bluuebunny/crossref_metadata_2025 huggingface dataset:
Comment on “A new class of out-gap discrete solitons in binary waveguide arrays” [Chaos 32, 073113 (2022)]
Authors: Johansson Magnus
Published: January 2023

Recent results [M. C. Tran and T. X. Tran, Chaos 32, 073113 (2022)] are put into the context of earlier work [A. V. Gorbach and M. Johansson, Eur. Phys. J. D 29, 77–93 (2004); M. Johansson and A. V. Gorbach, Phys. Rev. E 70, 057604 (2004)]. The two newly found families of “beyond-band discrete solitons” [M. C. Tran and T. X. Tran, Chaos 32, 073113 (2022)] are found to be smooth continuations of “on-top breathers” briefly mentioned by Gorbach and Johansson [Eur. Phys. J. D 29, 77–93 (2004)] and Johansson and Gorbach [Phys. Rev. E 70, 057604 (2004)] and the relevant bifurcation scenarios are described. One family is shown to be linearly unstable with respect to symmetry-breaking oscillations.
THz generation in GaSe crystals pumped with laser photon energy below and around the bandgap
Authors: Zhai Dongwei , Herault Emilie , Garet Frederic , Coutaz Jean-Louis , Pan Ci-Ling
Published: January 2023

We study optical rectification in GaSe by performing THz generation with femtosecond laser pulses whose wavelength is tuned from below to above the GaSe bandgap. As expected from a theory, we observed a first THz emission peak at 1.77 eV, where phase matching is realized. A second THz emission peak was recorded, when the pump photon energy reaches the crystal bandgap (2.205 eV). This can be attributed to a resonance of the GaSe nonlinearity. In crystals thinner than the coherence length, the bandgap peak is stronger than the phase-matched one.
Interface regulation toward low driving voltage perovskite light-emitting diodes
Authors: Xue Xulan , Bai Jialin , Zhang Han , Ji Wenyu
Published: January 2023

Electroluminescence (EL) at sub-bandgap voltages has been observed in perovskite light-emitting diodes (PeLEDs), which, however, does not appear as a universal phenomenon in current reports, and the mechanism remains in debate. Herein, we verify that the turn-on voltage of PeLEDs depends neither on the carrier injection nor on the energy levels of charge-transport layers, ruling out the Auger-assisted upconversion charge injection effect. The recombination of diffused and thermally generated charge carriers, rather than the high-order effect, is believed to be responsible for the sub-bandgap EL behavior. Moreover, we demonstrate that a critical prerequisite for the sub-bandgap EL is the strong confinement of charge carriers in the emissive layer, which can be achieved by inserting a CdSe/ZnS quantum-dot monolayer at the interface of the perovskite/electron-transport layer. The accumulated holes induced by the CdSe/ZnS monolayer can reduce the electron-injection barrier, thus leading to an observable EL at a sub-bandgap voltage. Our work provides a substantial evidence for the sub-bandgap EL turn-on processes and addresses the debate in PeLEDs.
Tip vortex cavitation suppression and parametric study of an elliptical hydrofoil by water injection
Authors: Liu Kang , Wei Ping , Cao Liushuai , Wan Decheng
Published: January 2023

Tip vortex cavitation (TVC) affects hydrodynamic performance and can cause drastic vibration and noise; therefore, it is crucial to predict the evolution of TVC, understand its generation mechanism, and determine methods to control it. In this work, a large eddy simulation was performed to resolve unsteady turbulence, and the Schnerr–Sauer cavitation model was used to capture transient cavitating flow. Both wetted and cavitating conditions were used in the first step to validate the numerical methods. The mechanism of TVC development and the interactions between the tip vortex and TVC were also revealed. Next, active control by water injection was performed to suppress TVC, and the side and top injection circumstances were explored and compared. Parametric studies were conducted for the side injection condition by changing the injection velocity and angle. The results showed that both side and top injections had remarkable effects on TVC control. Flow field analysis demonstrated that the top injection flow affected the local velocity magnitude and direction of the incident flow of the tip vortex, thus reducing the vortex strength and TVC. For the side injection condition, the injection flow directly influenced the incepted structures of the tip vortex. As a result, injection flow deeply deformed the tip vortex and decreased the generation and intensity of TVC. Furthermore, increasing the injection velocity or the component of the velocity in the cross-streamwise direction could effectively increase the cavitation inhibition rate.
The sustainable development of a low-carbon system using a system dynamics model: A case study of China
Authors: Wei Wang , Xin-gang Zhao , Wenjie Lu , Shuran Hu
Published: January 2023

With the process of economic transformation and structural adjustment, low-carbon development has become an intrinsic and realistic demand for China's national economic and social development. This paper builds a system dynamic (SD) model of China's low-carbon development based on the internal influencing mechanisms of carbon sources, carbon flows, and carbon sinks, and then explores the impact of carbon sources, carbon flows, and carbon sinks system on carbon emissions under different scenarios. The model in our study is effective and practical, and it can not only clearly demonstrate the interaction mechanism between various systems but also provide effective policy recommendations for policymakers. The results show that (1) with the steady growth of the economy, China's total energy consumption and carbon emissions have increased significantly. By 2025, the total energy consumption will reach 628 798 ten thousand tons, and the carbon emissions will reach 689 257 ten thousand tons; (2) as for energy and industrial structure, on the one hand, energy restructuring is more effective in reducing carbon emissions than is industrial restructuring; (3) carbon sinks also play an important role in reducing greenhouse gas emissions.
Multiscale two-dimensional permutation entropy to analyze encrypted images
Authors: Muñoz-Guillermo María
Published: January 2023

