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We propose a mean-field approach to describe the fluxoid dependence of magnetoresistance oscillations measured on two YBa2Cu3O7−x (YBCO) nanorings. We unveil the relation between the quantum interference processes and current localization phenomena in superconductor nanorings, which are non-ideal because of the presence of stubs. The model, based on the change in supercurrent transmission due to fluxoid dynamics, provides a dependence of the measured differential voltage on the external magnetic field. In particular, the signature of the Little and Parks (LP) effect results from phase dynamics involving the transmission of probe currents crossing the ring, while magnetoresistance background is related to the screening currents dynamics driven by vortex nucleation. The model allows for tracing out the entire magnetoresistance, which is the result of the superposition of single vortex-like topological defects involving current localization. This approach provides a new conceptual frame to explain the LP effect that does not invoke the lowering of superconducting stiffness. [ABSTRACT FROM AUTHOR]

We present a theoretical study of resonant frequencies and spatial correlations of Josephson phases in frustrated arrays of Josephson junctions. Two types of one-dimensional arrays, namely, the diamond and sawtooth chains, are discussed in detail. For these arrays in the linear regime the Josephson phase dynamics is characterized by multiband dispersion relation , and the lowest band becomes completely flat at a critical value of frustration, f   =  f c. In a strongly nonlinear regime such critical value of frustration determines the crossover from non-frustrated (0  <  f   <  f c) to frustrated (f c  <  f   <  1) regimes. The crossover is characterized by the thermodynamic spatial correlation functions of phases on vertices, , i.e. displaying the transition from long- to short-range spatial correlations. We find that higher-order correlations functions, e.g. p   =  2 and p   =  3, restore the long-range behavior deeply in the frustrated regime, . Monte-Carlo simulations of the thermodynamics of frustrated arrays of Josephson junctions are in good agreement with analytical results. We also outline the extension of our results to the case of kagome lattice, prototypical 2D frustrated lattice, and other higher dimensional lattices. [ABSTRACT FROM AUTHOR]

Objective. Cooperation in the cardiorespiratory system helps maintain internal stability. Various types of system interactions have been investigated; however, the characteristics of the interactions have mostly been studied using data collected in well-defined physiological states, such as sleep. Furthermore, most analyses provided general information about the interaction, making it difficult to quantify how the systems influenced one another. Approach. Cardiorespiratory directional coupling was investigated in different age groups (20 young and 19 elderly subjects) in a wake-resting state. The directionality index (DI) was calculated using instantaneous phases from the heartbeat interval and respiratory signal to provide information about the strength and direction of interaction between the systems. Statistical analysis was performed between the groups on the DI and independent measures of directionality (ncr: influence from cardiac system to respiratory system, and ncc: influence from the respiratory system to the cardiac system). Main results. The values of DI were −0.52 and −0.17 in the young and elderly groups, respectively (p < 0.001). Furthermore, the values of ncr and ncc were found to be significantly different between the groups (p < 0.001), respectively. Significance. Changes in both directions between the systems influence different aspects of cardiorespiratory coupling between the groups. This observation could be linked to different levels of autonomic modulation associated with ageing. Our approach could aid in quantitatively tracking and comprehending how systems interact in response to physiological and environmental changes. It could also be used to understand how abnormal interaction characteristics influence physiological system dysfunctions and disorders. [ABSTRACT FROM AUTHOR]

Liquid phase transmission electron microscopy (TEM) provides a useful means to study a wide range of dynamics in solution with near-atomic spatial resolution and sub-microsecond temporal resolution. However, it is still a challenge to control the chemical environment (such as the flow of liquid, flow rate, and the liquid composition) in a liquid cell, and evaluate its effect on the various dynamic phenomena. In this work, we have systematically demonstrated the flow performance of an in situ liquid TEM system, which is based on ‘on-chip flow’ driven by external pressure pumps. We studied the effects of different chemical environments in the liquid cell as well as the electrochemical potential on the deposition and dissolution behavior of Cu crystals. The results show that uniform Cu deposition can be obtained at a higher liquid flow rate (1.38 ÎĽ l minâˆ'1), while at a lower liquid flow rate (0.1 ÎĽ l minâˆ'1), the growth of Cu dendrites was observed. Dendrite formation could be further promoted by in situ addition of foreign ions, such as phosphates. The generality of this technique was confirmed by studying Zn electrodeposition. Our direct observations not only provide new insights into understanding the nucleation and growth but also give guidelines for the design and synthesis of desired nanostructures for specific applications. Finally, the capability of controlling the chemical environment adds another dimension to the existing liquid phase TEM technique, extending the possibilities to study a wide range of dynamic phenomena in liquid media. [ABSTRACT FROM AUTHOR]

