bluuebunny/crossref_metadata_2025 huggingface dataset:
Achieving stability and prosperity: The Chinese way
Authors: Cheng Quan , Ng Alex
Published: June 2023

State governance in corporations controls the economy and employment to develop prosperity in China. Does privatization achieve both objectives? Privatization theory views that giving up state control benefits firms economically but is quite silent on the value of employment benefits. However, market mix theory (Sappington and Stiglitz, J Policy Anal Manag 6(4):567–582, 1987; Stiglitz, Whither Socialism? MIT Press, Cambridge, MA, and London, England, 1994) views that state control of firms to provide employment is valuable. It further implies that corporate performance and employment objectives can co-exist well together. We formalize Market Mix Theory to reveal its testable implications on dual objectives and performance. We test the notion that Chinese corporations pursue two objectives: maximizing economic value and employment, unlike the singular objective of value maximization in Western firms. As well, we test the benefit of partial privatization. First, we test the market mix theory by studying the relationship between state ownership and employment and financial performance as a combined objective. We show that mixed firms have the highest performance in wealth maximization and employment compared to private and state-controlled firms. Second, we examine Chinese SOEs’ Employment with a large sample of 2536 public firms using panel regressions. We find that state ownership and firm employment have a positive relationship. State ownership is positively related to employment stability. Moreover, performance has a negative relationship with state ownership–employment. This result supports our over-employment hypothesis, meaning that economic performance is sacrificed to provide employment. Lastly, we show executive pay for SOE managers is positively related to employment. The employment objective is real in determining state control in Chinese corporations without conflicting to maximize shareholder wealth. Rather, the mixed form of ownership is optimal and vitally contributes overall to the stability and prosperity of China. Our formalization of market mix theory better reflects the reality of motivation, performance and benefits of partial privatization as exemplified in Chinese state-owned enterprises.
Detecting directional forces in the evolution of grammar: A case study of the English perfect with intransitives across EEBO, COHA, and Google Books
Authors: Okuda Shimpei , Hosaka Michio , Sasahara Kazutoshi
Published: June 2023

Languages have diverse characteristics that have emerged through evolution. In modern English grammar, the perfect is formed with have+PP (past participle), but in earlier English, the be+PP form also existed. It is widely recognised that the auxiliary verb BE was replaced by HAVE throughout evolution, except for some special cases. However, whether this evolution was caused by natural selection or random drift is still unclear. Here we examined directional forces in the evolution of the English perfect with intransitive by combining three large-scale data sources: Early English Books Online (EEBO), Corpus of Historical American English (COHA), and Google Books. We found that most intransitive verbs exhibited an apparent transition from be+PP to have+PP, most of which were classified as ‘selection’ by a deep neural network-based model. These results suggest that the English perfect could have evolved through natural selection rather than random drift, and provide insights into the cultural evolution of grammar.
Linking public leadership and public project success: the mediating role of team building
Authors: Khan Naqib Ullah , Zhongyi Peng , Han Heesup , Ariza-Montes Antonio
Published: June 2023

The existing research has linked the mainstream leadership styles to project success and team building. However, there is a lack of research evidence on how public sector-specific leadership styles influence project success and team building. This research uses social information processing theory to explore the influence of public leadership on project success and team building. The study also explores the fundamental processes by which public leadership engenders project success via the mediating mechanism of team building. Analysis of 436 responses from both public sector projects managers-subordinates dyad showed that public leadership positively relates to project success and team building. The analysis also showed that team building positively influences project success. Moreover, the findings revealed that team building partially mediates the influence of public leadership on project success.
Understanding the stochastic dynamics of sequential decision-making processes: A path-integral analysis of multi-armed bandits
Authors: Li Bo , Yeung Chi Ho
Published: June 2023

The multi-armed bandit (MAB) model is one of the most classical models to study decision-making in an uncertain environment. In this model, a player chooses one of K possible arms of a bandit machine to play at each time step, where the corresponding arm returns a random reward to the player, potentially from a specific unknown distribution. The target of the player is to collect as many rewards as possible during the process. Despite its simplicity, the MAB model offers an excellent playground for studying the trade-off between exploration vs exploitation and designing effective algorithms for sequential decision-making under uncertainty. Although many asymptotically optimal algorithms have been established, the finite-time behaviors of the stochastic dynamics of the MAB model appear much more challenging to analyze due to the intertwine between the decision-making and the rewards being collected. In this paper, we employ techniques in statistical physics to analyze the MAB model, which facilitates the characterization of the distribution of cumulative regrets at a finite short time, the central quantity of interest in an MAB algorithm, as well as the intricate dynamical behaviors of the model. Our analytical results, in good agreement with simulations, point to the emergence of an interesting multimodal regret distribution, with large regrets resulting from excess exploitation of sub-optimal arms due to an initial unlucky output from the optimal one.
Field induced phase transition and magnetic phase diagram of multiferroic Ca2CoSi2O7
Authors: Pham Cong Thanh , Vuong Hiep Van , Nguyen Tuan Anh , Bui Tu Dinh , Hoang Nhat Nam
Published: June 2023