Multiscale versions of weighted (and non-weighted) permutation entropy for two dimensions are considered in order to compare and analyze the results when different experiments are conducted. We propose the application of these measures to analyze encrypted images with different security levels and encryption methods.
Mathematical and computational modeling of electrohydrodynamics through a nanochannel
Authors: Saurabh Kumar , Solovchuk Maxim
Published: January 2023

Fluid-ion transport through a nanochannel is studied to understand the role and impact of different physical phenomena and medium properties on the flow. Mathematically, the system is described through coupled fourth order Poisson–Nernst–Planck–Bikerman and Navier–Stokes equations. The fourth order-Poisson–Nernst–Planck–Bikerman model accounts for ionic and nonionic interactions between particles, the effect of finite size of the particles, polarization of the medium, solvation of the ions, etc. Navier–Stokes equations are modified accordingly to include both electroviscous and viscoelectric effects and the velocity slip. The governing equations are discretized using the lattice Boltzmann method. The mathematical model is validated by comparing the analytical and experimental ion activity while the numerical model is validated by comparing the analytical and numerical velocity profiles for electro-osmotic flow through a microchannel. For a pressure driven flow, the electroviscous and viscoelectric effects decrease the fluid velocity while the velocity slip enhances it. The acidity of the medium also influences the fluid velocity by altering the ζ potential and ion concentration. The finite size of the particle limits the concentration of ionic species, thus, reducing electroviscous effects. As the external concentration decreases, the impact of finite size of particles also reduces. The inhomogeneous diffusion coefficient also influences electroviscous effects as it changes the concentration distribution. The variation in external pressure does not influence the impact of steric and viscoelectric effects significantly. The maximum impact is observed for ΔP = 0 (electro-osmotic flow).
Improved wall-plug efficiency of III-nitride tunnel junction micro-light-emitting diodes with AlGaN/GaN polarization charges
Authors: Wong Matthew S. , Raj Aditya , Chang Hsun-Ming , Rienzi Vincent , Wu Feng , Ewing Jacob J. , Trageser Emily S. , Gee Stephen , Palmquist Nathan C. , Chan Philip , Kang Ji Hun , Speck James S. , Mishra Umesh K. , Nakamura Shuji , DenBaars Steven P.
Published: January 2023

The electrical performances of III-nitride blue micro-light-emitting diodes (µLEDs) with different tunnel junction (TJ) epitaxial architectures grown by metalorganic chemical vapor deposition are investigated. A new TJ structure that employs AlGaN is introduced. The current density–voltage characteristic is improved by incorporating AlGaN layer above the n-side of the TJ layer, and the effects of the AlGaN/GaN superlattices is examined. Based upon the data from band diagram simulation, net positive polarization charge is formed at the AlGaN/GaN interface, which results in a reduction in tunneling distance and increase in tunneling probability. Moreover, similar electrical improvement is observed in various device dimensions and is independent of operating current density, suggesting that AlGaN/GaN biaxial tensile strain or current spreading is not the main contribution for the improvement. Finally, the effects on the efficiency performances are determined. While the maximum external quantum efficiency of the TJ devices remains identical, the wall-plug efficiency of µLEDs is enhanced significantly by the proposed AlGaN-enhanced TJ design. This work reveals the possibility of energy efficient TJ contact with high transparency in the visible wavelength range.
Drag reduction of turbulent boundary layer over sawtooth riblet surface with superhydrophobic coat
Authors: Hu Jinge , Yao Zhaohui
Published: January 2023

The application of drag reduction tech holds great significance to energy saving. To achieve better drag reduction, we investigated the flow characteristics of the turbulent boundary layer (TBL) over a composite surface made of sawtooth riblets with superhydrophobic coat (rib&SHS), a superhydrophobic surface (SHS), and a smooth surface using particle image velocimetry. The results showed that the drag reduction rate of the composite surface was higher than that of the superhydrophobic surface at the same Reynolds number. When the Reynolds number reached 2015, the drag reduction effect of SHS was almost ineffective (drag reduction was only 1.2%), whereas rib&SHS maintained satisfactory results (drag reduction was 20.2%). By proper orthogonal decomposition (POD), the second-order POD mode showed the tilt angles of the interface of Q2 and Q4 events inside the TBL over rib&SHS, and SHS were reduced compared with the smooth surface in the drag reduction cases. With drag reduction of rib&SHS and SHS, the hairpin vortexes were lifted away from the wall and the distances of vortexes within hairpin vortex packets decreased. Compared with SHS, rib&SHS had a greater effect on hairpin vortexes and hairpin vortex packets because the riblets made the Q2 events of rib&SHS weaker than that of SHS. So, the rib&SHS has a higher drag reduction rate and a larger drag reduction Reynolds number range than the SHS. It can be used to guide the drag reduction design of underwater vehicles.
Compact and complete description of non-Markovian dynamics
Authors: Sayer Thomas , Montoya-Castillo Andrés
Published: January 2023