Experiment-based circuit models for Josephson plasma emitters (JPEs) made of cuprate superconductor Bi2Sr2CaCu2O8+ δ single crystals are proposed. Introducing an LCR resonator shunting an RCSJ parallel circuit allows us to reproduce experimental radiation intensity as a function of device voltage. Mismatch in the resonance frequencies of the total device and the LCR part is related to the wide-range tuning of the radiation frequency of JPE. It is found that coupling capacitances for simultaneously biased operations provide significant increases in radiation intensities, which have been reported as synchronized radiation from multiple mesas in the literature. [ABSTRACT FROM AUTHOR]

Synchronisation plays a fundamental role in a variety of physiological functions, such as visual perception, cognitive function, sleep and arousal. The precise role of the interplay between local dynamics and directed cortical topology on the propensity for cortical structures to synchronise, however, remains poorly understood. Here, we study the impact that directed network topology has on the synchronisation properties of the brain by considering a range of species and parcellations, including the cortex of the cat and the Macaque monkey, as well as the nervous system of the C. elegans round worm. We deploy a Kuramoto phase model to simulate neural dynamics on the aforementioned connectomes, and investigate the extent to which network directionality influences distributed patterns of neural synchrony. In particular, we find that network directionality induces both slower synchronisation speeds and more robust phase locking in the presence of network delays. Moreover, in contrast to large-scale connectomes, we find that recently observed relations between resting state directionality patterns and network structure appear to break down for invertebrate networks such as the C. elegans connectome, thus suggesting that observed variations in directed network topology at different scales can significantly impact patterns of neural synchrony. Our results suggest that directionality plays a key role in shaping network dynamics and moreover that its exclusion risks simplifying neural activation dynamics in a potentially significant way. [ABSTRACT FROM AUTHOR]

Quiescent H-mode (QH-mode) has been identified as an attractive stationary operational regime in tokamaks due to its lack of edge localized modes (ELMs), along with good particle and impurity control aided by the presence of magnetohydrodynamic modes such as the edge harmonic oscillation (EHO) or edge turbulence. Experiments on the DIII-D tokamak explore local access conditions for QH-mode through measurements of the critical edge rotational shear necessary for the transition from a QH-mode with a coherent EHO to a typical ELMy H-mode. The critical E  ×  B shear and EHO frequency are predicted by a nonlinear phase-dynamics model relating the pressure and velocity perturbations in the edge pedestal region. The reduced theoretical model predicts a linear relationship between critical shearing rate and , where is the ion acoustic velocity, Lp the pressure gradient scale length, and the radial width of the mode. This scaling of the critical shearing rate agrees with the experimental trend, although the absolute magnitude of the shearing rate threshold is over-predicted by the model. Through a normalized predicted scaling, the model demonstrates the dynamic transition into and out of QH-mode qualitatively, within a single plasma discharge. The experimental comparison lends insight into improving the theoretical model by including more accurate geometry and toroidal mode number physics for more accurate quantitative predictions. [ABSTRACT FROM AUTHOR]

We analyze the effect of adding a weak, localized, inhomogeneity to a two dimensional array of oscillators with nonlocal coupling. We propose and also justify a model for the phase dynamics in this system. Our model is a generalization of a viscous eikonal equation that is known to describe the phase modulation of traveling waves in reaction–diffusion systems. We show the existence of a branch of target pattern solutions that bifurcates from the spatially homogeneous state when , the strength of the inhomogeneity, is nonzero and we also show that these target patterns have an asymptotic wavenumber that is small beyond all orders in . The strategy of our proof is to pose a good ansatz for an approximate form of the solution and use the implicit function theorem to prove the existence of a solution in its vicinity. The analysis presents two challenges. First, the linearization about the homogeneous state is a convolution operator of diffusive type and hence not invertible on the usual Sobolev spaces. Second, a regular perturbation expansion in does not provide a good ansatz for applying the implicit function theorem since the nonlinearities play a major role in determining the relevant approximation, which also needs to be ‘correct’ to all orders in . We overcome these two points by proving Fredholm properties for the linearization in appropriate Kondratiev spaces and using a refined ansatz for the approximate solution which was obtained using matched asymptotics. [ABSTRACT FROM AUTHOR]

Motivated by Gutzwiller’s semiclassical quantization, in which unstable periodic orbits of low-dimensional deterministic dynamics serve as a WKB ‘skeleton’ for chaotic quantum mechanics, we construct the corresponding deterministic skeleton for infinite-dimensional lattice-discretized scalar field theories. In the field-theoretical formulation, there is no evolution in time, and there is no ‘Lyapunov horizon’; there is only an enumeration of lattice states that contribute to the theory’s partition sum, each a global spatiotemporal solution of system’s deterministic Eulerâ€"Lagrange equations. The reformulation aligns ‘chaos theory’ with the standard solid state, field theory, and statistical mechanics. In a spatiotemporal, crystallographer formulation, the time-periodic orbits of dynamical systems theory are replaced by periodic d -dimensional Bravais cell tilings of spacetime, each weighted by the inverse of its instability, its Hill determinant. Hyperbolic shadowing of large cells by smaller ones ensures that the predictions of the theory are dominated by the smallest Bravais cells. The form of the partition function of a given field theory is determined by the group of its spatiotemporal symmetries, that is, by the space group of its lattice discretization, best studied on its reciprocal lattice. Already one-dimensional lattice discretization is of sufficient interest to be the focus of this paper. In particular, from a spatiotemporal field theory perspective, ‘time’-reversal is a purely crystallographic notion, a reflection point group, leading to a novel, symmetry quotienting perspective of time-reversible theories and associated topological zeta functions. [ABSTRACT FROM AUTHOR]

The fish can be driven by the sarcomere at different locations of the body. To study the hydrodynamic performance of the fish in this process, the self-propulsion of a composite plate driving on two points was investigated. It is supposed that the forces were exerted on the junction point to maintain a given pitch motion of the rigid portion, and an additional external moment was exerted at a point on the flexible plate. The ratio between the lengths of the rigid portion and the flexible portion was fixed as 1/9, which was reasonable for a real fish. The acting point and phase angle of the additional external moment was varying to study the cooperation of the forces on different points. It was found that the additional external moment was not always promoting the propulsion velocity and efficiency of the composite plate. The additional external moment near the joint point was most suitable for improve the propulsive velocity and efficiency of the composite plate. The anti-phase additional external moment was prejudicing the propulsion of the plate. The additional external moment could change the vibration shape of the flexible plate and the flow structure around it. As ϕ = π, the amplitude and the gradient of the deformation was largely reduced, and the wake became long and narrow. The hydrodynamic forces at the head and tail portion of the flexible plate were hindering the propulsion of the plate, while the thrust was mainly produced on the intermediate portion. It was expected that our investigation can be helpful for the design of the soft robotic fish. [ABSTRACT FROM AUTHOR]

We theoretically demonstrate stacked-dipole-resonatorsâ€"based (broadside near-field coupling configuration) multilayer metasurfaces separated by a vanadium dioxide film to achieve stronger field confinement in the spacer (VO2) region. Under relatively intense terahertz excitation (20 Vmâˆ'1) assisted by larger area electric field confinement, insulator-to-metal transition (IMT) in VO2 spacer is realized resulting in frequency (dipole mode) and amplitude (Fano mode) tunable metasurfaces. Enhancement in probing THz field triggers much stronger field confinement inside the spacer layer leading to increased VO2 conductivity (responsible for IMT) through the Poole-Frankel effect. Such broadside coupled IMT-based terahertz metamaterials can help in realizing active meta devices for THz domain. [ABSTRACT FROM AUTHOR]

Dynamics of nonlinear dissipative waves propagating in one dimension under a feedback-mediated spatio-temporal forcing is investigated. The feedback induced in the time evolution equation is taken to be proportional to the sum of two spatial wave profiles shifted in the forward and backward directions at the same space shift d. It is found that, when the magnitude of the feedback exceeds a certain critical value depending on d, the waves cease propagating. This phenomenon can be understood almost completely by a phase dynamics approach. [ABSTRACT FROM AUTHOR]

