We investigate the dynamics of active nematic liquid crystals on deformable membranes, focusing on the interplay between active stress and anisotropic curvature coupling. Using a minimal model, we simulate the coupled evolution of the nematic order parameter and membrane height. We demonstrate a continuous transition from a curvature-dominated regime, where topological defects are trapped by local deformation, to an activity-dominated regime exhibiting active turbulence. A scaling analysis reveals that the critical activity threshold ${\zeta }_c$ scales as ${\alpha }^2/\kappa$, where $\alpha$ and $\kappa$ are the coupling constant and bending stiffness, respectively; this relationship is confirmed by our numerical results. Furthermore, we find that significant correlations between the orientational pattern and membrane geometry persist even in the turbulent regime. Specifically, we identify that “walls” in the director field induce characteristic wave-like curvature profiles, providing a mechanism for dynamic coupling between order and shape. These results offer a physical framework for understanding defect-mediated deformation in nonequilibrium biological membranes.

We investigate magnetic active matter in confined geometries using both experiments with magnetic toy robots, Hexbugs, and simulations of elongated magnetic active Brownian particles in circular domains. Standard active particles tend to accumulate at boundaries, forming clusters even at relatively low densities. In the presence of magnetic interactions, we provide evidence for a fluidization effect that inhibits clustering and shifts its onset to higher packing fractions. Moreover, magnetic dipolar interactions give rise to collective behaviors such as train-like formations, rotating pairs, and rotating clusters.

In this paper, we consider a run-and-tumble particle (RTP) with stochastic resetting confined to the half line $[0,\infty )$ with a sticky boundary at $x=0$. In the bulk, the RTP tumbles at a constant rate $\alpha >0$ between velocity states $\pm v$ with $v>0$ and randomly resets to its initial position and orientation $(x_0,k_0)\in ({\mathbb{R}}^{+},\pm )$. When the RTP reaches the target at $x=0$, it attaches to the boundary for some random waiting time before either detaching and continuing to navigate the bulk domain or (permanently) entering the target. These events are the analogs of adsorption, desorption, and absorption of a particle by a partially reactive surface in physical chemistry. We use renewal theory to characterize the particle trajectory in terms of successive binding events at $x=0$ under two distinct desorption protocols: via resetting to $(x_0,k_0)$ and via continuous movement from $x=0$ with velocity $+v$. First, we derive the nonequilibrium stationary state (NESS) in the case of no absorption and characterize the accumulation at the boundary. Second, we compute the mean first passage time (MFPT) statistics. In addition to observing the usual unimodal dependence of the MFPT on bulk resetting, both the NESS and MFPT strongly depend on the initial orientation $k_0$ and the desorption protocol. For instance, if the initial orientation is toward the boundary, we find that the desorption-induced resetting protocol can reduce the MFPT more effectively than the nonresetting desorption protocol. We also show how matching the desorption kinetics with the bulk resetting or tumbling rate introduces a tradeoff between minimizing the adsorption and absorption times. In this setting, we find that the desorption protocol which minimizes the absorption MFPT for a given set of parameters is almost always the opposite of that favored when desorption and bulk kinetics are not the same. These results collectively highlight the utility of the renewal formalism in characterizing two distinct desorption protocols particular to an RTP.

We introduce an Ising spin-glass model with correlated disorder which continuously interpolates between the pure ferromagnetic Ising model and the Edwards-Anderson model with symmetric disorder. For this model, we prove that a Nishimori line (NL) can be defined, analogously to the Edwards-Anderson model, on which physical quantities can be expressed exactly in terms of those of the pure Ising model at a well-defined effective temperature on any lattice in any dimension. For example, the energy on the NL is equal to the energy of the pure Ising model at the effective temperature up to a constant and a trivial factor. More remarkably, the specific heat on the NL equals the energy, not the specific heat, of the pure Ising model at the effective temperature, again up to a constant and a trivial factor. Gauge-noninvariant quantities such as the magnetization and correlation functions are exactly equal to the corresponding quantities of the pure Ising model at the effective temperature. These exact relations imply that the leading critical behavior at that multicritical point for the disorder-correlated model is pure-Ising-like, in contrast to the conventional multicritical universality class of the standard Edwards-Anderson model. Our results motivate further investigations of the relatively unexplored topic of correlations in disorder in spin glasses and related problems.