Generalized master equations provide a theoretically rigorous framework to capture the dynamics of processes ranging from energy harvesting in plants and photovoltaic devices to qubit decoherence in quantum technologies and even protein folding. At their center is the concept of memory. The explicit time-nonlocal description of memory is both protracted and elaborate. When physical intuition is at a premium, one would desire a more compact, yet complete, description. Here, we demonstrate how and when the time-convolutionless formalism constitutes such a description. In particular, by focusing on the dissipative dynamics of the spin-boson and Frenkel exciton models, we show how to: easily construct the time-local generator from reference reduced dynamics, elucidate the dependence of its existence on the system parameters and the choice of reduced observables, identify the physical origin of its apparent divergences, and offer analysis tools to diagnose their severity and circumvent their deleterious effects. We demonstrate that, when applicable, the time-local approach requires as little information as the more commonly used time-nonlocal scheme, with the important advantages of providing a more compact description, greater algorithmic simplicity, and physical interpretability. We conclude by introducing the discrete-time analog and a straightforward protocol to employ it in cases where the reference dynamics have limited resolution. The insights we present here offer the potential for extending the reach of dynamical methods, reducing both their cost and conceptual complexity.
Motion profile and control design of fast steering mirror for backscanning step and stare imaging
Authors: Li Zhibin , Wen Junchen , Sun Chongshang , Zhang Jianqiang , Huang Hetianyu , Zhang Chengxin , Zhang Yanfeng , Pan Jianan
Published: January 2023

Fast steering mirrors (FSMs) have been used for decades to improve the performance of electro-optical imaging systems, such as airborne imaging systems and space-based optical surveillance systems. With the advantage of increasing the accuracy of image motion compensation and the efficiency of scanning imaging, backscanning step-and-stare imaging has become the main approach to realizing wide-area surveillance for airborne imaging systems. According to the operating mode and motion profile of the FSM in the imaging system, a combined optimized profile (COP) is designed to avoid abrupt changes in the velocity and acceleration of the FSM. The angular position sensor based on a four-quadrant detector is used in FSMs to expand the measuring range and cut the cost at the expense of larger measurement noise. Combining a Kalman filter with a disturbance observer and zero-phase error tracking control, a control method is proposed to improve the control precision and bandwidth while suppressing measurement noise. Simulation and experimental results show that the profile designed by COP is smooth enough to meet the special requirements of FSM’s backscanning image motion compensation and that the Kalman filter-based FSM control method can significantly improve the control accuracy.
Piston problem for the isentropic Euler equations for a modified Chaplygin gas
Authors: Huang Meixiang , Wang Yuanjin , Shao Zhiqiang
Published: January 2023

We constructively solve the piston problem for the one-dimensional isentropic Euler equations for a modified Chaplygin gas. We give a rigorous proof of the global existence and uniqueness of a shock wave separating constant states ahead of the piston when the piston advances into the gas. The results are quite different from those for a pure Chaplygin gas or a generalized Chaplygin gas, in which a Radon measure solution is constructed to deal with the concentration of mass on the piston. When the piston recedes from the gas, we show strictly that only a first-family rarefaction wave exists in front of the piston and that concentration will never occur. In addition, by studying the limiting behavior, we show that the piston solutions of the modified Chaplygin gas equations tend to the piston solutions of the generalized or pure Chaplygin gas equations as a single parameter of the pressure state function vanishes.
Prediction of electrodiffusio-osmotic transport of shear-thinning fluids in a nanochannel using artificial neural network
Authors: Ismayeel Md , Mehta Sumit Kumar , Mondal Pranab Kumar
Published: January 2023

We have numerically investigated the electrodiffusio-osmotic (EDO) transport of non-Newtonian electrolytic solution, governed by an externally applied electric field and concentration difference, in a charged nanochannel connected with two reservoirs. We have examined the EDO transport characteristics by varying electrical, chemical, and rheological parameters. The relative augmentation in net throughput due to EDO transport is compared to the pure electro-osmotic flow and is found to be greater than unity [reaches up to the order of ∼O(103)] for the considered range of concentration difference and flow-behavior index. As shown, the EDO throughput with concentration difference follows an increasing–decreasing trend at the smaller nanochannel height (<10 nm), while exhibiting an increasing trend at the higher nanochannel height (>10 nm). Notably, the net flow for shear-thinning fluid gets fully reversed at higher concentration differences and for a higher value of zeta potential. In the second part of the work, we discuss the use of an artificial neural network (ANN) essentially to predict the net EDO throughput from the nanochannel. The ANN model considered here is of a single-hidden-layer feedforward type. For activation, we used a sigmoid-purelinear transfer function between the layers. Additionally, the Levenberg–Marquardt algorithm is used to perform the backpropagation. To predict the volume flow rate per unit width, we have used four input features: concentration difference, flow-behavior index, nanochannel height, and zeta potential. We have established that an ANN model with eight neurons in the hidden layer accurately predicts the flow rate per unit width with a very small root mean squared error. The inferences of this analysis could be of huge practical importance in designing the state-of-the-art nanodevices/systems intended for offering finer control over the underlying transport.
Carreau–Yasuda fluid flow generated via metachronal waves of cilia in a micro-channel
Authors: Kada Belkacem , Pasha Amjad Ali , Asghar Zeeshan , Khan Muhammad Waris Saeed , Aris Ishak Bin , Shaikh Muhammad Shafique
Published: January 2023

The accretion of excessive bio-fluid in human tissues is triggered due to several reasons, such as pregnancy, local injuries, and allergic reactions or by using certain therapeutic drugs. Motivated by such numerous biomedical applications, this article aims to elaborate on the shear-dependent peristaltic flow of Carreau–Yasuda fluid inside the micro-channel by incorporating the ciliary walls. The long wavelength and the low Reynold's number approximation simplify the problem. Furthermore, the MATLAB-based algorithm known as the bvp5c is adopted for the problem's numerical solution. The impact of emerging parameters on the velocity, pressure gradient, and streamlines is examined through various graphs. The results reveal that while using Carreau–Yasuda fluid, the pumping apparatus performs better than Newtonian or Carreau fluid. The findings could aid our understanding of biofluid movement in the human body. Furthermore, it is believed that this solution has an important contribution in the biomedical industry for the advancement and improvement of several kinds of drug delivery devices.
Research on load characteristics of squeeze-film air bearings based on fluid–solid coupling
Authors: Quan Hui , Lan Jianying , Du Yuanying
Published: January 2023

In order to obtain the loading capacity and its variation of the squeeze-film air bearing, taking an air bearing as the research object, the structure model and the equivalent disk model of the squeeze-film air bearing are established. The modal analysis of the designed structure is carried out, and the mode of the bearing structure in the ultrasonic frequency range and the working squeeze frequency of the bearing are obtained. At the same time, the influence of air film thickness on the load characteristics of squeeze-film air bearing is analyzed by the fluid–solid coupling method. The relationship between air film thickness and loading capacity, and the relationship between contact area and loading capacity are obtained, respectively, by the above method. The results show that reducing the gap between the bearing bush and the rotor, increasing the amplitude of the bearing bush, and increasing the contact area between the bearing bush and the rotor can improve the loading capacity of the squeeze-film air bearing.
Effects of stabilizing and destabilizing thermal gradients on reversed shear-stratified flows: Combined Kelvin–Helmholtz Rayleigh–Taylor instability
Authors: Sengupta Aditi , Joshi Bhavna
Published: January 2023

Numerical investigation of the coupled Kelvin–Helmholtz Rayleigh–Taylor instability (KHRTI) is presented here by solving the compressible Navier–Stokes equations for two air streams differentially heated in two halves of a three-dimensional (3D) box. Here, we explore the role of a stabilizing and destabilizing thermal gradient and that of reversing the direction of the air streams considered for Atwood numbers of ±0.1567 and dimensionless tangential shear of ΔU=0.68 and 4.1. The onset of the KHRTI and development of the turbulent mixing layer are explored via time-resolved and instantaneous distributions of temperature and vorticity. Early stages of the KHRTI with reversed air streams follows a Kelvin–Helmholtz (KH) mechanism, with Rayleigh–Taylor (RT) dynamics becoming important at later times. This leads to an earlier development of the turbulent mixing layer. The KHRTI with stabilizing or destabilizing thermal gradients shows a dominance of the buoyancy-driven mechanism, right from the onset. The transition from laminar to turbulent mixing layer involves the creation of coherent structures of spikes, bubbles, and KH whirls for the destabilizing, stabilizing thermal gradient, and reversed shear cases, respectively. The spectra of the turbulent signals reveal a −5/3 scaling when the shear-driven mechanism is prevalent in the flow and −11/5 scaling when the buoyancy-driven effects become prominent. The compressible enstrophy budget of the KHRTI shows that the onset process is dominated by vortex stretching or compressibility effects, followed by a sharp rise in baroclinic torque contribution once the buoyancy effects become relevant.
Unsteady flow behaviors and noise generation mechanisms of tandem orifices in a circular duct
Authors: Li Fuqi , Wang Peng , Liu Yingzheng
Published: January 2023