Sheared flows are known to reduce turbulent transport by decreasing the correlation length and/or intensity of turbulent structures. The transport barrier that takes place at the edge during improved regimes such as H mode, corresponds to the establishment of a large shear of the radial electric field. In this context, the radial shape of the radial electric field or more exactly of the perpendicular E Ă— B velocity appears as a key element in accessing improved confinement regimes. In this paper, we present the radial profile of the perpendicular velocity measured using Doppler back-scattering system at the edge of the plasma, dominated by the E Ă— B velocity, during the first campaigns of the WEST tokamak. It is found that the radial velocity profile is clearly more sheared in lower single null configuration (with the B Ă— ∇ B magnetic drift pointing toward the active X -point) than in upper single null configuration for ohmic and low current plasmas (B = 3.7 T and q 95 = 4.7), consistently with the expectation comparing respectively ‘favourable’ versus ‘unfavourable’ configuration. Interestingly, this tendency is sensitive to the plasma current and to the amount of additional heating power leading to plasma conditions in which the E Ă— B velocity exhibits a deeper well in USN configuration. For example, while the velocity profile exhibits a clear and deep well just inside the separatrix concomitant with the formation of a density pedestal during Lâ€"H transitions observed in LSN configuration, deeper E r wells are observed in USN configuration during similar transitions with less pronounced density pedestal. [ABSTRACT FROM AUTHOR]

Coupled dissipative nonlinear oscillators exhibit complex spatiotemporal dynamics. Frenkel-Kontorova is a prototype model of coupled nonlinear oscillators, which exhibits coexistence between stable and unstable state. This model accounts for several physical systems such as the movement of atoms in condensed matter and magnetic chains, dynamics of coupled pendulums, and phase dynamics between superconductors. Here, we investigate kinks propagation into an unstable state in the Frenkel-Kontorova model with dissipation. We show that unlike point-like particles π-kinks spread in a pulsating manner. Using numerical simulations, we have characterized the shape of the π-kink oscillation. Different parts of the front propagate with the same mean speed, oscillating with the same frequency but different amplitude. The asymptotic behavior of this propagation allows us to determine the minimum mean speed of fronts analytically as a function of the coupling constant. A generalization of the Peierls-Nabarro potential is introduced to obtain an effective continuous description of the system. Numerical simulations show quite fair agreement between the Frenkel-Kontorova model and the proposed continuous description. [ABSTRACT FROM AUTHOR]

Resonance phenomena in a model of intrinsic Josephson junctions shunted by LC-elements (L-inductance, C-capacitance) are studied. The phase dynamics and IV-characteristics are investigated in detail when the Josephson frequency approaches the frequency of the resonance circuit. A realization of parametric resonance through the excitation of a longitudinal plasma wave, within the bias current interval corresponding to the resonance circuit branch, is demonstrated. It is found that the temporal dependence of the total voltage of the stack, and the voltage measured across the shunt capacitor, reflect the charging of superconducting layers, a phenomenon which might be useful as a means of detecting such charging experimentally. Thus, based on the voltage dynamics, a novel method for the determination of charging in the superconducting layers of coupled Josephson junctions is proposed. A demonstration and discussion of the influence of external electromagnetic radiation on the IV-characteristics and charge-time dependence is given. Over certain parameter ranges the radiation causes an interesting new type of temporal splitting in the charge-time oscillations within the superconducting layers. [ABSTRACT FROM AUTHOR]

