Papers

We study the energy expenditure and structural correlations in semi-dilute to concentrated suspensions of squirmers using active fast Stokesian dynamics simulations. Specifically, we simulate apolar active suspensions of squirmers, or 'shakers,' and show that shear enhances the total dissipation but reduces the relative viscosity for both puller- and pusher-type shakers. At low shear rates where activity dominates, hydrodynamic interactions increase the active dissipation, more so for pullers at higher volume fractions, whereas pushers exhibit a higher viscosity, in contrast to bacterial suspensions displaying a 'superfluid' transition. At high shear rates where shear dominates, pullers and pushers behave effectively as passive spheres, generating negative normal stress differences due to shear-induced collision. Remarkably, the rate-dependent rheological responses are accompanied by unusual microstructural signatures of an enhanced nematic order and anisotropic pair correlation, both of which contribute to a higher viscosity under shear. Further simulations of self-propelled, neutral squirmers exhibit similar but weaker shear-thinning, highlighting the importance of activity over motility, underpinned by hydrodynamic interactions. Overall, our results elucidate the interplay of internal activity and external flow on the dissipation and microstructure in sheared active suspensions of squirmers.

We applied heat treatments to 80.5 MHz quarter-wave resonators made from bulk niobium and prepared with buffered chemical polishing BCP. We evaluated their performance at 4.3 K. We found that a 48 hour, 120 C bake-out ("low-temperature bake out") reduces the surface resistance by a factor of 2 to 3, stemming from a reduction in the Bardeen-Cooper-Schrieffer contribution, consistent with previous findings. This decrease leads to a 38% decrease on average in the medium-field Q-slope when compared to cavities which had only BCP. Mechanisms for the change in quality factor with low-temperature baking have been explored. We observed no improvement in cavity performance after a 3-hour bake-out at 350 C ("medium-temperature bake out"), in contrast to observations for higher-frequency cavities.

The year 2025 marked the centennial of quantum mechanics, inaugurated by Heisenberg's matrix formulation and the foundational contributions of Pauli, Schrodinger, and Dirac. Concurrently, 2026 marks the centennial of the Klein - Gordon equation, the second-order relativistic wave equation from which both the Schrodinger and Dirac equations were derived. This article supplements the recent review published in J.Phys. A: Math.Theor.,58 (2025) 053001 by providing a more detailed examination of the formative period 1925 - 1928, with particular attention to contributions that have received insufficient recognition in the standard narrative. We reconstruct Kramers' independent derivation of the Dirac equation - obtained essentially simultaneously with Dirac's own result yet unpublished for seven years - and discuss its relation to Van der Waerden's group-theoretical approach. The role of Charles Galton Darwin in elucidating the physical content of the Dirac equation is also highlighted. In addition, we present two modern derivations not catalogued in the earlier review: one based on Operational Dynamical Modeling, which deduces the Dirac equation from relativistic Ehrenfest relations and the canonical commutation algebra, and one rooted in the Madelung hydrodynamic formulation. Three broad periods of quantum theory development – foundational, consolidation, and the modern era of quantum information – are briefly surveyed.

This study presents a proof-of-concept experimental investigation of a multi-buoy cooperative point-absorber wave energy converter (WEC). The proposed concept consists of an array of surface-penetrating buoys connected through a shared closed-loop hydraulic power take-off (PTO) system. Energy is extracted through the collective motion of the buoy array, where pressurised flow generated by individual buoys drives a turbine within the hydraulic circuit. A 1:40 scale model was tested in the wave tank facilities at the University of Oslo. Experiments with regular and irregular long-crested waves at two different incident angles were conducted to assess power absorption, wave period response, and interaction effects. Two array configurations were investigated: an eight-buoy array with an axis-to-axis spacing of 1.5 buoy diameters, and a four-buoy array with a 3.0 diameter spacing. Although piston head leakage affected the power measurements, our results demonstrate that the WEC absorbs incoming wave energy and produces measurable power. The eight-buoy configuration achieved the highest power output per buoy compared to the four-buoy configuration, but exhibited increased sensitivity to wave period and wave heading, due to buoy-buoy interactions, such as collisions. This study highlights buoy count and internal buoy spacing as key design parameters for cooperative point-absorber wave energy systems. The results indicate that higher buoy counts enhance hydraulic cooperation, and increased buoy spacing improves robustness to wave heading and reduces destructive interaction effects. We also suggest that a lower system inertia can improve responsiveness to shorter waves. These insights provide a foundation for further optimisation and future full-scale development.