We investigate site and bond percolation in triangular and square lattices subjected to linear distortion. In contrast to previously studied distortion schemes that preserve lattice geometry, linear distortion dislocates regular lattice sites along a fixed direction. Nearest neighbors of a regular lattice need to satisfy a distance-based connection criterion to remain neighbors in the linearly distorted lattice. Using extensive Monte Carlo simulations and finite-size scaling analyses, we examine how site and bond percolation thresholds vary with the distortion parameter and the connection threshold. For triangular lattices, we observe pronounced directional dependence of both site and bond percolation thresholds, as well as of the critical connection threshold. This arises from the distortion-induced anisotropic modification of nearest-neighbor separations. In particular, bond percolation exhibits nontrivial behavior that cannot be explained solely in terms of changes in the average coordination number. In contrast, square lattices remain effectively isotropic under linear distortion, resulting in identical percolation thresholds for distortions applied along different directions. Percolation thresholds in the thermodynamic limit, evaluated for a selected set of values of distortion parameter and connection threshold, confirm that the results for large finite lattices provide reliable estimates of the infinite-system behavior.

Chimera states are synchronization patterns in which coherent and incoherent regions coexist in systems of identical oscillators. This elusive phenomenon has attracted significant interest and has been widely analyzed, revealing several types of dynamical states. Most studies involve reciprocal pairwise couplings, where each oscillator exerts and receives the same interaction from neighboring ones, thus being modeled via symmetric networks. However, real-world systems often exhibit nonreciprocal, nonpairwise (many-body) interactions. Previous studies have shown that chimera states are more elusive in the presence of nonreciprocal pairwise interactions, while they are easier to observe when the interactions are reciprocal and higher-order (many-body). In this work, we investigate the emergence of chimera states on nonreciprocal higher-order structures, called $m$-directed hypergraphs, which we compare with their corresponding networks, and we observe that some types of chimera states can emerge due to directionality, which had not been previously observed in its absence. We also compare the effect of nonreciprocal interactions between higher-order and pairwise couplings, and we find numerically that chimera states appear over a broader parameter range when considering higher-order interactions than in the corresponding network case, demonstrating the impact of directionality and the effect of higher-order interactions. Finally, the nature of phase chimeras has been further validated through phase reduction theory.

$E$-values have recently emerged as a robust and flexible alternative to $p$-values for hypothesis testing, especially under optional continuation, i.e., when additional data from further experiments are collected. In this work we define optimal $e$-values for testing between maximum entropy models, in both the microcanonical (hard constraints) and canonical (soft constraints) settings. We show that, when testing between two hypotheses that are both microcanonical, the so-called growth-rate optimal e-variable admits an exact analytical expression, which also serves as a valid e-variable in the canonical case. For canonical tests, where exact solutions are typically unavailable, we introduce a microcanonical approximation and verify its excellent performance via both theoretical arguments and numerical simulations. We then consider constrained binary models, focusing on $2\times k$ contingency tables—an essential framework in statistics and a natural representation for various models of complex systems. Our microcanonical optimal e-variable performs well in both settings, constituting a tool that remains effective even in the challenging case when the number $k$ of groups grows with the sample size, as in models with growing features used for the analysis of real-world heterogeneous networks and time series.