The EPED1 model and self-consistent core-pedestal coupling in integrated modeling are used to design the pedestal structure of the China Fusion Engineering Testing Reactor (CFETR) steady-state scenario. The key parameters, such as β p and q 95, are based on the grassy edge-localized-mode (ELM) experimental database. In this work, we use the BOUT++ six-field two-fluid code to simulate the onset of the ELM in the CFETR steady-state scenario. The ELM size is around 0.2% in nonlinear simulations, which is in the experimental range of the grassy ELM discharges, 0.1%â€"1% observed in multiple tokamak devices. Linear and nonlinear simulations show that the dominant high- n ballooning modes peak around n = 40. Compared to type-I ELM crashing dynamics, grassy ELM crashing has a smaller initial crash and is then followed by three phases of turbulence spreading, which are dominated by multi-modes, a high- n mode of n = 45 and low- n mode of n = 5, respectively. In contras to type-I ELM, the perturbation of the high- n mode has a narrow width around ψ = 0.95, and magnetic island formation and reconnection occur only beyond ψ = 0.95, leading to a small initial crash. Modeâ€"mode interaction in the multi-mode coexistence stage stops the growth of individual modes and reduces the transport of particles and heat, and these are the two reasons why the ELM size is small. Inâ€"out asymmetry of transient heat flux with a ratio of E out/ E in = 3.5 is found during grassy ELM crash. The rise and delay times of the heat flux match the calculation from the free-streaming model. To evaluate the erosion of the divertor target, the energy fluence at the outer divertor target is calculated, which is 0.029 MJ mâˆ'2, 5.5 times smaller than the tungsten melting limit 0.16 MJ mâˆ'2. The calculated energy fluency still follows the experimental scaling law from type-I ELM experiments. The fluctuation eddies in the toroidal direction show a filament structure at the outer mid-plane. Parallel heat flux patterns with a toroidal mode number n = 10 are found at the outer divertor with an amplitude of 680 MW mâˆ'2. [ABSTRACT FROM AUTHOR]

Wavy annular flow and subsequent droplet dispersion in air-water two-phase flow has been studied numerically using conventional Eulerian volume of fluid (VOF) solver and coupled Eulerian-Lagrangian approach. The VOF based investigation has been reported to highlights the formation of droplet swarm and its population dynamics. Coupled Eulerian-Lagrangian method has also been shown to replicate similar features with lesser computational effort. Entrainment, deposition, fragmentation and unification are traced from the numerical simulation, which ultimately predicts the volume filling behavior of the droplets inside the tube. Flow kinematics around droplet is critically assessed numerically for finding out reasons behind deposition, fragmentation and unification. A comparative behavior between different velocity ratios of gas and liquid flow rates are presented which clearly shows higher entrainment rate as shear between annular liquid and gaseous core increases. An assessment of the droplet population in coupled Eulerian-Lagrangian method shows the generation of the smaller sized spherical droplet by entrainment and fragmentation route. [ABSTRACT FROM AUTHOR]

Non-thermal plasma systems offer unique opportunities in the fields of bio-imaging, drug delivery, photovoltaics, microelectronics manufacturing. Such interests are largely inspired by the fact that hot plasma electrons coexist with neutral species and ions close to room-temperature under non-thermal plasma conditions. Modeling of these systems requires a deep understanding of the atomistic processes underlying the rich chemistry of the various radicals and ions with the nascent nanoparticle (NP) surface. A key parameter for determining the contribution of a certain radical/ion species to the NP surface growth, called sticking coefficient, is computed as a weighted sum from the simulated sticking outcomes with different collision velocities drawn from a Maxwell–Boltzmann distribution at certain temperatures. In this work, the collisions of SiHx (x = 1–4) fragments and silicon cluster (Si4, Si2H6, and Si29H36) surfaces, responsible for the sticking coefficients, are simulated by molecular dynamics with a reactive force field. The dependence of sticking coefficients on temperature, H coverage of both silane fragments and cluster surfaces, and the size of the cluster, are systematically examined. And the mechanism underlying the sticking events, specifically the conversion of physical aggregation to chemisorption is investigated to better understand the complex interplay between factors influencing the surface growth. The detailed and multi-parameter model of sticking coefficients, accompanied by the mechanism study of physisorption to chemisorption conversion, provides a more accurate and robust approximation of surface growth rate using sticking coefficients, and a deeper understanding of surface growth processes, for the wider non-thermal plasma simulation community. [ABSTRACT FROM AUTHOR]

