The Widom line, initially identified as a crossover line between liquidlike and gaslike behavior in water and supercritical fluids, separates these two types of behavior. Here, we show that an analogous line arises in spin models on scale-free networks as a consequence of degree heterogeneity, which we analyze using the annealed network approximation. For the Ashkin-Teller and invisible Potts models, the Widom line exists within a finite range of the degree exponent. It separates two distinct ordered regimes—distributed spin alignment and hub-dominant alignment—while also giving rise to a supercritical-like state where the two alignments become indistinguishable. These results demonstrate that degree heterogeneity alone can generate mesoscopic crossovers beyond conventional phase-transition theory, opening new directions for understanding and controlling collective dynamics in complex networks.

We investigate vapor-liquid phase separation of an active near-critical Lennard-Jones fluid confined within a cylindrical pore using molecular dynamics simulations. Activity is introduced via Vicsek-type alignment interactions, enabling a systematic study of how self-propulsion modifies domain morphology and coarsening kinetics under quasi-one-dimensional confinement. In the passive limit, the system undergoes early-time spinodal decomposition (diffusive growth characterized by the Lifshitz-Slyozov exponent $\alpha =1/3$), followed by the formation of periodically modulated, pluglike liquid domains along the pore axis. At late times, coarsening becomes kinetically arrested, and the system remains trapped in a metastable striped state. Introducing activity destabilizes this arrested morphology by enhancing collective domain transport, leading to frequent domain mergers and complete phase separation at sufficiently high activity. The late-stage coarsening then exhibits a crossover to faster, ballistic growth with an effective exponent $\alpha =2/3$, consistent with a cluster-coalescence mechanism. Analysis of two-point correlation functions and structure factors confirms dynamic scaling across all activity regimes. Our results demonstrate that alignment-induced activity can overcome confinement-driven kinetic arrest, providing insight into phase separation in confined active fluids. The relevant growth laws are analyzed and interpreted using appropriate theoretical frameworks.

The capstan equation predicts that the tension along a flexible band wrapped around a cylinder decreases exponentially with the number of turns due to solid friction, preventing relative slipping. However, we demonstrate in a controlled experiment that a loosely wound roll can in fact be tightened efficiently. The key lies in the interplay between solid friction and interfacial compressibility due to surface roughness: a circular slipping zone nucleates at the fixed core and propagates outwards through a stick-slip sequence, producing successive tightening waves. Each wave slightly reduces the interlayer spacing while conserving length, so that slack accumulates and the outer part rewinds onto the inner layers. We quantify the front kinematics and the force build up, and demonstrate that the process is governed by the compression of interfacial roughness, which depends logarithmically on the pressure.

In many systems with chiral symmetry, including dry active matter around circular obstacles, vortices exhibit no intrinsic preference for clockwise or counterclockwise rotation. Here, we investigate the rotation of an active vortex around a circular obstacle in a nonaligning dry active-matter system with $M$ half-circles distributed around the central disk. We define a dimensionless control parameter as the ratio between the mean angular velocity of the controlled vortex ($M>0$) and the root-mean-square angular velocity of the isolated vortex ($M=0$), when there is no half-circular obstacle distributed around the circular obstacle. Two rotational regimes emerge from the obstacle geometry: clockwise rotation when the flat sides of the half-circles face the vortex and counterclockwise rotation when the curved sides face the vortex. We further show that this geometric control induces a nonmonotonic dependence of vortex stability (maintenance and rotation direction) on the distance between the half-circles from the circular obstacle, demonstrating how geometric constraints can be exploited to control spontaneous collective motion in nonaligning dry active-matter systems.

We employ the derivative expansion of the nonperturbative renormalization group to address the phenomenon of anisotropic scale invariance and the associated functional fixed points, also known as Lifshitz points, in systems characterized by a scalar order parameter. We demonstrate the existence of the Lifshitz fixed point featuring a nonclassical value of the anisotropy exponent $\theta <1/2$ and provide estimates for values of a set of critical exponents in the physically most relevant case of the three-dimensional uniaxial Lifshitz point $(d,m)=(3,1)$, $m$ denoting the anisotropy index. We compare our predictions with existing estimates from perturbative expansions around dimensionality $d=4+\frac{1}{2}$ as well as those from the $1/N$ expansion.

Economic inequality emerges from the interplay between regional growth-rate differences and the interaction network that couples regions. We propose a minimal income-dynamics model, where heterogeneity is governed by growth-rate assortativity $\mathcal{A}$ and regional concentration $\mathcal{R}$, allowing us to quantify the spatiotemporal patterns of empirically observed log-income distributions. To systematically analyze these patterns, we derive closed-form approximations for the Hellinger distance and the Gini index in limiting configurations. Our findings highlight the spatial segregation of growth rates as a key driver of economic class division and demonstrate how small-world shortcuts in the underlying network can disrupt this segregation. Finally, our framework provides a robust explanation for the bimodality and strong regional correlations found in global income distributions.

The Nuclear Pore Complex (NPC) is an ancestral feature of eukaryotic cells, essential for the exchange of material and information between cytoplasm and nucleoplasm. While typical eukaryotic cells harbor thousands of NPCs covering the nuclear surface, a quantitative characterization of their spatial distribution remains lacking. Taking advantage of super-resolution microscopy, we imaged and segmented individual NPCs in myoblast cells to reconstruct the nuclear surface. Our spatial statistics analysis of NPCs on the nuclear surface reveals the existence of a 400 nm repulsion length between NPCs, likely reflecting the mesh size of the underlying lamin network. Furthermore, we identify three key correlates of NPC density: (1) myoblast actin fibers, which can indent the nucleus, correlate with a decrease in NPC surface density, contrary to what was reported in previous studies; (2) regions of the nuclear envelope near large heterochromatin domains exhibit reduced NPC surface density; and. (3) there is a nonmonotonous relationship between NPC density and the nuclear envelope curvature. This last observation is consistent with the existence of NPC-preferred curvature suggesting curvature sensing properties. In conclusion, this study provides insights into the spatial distribution of NPCs, shedding light on potentially previously unknown determinants of NPC spatial distribution.

We introduce a simple symmetric Hamiltonian map that models the magnetic field lines of a double-null diverted tokamak and compare its behavior with the corresponding symmetric single-null map. The phase-space structure of both models is characterized using the finite-time Lyapunov exponent and the escape time of magnetic field line trajectories. For increasing perturbation strength, the area of the chaotic layer grows in both systems, but their escape fractions exhibit distinct oscillatory behaviors. To understand the origin of these oscillations, we analyze the mean transient measure and trace the invariant manifolds of hyperbolic fixed points. The results reveal that variations in the escape fraction arise from changes in the formation of escape channels and from the presence of stickiness near secondary island chains.

Based on the data recorded during the Parker Solar Probe mission, it can be suggested that there is no balance between kinetic and magnetic energy in the vicinity of the Sun. The spectra collected at different radial distances show an energy transfer from one component to another, followed by a change in inertial range slope and large-scale break shifted towards lower wave numbers. Using the shell (cascade) modeling approach, we attempt to explain and understand this observed spectra transformation, considering a free-decay turbulence process and modeling a simple transition to a quasistationary equilibrium between the magnetic and kinetic energies. Varying the parameters of turbulence mirror asymmetry (helicity), we numerically simulate changes in spectral indexes, large-scale shift position, and inertial range transformations, comparing our model results with spacecraft observations of solar wind turbulence. We present and discuss the chaotic nature of the spectral magnetic helicity distributions, as well as the fact that helicity can accumulate at large scales. The applicability of a simple magnetohydrodynamics shell model to repeat the key features of solar wind turbulence dynamics offers wide possibilities for its further use.

A wide variety of spectroscopic methods are used for the diagnostics of laser-produced plasma. One particularly powerful diagnostic is high-resolution emission line spectroscopy, in conjunction with atomic calculations and radiation hydrodynamic simulations. In this work, we present line-resolved spectra of L-shell molybdenum $(Z=42)$ plasma produced by high-energy laser pulses of ∼200–400 J at a wavelength of 351 nm, with durations of 1–3 ns. The experiments were conducted at the National Laser Facility, Soreq, Israel. Time-integrated spectra were recorded in the range of 2 to 4.1 keV with a high-resolution crystal spectrometer $(E/\mathrm{\Delta }E>400)$. Lines of Al-like ${\mathrm{Mo}}^{+29}$ to F-like ${\mathrm{Mo}}^{+33}$ were identified, although the spectrum is dominated by the intense Ne-like ${\mathrm{Mo}}^{+32}$ lines. Collisional-radiative calculations using the HULLAC and nomad codes are in good agreement with the experimental results, providing estimates of an electron density of $n_{\mathrm{e}}=0.6-3\times {10}^{21}\mathrm{c}{\mathrm{m}}^{-3}$ and an electron temperature of $k{T}_{\mathrm{e}}=1.1-1.3\mathrm{keV}$ originating from the coronal region of the plasma.

We introduce DeepFHT, a survival-analysis framework that couples deep neural networks with first hitting time (FHT) distributions from stochastic process theory. Time to event is represented as the first passage of a latent diffusion process to an absorbing boundary. A neural network maps input variables to physically meaningful parameters including initial condition, drift, and diffusion, within a chosen FHT process such as Brownian motion, both with drift and driftless. This yields closed-form survival and hazard functions and captures time-varying risk without assuming proportional hazards. We compare DeepFHT with Cox regression and DeepHit using synthetic and real-world datasets. The method achieves predictive accuracy on par with state-of-the-art approaches, while maintaining a physics-based interpretable parametrization that elucidates the relation between input features and risk. This combination of stochastic process theory and deep learning provides a principled avenue for modeling survival phenomena in complex systems.

Fluids composed of polarizable particles exhibit tunable structural and functional properties when subjected to external electric fields, as the particles tend to reorient and align along the field direction. This field-induced anisotropy leads to pronounced changes in macroscopic properties, rendering these systems highly relevant for applications in nanotechnology. Understanding the dynamics of their response to external fields is crucial for designing responsive materials with fast and controllable actuation. In this work, we employ molecular simulation to study the behavior of suspensions of polarizable rodlike particles under the action of a uniform electric field, with particular attention given to the transient dynamics associated with the switching on and off of the field. Induced dipoles are modeled by independently varying charge magnitude and field strength, yielding a variable effective polarizability. The induced dipole moment of each rod is treated as an effective, externally controlled parameter, and collective polarization effects arising from local electric fields generated by neighboring particles are not explicitly included. The system is studied in a dense regime, where interparticle interactions play a significant role and are implicitly controlled via pressure. We investigate how the characteristic response time depends on the competition between thermal motion and electric forces across a range of temperatures and field strengths. Our results reveal a rich dynamical behavior: at low to moderate field intensities, increasing the temperature significantly reduces the response time, as thermal agitation facilitates reorientation. However, beyond a critical field strength, the response time plateaus, becoming effectively temperature-independent. This saturation indicates a regime where the aligning torque from the field dominates over thermal fluctuations, setting a lower bound for how fast the system can respond. More specifically, we show that the alignment dynamics cannot be inferred from single-particle behavior alone, but emerges from a nontrivial interplay of field-induced dipolar torques, thermal fluctuations, and steric interactions at finite density, producing strongly temperature-dependent and nonlinear trends in both the nematic order parameter and response times.

We propose two algorithmic quantum Otto refrigerators (AQOR) in which the standard isochoric cooling stroke is replaced by two distinct heat-bath algorithmic cooling (HBAC) protocols based on the partner-pairing algorithm (PPA). For each protocol, we derive closed-form expressions for the target qubit's asymptotic polarization and explicitly incorporate the work performed by HBAC into the coefficient of performance (COP). We further quantify the thermodynamic cost of the HBAC stroke and Landauer's bound for both protocols. Our analytical COP curves reveal parameter regimes where the AQOR surpasses the conventional Otto refrigerator. Furthermore, we show that, by tuning the auxiliary qubit's transition frequency and adjusting external control parameters, both protocols achieve enhanced COP and extend the operational window across a wider range of bath temperature differences. Therefore, the AQORs present a tradeoff between achieving high performance in specific regimes and maintaining enhanced applicability. These results demonstrate that algorithmic cooling can be seamlessly integrated into Otto cycles to realize quantum thermal machines with improved practicality on near-term hardware.

We investigate a quasiadiabatic thermal process for preparing finite-temperature ensembles in the thermodynamic limit. The process gradually transforms a thermal ensemble of a noninteracting system into that of an interacting system of interest over a finite operation time, with the temperature controlled by parameters associated with the entropy of the initial state. We analyze this process in both nonintegrable and integrable spin chains with translational invariance. For the nonintegrable case, numerical simulations combined with a thermodynamic argument indicate that the thermal properties of local observables are accurately reproduced with a single parameter, although the operation time increases exponentially with precision. In contrast, for the integrable transverse-field Ising model, we analytically show that an extensive number of parameters tied to local conserved quantities is generally necessary, and the performance is affected by the presence of a quantum phase transition. These results clarify the potential and limitations of the quasiadiabatic thermal process for an ensemble preparation and highlight the role of integrability in determining its efficiency.

Nonequilibrium steady states are investigated in a two-dimensional billiard table, called the Lorentz circuit, consisting of two circular urns connected by two rectangular strips: an active channel, where a feedback mechanism operates, and a passive finite-size Lorentz channel, which is a finite network of Sinai billiards, i.e., a specific environment populated with an array of circular scatterers of fixed radius. We show that, in the finite-horizon regime, a variation of any of the four geometrical parameters of the Lorentz channel can trigger a phase transition in the circuit. Our analytic derivations identify the critical parameters governing these transitions and predict whether they are continuous or discontinuous. We find that both transition orders are realized upon changing just one of the geometrical parameters. Our analysis further highlights the validity of Fick's law in the Lorentz channel, which in our model mirrors the validity of Ohm's law in electrical circuits. All analytic results are corroborated by an extensive set of numerical simulations of the particle dynamics.

