multiphase simulations of
gravity-driven flow over a fully submerged vegetated bed, capturing the coupled dynamics of air, water, and individual plant stems, under quasi-realistic conditions (the air/water viscosity ratio is real, while the density ratio is reduced tenfold). Our results show that vegetation submerged for four times its height regularizes the water surface suppressing strong deformations and homogenizing streamwise-propagating wave fronts along the transversal direction. Despite these alterations, the equivalent roughness perceived by the overlying air flow remains unchanged. These findings clarify vegetation-surface interactions and provide quantitative insights for nature-based wave mitigation strategies and atmospheric boundary-layer modeling.
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Optics
Direct observation of room-temperature exciton condensation
Jiaxin Yu, Guangyu Dai, Shuai Xing et al. (+5 more)
Exciton condensation–an interaction-driven, macroscopically coherent paired-
fermion state–offers the prospect for dissipationless energy transport in solids, akin to that in superconductivity. Although their light effective mass and strong Coulomb binding favour high transition temperatures, convincing demonstrations of pure-
exciton condensation have hitherto been limited to cryogenic conditions. Here, we report the direct observation of quasi-
equilibrium condensation of dark
excitons in monolayer tungsten diselenide at 300 K and ambient pressure. We achieve this by creating nanoscale spacing-graded Stark traps to confine free
excitons, setting the finite-size scale, non-resonant off-axis optical injection to control the local density-temperature trajectory, and employing surface plasmon polariton-enhanced microsphere-assisted microscopy to boost dark-
exciton emission and directly image first-order spatial coherence with sub-diffraction resolution. We observe a sharp degeneracy threshold and a clear phase transition, evidenced by extended first-order spatial coherence with algebraic decay and a critical exponent consistent with the universal Berezinskii-Kosterlitz-Thouless criterion. Identical condensation signatures are observed in over 30 independent samples. Our work establishes a room-temperature excitonic platform for exploring strongly correlated many-body physics and advancing near-dissipationless, coherent
quantum technologies.
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All authors Jiaxin Yu, Guangyu Dai, Shuai Xing, Weiwei Zhang, Lin Dou, Tianci Shen, Xinyu Zhang, Xialian Feng Fuxing Gu
Applied Physics · Cross-listed from cond-mat.mtrl-sci
Enhanced spectral range of strain-induced tuning of quantum dots in circular Bragg grating cavities
Ivan Gamov, Matthias Sauter, Samuel Huber et al. (+5 more)
Tunable sources of entangled and single
photons are essential for implementing
entanglement-based
quantum information protocols, as
quantum teleportation and
entanglement swapping depend on
photon indistinguishability. Tunable devices are fabricated from indium arsenide (InAs)
quantum dots (QDs) embedded in gallium arsenide (GaAs) nanomembranes placed on monolithic piezoelectric substrates. Circular Bragg grating (CBG) resonators enhance emission brightness and exploit the Purcell effect; however, the inclusion of CBGs reduces strain-mediated tunability compared to planar nanomembranes. A simple and effective solution is introduced: filling the CBG trenches with a stiff dielectric (aluminum
oxide) via atomic layer deposition (ALD) restores up to 95% of the tunability of planar structures. Finite element analysis (FEA) confirms that the tunability loss originates from bending in the device layers due to strain relief in the CBG geometry. Lowering the stiffness of intermediate layers between the QDs and the piezoelectric actuator, such as in bonding or reflector layers, further increases strain losses in uncoated CBGs. Coated devices maintain 98-99% strain-tuning efficiency across all simulated underlayer stiffnesses. The results demonstrate that advantageous optical cavity properties can be effectively combined with piezoelectric strain tuning, enabling scalable, bright, and tunable
quantum light sources.