The electron dynamics in a stable and non-filamentary Argon plasma jet, generated using AC excitation at kHz frequencies and interacting with a liquid surface either at floating potential or electrically grounded were examined using laser Thomson scattering. In the case of a floating liquid, two discharge events were observed during each half-cycle of the applied sinusoidal voltage. In the grounded liquid case only one discharge event was observed, which occurred during the positive half period. Through spatio-temporal imaging of the discharge, its repetitive breakdown behavior was analyzed and divided into pre-, main-, and post-breakdown phases. The dynamics and presence of the various phases differed depending upon the grounding of the liquid. Thomson scattering measurements revealed maximum electron densities and temperatures of 6.0–6.3 × 1014 cm−3 and 3.1–3.3 eV for the floating liquid case and 1.1 × 1015 cm−3 and 4.3 eV in the grounded liquid case. Electron-driven reactions are the primary source of reactive chemical species in a plasma jet. Therefore, the electrical characteristics of the liquid sample can impact the fundamental physicochemical processes at play in the discharge, ultimately influencing its chemical composition. [ABSTRACT FROM AUTHOR]

For both real fish and bionic fish, a rigid anterior portion is necessary for certain functions. How does the rigid anterior portion affect the locomotion of the flexible plate? Is it true that the rigid portion is redundant? It is lack of clear cognition on these questions. In this paper, the self-propulsion of the rigid-flexible composite plate is studied numerically. We suppose that the forces are exerted on the junction point to maintain a given pitch motion of the rigid portion, the deformation of the flexible portion is consequent. The ratio between the lengths of the flexible portion and the rigid portion is changed to model the composite plate, and the effect of the stiffness of the flexible plate is investigated. It is found that the propulsive velocity and the Froude efficiency actually decrease following the increasing proportion of the rigid plate. However, the conclusion is different as the elastic energy stored in the flexible plate is considered. We find that the case with larger flexible portion is efficient for the ultra-soft posterior plate, while the case with smaller flexible portion is efficient for the stiff posterior plate. It happens to coincide with the swimming behavior of live fish. The hydrodynamic force at the tail is hindering the propulsion of the plate, which means that the motion of the tail plays a decisive role on the force distribution on the plate, rather than the thrust only produced at the tail. We think that the short ultra-soft membrane at the tail of the real fish is an important feature to improve its swimming behavior. It is expected that the study in this paper will give a further insight into the mechanism of the locomotion of fish and give some implications for the design of the soft bionic fish. [ABSTRACT FROM AUTHOR]

Atmospheric pressure plasmas have shown great promise for the treatment of wounds and cancerous tumors. In these applications, the sample is usually covered by a thin layer of a biological liquid. The reactive oxygen and nitrogen species (RONS) generated by the plasma activate and are processed by the liquid before the plasma produced activation reaches the tissue. The synergy between the plasma and the liquid, including evaporation and the solvation of ions and neutrals, is critical to understanding the outcome of plasma treatment. The atmospheric pressure plasma sources used in these procedures are typically repetitively pulsed. The processes activated by the plasma sources have multiple timescales—from a few ns during the discharge pulse to many minutes for reactions in the liquid. In this paper we discuss results from a computational investigation of plasma–liquid interactions and liquid phase chemistry using a global model with the goal of addressing this large dynamic range in timescales. In modeling air plasmas produced by a dielectric barrier discharge over liquid covered tissue, 5000 voltage pulses were simulated, followed by 5 min of afterglow. Due to the accumulation of long-lived species such as ozone and NxOy, the gas phase dynamics of the 5000th discharge pulse are different from those of the first pulse, particularly with regards to the negative ions. The consequences of applied voltage, gas flow, pulse repetition frequency, and the presence of organic molecules in the liquid on the gas and liquid reactive species are discussed. [ABSTRACT FROM AUTHOR]

We study a physical system consisting of a Bose–Einstein condensate confined to a ring shaped lattice potential interrupted by three weak links. The system is assumed to be driven by an effective flux piercing the ring lattice. By employing path integral techniques, we explore the effective quantum dynamics of the system in a pure quantum phase dynamics regime. Moreover, the effects of the density’s quantum fluctuations are studied through exact diagonalization analysis of the spectroscopy of the Bose–Hubbard model. We demonstrate that a clear two-level system emerges by tuning the magnetic flux at degeneracy. The lattice confinement, platform for the condensate, is realized experimentally employing a spatial light modulator. [ABSTRACT FROM AUTHOR]

