Liquid coating films on solid surfaces exist widely in a plethora of industrial processes. In this study, we focus on the falling of a liquid film on the side surface of a vertical cylinder, where the surface is viewed as slippery, such as a liquid-infused surface. The evolution profiles and flow instability of the advancing contact line are comprehensively analyzed. The governing equation of the thin film flow is derived according to the lubrication model, and the traveling-wave solutions are numerically obtained. The results show that the wave speed increases with the increase of a larger slippery length. A linear stability analysis (LSA) is carried out to verify the traveling solutions and time responses. Although previous studies tell us that the wall slippage always promotes the surface flow instability of the thin film flow, the linear stability analysis, numerical simulations, and nonlinear traveling-wave solutions in the current study present a different conclusion. The analysis show that for a thin film flow with a dynamic contact line the wall slippage in different directions plays much more complex roles. The streamwise slippery effect always impedes the instability of the flow and suppresses the wave height of traveling wave, while the transverse slippery effect has a dual effect on the surface instability. The transverse slippery effect significantly improves the instability while the wave number of the perturbation is small, and simultaneously it reduces the cutoff wave number. The transverse slippery effect will change its role if the wave number of the perturbation exceeds a critical value, which can stabilize the contact line.

We studied parallel propagating electromagnetic waves in a magnetized quantum electron plasma of finite temperature, as an extension of our previous study on a zero temperature plasma. We obtained simple analytic dispersion relations in the long wavelength limit that included the thermal effect as correction terms to the zero temperature results. As in the zero temperature case, the lower branch of the R wave showed significant damping and became ill-defined at short wavelengths. Quantum effects seemed to give qualitative changes, such as the appearance of anomalous dispersion regions, to the classical dispersion relations when $v_F/v_{th}\le 0.2$ for a set of exemplary parameters of $v_F=0.1c$ and ${\omega }_{ce}/{\omega }_{pe}=0.05$ was used. We also noted that introduction of the Planck constant in the quantum Vlasov equation changed the shape of the anomalous dispersion region qualitatively, by forming a normal dispersion region in the middle of the original single broad anomalous dispersion region.

In the standard $q$-voter model, a given agent can change its opinion only if there is a full consensus of the opposite opinion within a group of influence of size $q$. A more realistic extension is the threshold $q$ voter, where a minimal agreement (at least $0<q_0\le q$ opposite opinions) is sufficient to flip the central agent's opinion, including also the possibility of independent (nonconformist) choices. Variants of this model including nonconformist behavior have been previously studied in fully connected networks (mean-field limit). Here we investigate its dynamics in random networks. Particularly, while in the mean-field case it is irrelevant whether repetitions in the influence group are allowed, we show that this is not the case in networks, and we study the impact of both cases, with or without repetition. Furthermore, the results of computer simulations are compared with the predictions of the pair approximation derived for uncorrelated networks of arbitrary degree distributions.

An engine producing a finite power at the ideal (Carnot) efficiency is a dream engine which is not prohibited by the thermodynamic second law. Some years ago, a two-terminal heat engine with asymmetric Onsager coefficients in the linear response regime was suggested by Benenti et al. [Phys. Rev. Lett. 106, 230602 (2011)], as a prototypical system to make such a dream come true with nondivergent system parameter values. However, such a system has never been realized, in spite of many trials. Here, we introduce an exactly solvable two-terminal Brownian heat engine with the asymmetric Onsager coefficients in the presence of a Lorenz (magnetic) force. Nevertheless, we show that the dream engine regime cannot be accessible, even with the asymmetric Onsager coefficients, due to an instability keeping the engine from reaching its steady state. This is consistent with recent tradeoff relations between the engine power and efficiency, where the (cyclic) steady-state condition is implicitly presumed. We conclude that the inaccessibility to the dream engine originates from the steady-state constraint on the engine.

Quantifying synchronization phenomena based on the timing of events has recently attracted a great deal of interest in various disciplines such as neuroscience or climatology. A multitude of similarity measures has been proposed for this purpose, including event synchronization (ES) and event coincidence analysis (ECA) as two widely applicable examples. While ES defines synchrony in a data-adaptive local way that does not distinguish between different timescales, ECA requires selecting a specific scale for analysis. In this paper, we use slightly modified versions of both ES and ECA that address previous issues with respect to proper normalization and boundary treatment, which are particularly relevant for short time series with low temporal resolution. By numerically studying threshold crossing events in coupled autoregressive processes, we identify a practical limitation of ES when attempting to study synchrony between serially dependent event sequences exhibiting event clustering in time. Practical implications of this observation are demonstrated for the case of functional network representations of climate extremes based on both ES and ECA, while no marked differences between both measures are observed for the case of epileptic electroencephalogram data. Our findings suggest that careful event detection along with diligent preprocessing is recommended when applying ES while less crucial for ECA. Despite the lack of a general modus operandi for both event definition and detection of synchronization, we suggest ECA as a widely robust method, especially for time-resolved synchronization analyses of event time series from various disciplines.

Filaments of the cellular protein actin can form bundles, which can conduct ionic currents as well as mechanical and voltage solitons. These inherent properties can be utilized to generate computing circuits solely based on self-assembled actin bundle structures. Starting with experimentally observed networks of actin bundles, we model their network structure in terms of edges and nodes. We compute and discuss the main electrical parameters, considering the bundles as electrical wires with either low or high filament densities. A set of equations describing the network is solved with several initial conditions. Input voltages, which can be considered as information bits, are applied in a set of points and output voltages are computed in another set of positions. We consider both an idealized situation, where pointlike electrodes can be inserted in any points of the bundles and a more realistic case, where electrodes lay on a surface and have typical dimensions available in the industry. We find that in both cases such a system can implement the main logical gates and a finite state machine.

Information storage and processing in the brain largely relies on the neural population coding principle. In this framework, information is reflected in the population firing rate that reflects asynchronous irregular spiking of its constituent neurons. Periodic modulations of neural activity can lead to neural activity oscillations. Data indicate that such oscillations are ubiquitous in brain activity and are modulated, in frequency and amplitude, in a functionally meaningful manner. The relationship between oscillations and the population rate code remains an open issue. While ample works show how changes in the mean firing rate may alter neural oscillations, the reverse connection is unclear. One notable possibility is that oscillatory activity impinging on a neural population modulates its mean firing rate, thereby impacting information processing. We suggest that such modulation requires nonlinearities and propose nonlinear excitatory coupling via slow N-methyl-D-aspartate (NMDA) receptors as the prevalent mechanism. The aim of our paper is to theoretically explore to what extent the NMDA-related mechanism could account for oscillation-induced mean firing rate changes. We consider a mean-field model of a neural circuit containing an excitatory and an inhibitory population with linear transfer functions. Along with NMDA excitation, the model included fast recurrent excitatory and inhibitory connectivity. To explicitly study the effects of impinging oscillation on the rate dynamics, we subjected the circuit to a sinusoidal input signal imitating an input from distant brain regions or from a larger network into which the circuit is embedded. Using time-scale separation and time-averaging techniques, we developed a geometric method to determine the oscillation-induced mean firing rate shifts and validated it by numeric simulations of the model. Our results indicate that a large-amplitude stable firing rate shift requires nonlinear NMDA synapses on both the excitatory and the inhibitory populations. Our results delineate specific neural synaptic properties that enable neural oscillations to act as flexible modulators of the population rate code.

Recently it was shown [V. N. Novikov and A. P. Sokolov, Phys. Rev. E 92, 062304 (2015)] that the second derivative with respect to inverse temperature of the structural relaxation time in some supercooled molecular liquids has a sharp maximum. It marks the point at which the apparent activation energy begins to saturate with decreasing temperature. The elastic model of glass-forming liquids expresses the temperature dependence of the structural relaxation time through that of the shear modulus. In this paper, we test whether this model is able to predict the maximum of the second derivative. We confirm its presence in the elastic model by analyzing the temperature dependence of the Brillouin light scattering in salol. This is a very subtle feature of the temperature dependence, which is greatly enhanced when taking derivatives. Its presence in the Brillouin data provides strong support to the elastic model of glass-forming liquids.

We present results of numerical and experimental investigations of thermal convection induced by internal heating in both a nonrotating and a rotating spherical gap filled with dielectric fluid. The inner and outer surfaces are maintained at constant temperatures $T_{\text{in}}$ and $T_{\text{out}}$, respectively. A radial force field is produced due to the dielectrophoretic effect. The buoyancy force in the Navier-Stokes equation and the source term in the energy equation depend on the imposed oscillating electric field according to $V_{\text{rms}}^2{r}^{-5}$ and $V_{\text{rms}}^2{r}^{-4}$, respectively, where $V_{\text{rms}}$ is the root mean squared value of the voltage between spherical surfaces and $r$ is the radial distance. Beginning with the nonrotating case, we perform linear instability analysis in the case of purely internal heating, i.e., both surfaces are maintained at the same temperature $\mathrm{\Delta }T=T_{\text{in}}-T_{\text{out}}=0$. Next, we consider a situation in which there is not only internal heating but also a temperature difference $\mathrm{\Delta }T>0$. While the spherical gap rotated, the occurring two-dimensional steady basic flow was calculated numerically. The stability of the basic flow was investigated by means of linear instability theory. The critical Rayleigh numbers and the critical azimuthal wave numbers are presented in dependence on the Taylor number. We calculate supercritical three-dimensional flows for comparison with experimentally obtained patterns in frames of the GeoFlow experiment on the International Space Station.