The propensity for pairs of diffusing species to pass each other within narrow channels or pores is of basic interest as a first-passage-type problem. It is also of relevance for solution-phase transport in nanoporous materials, and in particular for catalytic conversion reactions where high yield requires that product species can efficiently pass reactant species to exit the pores. We analyze a two-dimensional model with nonoverlapping circular and discorectangular species confined to a rectangular channel, and where passing is mediated by Brownian dynamics in an implicit solvent. For narrower channels where passing is still possible, the discorectangle must align with the channel to pass the circular species. Behavior of the passing propensity, $P$, can be assessed by strongly damped Langevin simulations, or within an equivalent Fokker-Planck equation (FPE) formalism. The latter corresponds to a diffusion problem in a “higher-dimensional channel” with a constriction. We assess the variation of the passing propensity, $P$, for a broad range of channel width including its scaling just above the threshold where passing is sterically blocked. Analysis of $P$ versus the rotational diffusion coefficient $D_r$ of the discorectangle reveals a significant decrease in $P$ for lower $D_r$ for moderate channel width. This prompts a direct analysis of the regime where $D_r\to 0$, for which the FPE can be reduced to a three-dimensional diffusion problem, precise analysis of which is facilitated by adaptive-mesh finite element methods. The dependence of $P$ on the aspect ratio of the discorectangle is also assessed.

We theoretically investigate the correlation functions of the phase of a light wave propagating through a turbulent medium. We use an equation for the logarithm of a wave packet envelope, which includes a second-order nonlinear term. Based on this equation, we develop a diagrammatic technique to calculate corrections to the correlation function obtained in the linear approximation. We calculate the first corrections determined by one-loop diagrams and find their asymptotic behaviors. We found that at short distances between points, the first correction to the pair correlation function of phase gradients has the same scaling behavior as the zero approximation, and at long distances, the first approximation decays faster than the zeroth one. Therefore, there is no evidence to suggest that the correction will destroy the zeroth approximation. Some nonperturbative conclusions are made using the symmetry properties of the equation. We demonstrated that small details of an image received by an optical system through the atmosphere are smeared due to turbulent fluctuations, and we estimated the maximum size of these details in terms of the Rytov dispersion, ${\sigma }_R^2$. These results allow us to conclude that the applicability condition for the perturbation theory is the smallness of the Rytov dispersion, and this condition holds uniformly over the distances between observation points. The relative correction at distances smaller than or of the order of the radius of the first Fresnel zone is of the same order as the Rytov dispersion, while at larger distances, the relative correction is much smaller than the Rytov dispersion. Therefore, if the single parameter (the Rytov dispersion) is small, the zeroth approximation can be used for the correlation function of phase gradients at any distance.

We investigate the dynamics and thermodynamics of a framework composed of interacting units in which parameters (temperatures and energies) assume distinct values due to the contact with distinct (cold and hot) thermal reservoirs. The influence of different ingredients, such as the contact between thermal baths (simultaneous versus not simultaneous contact), the coupling between them (equal or different couplings), and the topology of interactions (all-to-all versus local interactions) is investigated. Closed expressions for transition lines are obtained, expressed by a linear combination of interaction energies times reciprocal temperatures for the simultaneous thermal contact baths and deviates from it when the contact is not simultaneous. The interplay between performance and dissipation is investigated under different conditions, giving rise to a richness of operation regimes, such as the heat engine and heat pump. The relationship between thermodynamic quantities (power, efficiency, and dissipation) allows a careful choice of parameters to ensure the desirable compromise between them. Finally, the influence of different interactions energies [Ising, Potts versus Blume-Emery-Griffiths (BEG)-like] are investigated, revealing that Potts interactions, in general, present superior performances than BEG ones.

Synchronization transitions in oscillatory networks often manifest as the emergence of a periodic global mode. While perfect in the thermodynamic limit, this mode fluctuates for finite ensembles. We characterize the coherence of this mode in terms of the phase diffusion constant. In several examples, we always observed normal diffusion, but the dependence of the diffusion constant on the system size $D\sim N^{-\mu }$ depends on the nature of coupled units. For coupled chaotic systems, we found $\mu =1$, while for coupled periodic oscillators we observed, depending on the particular model, values between 2 and 2.7. These large values of the power index are attributed to the size dependence of collective chaos in the finite ensemble, which disappears in the thermodynamic limit. We also show that in the standard Kuramoto model for a symmetric set of frequencies, there is an additional transition to a symmetric chaotic state with vanishing diffusion of the global phase.