This report summarizes the contributions presented at the IAEA technical meeting on plasma disruptions and their mitigation, held virtually, 20–23 July 2020. The meeting brought together more than 120 experts from nuclear fusion research sites worldwide to discuss experimental, theoretical and modelling work in the field of plasma disruptions with special emphasis on developing a solid basis for possible disruption mitigation strategies in ITER and next generation fusion devices. The main topics of the meeting were: (i) disruption consequences, including electromagnetic loads, heat loads, and runaway electrons; (ii) disruption prediction and avoidance, including machine learning and physics-based approaches, and control aspects; and (iii) disruption mitigation, including shattered pellet injection, alternative techniques and general aspects of disruption mitigation. [ABSTRACT FROM AUTHOR]

The dynamics of large superwavelength open systems which are free-standing multi-wire lines with a large number of Josephson junctions, DC bias batteries and other lumped elements is analyzed using direct numerical simulation. Such systems represent the simplest version of the active Josephson antennas proposed in our earlier studies and show promise as terahertz and subterahertz radiation sources. We have studied dependences of the radiation characteristics on the antenna geometry, number of junctions, DC bias current and the lumped elements position and parameters. Detailed simulation results reveal a multitude of phase transitions between the dynamical states, which differ in the number of Josephson junctions synchronized by the excited waves of current and, hence, in the radiation power emitted into open space also as in radiation patterns. It is shown that, in the absence of noise, the Josephson antennas can emit completely coherent radiation. [ABSTRACT FROM AUTHOR]

Large-scale neurophysiological networks are often reconstructed from band-pass filtered time series derived from magnetoencephalography (MEG) data. Common practice is to reconstruct these networks separately for different frequency bands and to treat them independently. Recent evidence suggests that this separation may be inadequate, as there can be significant coupling between frequency bands (interlayer connectivity). A multilayer network approach offers a solution to analyze frequency-specific networks in one framework. We propose to use a recently developed network reconstruction method in conjunction with phase oscillator models to estimate interlayer connectivity that optimally fits the empirical data. This approach determines interlayer connectivity based on observed frequency-specific time series of the phase and a connectome derived from diffusion weighted imaging. The performance of this interlayer reconstruction method was evaluated in-silico. Our reconstruction of the underlying interlayer connectivity agreed to very high degree with the ground truth. Subsequently, we applied our method to empirical resting-state MEG data obtained from healthy subjects and reconstructed two-layered networks consisting of either alpha-to-beta or theta-to-gamma band connectivity. Our analysis revealed that interlayer connectivity is dominated by a multiplex structure, i.e. by one-to-one interactions for both alpha-to-beta band and theta-to-gamma band networks. For theta–gamma band networks, we also found a plenitude of interlayer connections between distant nodes, though weaker connectivity relative to the one-to-one connections. Our work is an stepping stone towards the identification of interdependencies across frequency-specific networks. Our results lay the ground for the use of the promising multilayer framework in this field with more-informed and justified interlayer connections. [ABSTRACT FROM AUTHOR]

We study the emergence of asymptotic patterns in Winfree ensemble such as the partial/complete phase-locking and bump states under the effect of heterogeneous frustrations. Although the Winfree model is the first model for the synchronization of limit-cycle oscillators, there is little literature on the mathematical validity of asymptotic patterns compared to the vast literature of the well-studied Kuramoto model. Recently, it has received a renewed attention in nonlinear dynamics and statistical physics communities due to its diverse asymptotic patterns that it can generate. In particular, we provide a rigorous result on the existence of bump states in a homogeneous ensemble with the same natural frequency. Our provided results exhibit the robustness of emerging asymptotic patterns with respect to frustrations. We derive several sufficient frameworks for the unique existence of an equilibrium state, bump states and uniform stability with respect to initial data. [ABSTRACT FROM AUTHOR]

Experiments on the DIII-D tokamak have advanced the operational limits of wide pedestal quiescent H-mode plasmas towards increased ITER relevance by simultaneously demonstrating well-matched plasma shape and net zero injected torque. Wide pedestal QH-modes are a compelling candidate regime for a future power producing device because they maintain a stationary pedestal without ELMs via additional edge transport. The pedestal is wider than what would be predicted from kinetic ballooning mode physics due to enhanced edge transport generated by broadband turbulence, a limit cycle oscillation, or some combination thereof. Compared to the double null shape, the lower single null shape is observed to have a lower density, narrower pedestal width, larger density fluctuations over a broad range of wavenumber, and operates closer to the peeling-ballooning instability boundary calculated from the simple pedestal scaling, , which is still observed to be wider than the EPED prediction. [ABSTRACT FROM AUTHOR]