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All authors Ivan Gamov, Matthias Sauter, Samuel Huber, Quirin Buchinger, Peter Gschwandtner, Ulrike Wallrabe, Sven Höfling, Tobias Huber-Loyola
Physics and Society
Threshold model of language competition including the bilingual state
Mikhail V. Tamm, Els Heinsalu, Stefano Scialla et al. (+1 more)
We propose a threshold model of
language competition which includes intermediate bilingual state. The model is based on the Minett-Wang model but through the introduction of thresholds in the
language shift rates it incorporates the effects of
memory and learning. The model is piecewise-linear, allowing the exact analytical treatment. We study the symmetric case where two competing
languages are equivalent in terms of status and social pressure and provide a complete list of the various dynamical regimes. We also study several limiting regimes corresponding to asymmetric systems and characterize the full spectrum of possible asymptotic behaviors. Unlike the Minett-Wang model, which always predicts the extinction of one of the
languages, the proposed new model exhibits a wide range of possible
equilibrium scenarios, including
equilibrium states of coexistence. Most commonly, in such coexistence regimes the minority
language speakers are either completely monolingual or completely bilingual.
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All authors Mikhail V. Tamm, Els Heinsalu, Stefano Scialla, Marco Patriarca
Optics · Cross-listed from quant-ph
Private Remote Phase Estimation over a Lossy Quantum Channel
Farzad Kianvash, Marco Barbieri and Matteo Rosati
Private remote
quantum sensing (PRQS) aims at estimating a parameter at a distant location by transmitting
quantum states on an insecure
quantum channel, limiting information leakage and disruption of the estimation itself from an adversary. Previous results highlighted that one can bound the estimation performance in terms of the observed noise. However, if no assumptions are placed on the channel model, such bounds are very loose and severely limit the estimation. We propose and analyse a PRQS using, for the first time to our knowledge, continuous-variable states in the single-user setting. Assuming a typical class of lossy attacks and employing tools from
quantum communication, we calculate the true estimation error and
privacy of our protocol, both in the asymptotic limit of many channel uses and in the finite-size regime. Our results show that a realistic channel-model assumption, which can be validated with measurement data, allows for a much tighter quantification of the estimation error and
privacy for all practical purposes.
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Instrumentation and Detectors
Towards low-cost lead screening with transmission XRF
Christoph Gaßner, Juliane Reisewitz, Jenna E. Forsyth et al. (+1 more)
Human exposure to lead (Pb) is a global health concern, yet existing technologies for detecting lead in our environment remain prohibitively expensive for widespread deployment. Here we present a new concept towards lead screening using X-ray fluorescence (XRF) in an unconventional geometry we coin transmission XRF in which the sample is placed between the source and detector. For cost reduction, we then show that $^{241}$Am found in ionizing smoke detectors is spectrally suitable for Pb L-shell XRF generation and can thus replace X-ray tubes used in conventional XRF devices. Exploring soil screening as the first application, we demonstrate with Monte Carlo simulations that a configuration with 7$\times$ $^{241}$Am sources and a standard silicon drift detector can enable screening-relevant detection limits (100 ppm Pb) in soil within practical measurement times (<30 min). We believe this concept opens a route toward low-cost and scalable XRF instrumentation for democratizing lead screening across a wide range of samples.
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All authors Christoph Gaßner, Juliane Reisewitz, Jenna E. Forsyth, Kian Shaker
Space Physics · Cross-listed from astro-ph.SR
Superhot (> 30 MK) flare observations with STIX: Joint spectral fitting
Muriel Zoë Stiefel, Natália Bajnoková and Säm Krucker
Spectroscopic analysis of large
flares (>X1) in the hard X-ray (HXR) range offers unique insights into the hottest (> 30 MK)
flare plasma, the so-called superhot thermal component. To manage the high count rates in large
flares, an attenuator is typically placed in front of the HXR detectors. However, this significantly limits the spectral diagnostic capabilities at lower energies, and consequently, it restricts the analysis of the lower temperatures in
flares. The Spectrometer/
Telescope for Imaging X-rays (STIX) on board the
Solar Orbiter mission was designed to observe
solar flares in hard X-rays. The imaging detectors use an attenuator during periods of high flux level. In contrast, the background (BKG) detector of STIX is never covered by the attenuator and is therefore dedicated to measure the unattenuated flux using differently sized apertures placed in front of the detector. We aim to demonstrate that joint spectral fitting using different detector configurations of STIX allows us to reliably diagnose both the hot and the superhot components in large
flares. We jointly fit the HXR spectra of the STIX BKG detector and the STIX imaging detectors using SUNKIT-SPEX software package to determine the spectral parameters of both the hot and superhot thermal components in
solar flares. Using joint fitting on 32 STIX
flares, we corroborate that for GOES X-class
flares, the HXR spectrum is better represented by two thermal components instead of an isothermal component. At the temperature peak time, the superhot HXR flux above 15 keV is typically stronger than the hot HXR flux. The GOES long-wavelength channel is dominated by the hot component with a superhot contribution up to 10%. This paper demonstrates that joint spectral fitting of the same detector type with different attenuation schemes is a simple and powerful method to monitor multithermal
flare plasma.