Heider balance theory provides a fundamental framework for understanding the formation of friendly and hostile relations in social networks. Existing stochastic formulations typically assume a uniform social temperature, implying that all interpersonal relations fluctuate with the same intensity. Howemver, studies show that social interactions are highly heterogeneous, with broad variability in stability, volatility, and susceptibility to change. In this work, we introduce a generalized Heider balance model on a complete graph in which each link is assigned its own social temperature. Within a mean-field formulation, we derive a distribution-dependent self-consistency condition for the collective opinion state and identify the criteria governing the transition between polarized and nonpolarized configurations. This framework reveals how the entire distribution of interaction heterogeneity shapes the macroscopic behavior of the system. We show that the functional form of the inverse temperature distribution, in particular whether it is light tailed or heavy tailed, leads to qualitatively distinct phase diagrams. We also establish universal bounds for the critical transition, where the homogeneous-temperature limit provides a universal lower bound for the critical mean of an inverse temperature distribution governing the transition. Numerical simulations confirm the theoretical predictions and highlight the nontrivial effects introduced by heterogeneity. Our results provide a unified route to understanding structural balance in realistic social systems and lay the groundwork for extensions incorporating fluctuations beyond mean field, external fields, and network topologies beyond the complete graph.

Filamentous actin, a species of dynamic protein polymers, is one of the main components of the cytoskeleton of eukaryotic cells. We formulate a class of models that predict the possibility of bistable steady states in populations of dynamic actin filaments. They are built upon a basic model of actin dynamics that includes severing and capping in the presence of a finite actin monomer pool. The key additional ingredient is the presence of a single species of effector molecules that is partially sequestered to an inactive state by binding to free G-actin. In its unbound active state, this effector species can enhance the rate of nucleation of filamentous actin or its growth speed, or inhibit the activity of capping or severing proteins. Using an explicit analytical solution of the basic actin dynamics model, we show that bistability is predicted to occur in all of the proposed models. We verify these predictions using particle-based stochastic simulations. In addition, we show that switching between the two stable states can be achieved by transient manipulation of the free G-actin pool size.

The Jeans instability is a fundamental mechanism driving the gravitational collapse and subsequent structure formation in diverse self-gravitating astrophysical environments. We present comprehensive numerical fluid simulations of the Jeans instability in a three component dusty plasma system. The high-energetic nonthermal electrons and ions are considered to follow κ distribution in velocity space with inertial dust as cold fluid. A Gaussian-type of initial density perturbation is introduced in the equilibrium density to initiate the simulations. The effects of the self-gravity parameter $\left({\alpha }_G\right)$ and nonthermal spectral index $\left(\kappa \right)$ on the Jeans instability have been investigated by tracking the evolution of plasma parameters in the simulations. In the absence of gravity $({\alpha }_G=0)$, the system exhibits stable dust acoustic wave propagation with no Jeans instability growth, confirming pressure-dominated dynamics. Whereas, for ${\alpha }_G>0$, the density increases exponentially at center of plasma system manifesting localized collapse. The nonlinear growth rates estimated from our simulations increase with ${\alpha }_G$ and show good agreement with the linear theory, particularly for lower ${\alpha }_G$ values. Simulations further demonstrate that the nonlinear growth rate is weakly dependent on $\kappa$; however, lower $\kappa$ values significantly decrease the characteristic collapse time $\left({\tau }_c\right)$. These findings establish that nonthermal (non-Maxwellian) environments in protoplanetary disks and molecular clouds are more efficient at catalyzing rapid structure formation than previously predicted by traditional thermal (Maxwellian) models.

Binary mixtures developed as thresholdless antiferroelectric (TLAF) materials, MC881-MC815 and MC881-MC452, are studied using optical rotatory power (ORP), resonant soft x-ray scattering (RSoXS), and dynamic light scattering (DLS). A single subphase is confirmed to exist in both mixtures by ORP, stably over a wide temperature range (around ${80}^{\circ }\mathrm{C}$ below RT) but in a narrow concentration range (1–3 wt.%), with curved boundaries; between $\mathrm{Sm}{C}_A^{*}$ and the subphase, the ratio of synclinic and anticlinic orderings changes continuously. The antiferroelectric four-layer superlattice structure of the subphase is now firmly established by RSoXS using free-standing films, although a two-layer $\mathrm{Sm}{C}_A^{*}$ structure is observed in silicon nitride membrane cells often used in RSoXS, highlighting the influence of surface conditions. The TLAF properties of the subphase are confirmed in homogeneously aligned cells by observing apparent tilt angles induced by an applied electric field. The relaxation times responsible for the TLAF properties are studied by DLS, indicating the smooth flip-flopping of a group of molecules in a single layer, which must also be responsible for the continuous change among $\mathrm{Sm}{C}_A^{*}$, the subphase, and $\mathrm{Sm}{C}^{*}$. Each smectic layer appears to play an important role as a mesoscopic entity.