Josephson effects are commonly studied in quantum systems in which dissipation or noise can be neglected or do not play a crucial role. In contrast, here we discuss a setup where dissipative interactions do amplify a photonic Josephson current, opening a doorway to dissipation-enhanced sensitivity of quantum-optical interferometry devices. In particular, we study two coupled nanolasers subjected to phase coherent drivings and coupled by a coherent photon tunneling process. We describe this system by means of a Fokker–Planck equation and show that it exhibits an interesting non-equilibrium phase diagram as a function of the coherent coupling between nanolasers. As we increase that coupling, we find a non-equilibrium phase transition between a phase-locked (PL) and a non-phase-locked (NPL) steady-state, in which phase coherence is destroyed by the photon tunneling process. In the coherent, PL regime, an imbalanced photon number population appears if there is a phase difference between the nanolasers, which appears in the steady-state as a result of the competition between competing local dissipative dynamics and the Josephson photo-current. The latter is amplified for large incoherent pumping rates and it is also enchanced close to the lasing phase transition. We show that the Josephson photocurrent can be used to measure optical phase differences. In the quantum limit, the accuracy of the two nanolaser interferometer grows with the square of the photon number and, thus, it can be enhanced by increasing the rate of incoherent pumping of photons into the nanolasers. [ABSTRACT FROM AUTHOR]

Bose–Bose droplets are self-bound objects emerging from a mixture of two interacting Bose–Einstein condensates when their interactions are appropriately tuned. During droplet formation three continuous symmetries of the system's Hamiltonian are broken: translational symmetry and two U(1) symmetries, allowing for arbitrary choice of phases of the mean-field wavefunctions describing the two components. Breaking of these symmetries must be accompanied by appearance of zero-energy excitations in the energy spectrum of the system recovering the broken symmetries. Normal modes corresponding to these excitations are the zero-energy modes. Here we find analytic expressions for these modes and introduce Hamiltonians generating their time evolution—dynamics of the droplet's centers of mass as well as dynamics of the phases of the two droplet's wavefunctions. When internal types of excitations (quasiparticles) are neglected then the very complex system of a quantum droplet is described using only a few 'global' degrees of freedom—the position of the center of mass of the droplet and two phases of two wave-functions, all these being quantum operators. We believe that our work might be useful in describing in a relatively easy way the low energy collisions of quantum droplets in situations where coherent flow of atoms between the droplets takes place. [ABSTRACT FROM AUTHOR]

The wave turbulence theory predicts that a conservative system of nonlinear waves can exhibit a process of condensation, which originates in the singularity of the Rayleigh-Jeans equilibrium distribution of classical waves. Considering light propagation in a multimode fiber, we show that light condensation is driven by an energy flow toward the higher-order modes, and a bi-directional redistribution of the wave-action (or power) to the fundamental mode and to higher-order modes. The analysis of the near-field intensity distribution provides experimental evidence of this mechanism. The kinetic equation also shows that the wave-action and energy flows can be inverted through a thermalization toward a negative temperature equilibrium state, in which the high-order modes are more populated than low-order modes. In addition, a Bogoliubov stability analysis reveals that the condensate state is stable. [ABSTRACT FROM AUTHOR]

This paper reviews the research on the reversed field pinch (RFP) in the last three decades. Substantial experimental and theoretical progress and transformational changes have been achieved since the last review (Bodin 1990 Nucl. Fusion 30 1717–37). The experiments have been performed in devices with different sizes and capabilities. The largest are RFX-mod in Padova (Italy) and MST in Madison (USA). The experimental community includes also EXTRAP-T2R in Sweden, RELAX in Japan and KTX in China. Impressive improvements in the performance are the result of exploration of two lines: the high current operation (up to 2 MA) with the spontaneous occurrence of helical equilibria with good magnetic flux surfaces and the active control of the current profile. A crucial ingredient for the advancements obtained in the experiments has been the development of state-of-art active feedback control systems allowing the control of MHD instabilities in presence of a thin shell. The balance between achievements and still open issues leads us to the conclusion that the RFP can be a valuable and diverse contributor in the quest for fusion electricity. [ABSTRACT FROM AUTHOR]