This paper presents a unified variational framework that integrates phase-field fracture (PFF) and third-medium contact (TMC) within finite deformation hyperelasticity. The key idea is that both crack and contact are treated through regularization: the sharp crack topology is regularized into a diffuse damage field, while the discrete contact interface is regularized by a compliant fictitious medium with auxiliary fields. This strategy eliminates the need for explicit contact detection or crack tracking algorithms. The framework is validated through two-dimensional three-point bending and three-dimensional Brazilian disk test simulations, demonstrating the interplay between contact-induced stress concentration and crack nucleation/propagation. In particular, the Brazilian disk simulation naturally reproduces secondary crushing-type fracture zones near the contact regions – a phenomenon consistently observed in experiments yet inaccessible to simplified loading models. These results pave the way for predictive simulation of coupled contact-fracture phenomena without recourse to explicit interface tracking.

Incorporating nanomaterials into food products provides key benefits, including extended shelf life, improved safety, and enhanced quality and texture. These innovations could help tackle major challenges in modern food systems, such as reducing waste and enhancing food quality and safety. However, potential toxicity remains a concern, compounded by the lack of physiologically relevant models for assessing ingested nanomaterials. Traditional in vitro and in vivo approaches often fail to mimic gastrointestinal complexity, resulting in inconsistent and non predictive nanotoxicity data that hinder accurate risk assessment of nano enabled foods. To address this gap, this review evaluates the potential of microphysiological systems (MPS), particularly gut-targeted MPS, for modeling gastrointestinal nanoparticle exposure. It examines how MPS technologies replicate key physiological processes relevant to food specific risk assessment, including intestinal barrier function, microbiota immune interactions, and gut organ communication. A comparative analysis of technological advances and their applications in nanotoxicology explores how MPS can be better adapted for nanofood safety evaluation.

Accurate identification of charged pions and kaons is essential for precision measurements in relativistic heavy-ion collisions, but becomes increasingly challenging at intermediate and high transverse momentum due to the overlap between time-of-flight mass-square ($m^{2}$) and ionization energy loss ($n\sigma$) distributions. In this work, we present a two-dimensional shift and rotation method that exploits the correlated information between $m^{2}$ and $n\sigma$ to enhance particle identification performance. The method is validated using Au+Au collision events generated with the AMPT model, where detector response effects are incorporated through a data-driven smearing procedure tuned to reproduce the particle identification performance of the STAR experiment. The reconstructed pion and kaon transverse momentum distributions show excellent agreement with the AMPT input, maintaining a purity exceeding 98% at high $p_T$ and extend the reliable identification range up to $p_T \approx$ 3 GeV/$c$. The extracted elliptic flow $v_2$ remains consistent with the input over the extended $p_T$ range, demonstrating that the proposed method provides a robust framework for high precision identified hadron measurements.