We investigate how gravity influences negative differential thermal resistance (NDTR) in fluids modeled by multiparticle collision dynamics. In the integrable case, we derive the heat flux formula for the system exhibiting the NDTR effect, and show that by introducing a gravity along the direction of the thermodynamic force, the temperature difference required for the occurrence of NDTR can be greatly reduced. Meanwhile, we also demonstrate that the heat-bath-induced NDTR mechanism—originally found to be applicable only to weakly interacting systems—can now operate in systems with stronger interactions due to the presence of gravity, and further remains robust even in mixed fluids. These results provide insights into heat transport and establish a theoretical foundation for designing fluidic thermal devices that harness the NDTR effect under gravity.

The experimental use of micropatterned quasi-one-dimensional substrates has emerged as a useful experimental tool to study the nature of cell-cell interactions and gain insight on collective behavior of cell colonies. Inspired by these experiments, we propose an active spin model to investigate the emergent properties of the cell assemblies. The lattice gas model incorporates the interplay of self-propulsion, polarity directional switching, intracellular attraction, and contact Inhibition Locomotion (CIL). In the absence of vacancies, which corresponds to a confluent cell packing on the substrate, the model reduces to an equilibrium spin model that can be solved exactly. In the presence of vacancies, the clustering is controlled by a dimensionless Peclét Number, $Q$—the ratio of magnitude of self-propulsion rate to directional switching rate of particles. In the absence of CIL interactions, we invoke a mapping to Katz-Lebowitz-Spohn model to determine an exact analytical form of the cluster size distribution in the limit $Q\ll 1$. In the limit of $Q\gg 1$, the cluster size distribution exhibits a universal scaling behavior (in an approximate sense), such that the distribution function can be expressed as a scaled function of $Q$, particle density, and CIL interaction strength. We characterize the phase behavior of the system in terms of contour plots of average cluster size. These measures exhibit a nonmonotonic dependence on CIL interaction strength, attractive interaction strength, and self-propulsion.

Low-density foams are of significant interest in inertial confinement fusion (ICF), with potential applications as fuel carriers, ablation layers, or as a hohlraum filling material. Despite their potential, the shock response of these materials remains poorly characterized, limiting the accuracy of hydrodynamic simulations. Here we report experimental measurements of the equation of state for $90{\text{mg/cm}}^3$ silica (${\mathrm{SiO}}_2$) aerogel foam under laser-driven shock compression, conducted at the GEKKO XII laser facility. Shock pressures between 50 and 160 GPa were achieved, and the corresponding states were determined using standard impedance-matching techniques with a quartz reference material. Initial measurements appeared to underestimate the foam shock velocity relative to predictions by the Quotidian Equation of State (QEOS) model. Experimental diagnostics indicated the presence of a vacuum gap between the reference material and the foam. The vacuum gaps were characterized, and one-dimensional radiation-hydrodynamic simulations were conducted to estimate their impact on the measured shock velocity. After applying simulation-based corrections, the experimental Hugoniot aligns closely with QEOS predictions, supporting the model's applicability to low-density foams.