Turbulent flow through tandem orifices in a circular duct is numerically modeled through dynamic delayed detached-eddy simulations to clarify the unsteady flow behaviors and noise generation mechanism. The characteristics of four configurations with different separation distances L/D = 0 (single orifice), 1, 2, and 4 are compared at a Reynolds number of 10 000. The acoustic sources and their noise-propagation behaviors are analyzed using Lighthill's acoustic analogy. The coherent flow structures (wavepackets) are determined through spectral proper orthogonal decomposition to clarify the resulting flow noise mechanism. The dominant noise sources are acoustic dipoles that are alternately energetic on the orifice's leading and trailing faces subjected to intermittent interaction with the unsteady flow. The total sound pressure level (SPL) for a single orifice is alternately dominated by the shedding and flapping behaviors of the large-scale vortical structures in the low-frequency range and Kelvin–Helmholtz (K–H) type wavepackets at high frequencies. For the tandem orifice configuration with L/D = 1, the total SPL is dominated by the contribution of the trailing face, attributable to the interactions between the K–H-type double-wavepacket structures. Both the upstream and downstream wavepackets start to split and generate four-wavepacket structures in the high-frequency range. In the cases of L/D = 2 and 4, the total SPL is dominated by the dipole sources at the downstream leading face that subjected to the intermittent interaction with the upstream separated shear layers. The dominant flow structures are independent wavepackets through each orifice at low frequencies, while at high frequencies the four-wavepacket structures break into two independent double-wavepacket structures close to each orifice.
Long-range corrected fragment molecular orbital density functional tight-binding method for excited states in large molecular systems
Authors: Einsele Richard , Hoche Joscha , Mitrić Roland
Published: January 2023

Herein, we present a new method to efficiently calculate electronically excited states in large molecular assemblies, consisting of hundreds of molecules. For this purpose, we combine the long-range corrected tight-binding density functional fragment molecular orbital method (FMO-LC-DFTB) with an excitonic Hamiltonian, which is constructed in the basis of locally excited and charge-transfer configuration state functions calculated for embedded monomers and dimers and accounts explicitly for the electronic coupling between all types of excitons. We first evaluate both the accuracy and efficiency of our fragmentation approach for molecular dimers and aggregates by comparing it with the full LC-TD-DFTB method. The comparison of the calculated spectra of an anthracene cluster shows a very good agreement between our method and the LC-TD-DFTB reference. The effective computational scaling of our method has been explored for anthracene clusters and for perylene bisimide aggregates. We demonstrate the applicability of our method by the calculation of the excited state properties of pentacene crystal models consisting of up to 319 molecules. Furthermore, the participation ratio of the monomer fragments to the excited states is analyzed by the calculation of natural transition orbital participation numbers, which are verified by the hole and particle density for a chosen pentacene cluster. The use of our FMO-LC-TDDFTB method will allow for future studies of excitonic dynamics and charge transport to be performed on complex molecular systems consisting of thousands of atoms.
Reliable impedance analysis of Li-ion battery half-cell by standardization on electrochemical impedance spectroscopy (EIS)
Authors: Zhang Baodan , Wang Lingling , Zhang Yiming , Wang Xiaotong , Qiao Yu , Sun Shi-Gang
Published: January 2023

Electrochemical impedance spectroscopy (EIS) is a powerful characterization technique for the in-depth investigation of kinetic/transport parameters detection, reaction mechanism understanding, and degradation effects exploration in lithium-ion battery (LIB) systems. However, due to the lack of standardized criterion/paradigm, severe misinterpretations occur frequently during an EIS measurement. In this paper, the significance of instrumental accuracy is described and the character/principle of selection on the simulation model is illuminated/proposed, showing that an adequate precision device and an appropriate fitting model are a prerequisite for a correct EIS analysis. Moreover, the drawbacks of conventional two-electrode EIS experiments for typical coin-type cells are rigorously pointed out by comparison with the ideal three-electrode configuration, where the real impedance information of the cathode would be masked by the sum of both the anode film resistance response and the unavoidable inductive loop signal. The three-electrode case enables efficient accurate observations on individual electrodes, thus facilitating abundant and useful information acquisition. Consequently, devices with a sufficient accuracy, rational simulation models, and advanced three-electrode cells are distinctly illustrated as standardized criterion/paradigm for EIS characterizations, which are essentially important for electrode and interface modifications in LIBs.
Multimodal epigenetic changes and altered NEUROD1 chromatin binding in the mouse hippocampus underlie FOXG1 syndrome
Authors: Akol Ipek , Izzo Annalisa , Gather Fabian , Strack Stefanie , Heidrich Stefanie , Ó hAilín Darren , Villarreal Alejandro , Hacker Christine , Rauleac Tudor , Bella Chiara , Fischer Andre , Manke Thomas , Vogel Tanja
Published: January 2023

Forkhead box G1 (FOXG1) has important functions in neuronal differentiation and balances excitatory/inhibitory network activity. Thus far, molecular processes underlying FOXG1 function are largely unexplored. Here, we present a multiomics data set exploring how FOXG1 impacts neuronal maturation at the chromatin level in the mouse hippocampus. At a genome-wide level, FOXG1 i) both represses and activates transcription, ii) binds mainly to enhancer regions, iii) reconfigures the epigenetic landscape through bidirectional alteration of H3K27ac, H3K4me3, and chromatin accessibility, and iv) operates synergistically with NEUROD1. Interestingly, we could not detect a clear hierarchy of FOXG1 and NEUROD1, but instead, provide the evidence that they act in a highly cooperative manner to control neuronal maturation. Genes affected by the chromatin alterations impact synaptogenesis and axonogenesis. Inhibition of histone deacetylases partially rescues transcriptional alterations upon FOXG1 reduction. This integrated multiomics view of changes upon FOXG1 reduction reveals an unprecedented multimodality of FOXG1 functions converging on neuronal maturation. It fuels therapeutic options based on epigenetic drugs to alleviate, at least in part, neuronal dysfunction.
Rapid synaptic and gamma rhythm signature of mouse critical period plasticity
Authors: Quast Kathleen B. , Reh Rebecca K. , Caiati Maddalena D. , Kopell Nancy , McCarthy Michelle M. , Hensch Takao K.
Published: January 2023