Droplets interacting with deformable moving boundaries is ubiquitous. The flexible boundaries may dramatically affect the hydrodynamic behavior of droplets. A numerical method for simulating droplet impact on flexible substrates is developed. The effect of flexibility is investigated. To reduce the contact time and increase the remaining upward momentum in the flexible cases, the Weber number should be larger than a critical value. Moreover, the ratio of the natural frequency of the plate to that of the droplet $F_r$ should approximately equal to the reciprocal of the contact time of droplets impact on the rigid surfaces $\left(t_{\text{ctr}}\right)$ at the same We, e.g., $F_r\approx 1/t_{\text{ctr}}$. Only under this circumstance would the kinetic energy convert into the surface energy of the droplet and the elastic energy of the plate simultaneously, and vice versa. Moreover, based on a double spring model, we proposed scaling laws for the maximal deflection of the plate and spreading diameter of the drop. Finally, the droplet impact under different wettability is qualitatively studied. We found that the flexibility may contribute to the droplet bouncing at a smaller contact angle.

Interactions of two-plasmon decay (TPD) and side-stimulated Raman scattering (SSRS) were studied using three-dimensional particle-in-cell simulations under inertial-confinement-fusion-relevant conditions for linearly and circularly polarized lasers. In the linear stage, SSRS took place under $n_e=0.235n_{\mathrm{c}}$ and TPD dominated near the quarter-critical density surface and their growth rates agreed with theory. In the nonlinear stage, SSRS reduced TPD through pump depletion. Hot electrons were found to be first accelerated by SSRS plasma waves and then by TPD plasma waves through a cogeneration mechanism. Compared to the linearly polarized case with the same laser intensity, both SSRS and TPD were reduced due to the lower laser amplitude in the circularly polarized case. As a result, a 30% decrease in hot electron flux was observed.

Compressing and charge neutralization of the heavy-ion beam in an inertial fusion reactor are considered as pivotal processes for increasing the energy gain. For this purpose, the ion beam is usually transported through the plasma channel so that multispecies Weibel instability can grow in this system. Recently, a small solenoidal magnetic field has been added to this method to have additional control of these processes. On the other hand, charge and current may not be completely neutralized in this transport; as a result, the fractional charge and current neutralization can affect the growth rate of this instability. In this work, the dispersion equation has been obtained in cylindrical, cold, magnetized, non-neutral plasma in the macroscopic fluid frame. Numerical results show that if the electron cyclotron frequency of the background plasma normalized by plasma frequency is larger than the ion beam velocity normalized by the speed of light, as well as the current fraction being smaller than 1/2, the eigenmodes of multispecies Weibel instability can be completely stabilized. Moreover, these results are valid when the percent deviation from the charge-neutral state is positive. In the negative regime of percent deviation, the instability increases drastically so that the system can be completely unstable only for more than 2%. Therefore, selecting the radius of the ion beam smaller than the electron skin depth of the plasma and the beam pulse duration much longer than the plasma oscillation time are proposed for quenching of this instability.

A three-dimensional (3D) lattice Boltzmann flux solver is presented in this work for simulation of fluid-solid conjugate heat transfer problems with a curved boundary. In this scheme, the macroscopic governing equations for mass, momentum, and energy conservation are discretized by the finite-volume method, and the numerical fluxes at the cell interface are reconstructed by the local solution of lattice Boltzmann equation. For solving the 3D fluid-solid conjugate heat transfer problems, the density distribution function (D3Q15 model) is utilized to compute the numerical fluxes of continuity and momentum equations, and the total enthalpy distribution function (D3Q7 model) is introduced to calculate the numerical flux of the energy equation. The connections between the macroscopic fluxes and the local solution of the lattice Boltzmann equation are provided by the Chapman-Enskog expansion analysis. As compared with the lattice Boltzmann method, in which the time step and grid spacing are correlated, the local solution of the lattice Boltzmann equation at each cell interface used in the present scheme is independent of each other. As a result, the drawback of the tie-up between the time step and grid spacing can be effectively removed and the developed method applies very well to nonuniform mesh and curved boundaries. To validate the performance of the developed method, the steady and unsteady natural convection in a finned 3D cavity and in a finned 3D annulus are simulated. Numerical results showed that the present scheme can effectively solve the 3D conjugate heat transfer problems with a curved boundary.