Magnetic phase transitions are important for the application of individual materials toward modern spintronics and sensing. Using high-resolution sound velocity and pyrocurrent measurements, we have obtained a detailed magnetic phase diagram of multiferroic Ca2CoSi2O7 for magnetic fields applied along the crystallographic [100]- and [001]-directions. The magneto-acoustic measurements were conducted for both longitudinal and transverse modes in both static and pulsed magnetic fields up to 17 and 68 T, respectively. Distinct anomalies with significant changes in sound velocity and sound attenuation were observed at the onset of the structural and magnetic phase transitions. Interestingly, results obtained for fields parallel to the [100]-direction reveal a hysteresis and step-like decrements in ultrasound indicating a transition into a different metastable structural distortion below TN and at magnetic fields between 4 and 10 T that has not been previously reported. We believe that this field-induced distorted structure phase may be the cause of the subsequent phase transition at 11 T. At low temperatures, a softening of the lattice within the ordered phases is also observed, which may be due to residual spin fluctuations.
Homoclinic bifurcation and switching of edge state in plane Couette flow
Authors: Lustro Julius Rhoan T. , Shimizu Yudai , Kawahara Genta
Published: June 2023

We identify the presence of three homoclinic bifurcations that are associated with edge states in a system that is governed by the full Navier–Stokes equation. In plane Couette flow with a streamwise period slightly longer than the minimal unit, we describe a rich bifurcation scenario that is related to new time-periodic solutions and the Nagata steady solution [M. Nagata, J. Fluid Mech. 217, 519–527 (1990)]. In this computational domain, the vigorous time-periodic solution (PO3) with comparable fluctuation amplitude to turbulence and the lower branch of the Nagata steady solution are considered as edge states at different ranges of Reynolds number. These edge states can help in understanding the mechanism of subcritical transition to turbulence in wall-bounded shear flows. At the Reynolds numbers at which the homoclinic bifurcations occur, we find the creation (or destruction) of the time-periodic solutions. At a higher Reynolds number, we observe the edge state switching from the lower-branch Nagata steady solution to PO3 at the creation of this vigorous cycle due to the homoclinic bifurcation. Consequently, the formation of the boundary separating the basins of attraction of the laminar attractor and the time-periodic/chaotic attractor also switches to the respective stable manifolds of the edge states, providing a change in the behavior of a typical amplitude of perturbation toward triggering the transition to turbulence.
Impact of external excitations on blinking enhanced synchronization in bistable vibrational energy harvesters
Authors: Durairaj Premraj , Kanagaraj Sathiyadevi , Duraisamy Prakash , Karthikeyan Anitha , Rajagopal Karthikeyan
Published: June 2023

Vibrational energy harvesters are capable of converting low-frequency broad-band mechanical energy into electrical power and can be used in implantable medical devices and wireless sensors. With the use of such energy harvesters, it is feasible to generate continuous power that is more reliable and cost-effective. According to previous findings, the energy harvester can offer rich complex dynamics, one of which is obtaining the synchronization behavior, which is intriguing to achieve desirable power from energy harvesters. Therefore, we consider bistable energy harvesters with periodic and quasiperiodic excitations to investigate synchronization. Specifically, we introduce blinking into the coupling function to check whether it improves the synchronization. Interestingly, we discover that raising the normalized proportion of blinking can initiate synchronization behaviors even with lower optimal coupling strength than the absence of blinking in the coupling (i.e., continuous coupling). The existence of synchronization behaviors is confirmed by finding the largest Lyapunov exponents. In addition, the results show that the optimal coupling strength needed to achieve synchronization for quasiperiodic excitations is smaller than that for periodic excitations.
Compact single fiber optical tweezer–micropipette system for completely noninvasive cell sorting
Authors: Wang Yunkai , Lu Yan , Sun Yongqiang , Dong Taiji , Zhou Yekun , Li Dong , Yan Lun , Sun Jiayao , Jiang Chun Lei
Published: June 2023