Early-life experience enduringly sculpts thalamocortical (TC) axons and sensory processing. Here, we identify the very first synaptic targets that initiate critical period plasticity, heralded by altered cortical oscillations. Monocular deprivation (MD) acutely induced a transient (<3 h) peak in EEG γ-power (~40 Hz) specifically within the visual cortex, but only when the critical period was open (juvenile mice or adults after dark-rearing,
Lynx1
-deletion, or diazepam-rescued GAD65-deficiency). Rapid TC input loss onto parvalbumin-expressing (PV) inhibitory interneurons (but not onto nearby pyramidal cells) was observed within hours of MD in a TC slice preserving the visual pathway – again once critical periods opened. Computational TC modeling of the emergent γ-rhythm in response to MD delineated a cortical interneuronal gamma (ING) rhythm in networks of PV-cells bearing gap junctions at the start of the critical period. The ING rhythm effectively dissociated thalamic input from cortical spiking, leading to rapid loss of previously strong TC-to-PV connections through standard spike-timing-dependent plasticity rules. As a consequence, previously silent TC-to-PV connections could strengthen on a slower timescale, capturing the gradually increasing γ-frequency and eventual fade-out over time. Thus, ING enables cortical dynamics to transition from being dominated by the strongest TC input to one that senses the statistics of population TC input after MD. Taken together, our findings reveal the initial synaptic events underlying critical period plasticity and suggest that the fleeting ING accompanying a brief sensory perturbation may serve as a robust readout of TC network state with which to probe developmental trajectories.
James–Stein for the leading eigenvector
Authors: Goldberg Lisa R. , Kercheval Alec N.
Published: January 2023

Recent research identifies and corrects bias, such as excess dispersion, in the leading sample eigenvector of a factor-based covariance matrix estimated from a high-dimension low sample size (HL) data set. We show that eigenvector bias can have a substantial impact on variance-minimizing optimization in the HL regime, while bias in estimated eigenvalues may have little effect. We describe a data-driven eigenvector shrinkage estimator in the HL regime called “James–Stein for eigenvectors” (JSE) and its close relationship with the James–Stein (JS) estimator for a collection of averages. We show, both theoretically and with numerical experiments, that, for certain variance-minimizing problems of practical importance, efforts to correct eigenvalues have little value in comparison to the JSE correction of the leading eigenvector. When certain extra information is present, JSE is a consistent estimator of the leading eigenvector.
Nematic phases and elastoresistivity from a multiorbital non-Fermi liquid
Authors: Hardy Andrew , Haldar Arijit , Paramekanti Arun
Published: January 2023

We propose and study a two-orbital lattice extension of the Sachdev-Ye-Kitaev model in the large-
N
limit. The phase diagram of this model features a high-temperature isotropic non-Fermi liquid which undergoes first-order thermal transition into a nematic insulator or continuous thermal transition into a nematic metal phase, separated by a tunable tricritical point. These phases arise from spontaneous partial orbital polarization of the multiorbital non-Fermi liquid. We explore the spectral and transport properties of this model, including d.c. elastoresistivity, which exhibits a peak near nematic transition, as well as nonzero frequency elastoconductivity. Our work offers a useful perspective on nematic phases and transport in correlated multiorbital systems.
Feedback in the β-catenin destruction complex imparts bistability and cellular memory
Authors: Cantoria Mary Jo , Alizadeh Elaheh , Ravi Janani , Varghese Reeba P. , Bunnag Nawat , Pond Kelvin W. , Kettenbach Arminja N. , Ahmed Yashi , Paek Andrew L. , Tyson John J. , Doubrovinski Konstantin , Lee Ethan , Thorne Curtis A.
Published: January 2023

Wnt ligands are considered classical morphogens, for which the strength of the cellular response is proportional to the concentration of the ligand. Herein, we show an emergent property of bistability arising from feedback among the Wnt destruction complex proteins that target the key transcriptional co-activator β-catenin for degradation. Using biochemical reconstitution, we identified positive feedback between the scaffold protein Axin and the kinase glycogen synthase kinase 3 (GSK3). Theoretical modeling of this feedback between Axin and GSK3 suggested that the activity of the destruction complex exhibits bistable behavior. We experimentally confirmed these predictions by demonstrating that cellular cytoplasmic β-catenin concentrations exhibit an “all-or-none” response with sustained memory (hysteresis) of the signaling input. This bistable behavior was transformed into a graded response and memory was lost through inhibition of GSK3. These findings provide a mechanism for establishing decisive, switch-like cellular response and memory upon Wnt pathway stimulation.
Re-formation of synaptic connectivity in dissociated human stem cell-derived retinal organoid cultures
Authors: Ludwig Allison L. , Mayerl Steven J. , Gao Yu , Banghart Mark , Bacig Cole , Fernandez Zepeda Maria A. , Zhao Xinyu , Gamm David M.
Published: January 2023

Human pluripotent stem cell (hPSC)-derived retinal organoids (ROs) can efficiently and reproducibly generate retinal neurons that have potential for use in cell replacement strategies [Capowski
et al.
,
Development
 146, dev171686 (2019)]. The ability of these lab-grown retinal neurons to form new synaptic connections after dissociation from ROs is key to building confidence in their capacity to restore visual function. However, direct evidence of reestablishment of retinal neuron connectivity via synaptic tracing has not been reported to date. The present study employs an in vitro, rabies virus-based, monosynaptic retrograde tracing assay [Wickersham
et al., Neuron
 53, 639–647 (2007); Sun
et al., Mol. Neurodegener.
 14, 8 (2019)] to identify de novo synaptic connections among early retinal cell types following RO dissociation. A reproducible, high-throughput approach for labeling and quantifying traced retinal cell types was developed. Photoreceptors and retinal ganglion cells—the primary neurons of interest for retinal cell replacement—were the two major contributing populations among the traced presynaptic cells. This system provides a platform for assessing synaptic connections in cultured retinal neurons and sets the stage for future cell replacement studies aimed at characterizing or enhancing synaptogenesis. Used in this manner, in vitro synaptic tracing is envisioned to complement traditional preclinical animal model testing, which is limited by evolutionary incompatibilities in synaptic machinery inherent to human xenografts.
When aging gets on the way of disposal: Senescent cell suppression of efferocytosis
Authors: Rothlin Carla V. , Ghosh Sourav
Published: January 2023

Chronic senescence can trigger pathological inflammation. In this issue, Schloesser et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202207097) demonstrate that senescent cells employ “don’t eat me” signals that inhibit the ability of macrophages to engulf them and additionally prevent macrophages from removing neighboring corpses, revealing a new mechanism by which senescence may contribute to triggering inflammation.
Directional Chiral Optical Emission by Electron-Beam-Excited Nano-Antenna
Authors: Xiong Xiang , Zeng Zhao-Yuan , Peng Ruwen , Wang Mu
Published: January 2023

Manipulating directional chiral optical emissions on a nanometer scale is significant for material science research. The electron-beam-excited nanoantenna provides a favorable platform to tune optical emissions at the deep subwavelength scale. Here we present an L-shaped electron-beam-excited nanoantenna (LENA) with two identical orthogonal arms. By selecting different electron-beam impacting sites on the LENA, either the left-handed circularly polarized (LCP) or the right-handed circularly polarized (RCP) emission can be excited. The LCP and RCP emissions possess different emission directionality, and the emission wavelength depends on the arm length of the LENA. Further, we show a combined nanoantenna with two LENAs of different arm lengths. Induced by the electron beam, LCP and RCP lights emit simultaneously from the nanoantenna with different wavelengths to different directions. This approach is suggested to be informative for investigating electron-photon interaction and electron-beam spectroscopy in nanophotonics.
Generating transient noise artefacts in gravitational-wave detector data with generative adversarial networks
Authors: Powell Jade , Sun Ling , Gereb Katinka , Lasky Paul D , Dollmann Markus
Published: January 2023

Transient noise glitches in gravitational-wave detector data limit the sensitivity of searches and contaminate detected signals. In this paper, we show how glitches can be simulated using generative adversarial networks (GANs). We produce hundreds of synthetic images for the 22 most common types of glitches seen in the LIGO, KAGRA, and Virgo detectors. We show how our GAN-generated images can easily be converted to time series, which would allow us to use GAN-generated glitches in simulations and mock data challenges to improve the robustness of gravitational-wave searches and parameter-estimation algorithms. We perform a neural network classification to show that our artificial glitches are an excellent match for real glitches, with an average classification accuracy across all 22 glitch types of 99.0%.
Gravity entanglement, quantum reference systems, degrees of freedom
Authors: Christodoulou Marios , Di Biagio Andrea , Howl Richard , Rovelli Carlo
Published: January 2023

Gravity mediated entanglement (GME) has been proposed as the first experimentally testable signature of quantum gravity. However, to what extent the effect is due to quantum gravity is under debate. In this note, we argue in several ways that the observation of GME does indeed tell us something new about gravity compared to previous experiments. In particular, we consider a quantum reference frame treatment of the experiment that allows us to pinpoint the single degree of freedom responsible for the effect. We also discuss the relevance of the Newtonian limit, the longitudinal/transverse decomposition of the field, and the local operations and classical communication theorem. Our conclusion is that experiments trying to detect GME would be interesting because (a) either positive or negative results would be able to falsify several theories (b) observation of GME would represent something truly novel.
Effect of extended gravitational decoupling on isotropization and complexity in

f(R,T)

theory
Authors: Sharif M , Naseer Tayyab
Published: January 2023

This paper develops some new analytical solutions to the

f
(

R

,

T

)

field equations through extended gravitational decoupling. For this purpose, we take spherical anisotropic configuration as a seed source and extend it to an additional source. The modified field equations comprise the impact of both sources which are then decoupled into two distinct sets by applying the transformations on g

tt
and g

rr
metric potentials. The original anisotropic source is adorned by the first sector, and we make it solvable by considering two different well-behaved solutions. The second sector is in terms of an additional source and we adopt some constraints to find deformation functions. The first constraint is the isotropization condition which transforms the total fluid distribution into an isotropic system only for a specific value of the decoupling parameter. The other constraint is taken as the complexity-free fluid distribution. The unknown constants are calculated at the hypersurface through matching conditions. The preliminary information (mass and radius) of a compact star

4
U
1820
−
30

is employed to analyze physical attributes of the resulting models. We conclude that certain values of both the coupling as well as decoupling parameter yield viable and stable solutions in this theory.
Interacting trajectory representation of quantum dynamics: influence of boundary conditions on the tunneling decay of resonant states
Authors: Cruz-Rodríguez L , Uranga-Piña L , Martínez-Mesa A , Meier C
Published: January 2023

We perform quantum trajectory simulations of the decay dynamics of initially localized resonant states. Quantum dynamics is represented by a swarm of interacting trajectories which maps the originally quantum problem into the motion of an equivalent (higher-dimensional) classical system. We address two model problems, in which the decay of the initial resonance leads to either spatially confined or asymptotically free wave-packet dynamics, specifically on a double well potential and on a potential plain. The traditional choice of fixed boundary conditions in the interacting trajectory representation (ITR), set at infinity, is found to have a moderate influence on the accuracy of the ITR of quantum trajectory dynamics, for the motion on a double well potential, i.e. the results of the trajectory-based scheme are in good correspondence with those obtained via quantum wave-packet propagation up to several fundamental vibrational periods. On the other hand, standard boundary conditions have negligible effect on the interacting trajectory dynamics of a decaying shape resonance, whose predictions reproduce quantum mechanical results at long times.
Steady state quantum statistics of a hybrid optomechanical-ferromagnet system: photon and magnon blockade
Authors: Kheirabady M Setodeh , Tavassoly M K
Published: January 2023

Magnon and photon blockade implementation and manipulation have significant practical applications in quantum information processing and quantum metrology due to their tight relations to single-photon and -magnon source devices. In this paper, we propose an experimentally feasible hybrid scheme for the dynamical description of the tripartite interacting system consisting of magnon and phonon modes with photons in an optomechanical system, from which we aim to explore the quantum statistics, as well as the magnon and photon blockade phenomenon. To achieve the purpose, the dissipative solution of the system is obtained with the help of the Lindblad master equation. Via employing the equal-time second-order correlation function and using the steady state solution of the system, the statistics and blockade effects of magnon and photon are analyzed and also their dependence on the parameters involved in the system are discussed. Utilizing feasible parameters, our simulations illustrate that, sub-Poissonian behavior and therefore, blockade of magnon and photon are simultaneously achieved. More importantly, the mentioned blockade effects can be obtained in a range of parameters (and not with specific) which makes our proposal easy to access, experimentally. Considering the above realizations, the introduced scheme opens up a pathway to design single-magnon and -photon generators, which are of crucial importance in advanced quantum science and technologies.
Excited muon production in muon colliders via contact interaction
Authors: Sahin M , Caliskan A
Published: January 2023

In recent years, with the enlightenment of some issues encountered in muon colliders, muon colliders have become more feasible for the high-energy physics community. For this reason, we studied the single production of an excited muon in muon colliders via contact interactions. In addition, we assumed that the excited muon decayed into a photon and muon through gauge interactions. Then, signal and background analyses were performed in muon–antimuon collider options with center-of-mass energies of 6, 14, and 100 TeV. The attainable mass and compositeness scale limits were calculated for the excited muon in these collider options. Based on the calculations, it was concluded that muon–antimuon colliders would be a perfect collider option for excited muon investigations.
A wavelet-based separation method for tonal and broadband components of low Reynolds-number propeller noise
Authors: Meloni S , de Paola E , Grande E , Ragni D , Stoica L G , Di Marco A , Camussi R
Published: January 2023

Propeller noise generally exhibits a rich mixture of tonal and broadband components related to different physical mechanisms. Specifically, the tones are characterized by having deterministic and persistent characteristics, while the broadband counterpart has random behaviour. The separation is essential for the experimenters as they provide information on the different noise sources. In this framework, the study presents a novel wavelet-based method able to separate the noise emitted by a low Reynolds number propeller into its tonal and broadband components. The technique is applied to an isolated rotor operating under different loading configurations, including hover and cruise conditions. The acoustic pressure data are obtained in the anechoic tunnel (A-tunnel) of the TU Delft low-speed laboratory with a near-field polar and azimuthal distribution of microphones. The method is based upon a threshold varying procedure that separates the tonal and broadband components through the computation of two-point statistics. Advantages and drawbacks with respect to other methodologies already known from the literature are discussed. The application of the method provides the spectral content of the tonal and broadband components as well as the different polar and azimuthal directivity. Specifically, the observed dipole-like shape directivity for the tonal part and flatter broadband OASPL, confirm that the method can provide quite a good separation. Furthermore, the overall flow behaviour is inferred from the decomposition and validated through benchmarked flow visualizations.