We study theoretically and observe experimentally the evolution of solitary surface gravity water wavepackets propagating in homogeneous and time-dependent flow created by a computer-controlled water pump, resulting in an effective linear potential. Unlike a potential free soliton, in this case the wavepacket envelope accelerates, while its phase is proportional to the cubic power of the position in the water tank. For increased wave steepness, we observe the emergence of asymmetry in the envelope, and hence it no longer retains its soliton shape. Furthermore, we study a case of ballistic dynamics of solitary surface gravity water wavepackets with initial nonzero momentum and demonstrate that their trajectory is similar to that of a projectile pulled by gravity. Nevertheless, their envelope shape is preserved during propagation, and the envelope phase is identical to that measured without an initial momentum.

With the recent realization of kilotesla quasistatic magnetic fields, the interaction of a laser with magnetized solids enters an unexplored new regime. In particular, a circularly polarized (CP) laser pulse may propagate in a highly magnetized plasma of any high density without encountering cutoff reflection in the whistler mode. With this, we propose a scheme for producing uniform warm dense matter (WDM) by direct laser heating with a CP laser irradiating onto the target along the magnetic field. It is shown by particle-in-cell simulations, which include advanced ionization dynamics and collision dynamics, moderately intense right-hand CP laser light at ${10}^{15}\mathrm{W}/{\mathrm{cm}}^2$ can propagate in solid aluminum and heat it efficiently to the 100 eV level within picoseconds. By using two laser pulses irradiating from two sides of a thin solid target, uniform heating to WDM can be achieved. This provides a controllable way to create WDM at different temperatures.

We study heterogeneous traffic dynamics by introducing quenched disorders in all the parameters of Newell's car-following model. Specifically, we consider randomness in the free-flow speed, the jam density, and the backward wave speed. The quenched disorders are modeled using beta distributions. It is observed that, at low densities, the average platoon size and the average speed of vehicles evolve as power laws in time as derived by Ben-Naim, Krapivsky, and Redner. No power-law behavior has been observed in the time evolution of the second moment of density and density distribution function, indicating no equivalence between the present system and the sticky gas. As opposed to a totally asymmetric simple exclusion process, we found no power-law behavior in the stationary gap distribution and the transition from the platoon forming phase to the laminar phase coincides with the free flow to congestion transition and is always of first order, independent of the quenched disorder in the free-flow speed. Using mean-field theory, we derived the gap distribution of vehicles and showed that the phase transition is always of first order, independent of the quenched disorder in the free-flow speed corroborating the simulation results. We also showed that the transition density is the reciprocal of the average gap of vehicles in the platoon in the thermodynamic limit.

We study an arbitrary nonequilibrium dynamics of a quantum bipartite system coupled to a reservoir. For its characterization, we present a fluctuation theorem (FT) that explicitly addresses the quantum correlation of subsystems during the thermodynamic evolution. To our aim, we designate the local and the global states altogether in the time-forward and the time-reversed transition probabilities. In view of the two-point measurement scheme, only the global states are subject to measurements whereas the local states are used only as an augmented information on the composite system. We specifically derive a FT in such a form that relates the entropy production of local systems in the time-forward transition to the change of quantum correlation in the time-reversed transition. This also leads to a useful thermodynamic inequality and we illustrate its advantage by an example of an isothermal process on Werner states.

We show that finite system-reservoir coupling imposes a distinct quantum limit on the performance of a nonequilibrium quantum heat engine. Even in the absence of quantum friction along the isentropic strokes, finite system-reservoir coupling induces correlations that result in the generation of coherence between the energy eigenstates of the working system. This coherence acts to hamper the engine's power output, as well as the efficiency with which it can convert heat into useful work, and cannot be captured by a standard Born-Markov analysis of the system-reservoir interactions.

We consider a random two-phase process which we call a reset-return one. The particle starts its motion at the origin. The first, displacement, phase corresponds to a stochastic motion of a particle and is finished at a resetting event. The second, return, phase corresponds to the particle's motion toward the origin from the position it attained at the end of the displacement phase. This motion toward the origin takes place according to a given equation of motion. The whole process is a renewal one. We provide general expressions for the stationary probability density function of the particle's position and for the mean hitting time in one dimension. We perform explicit analysis for the Brownian motion during the displacement phase and three different types of the return motion: return at a constant speed, return at a constant acceleration with zero initial speed, and return under the action of a harmonic force. We assume that the waiting times for resetting events follow an exponential distribution or that resetting takes place after a fixed waiting period. For the first two types of return motion and the exponential resetting, the stationary probability density function of the particle's position is invariant under return speed (acceleration), while no such invariance is found for deterministic resetting, and for exponential resetting with return under the action of the harmonic force. We discuss necessary conditions for such invariance of the stationary PDF of the positions with respect to the properties of the return process, and we demonstrate some additional examples when this invariance does or does not take place.