Simulating long-term, fully dynamic sequences of earthquakes and aseismic slip (SEAS) on geometrically complex fault networks remains computationally demanding due to the cost of resolving elastodynamic interactions. Although high-performance computing improves feasibility, simulations remain expensive, particularly for multicycle evolution, motivating the widespread use of quasi-dynamic approximations based on radiation damping. Here we present an efficient numerical framework for fully elastodynamic SEAS simulations on complex fault networks. The method adopts a divide-and-conquer strategy in which elastodynamic self-effects and fault-to-fault interactions are treated separately using boundary integral formulations tailored to each interaction type. Self-interactions along planar faults are computed using a non-replicating spectral boundary integral formulation that eliminates periodic-image artifacts, while interactions between arbitrarily oriented faults are evaluated through a fully dynamic space-time boundary integral representation accelerated by hierarchical matrices (H-matrices). A key advance is a selective H-matrix compression strategy based on fault-wise assembly of independent binary trees, enabling low-rank approximation of long-range interactions while preserving near-field accuracy and excluding self-effects from the hierarchical structure. Additional efficiency arises from physics-informed truncation of elastodynamic histories using mode-dependent time windows and causality-based kernel truncation. Benchmark multi-fault simulations validate accuracy against reference uncompressed solutions. The method reduces interaction complexity from O(N^3) to O(N^2 log N), yielding up to three orders of magnitude speedup and an order-of-magnitude memory reduction for typical problem sizes (~3e10 degrees of freedom), enabling fully dynamic SEAS simulations on workstation hardware.

Kilonovae, the electromagnetic transients produced from two merging neutron stars, exhibit evolving spectral signatures in ultraviolet, visible, and infrared radiation. Starting around one week post-merger, equilibrium assumptions describing the local ionization balance and atomic level populations in the ejecta come into question, and non-equilibrium modeling is required. In this non-equilibrium regime, interactions with non-thermal electrons are critical inputs to ionization balance models. With most databases storing rate coefficients, the necessary cross sections describing these interactions are generally unavailable. We report new level-resolved calculations of the ionization cross sections of a species tentatively identified in kilonovae, Te I - III, using the Flexible Atomic Code. Good agreement is found between the calculated cross sections and a limited number of available measurements. Particular attention is paid to diagnosing the accuracy of the above-threshold channels that contribute through excitation autoionization. Calculations in the configuration average approximation yield ionization cross sections close to both experimental and level-resolved theoretical values. The computed cross sections are combined with a Spencer-Fano non-thermal electron energy solver and subsequent ionization balance models to probe the impact of improved cross section datasets on ion fractions of Te I - IV at kilonova-like plasma conditions.

In this paper, we compare experimental and numerical simulation results to benchmark the PERSEUS code against gas-puff $Z$-pinch implosions on COBRA. We then use the code to investigate the structure of the plasma sheath. To this end, we study the morphology of the implosion, focusing on non-magnetohydrodynamical (MHD) effects such as electron drifts governed by the Hall term within the growing magneto-Rayleigh-Taylor instability (MRTI). The spatial wavelength of MRTI is better reproduced when both the Hall term and an anomalous resistivity driven by the electron drift are included. Additionally, cathode-anode gap polarity effects are more accurately captured when the Hall term is turned on. The plasma sheath structure, which includes both the accelerating piston driven by the magnetic pressure and the shockwave ahead of it, matches interferometric measurements in width only when a current-driven anomalous resistivity model is used. This anomalous resistivity is assumed to be driven by the lower-hybrid-drift instability, which generates small-scale turbulence with typical wavelengths < 30{\mu}m.

Physics instructors need support to successfully adopt and adapt evidence-based active engagement (EBAE) approaches because improving teaching and learning is a process and support is needed to ensure that they do not get disheartened if a particular EBAE approach does not produce the desired outcome. The instructors not only need support to refine their implementation of a specific EBAE approach to make them effective, but also to use a variety of EBAE methods to improve student learning. Here we illustrate how, with appropriate support, a quantum mechanics instructor did not give up when an EBAE approach involving implementation of a sequence of clicker questions on addition of angular momentum did not yield expected learning outcomes. The support ensured that the instructor remained optimistic and used another EBAE method that did not require him to spend more time in class on this topic. In particular, the instructor created an opportunity for students to productively struggle with the same problems (they had not performed well on after clicker questions) by giving them grade incentives to correct their mistakes outside of class. Student performance on one of the addition of angular momentum problems posed on the final exam suggests that students who corrected their mistakes benefited from the task and learned about addition of angular momentum better than those who did not correct their mistakes. Encouraging and supporting physics instructors can even be accomplished using an online community of physics educators. This type of support can go a long way in helping students learn physics because it is likely to increase their persistence in using various EBAE approaches as they refine their implementation to suit their students as well as their own instructional style.

The relationship between balance laws and the Principle of Virtual Work as well as the structure of contact interactions in continua remain foundational issues in Mechanics. In this work, we revisit these issues within the distributional framework emphasized by Paul Germain. We show that while the Principle of Virtual Work implies balance of forces and moments for $n$th-gradient continua, balance laws alone do not suffice to characterize equilibrium for $n \geq 2$. We then reexamine Noll's classical theorem asserting that surface contact forces depend solely on the unit normal to the surface and identify the precise role of his additional assumptions, namely the absence of edge and wedge contact interactions and the boundedness of the surface contact density on the space of oriented surfaces. We demonstrate that these hypotheses fail for general higher-gradient continua. Consequently, the presence of curvature-dependent surface contact forces in such materials does not conflict with Noll's theorem and refutes his claim of their nonexistence.

In one-dimensional diffusive processes with discrete steps characterized by geometrically decaying magnitudes, the usual Gaussian broadening familiar from Brownian motion is replaced by bounded probability distributions over particle positions that are characterized by multi-scale fractal structures. In this work, we study random walks with shrinking steps (known as Bernoulli convolutions), focusing on their behavior in the vicinity of the dyadic contraction ratio 1/2. Our analytical and numerical results show that the coarse-grained Shannon entropy of particle distributions induced by Bernoulli convolutions exhibits a local maximum at the dyadic ratio, arising from the competition between diffusive spreading, which increases entropy, and emergent fine structure, which tends to decrease it. This entropy maximum is a general property of systems driven by non-Gaussian discrete noise, whose dynamics near stable fixed points can be viewed as an autoregressive process - an approximation that is mathematically equivalent to unbiased random walks with shrinking steps. We discuss potential implications of Bernoulli convolution dynamics for protocell self-replication and vesicle proliferation, establishing a link between our information-theoretic approach and biophysical models of cell division.

The propagation of premixed flames in narrow Hele-Shaw cells and permeable porous media is governed by Darcy's law, leading to hydrodynamic behaviour distinct from conventional flames. This study investigates the role of confinement on flame dynamics, focusing on the associated Markstein numbers. A hydrodynamic model treating the flame as a discontinuity surface is presented, in which the burning rate depends on curvature and tangential flow strain, characterised by two Markstein numbers $\mathcal{M}_c$ and $\mathcal{M}_t$. A major finding is that $\mathcal{M}_c \neq \mathcal{M}_t$ under Darcy's law, as the law permits tangential velocity discontinuities at the flame front due to viscosity variations. Additionally, a third Markstein number $\mathcal{M}_g$ associated with gravity also emerges uniquely under Darcy's law. The Darcy-specific effects vanish in purely radial flows but are important for strained flames. In planar counterflows, for instance, the strain rate jump across the flame is dictated by the unburnt-to-burnt viscosity ratio $\mathfrak{m}$ rather than the density ratio $\mathfrak{r}$, a dramatic departure from conventional behaviour. The influence of confinement on the combined hydrodynamic instabilities of planar flames, namely Darrieus–Landau, Saffman–Taylor, and Rayleigh–Taylor instabilities, is discussed. Weakly nonlinear dynamics under strong confinement is found to follow a Michelson–Sivashinsky equation with modified coefficients (long-wave instability), while under moderate confinement, Ginzburg–Landau dynamics (finite-wavenumber instability) is found to apply. Strong confinement amplifies the Darrieus–Landau instability, enhancing hydrodynamic coupling in conjunction with augmented streamline refraction caused by tangential velocity discontinuities.

In many real-world systems, partial synchronization is the dominant dynamical regime and, in systems such as the brain, is often accompanied by collective oscillations in which multiple overlapping modes interact to produce complex rhythmic activity. Here, we investigate duplex networks with reactive interlayer links, where full synchronization cannot be achieved. We show that when interlayer frequency differences between mirror nodes are uniformly distributed with sufficient width, the network self-organizes into collective macroscopic oscillations composed of multiple interacting modes. By linking macroscopic phase transitions to microscopic directed information transfer between nodes, we uncover the mechanisms underlying the emergence of these multimodal dynamics.

Controlling the flow of light within complex and dynamic environments is essential for a wide range of applications, from deep-tissue imaging and optogenetics to precision phototherapy. Typically, such light flows are controlled using external optical systems requiring line-of-sight access or by embedded nanoparticle scatterers with limited directional control, underscoring the need for mobile photonic agents capable of actively delivering and steering light within complex media. Here, we present magneto-photonic metaparticles: mobile, magnetically actuated microstructures that integrate a magnetic core with a nanoimprinted photonic surface. This hybrid design merges the reconfigurability of photonic metasurfaces with the mobility of magnetic actuation, enabling programmable translation, rotation, and real-time beam steering in aqueous media. In a concept-proof demonstration, we realize polymeric metaparticles with embedded magnetic core and nanoimprinted surface that exhibit controlled locomotion and active, magnetically programmable beam steering. Our design approach further points to more sophisticated metaparticle designs with high-efficiency, polarization-insensitive light steering, compatible with a scalable, single-step nanoimprint process. The mobile magneto-photonic metaparticle platform combines metasurface-level optical control with magnetic mobility, offering a versatile and scalable approach for active photonic control in complex environments.

We study a new paradigm for ultrasonic driven object coating by using a model system where MHz-level surface acoustic waves (SAWs) drive the spreading of a silicone oil film atop topographical obstacles. We use experiments to show that nanometer-amplitude SAWs, propagating in the substrate of a piezoelectric actuator, propel macroscopic oil films to climb and traverse solid obstacles placed on the actuator. The oil dynamics reveal rich coupling between ultrasonic forcing, capillarity, and gravity; the balance of which determines coating success. We formulate a simplified two-dimensional theoretical model that incorporates obstacle geometry directly in the oil thin-film evolution equation, introducing a new representation of acoustic streaming in the presence of substrate height variations. Despite the simplifications inherent in the modeling, simulations show qualitative agreement with the experiments, providing evidence that the model captures the key physics.

In a typical Rydberg mixer, modulated communication signals are detected using a radio frequency (RF) heterodyne technique. The mixer outputs an intermediate frequency (IF), which must be filtered and mixed down to baseband. In this work, we apply an RF-homodyne technique to demonstrate simultaneous detection and a direct, baseband readout of the in-phase (I) and quadrature (Q) components of standard communication signals using a dual ladder Rydberg receiver. We further show that the inherent polarization sensitivity of this receiver can be used to determine the signal's angle of arrival. We also compare the dual ladder system with a typical Rydberg mixer. The RF-heterodyne-based system's maximum detectable symbol rate is constrained by a signal amplitude which decays with the heterodyne field's detuning from the Rydberg-Rydberg atomic transition used to detect the signal, but the dual ladder design is not subject to this limitation. However, the dual ladder system is more sensitive to low-frequency noise. As a result, its performance is degraded relative to its conventional counterpart when subjected to pink noise. We show that once pink noise effects have been accounted for, both systems behave comparably.

High-brightness X-ray Free Electron Lasers (FELs) produce spatially and temporally coherent pulses on attosecond to femtosecond timescales, providing a transformative tool for discovery across biology, chemistry, physics, and materials science. This paper proposes a compact accelerator that enables a high-repetition-rate (MHz) 1 nm soft X-ray FEL with a footprint of less than 100 meters. Such an FEL is suitable for installation within research institution settings where space is limited. The accelerator leverages a multi-turn recirculating linear accelerator that integrates state-of-theart superconducting accelerator technology with recent advances in diffraction-limited storage rings. We present the conceptual layout and analyze the impact of two most challenging factors for such a compact accelerator, incoherent and coherent synchrotron radiation. We have systematically studied both effects for different multi-bend achromat lattices and electron beam peak currents. For a peak current of 60 Ampere before final compression and using 11-bending magnets, the horizontal emittance growth after the 90-degree arc can be kept below 10%, demonstrating that these effects are not limiting factors for achieving high-quality electron beams. Such a compact X-ray FEL facility would substantially reduce both construction and operational costs, greatly expanding access to these powerful research tools. Furthermore, this concept provides a potential upgrade path to generating hard X-ray radiation by incorporating high accelerating gradient structures to further accelerate a portion of the MHz electron beam.

We report on magneto-optical trapping of the two fermionic isotopes of atomic titanium, $^{47}$Ti and $^{49}$Ti. Unlike the even mass-number isotopes, which were recently laser cooled, $^{47}$Ti and $^{49}$Ti have nonzero nuclear spins and, consequently, their atomic levels are split by hyperfine structure. Combining and comparing theoretical calculations and atomic beam-spectroscopy measurements, we determine the hyperfine structures and isotope shifts of the $\mathrm{3d^24s^2}$ $\mathrm{a^3F_4\rightarrow 3d^2(^3P)4s4p(^3P^o)}$ $\mathrm{y^5D_4^o}$ optical-pumping transition at optical wavelength 391nm and the $\mathrm{3d^3(^4F)4s}$ $\mathrm{a^5F_5\rightarrow 3d^3(^4F)4p}$ $\mathrm{y^5G_6^o}$ laser-cooling transition at wavelength 498nm. With this information, we produce magneto-optical traps of both $^{47}$Ti and $^{49}$Ti by applying two additional tones of light to repump atoms to the maximum-spin states on the laser-cooling transition. Directly loading from the atomic flux of a titanium sublimation pump, we produce $^{47}$Ti and $^{49}$Ti traps with 731(190) and 1142(240) atoms, and with lifetimes of 330(15)ms and 310(8)ms, respectively.

Living collectives and artificial swarms frequently employ a division of labor, wherein individuals take on different tasks or perform different amounts of work. However, the mechanisms used by collectives to divide labor remain poorly understood. Here, we study how workload inequality arises in collectives by monitoring excavation in Solenopsis invicta fire ants, whose coordination in constrained environments makes them an attractive system for studying division of labor. We vary group size (between 2 and 25 ants) and track digging activity to create Lorenz curves and corresponding Gini coefficients, which represent relative workload inequality. We find that that workload becomes more unequal as group size increases: the number of "active" ants scales with the square root of the group size. We implement a cellular automata (CA) model in which agents regulate their activity based on local crowding in the tunnel. The CA reproduces experimental Gini coefficients over a wide range of parameters and group sizes, indicating that local decisions emergently account for the scaling of workload inequality. An analytic rate equation model recovers the square root scaling with the assumption that individuals exit the tunnel at a rate which scales quadratically with the group size. Power law scalings in workload distribution have been observed in other systems, including social and natural sciences; however, these laws are primarily observational. Here, we provide a mechanistic explanation for the emergent workload scaling patterns in constrained biological collectives, offering insight into organization in both natural and future task capable engineered collectives and swarms.

This study presents an automated topology optimization framework for designing pentamode acoustic metamaterials. It provides precise control over the material effective acoustic properties while minimizing the shear modulus to achieve fluid-like behavior. The approach combines low-frequency homogenization for accurate property evaluation and the adjoint method for efficient sensitivity analysis. The Virtual Temperature Method (VTM) ensures structural connectivity and manufacturability, addressing the typical challenges of low-stiffness, high-mass-density microstructures. The framework is demonstrated through the design of a Lüneburg lens and an acoustic invisibility cloak for underwater applications. Acoustic-elastic simulations validate the performance of both the unit cells and the complete devices. This method eliminates the need for predefined geometries, offering a flexible, reliable, and scalable alternative to conventional parametric optimization. It provides a powerful tool for the automated design of complex, anisotropic, pentamode metamaterials.

We investigate the effect of wall fluid slip on the orientation of non-Brownian, short, rigid, and high aspect ratio cylindrical fibers suspended in a Newtonian fluid in flow through a symmetric hyperbolic planar channel. The fiber orientation is described using a second-order tensor formulation that accounts for fiber-fiber interactions and employs a hybrid closure to approximate the fourth-order orientation tensor, while neglecting the extra-stress contribution of the fibers to the total stress tensor. Building on our previous work on the no-slip case (Housiadas, Beris and Advani, J. Rheol., 2025), the analytical Newtonian velocity field that has been obtained via the extended lubrication theory is utilized (Sialmas and Housiadas, Eur. J. Mech. B Fluids, 2024). Corresponding to this velocity field, the magnitude of the rate-of-deformation decreases as the slip coefficient increases. The resulting equations for the orientation tensor are solved numerically using a fully implicit finite difference method.The results show that the fiber orientation gradually evolves from its initial pure-shear state at the inlet toward a more aligned configuration as the channel exit is approached.The region of higher fiber alignment, that is most pronounced at the midplane where the flow is purely extensional, extends further toward the walls as the slip increases.

While the generalized Langevin equation (GLE) is a powerful tool to understand the behavior of complex dissipative systems, driving by external fields renders standard GLE construction workflows invalid. Filtering approaches that separate fluctuations from the non-equilibrium response can sometimes circumvent the need for a non-equilibrium formalism when the residual fluctuations are homoskedastic, stationary, and preferably Gaussian. Here, we introduce the temperature time series from Boulder, Colorado, as representative of the more general and complex case where the filtered time series remains non-Gaussian, non-stationary, and heteroskedastic. With this example, we develop a protocol to build an accurate and efficient low-dimensional description of the weather fluctuations. Our protocol classifies the weather data based on the position in the annual cycle, and introduces local homoskedasticity as a metric to identify seasons of likely stationarity. Within these seasons, we build pseudo-equilibrium models. Leveraging state-based generalized master equation modelling as an alternative to the GLE, we resolve difficulties like non-Gaussianity and position dependence of the memory (friction) kernel. Our data-driven approach accurately reproduces the evolving fluctuations of the Boulder temperature time series, illustrating the feasibility of our method as a general tool to describe driven, dissipative systems.

We use micromagnetic simulations to demonstrate how machine learning can be applied to arrays of chiral magnonic resonators to build a magnonic full adder. The chiral magnonic resonators have form of nano-sized permalloy disks that nonlinearly scatter spin waves propagating in a YIG waveguide. The spin waves are injected from multiple outputs, and the dynamic stray magnetic field of the scattered spin waves is sampled in multiple locations to form several physical output signals. These signals are weighted and combined, either linearly or nonlinearly, to satisfy the logic output of a full adder. The process is known as training and forms the device's output layer. The full adder's performance is evaluated in terms of robustness to input and output noise for a given number of physical output signals and the form of the output layer. When the output layer is linear, as few as three physical signals per logical output are sufficient. When a multilayer perceptron neural network forms the output layer, the number of required output signals is reduced to one, and a nearly perfect classification accuracy is achieved when appropriate preprocessing and augmentation strategies are used.

We report on extensive experimental investigation of novel barium chalcogenides (BaGa4Se7, BaGa2GeSe6 and BaGa2GeS6) for generation of a strong narrowband terahertz (THz) radiation. The Ba-containing compounds demonstrate the large bandgap values, high optical damage threshold and wide transparency range from the visible to mid-infrared region, coupled with narrowband transparency windows in the THz frequency range. In these windows a THz generation via the second-order nonlinear process of optical rectification occurs under optical pumping by a 50-GW high-power Cr:forsterite laser leading to intrinsically narrowband THz pulses. The highest optical-to-THz conversion efficiency of 0.8^10(-5) is reached in the Z-cut BaGa2GeS6 crystal in the saturation regime and corresponds to an output energy of 20 nJ. Ba compounds provide narrow-bandwidth THz pulses at the frequencies in the range from 1.9 to 2.5 THz with a relative bandwidth of 3-4%, necessary for imaging and spectroscopy for security or medical applications.