Bridging optical tweezers and microfluidics can form a multifunctional platform, which can overcome the difficulties of precise manipulation in hydrodynamic flow in a noninvasive method. However, when integrated into a microfluidic chip, the fiber optic tweezer loses its flexibility. Here, we propose a compact single fiber optical tweezer–micropipette system. It can sort particles by differences in shape and refractive index in a completely noninvasive way while retaining the flexibility, high selectivity, and precision of a fiber optical tweezer. Compact microfluidic channels are formed by combining two different-diameter micropipettes. The internal diameter of the circular microfluidic channel is less than 30 μm. Furthermore, we calculated the trapping and pushing regions of Yeast and Chlorella and achieved the separation of Yeast from Chlorella in the experiments. We did 90 sets of tests on the sorting accuracy of single fiber optical tweezer (SFOT). SFOT was able to distinguish between two types of particles in each test. With the advantages of high selectivity, high accuracy, low optical power consumption, and compact structure, such methods can be used in the fields of optical separation, cell transportation, cell sorting, and single-cell analysis.
A resonant single-wing bionic piezoelectric motor based on a biasing self-clamping mechanism
Authors: He Liangguo , Qian An , Dong Yuge , Li Xinyu , Wan Zhikai , Yue Xukang
Published: June 2023

In this study, a resonant single-wing bionic piezoelectric motor based on a biasing self-clamping mechanism inspired by dragonfly flight was designed, assembled, and tested. The main mechanism of the designed piezoelectric motor includes a mover (including a vibrator, clamping foot, bionic pedestal, etc.), a stator, and other auxiliary components. The clamping foot of the mover contacts the side of the stator to form a biasing self-clamping mechanism, which can achieve a clamping effect within half a cycle of the vibrator’s resonant vibration. The piezoelectric plate on the vibrator receives a single harmonic excitation from the signal generator, causing the base plate to bend and distort. The base plate drives the clamping foot to move regularly, causing the mover to perform a linear motion. Moreover, repeated single harmonic excitations can realize the continuous movement of the mover. The structure of the piezoelectric motor was optimized using COMSOL6.0, which is a finite element analysis software. The first-order bending vibration of the vibrator was chosen as the working mode through finite element simulation, and an experimental platform was built. The performance of the prototype piezoelectric motor was tested and verified on the experimental platform. The final experimental data show that under the conditions of 300 Vp–p excitation voltage and 109 Hz driving frequency, the maximum no-load speed of the prototype reaches 6.184 mm/s, and the maximum load of the motor is 4 g.
Epileptic detection in single and multi-lead EEG signals using persistent homology based on bi-directional weighted visibility graphs
Authors: Yang Xiaodong , Ren Yanlin , Hong Binyi , He Aijun , Wang Jun , Wang Zhixiao
Published: June 2023

Epilepsy is a widespread neurological disorder, and its recurrence and suddenness are making automatic detection of seizure an urgent necessity. For this purpose, this paper performs topological data analysis (TDA) of electroencephalographic (EEG) signals by the medium of graphs to explore the potential brain activity information they contain. Through our innovative method, we first map the time series of epileptic EEGs into bi-directional weighted visibility graphs (BWVGs), which give more comprehensive reflections of the signals compared to previous existing structures. Traditional graph-theoretic measurements are generally partial and mainly consider differences or correlations in vertices or edges, whereas persistent homology (PH), the essential part of TDA, provides an alternative way of thinking by quantifying the topology structure of the graphs and analyzing the evolution of these topological properties with scale changes. Therefore, we analyze the PH for BWVGs and then obtain the two indicators of persistence and birth–death for homology groups to reflect the topology of the mapping graphs of EEG signals and reveal the discrepancies in brain dynamics. Furthermore, we adopt neural networks (NNs) for the automatic detection of epileptic signals and successfully achieve a classification accuracy of 99.67% when distinguishing among three different sets of EEG signals from seizure, seizure-free, and healthy subjects. In addition, to accommodate multi-leads, we propose a classifier that incorporates graph structure to distinguish seizure and seizure-free EEG signals. The classification accuracies of the two subjects used in the classifier are as high as 99.23% and 94.76%, respectively, indicating that our proposed model is useful for the analysis of EEG signals.
3D structured Bessel beam polarization and its application to imprint chiral optical properties in silica
Authors: Lu Jiafeng , Hassan Mostafa , Courvoisier François , Garcia-Caurel Enrique , Brisset François , