This is an investigation of collective motion of fish swimming in the presence of obstacles. The authors analyzed trajectories of zebrafish swimming in a tank with varying densities of pillars. As the density of pillars increased, the experiments exhibited a transition from mostly aligned fish, to fish oriented along the axes of the pillar lattice. The authors considered the relative orientations of two fish and developed a stochastic model, which qualitatively reproduced the experimental data.

A model for coordinated motion of cilia is examined in this work. In this model, wave dynamics of cilia are represented by motions of microspheres elastically bound to circular orbits that are inclined with respect to a no-slip surface. Parameters are explored with analytical studies and simulations. The authors demonstrate traveling waves whose dynamics and direction may be tuned by the elasticity.

Cell adhesion proteins bind the cell membrane to its environment and, at the same time, aggregate into stable clusters. In this paper, the proteins’ sensing of the cell membrane curvature is investigated as a mechanism to stabilize these clusters, predicting the emergence of diverse spatial patterns.

When injected into a plasma, a proton bunch triggers oscillatory phenomena which can lead to different instability regimes. The authors present experimental evidence of the appearance of the oblique two-stream instability, generating filamentation in the bunch-plasma system, in accordance with theoretical and numerical predictions.

In stochastic thermodynamics, entropy production can be estimated for physical systems with a Markovian description. For realistic situations the full Markovian description may not be accessible, and this paper uses an information-theoretic bound to establish an effective approach for such a scenario.

Scarred functions serve as a basis to calculate eigenstates in quantum chaotic systems, and are useful to study the correspondence between classical and quantum systems in the presence of chaos. In this paper, the authors propose a method, based on a machine learning algorithm, to calculate the scarred functions and corresponding eigenstates of the coupled quartic oscillator, and they report that the algorithm increases accuracy and reduces the execution time.

The distribution of vegetation clusters in a tropical rainforest shows evidence of scale-invariance, suggesting a system close to a critical state. This observation could help to diagnose the health of rainforests and other ecosystems in the face of environmental change.

Odd viscoelastic materials obey fewer symmetries than traditional materials, and as a consequence exhibit unusual features. This paper reports an investigation into the motion of a probe particle in an odd viscoelastic fluid, as a means to explore the consequences of the broken symmetries.

The authors investigate an Ising model of an electorate in which voters are influenced by opinion polls, as well as by their neighbors. The voters hold one of two opposite opinions. The work shows that opinion polls tend to bring about polarized societies, with spatially separated groups having different opinions. The authors discuss factors that influence the voters and note that electorates with greater than a million voters tend to have very close elections.

According to quantum electrodynamics, in very strong electromagnetic fields electron–positron pairs can be created, and with a high density of pairs an electron-positron plasma can form. In this paper, the authors simulate this process for a relativistic electron beam colliding with an intense laser pulse, and identify observations that could be used as diagnostics in future experiments.

Nodes with high connectivity, also called hubs, play a critical role in determining the structural and functional properties of networked systems. The author develops classification methods for directed networks that provide a definition of network hubs, and demonstrates them in a range of example applications.

A soliton gas, a large random ensemble of solitons, does not reach thermodynamic equilibrium because there are infinitely many conserved quantities. The authors report water wave experiments with two interacting jets of soliton gases, and find good quantitative agreement with the predictions of spectral kinetic theory.

In first-passage percolation one is interested in the region that can be reached from an origin within a given time. The authors show that on a square lattice with disorder, the boundary of this region behaves as a fluctuating interface in the Kardar-Parisi-Zhang universality class.

An exclusion process on a ring is studied in this paper, where the presence of a defect particle immersed in a bath of normal particles leads to phase transitions between localized and shock phases. The authors use the functional Bethe ansatz to analytically compute the mean current and, for the first time, the diffusion constant, and report good agreement with Monte Carlo simulations.

The formation and evolution of opinion in social networks is a topic receiving increasing attention. By employing the multistate voter model on a network, the authors derive a general method to compute the probability of disagreement between a pair of agents in the model, which is applicable to any directed, weighted network.

This article presents a mean-field method to determine the transfer function that describes the behavior of spiking neurons in a network. The authors extend a Fokker-Planck approach to the case of conductance-based integrate-and-fire neurons with various sources of noise, and find good agreement with data from simulations.

This work provides a framework for determining the buckling kinetics of membranes under compressive stress. The authors investigate a model of graphene with molecular dynamics simulations and find three regimes: I. Buckling time increases with temperature, II. Buckling time decreases with temperature, and III. Buckling time is independent of temperature.

The target gain greater than unity achieved in a recent fusion experiment was made possible by using additional laser energy at fixed power and controlling sources of degradation. This resulted in increased compression of the fuel and a high fusion yield corresponding to a novel physical regime. This paper describes the experimental evidence for these critical aspects and new observables.

In 2022, a National Ignition Facility controlled-fusion experiment reached a target gain $G>1$, with the fusion energy produced exceeding the amount of laser energy required to drive the target. This result was obtained thanks to careful design described in this paper. This design has been shown to be robust and allows a better understanding of the physical conditions necessary to reach ignition.

This work describes Richtmyer-Meshkov experiments to measure the strain-rate sensitivity of copper in the high-rate regime. The authors extend the maximum strain rate by more than two orders of magnitude. At higher strain rates, their strength estimates show a steep increase that agrees well with extrapolations from some of the data in the literature. The work contributes to the important effort to understand how impacts can affect the strength of solids.

Time-delayed relay systems, systems with switches transmitting a signal with a time delay, can be found in the biological world as well as in mechanical or electrical systems. In this paper, the authors model them using second-order linear delay differential equations and analyze their solutions, finding that, for the same values of the parameters, many stable solutions coexist.

A new technique could allow researchers to distinguish the swimming motion of a species of microorganisms without the need to track individuals within a population.

The limitations that thermodynamics imposes on quantum information theory are investigated in this paper, which examines an ideal gas with an internal quantum degree of freedom undergoing a cycle. By considering a demon capable of distinguishing two quantum states, the author shows that the ability to distinguish quantum states is bounded by the second law of thermodynamics.

Usually, gravity causes liquid to drain out of a foam vertically, but simulations have predicted that if the foam is sheared, the drainage will be anisotropic. This paper describes an experimental verification of that prediction by neutron radiography, which shows that the vertical drainage flow is indeed deflected horizontally.

The rate at which a raft made of ants is stretched determines its properties because the ants take time to fix holes.