High-accuracy modeling of laser-plasma interactions at high intensity requires precise knowledge of the laser field, including its asymmetries. However, the experimental characterization of such lasers is often limited to fluence measurements in transverse planes, which creates the need for a reliable field reconstruction method. In this work, we present an implementation of the Gerchberg-Saxton algorithm with mode decomposition (GSA-MD) using the Laguerre-Gauss mode basis in cylindrical geometry. We show that, for lasers with a high degree of cylindrical symmetry, this approach can be more efficient than its Cartesian counterpart. Additionally, we show how the reconstructed laser field can be more directly used as input in particle-in-cell simulations using the azimuthal Fourier decomposition through simple analytical expressions. Both versions of the GSA-MD and examples of inputs integrating the reconstructed laser in particle-in-cell simulations are made available.

A simple and broadly applicable a posteriori stochastic resetting protocol that enables the exploration of resetting dynamics without physically performing resets during experiments is proposed. To demonstrate the utility and applicability of the method, we apply it to an autonomous Hexbug robot navigating within a confined rectangular arena with reflecting like boundaries and a single absorbing target (hole). In each trial, the Hexbug starts from a fixed initial position and is allowed to move freely until it reaches the target, marking the first passage time (FPT). This process is repeated for 201 independent realizations to build an empirical distribution of FPTs. Instead of applying resets during the experiments, we implement stochastic resetting a posteriori by applying exponentially distributed resets (i.e., Poissonian resetting) to the recorded FPTs. This strategy allows us to compute the mean first passage time (MFPT) at any reset rate without perturbing the experiments. Moreover, this method generates a new set of FPTs every time the algorithm is implemented. This enables one to render a theoretically infinite amount of data from a small experimental dataset. Our results reveal a clear nonmonotonic dependence of the MFPT on the reset rate, with a distinct minimum, a hallmark signature of optimal resetting. Furthermore, the data generated by the algorithm also obey Reuveni universality. This strategy can be indispensable in setups in which physical resetting is not feasible. It circumvents the challenges of repeated experimental resets, offering an accessible platform to investigate optimization strategies and/or first passage phenomena.

A floating Leidenfrost droplet exhibits curvature inversion of its underside, due to the balance of vapor pressure and surface tension. Using interferometric imaging, we find different behavior for a levitated hydrogel sphere. Curvature inversion is observed briefly just after deposition, but quickly gives way to a steady state with no inversion. We show the essential role of vaporization in shaping the underbelly of the hydrogel, where changes due to direct mass loss are more significant than the balance of vapor pressure and elastic forces.

We investigate the critical phenomena of the asymmetric quantum Rabi model (AQRM), where parity symmetry is broken by an external bias. Through both analytical and numerical calculations, we identify second-order and first-order phase transitions, with the latter absent in the standard quantum Rabi model. We derive an analytical two-variable scaling function that describes the finite-frequency scaling behavior of the AQRM, and numerical results confirm this framework. The introduction of bias leads to additional critical exponents, including a bias-related critical exponent ${\nu }_h$ and susceptibility exponent $\gamma$. Moreover, we demonstrate that critical scaling persists even below the conventional critical coupling, indicating the emergence of field-induced quantum criticality. These findings establish a robust theoretical framework for understanding universal quantum criticality in light-matter systems.

Shortcuts to adiabaticity (STA) were first developed in quantum dynamics to realize rapid transformations with suppressed residual excitations. Here we show how the same idea can be implemented in classical nonlinear dissipative Lagrangian systems. Using a coupled $r\text{−}\theta$ manipulator as an illustrative model, we perform inverse engineering on the Euler-Lagrange equations with Rayleigh dissipation by prescribing end-point-stationary trajectories, obtaining the corresponding force and torque profiles and quantifying how geometric coupling amplifies errors and residual energy. We further compare smooth STA protocols with actuator-bounded time-optimal solutions and with proportional-integral-derivative tracking, which highlights a trade-off among smoothness, speed, and robustness. Finally, we introduce a single-shot correction based on one midcourse measurement to reduce the effect of early deviations while keeping the inputs nearly smooth. These results provide a practical bridge between quantum STA concepts and their classical counterparts.