We provide a complete census of the baryons in early galaxies to investigate the phases in which gas and stars reside, their corresponding budgets, depletion times, and stellar return fraction as a function of redshift and stellar age. We use the ColdSIM hydrodynamical time-dependent non-equilibrium chemistry simulations and perform a detailed analysis of the cold, warm, hot, and stellar phases for both bound structures (galaxies/CGM) and the diffuse IGM. We investigate in depth the cold HI and H2 components, explicitly computed in our simulations, and their relations with host mass, SFR, metallicity and depletion times. We also provide observational insights and discuss the implications for stellar mass functions, PopIII star formation and changes in the IMF. We find that cosmic gas prior to reionisation is mostly cold, while at later epochs the warm phase becomes dominant due to enhanced star formation activity and increasing UV reionising radiation. Stellar return fractions at these times are ~0.15-0.20, a factor of two lower than the values usually adopted. Cold, warm, and hot gas masses as well as HI and H2 components show increasing trends with mass and SFR, while depletion times decrease down to 0.01-0.1 Gyr with a weak metallicity dependence. The resulting star formation efficiency remains at the level of a few per cent and gas-to-star fractions decline with mass, influenced by local feedback and environment. Our findings are consistent with ALMA, VLA and IRAM surveys at later epochs, including ALFALFA, xCOLDGASS, GASS, xGASS, EDGE-CALIFA, PHIBBS, and ASPECS. Gas phases are quantitatively related to the underlying stellar populations and can be used to infer unknown quantities. In the appendix we provide fit functions describing the trends of the stellar return fraction, the main sequence, phase mass relations, gas-to-star fractions and depletion times.

We present a joint experimental and theoretical study of a ratchet implemented in arra ys of evanescently coupled plasmonic waveguides with tailored losses. In this setup the time-periodic dissipation is the only active mechanism and notably, we find better rectified transport and lower losses in the transmitted signal with increased local dissipation. Using Floquet theory, we uncover a driving regime that allows efficient directional tr ansport for suitable driving frequencies and loss rates, which are linked to linear qu asienergy bands with minimal losses. These regions are separated from non-resonant beh avior by sharp transitions with characteristic exceptional points in the spectrum. Direct experimental observation of the Floquet-dissipative ratchet effect using a comb ination of real- and Fourier-space leakage radiation microscopy is provided.

The non-relativistic Goedecke equation (1975), which describes the motion of a point charge taking into account the radiation reaction, has no "runaway" solutions. A "physical" method of covariant generalization of this equation is proposed, a special case of which is based on the Lorentz transformations in a coordinate–free covariant representation. Two equivalent forms of a new classical relativistic equation of motion of a point charge are obtained. It is shown that the Abraham–Lorentz–Dirac (ALD) and the Mo–Papas (MP) equations are approximate consequences of the presented theory.

LLM agents are increasingly used for code generation, but physics-based simulation poses a deeper challenge: natural-language descriptions of simulation models are inherently underspecified, and different admissible resolutions of implicit choices produce physically valid but scientifically distinct configurations. Without explicit detection and resolution of these ambiguities, neither the correctness of the result nor its reproducibility from the original description can be assured. This paper investigates agentic scientific simulation, where model construction is organized as an execution-grounded interpret-act-validate loop and the simulator serves as the authoritative arbiter of physical validity rather than merely a runtime. We present JutulGPT, a reference implementation built on the fully differentiable Julia-based reservoir simulator JutulDarcy. The agent combines structured retrieval of documentation and examples with code synthesis, static analysis, execution, and systematic interpretation of solver diagnostics. Underspecified modelling choices are detected explicitly and resolved either autonomously (with logged assumptions) or through targeted user queries. The results demonstrate that agent-mediated model construction can be grounded in simulator validation, while also revealing a structural limitation: choices resolved tacitly through simulator defaults are invisible to the assumption log and to any downstream representation. A secondary experiment with autonomous reconstruction of a reference model from progressively abstract textual descriptions shows that reconstruction variability exposes latent degrees of freedom in simulation descriptions and provides a practical methodology for auditing reproducibility. All code, prompts, and agent logs are publicly available.