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Geophysics
Introducing GeoHEAT: Georadar-aided High-resolution Exploration for Advancing geoThermal energy usage
Alexis Shakas, Linus Villiger, Edoardo Pezzulli et al. (+22 more)
We present a novel geothermal exploration approach that integrates innovations at three spatial scale. At the regional scale (~100 km) we create LCOE heat maps using a techno-economic and metamodel analysis. This allows us to choose several potential sites to perform a reservoir scale (~10 km) assessment with passive seismics and
gravity. By integrating the latter with probabilistic geological and geomechanical modeling we propose locations to drill exploration boreholes. Then follows a high-resolution borehole characterization incorporating various analyses, the central one being a georadar probe that allows to illuminate permeable structures. Within this project, we also design and build a geothermal grade georadar. Here, we present the approach and result from the application of our methodology to the Swiss canton of Thurgau, with the purpose of large-scale geothermal exploration.
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All authors Alexis Shakas, Linus Villiger, Edoardo Pezzulli, Matthew Schubert, Johan Friborg, Anton Nordenstam, Arnaud Mignan, Paul Lehmann, Dieter Werthmüller, Maren Breme, Michèle Marti, Stefan Wiemer, Geneviève Savard, Francisco Munoz-Burbano, Matteo Lupi, Christin Bobe, Florian Wellmann, Ezgi Satiroglu, Tabea Kautz, Kavan Khaledi, Francesco Grigoli, Claudia Finger, Erik Saenger, Evert Slob, Katrin Loer
Optics · Cross-listed from quant-ph
Inherently unpredictable beam steering for quantum LiDAR
Junyeop Kim, Dongjin Lee, Woncheol Shin et al. (+2 more)
Quantum LiDAR offers noise resilience and stealth observation capabilities in low-light conditions. In prior demonstrations, the
telescope pointing was raster-scanned, making the observation direction predictable from the pointing direction. However, while
Quantum LiDAR can enable stealth observation, operational stealth is enhanced by inherently unpredictable beam steering. Here, we introduce a novel stealth beam steering method that is fundamentally immune to prediction. In a
photon pair, the probe
photon undergoes diffraction in an unpredictable direction at a grating due to wavelength randomness. The arrival time of the heralding
photon, delayed by propagation through a dispersive medium, enables the determination of the probe
photon's diffraction direction. Our method successfully detects multiple targets in parallel, demonstrating up to a 1000-fold enhancement in signal-to-noise ratio compared to classical
LiDAR. This breakthrough establishes a new paradigm for
quantum-enhanced sensing, with far-reaching implications for
quantum metrology, secure communications, and beyond.
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All authors Junyeop Kim, Dongjin Lee, Woncheol Shin, Yeoulheon Seong, Heedeuk Shin
Plasma Physics
Hydrodynamic PIC analysis of THz generation by two color laser in various plasma gases
A. A. Molavi Choobini and S. S. Ghaffari-Oskooei
In the present study, a theoretical and PIC numerical investigation of THz emission driven by two color femtosecond
laser fields in gaseous
plasmas is conducted. The model is formulated in cylindrical coordinates to capture the inherent radial
symmetry of
laser plasma interactions. Starting from a hydrodynamic description of
plasma electrons coupled with Maxwells equations, the nonlinear photocurrent dynamics that underpin the emission process is derived. The results reveal that the asymmetry induced by the superposition of the fundamental and second-harmonic fields plays a central role in breaking inversion
symmetry, thereby generating a net directional current that radiates in the THz regime. Systematic analysis demonstrates that gas composition, ionization fraction, and the intensity ratio of the two fields strongly influence both the spectral characteristics and efficiency of THz radiation.
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Plasma Physics
3D PIC simulation and theoretical modeling of RF Laser pulse in magnetized plasma for the generation of multidimensional relativistic Wakefields
A. A. Molavi Choobini and M. Shahmansouri
The present study, investigates the modulation of
plasma wakefields in dense magnetized
plasma driven by relativistic electron beams under transverse RF excitation. A self consistent theoretical framework, comprising the RF vector potential, Maxwells equations, and relativistic electron motion, is extended through full 3D electromagnetic particle in
cell simulations. The results reveal systematic amplification and reshaping of wakefields under the combined action of external
magnetic fields and RF drivers. Variations in the cyclotron to
plasma frequency ratio dictate the radial positioning and gyromotion of
plasma electrons, sharpening transverse confinement and stabilizing blowout structures. The RF amplitude introduces progressive modulation of radial excursions and transverse forces, enhancing wakefield
symmetry and depth. Current density distributions confirm the nonlinear scaling with RF strength, evolving from weak perturbations into sharply structured ion channels. Scalar potentials and longitudinal fields exhibit pronounced sensitivity to pulse shape, polarization angle, frequency ratio, and driver density, each parameter producing distinct oscillatory features and confinement regimes.
Plasma density sets the field strength and radial localization, while the modulation parameter governs the emergence of fine scale oscillatory bands, producing smooth to multiband transitions in longitudinal electric fields. Across all conditions, simulations confirm the reinforcement of ponderomotive force, resulting in controlled narrowing of electron sheaths, sharper scalar potential gradients, and extended acceleration zones.
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Plasma Physics
Spatiotemporal THz emission from radial and longitudinal wakefields by copropagating chirped lasers in magnetized rippled plasma
A. A. Molavi Choobini and F. M. Aghamir
The excitation of radial and longitudinal wake-fields by two co-propagating chirped
laser pulses in a rippled, magnetized
plasma has been examined. This study aimed to clarify the spatiotemporal
evolution of wake structures and assess their role in the generation of THz radiation. A
Fourier-Bessel Particle-In-
Cell (FBPIC) simulation framework, optimized for cylindrical geometries, has been employed to model the relativistic dynamics of
plasma electrons under the combined influence of
laser-induced ponderomotive forces and an external
magnetic field. It has been shown that the beat frequency between the pulses modulates the ponderomotive force, driving nonlinear wake-field structures sustained by electron oscillations. Simulations performed with high spatial resolution have revealed that wake-field amplitude and coherence are strongly influenced by
laser chirp, pulse duration, and
plasma density. Distinct THz peaks have been identified in the
Fourier-transformed spectra, with their amplitudes enhanced by resonant coupling between wake-field harmonics and the
laser frequency modulation. Moreover, electron motion has been confined by the
magnetic field, leading to improved energy gain and shaping of angular radiation patterns. These findings suggest that tailored
laser and
plasma configurations can be used to optimize energy transfer mechanisms, paving the way for more efficient wake-field usage and THz generation.
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Applied Physics
Super-resolution imaging of azimuthal features with illumination carrying OAM
Nilakshi Senapati, Abhinandan Bhattacharjee, Kedar Khare et al. (+1 more)
Super-resolution imaging refers to imaging techniques that surpass the Rayleigh resolution limit. One standard way to achieve super-resolution is by structuring the phase of the field illuminating the object. Although super-resolution techniques are already employed in commercial imaging devices, intense research efforts continue to enhance the resolution even further. In this work, we show that if the field illuminating the object is structured in the azimuthal coordinate–such as a field carrying orbital angular momentum (OAM)–the azimuthal features of the object can be imaged with enhanced imaging resolution. We experimentally demonstrate it with two objects, namely, an azimuthal double-slit and a Siemens
star. We find that for a given azimuthal feature, there is an optimum OAM mode index of the illumination that gives the best imaging resolution. Super-resolution imaging of azimuthal feature can have important implications, especially for some biological objects that are known to have predominantly azimuthal features.
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All authors Nilakshi Senapati, Abhinandan Bhattacharjee, Kedar Khare, Anand K Jha
Applied Physics
Feasibility of Free-Space Transmission using L-Band Maser Signals in Organic Gain Media
Sophia Long, Priyanka Choubey, Max Attwood et al. (+3 more)
Atmospheric conditions such as fog, humidity, and scattering by foliage routinely degrade optical free-space (FS) links, motivating alternatives that are robust in adverse conditions. Coherent microwave sources offer a compelling alternative for
quantum-secure communication, yet their propagation outside enclosed resonators has remained untested. Here, we demonstrate room-temperature FS transmission of maser signals generated using organic L-band (1-2 GHz) gain media, pentacene doped p-terphenyl (Pc: PTP), and Diazapentacene-doped p-terphenyl (DAP:PTP). Spectral and temporal coherence is preserved over distances up to 25 cm, approximately one wavelength at the masing frequency. Tests included polarisation misalignment, high-humidity conditions, and partial occlusion by foliage to emulate realistic FS reception scenarios. Strong
spin-
photon coupling was maintained, as confirmed by persistent rabi oscillations and normal-mode splitting. An instantaneous peak output of 4.29 mW (+6.32 dBm) from a 0.01% DAP:PTP gain medium. with a pulse duration of ~4 {\mu}s, marks a performance
benchmark for directly coupled masers. These findings demonstrate a proof-of-concept for masers as viable platforms for short-range, interference-resilient coherent microwave links, with future relevance to
quantum sensing and secure communication technologies.
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All authors Sophia Long, Priyanka Choubey, Max Attwood, Justin Chan, Hamdi Torun, Juna Sathian
Applied Physics
L-Band Milliwatt Room-Temperature Solid-State Maser
Sophia Long, Max Attwood, Justin Chan et al. (+3 more)
Molecular room temperature masers have emerged as promising sources of coherent microwaves, but systematic comparisons of organic gain media under uniform conditions remain limited. This paper presents a characterization of two systems, pentacene doped para terphenyl (Pc:PTP, 1.45 GHz) and 6,13 diazapentacene doped para terphenyl (DAP:PTP, 1.478 GHz), examined at four concentrations, including a new 0.05 percent DAP:PTP sample. By evaluating L band masing media under identical conditions, optimal doping levels and gain materials for high power operation are identified. The optimized system produced room temperature continuous wave masing with a peak output of 2.34 mW (+3.69 dBm), marking the first milliwatt level emission from an organic maser. Spectral coherence times of 465 ns and coherence lengths up to 150 m were obtained. Coupling to a high Q cavity mode enables collective
spin photon interactions, with Rabi oscillations revealing coherent ensemble dynamics. Frequency domain analysis shows normal mode splitting of 1.37 MHz for Pc:PTP and 2.14 MHz for DAP:PTP, confirming strong coupling. Cavity QED analysis yields cooperativities C* = 304-803 for Pc:PTP and 405-1071 for DAP:PTP, among the highest for organic systems. Quantitative metrics of signal to noise ratio, spectral coherence distance, and throughput demonstrate the potential of these masers for radar, secure communication, and
quantum interface technologies.
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All authors Sophia Long, Max Attwood, Justin Chan, Priyanka Choubey, Hamdi Torun, Juna Sathian
Space Physics
Time-Dependent Radiation Quality Factor <Q> of Galactic Cosmic Rays in Deep Space and Shielding Environments: Modeling and Measurements
Weihao Liu, Mikhail Dobynde, Jingnan Guo et al. (+2 more)
Understanding the long-term variation of the
galactic cosmic ray (GCR) radiation environment is critical for assessing radiation risks in space exploration missions. In this study, we systematically model the linear energy transfer (LET) spectra of GCRs and the corresponding radiation quality factor, <Q>, in deep space and shielding environments. The Badhwar-O'Neill 2020 (BON20) model is used to represent GCR fluxes under different
solar modulation potentials (phi), which characterize the level of
solar activity. GCR interactions with spherical shielding of different thicknesses are simulated to obtain the LET spectra, absorbed dose, dose equivalent, and <Q>. We present a comprehensive
dataset of these quantities for a range of phi values and shielding thicknesses. The results show that <Q> depends strongly on the shielding thickness but only weakly on
solar activity. Furthermore, model predictions are validated against long-term measurements from the
Cosmic Ray
Telescope for the Effects of Radiation (CRaTER) orbiting the Moon, and the Liulin-MO detector on board the ExoMars Trace Gas Orbiter (TGO) orbiting Mars. In this comparison, we consider factors for anomalous
cosmic ray (ACR) contributions and radial gradients of both GCRs and ACRs, applying scaling factors of 6.3% at 1 AU and 11.0% at 1.5 AU to the calculated absorbed dose rate. With these corrections, the modeled absorbed dose rate and <Q> exhibit consistent temporal variations with the observations under both thin and thick shielding conditions. Moreover, we investigate the distinct temporal
evolution of <Q> for light and heavy GCR
nuclei, revealing how
solar modulation influences the elemental radiation quality factor across GCR species. These results offer new insights into the temporal and environmental dependence of the space radiation quality factor, with implications for radiation dose estimate and crewed mission design.
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All authors Weihao Liu, Mikhail Dobynde, Jingnan Guo, Jordanka Semkova, Krasimir Krastev
Fluid Dynamics
Prediction of bypass transition in hypersonic blunt-plate boundary layers subject to noisy conditions
Qinyang Song, Ming Dong and Lei Zhao
In hypersonic boundary-layer flows over blunt bodies, laminar-turbulent transition exhibits two distinct regimes: for small nose radii, increased bluntness delays transition; beyond a critical radius, further increasing bluntness reverses this trend. The latter regime corresponds to a bypass transition route, whose onset remains challenging to predict. The primary difficulty lies in capturing the excitation of non-modal streaks in the nose region, which is strongly affected by the bow shock and
entropy layer effects. Recently, Zhao & Dong (J. Fluid Mech., 2025, 1013: A44) develops a high-efficient, high-accuracy shock-fitting harmonic linearised Navier-Stokes (SF-HLNS) approach to quantify the excitation of linear non-modal perturbations. In this paper, we present a predictive framework for bypass transition by integrating the SF-HLNS approach with the nonlinear parabolised stability equations (NPSE) and the bi-global stability analysis (BSA). The NPSE is employed to track the nonlinear
evolution of the streaky perturbations up to nonlinear saturation, while the BSA approach is used to capture the high-growth secondary instabilities. By integrating the growth rates of these secondary instability from their neutral positions, an amplitude amplification factor is obtained, enabling the prediction of transition onset. Under slow-acoustic forcing conditions drawn from wind-tunnel experiments, the present hybrid framework successfully reproduces the transition-reversal phenomenon at large nose radii, and yields quantitative agreement with measured transition locations, thereby validating its predictive capability.
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Instrumentation and Detectors · Cross-listed from astro-ph.IM
Design of a Six-band, 2.4-Octave (80–420 GHz) Hierarchically Summed Phased-Array Slot-Dipole Antenna Array for NEW-MUSIC
Xiaolan Huang, Shibo Shu, Miao Li et al. (+2 more)
The Next-generation Extended Wavelength Multi-band Sub/millimeter Inductance Camera (NEW-MUSIC), located on the Leighton Chajnantor
Telescope (LCT), will be the first six-band trans-millimeter wave polarimeter. This paper proposes a broadband, hierarchical phased-array
antenna with integrated band-defining filters necessary to realize NEW-MUSIC. It covers a spectral bandwidth of 2.4 octaves from 80~GHz to 420~GHz, a frequency range ideal for studying trans-millimeter emission from a range of time-domain sources, using the Sunyaev-Zeldovich effects to study hot
plasmas in
galaxy clusters and
galaxies, and to observe dusty sources, from
star-forming regions in our
galaxy to high-
redshift dusty,
star-forming
galaxies. To achieve these goals, three groups of superconducting lumped-element on-chip low-pass/band-pass filter-banks were designed to hierarchically sum the superconducting, broadband, non-resonant, slot-dipole
antenna arrays and band-pass filter the trans-mm light before outputting it on microstripline to detectors (KIDs in the case of NEW-MUSIC).
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All authors Xiaolan Huang, Shibo Shu, Miao Li, Sunil R. Golwala, Feng Liu
Applied Physics
Strain-tunable inter-valley scattering defines universal mobility enhancement in n- and p-type 2D TMDs
Sheikh Mohd Ta-Seen Afrid, He Lin Zhao, Arend M. van der Zande et al. (+1 more)
Strain fundamentally alters carrier transport in
semiconductors by modifying their band structure and scattering pathways. In transition-metal dichalcogenides (TMDs), an emerging class of 2D
semiconductors, we show that mobility modulation under biaxial strain is dictated by changes in inter-valley scattering rather than effective mass renormalization as in bulk silicon. Using a multiscale full-band transport framework that incorporates both intrinsic
phonon, extrinsic
impurity, and dielectric scattering, we find that tensile strain enhances n-type mobility through K-Q valley separation, while compressive strain improves p-type mobility via {\Gamma}-K decoupling. The tuning rates calculated from our full-band model far exceed those achieved by strain engineering in silicon. Both relaxed and strain-modulated carrier mobilities align quantitatively with experimentally verified measurements and are valid across a wide range of practical FET configurations. The enhancement remains robust across variations in temperature, carrier density,
impurity level, and dielectric environment. Our results highlight the pivotal role of strain in improving the reliability and performance of 2D TMD-based electronics.
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All authors Sheikh Mohd Ta-Seen Afrid, He Lin Zhao, Arend M. van der Zande, Shaloo Rakheja
Medical Physics
An image-guided high-precision research platform for ultra-high dose rate spinal cord toxicity studies
Banghao Zhou, Lixiang Guo, Yi-Chun Tsai et al. (+7 more)
Objective: While FLASH radiotherapy is recognized for short-term normal tissue sparing, its durability in late-responding organs remains uncertain, limiting clinical adoption. With its clinical importance and steep dose-response, the spinal cord is an ideal model for evaluating FLASH effect on late toxicity. This work introduces a robust image-guided research platform for high-precision irradiation at both CONV and UHDR to enable FLASH late toxicity studies using a rat spinal cord model. Approach: A modified LINAC was employed to irradiate the C1-T2 rat spinal cord with 18 MeV UHDR and CONV beams. A custom rat immobilization device, a portable X-ray imaging system, and an ion-chamber-based UHDR output monitoring system were integrated to ensure accurate C1-T2 localization and precise dose delivery. A Monte Carlo (MC) dose engine was developed to provide accurate dosimetry and support interpretation of in vivo results. Scintillator measurements were performed within the spinal cord to verify MC results and the precision of our platform. Results: We achieved submillimeter C1-T2 setup accuracy and maintained submillimeter intrafraction motion. Ion chamber readings showed linear correlation with UHDR output. MC indicated uniform irradiation along the central ~13 mm cord. Our CONV beam exhibited distribution close to that of the UHDR beam, with difference <3%, isolating dose rate as the only variable. Scintillator-measured dose agreed with MC within 4%, confirming both MC accuracy and the platform's high-precision delivery. Significance: We developed the first comprehensive, image-guided preclinical platform for accurate UHDR and CONV irradiation to investigate FLASH-mitigated spinal cord toxicity in rats. This work thus establishes a robust foundation for systematic evaluation of the FLASH effect in late-responding organs and for determining clinical applicability of FLASH.
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All authors Banghao Zhou, Lixiang Guo, Yi-Chun Tsai, Albert van der Kogel, John Wong, Iulian Iordachita, Kai Jiang, Weiguo Lu, Paul Medin, Ken Kang-Hsin Wang
Atmospheric and Oceanic Physics
A high-resolution prediction dataset for solar energy across China (2015-2060)
Daoming Zhu, Xinghong Cheng, Yanbo Shen et al. (+7 more)
A high spatiotemporal resolution and accurate middle-to-long-term prediction data is essential to support China's dual-carbon targets under global warming scenarios. In this study, we simulated hourly
solar radiation at a 10 km* 10 km resolution in January, April, July, and October at five-year intervals from 2015 to 2060 across China using the WRF-Chem model driven by bias-corrected CMIP
datasets and future emission inventories. We further calculated the monthly photovoltaic power potentials based on an improved assessment model. Results indicate that the WRF-Chem model can reproduce the spatiotemporal
evolution of
solar radiation with small simulation errors. GHI in 2030 and 2060 over China are characterized by a pronounced west-to-east gradient. The interannual fluctuations of GHI from 2015 to 2060 over China's major PV power generation bases are small, and the interannual variability of GHI is mainly dominated by TCC and the influence of AOD is limited. National averaged PV power generation in China shows a significant growth trend and increases from 68.7 TWh in 2015 to 129.7 TWh in 2060, which is approximately twice the 2015 value. The
dataset will provide an important scientific basis for renewable energy planning and grid security under China's dual-carbon strategy.
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All authors Daoming Zhu, Xinghong Cheng, Yanbo Shen, Chunsong Lu, Duanyang Liu, Shuqi Yan, Naifu Shao, Zhongfeng Xu, Jida Peng, Bing Chen
Instrumentation and Detectors · Cross-listed from astro-ph.IM
Improved Modeling of Quasi-Static Thermal and Optical Response of Lumped-Element Aluminum Manganese KIDs
Adriana Gavidia, Sunil Golwala, Andrew D. Beyer et al. (+11 more)
We report on the optical characterization of the AlMn kinetic inductance detectors (KIDs) in development for use in the Next-generation Extended Wavelength-MUltiband Sub/millimeter Inductance Camera (NEW-MUSIC) on the Leighton Chajnantor
Telescope (LCT). NEW-MUSIC will cover 80-420 GHz, split into six spectral bands, with polarimetry. This broad spectral coverage will enable study of a range of scientific topics such as the
accretion and feedback in
galaxies and
galaxy cluster
evolution via the Sunyaev-Zeldovich effect, the transient synchrotron emission from the explosive deaths of massive
stars and other time-domain phenomena, and dusty sources from low to high
redshift (with polarization). Al KIDs have already been demonstrated for bands 2-5. AlMn KIDs will be used for the 90~GHz band, as Al's pair-breaking energy is too high. However, AlMn has only barely been explored as a KID material. To this end, we first improved the modeling techniques used for Al KIDs within BCS theory by eliminating the use of analytical approximations for the expressions of the complex conductivity and found these changes reduced fit parameter degeneracy in the analysis of AlMn. Then, we tested the addition of a gap smearing parameter, a standard extension to BCS theory in use for high kinetic inductance materials, and found it did not improve the fits.
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All authors Adriana Gavidia, Sunil Golwala, Andrew D. Beyer, Daniel Cunnane, Peter K. Day, Fabien Defrance, Clifford F. Frez, Xiaolan Huang, Junhan Kim, Jean-Marc Martin, Jack Sayers, Shibo Shu, Shiling Yu, Yann Sadou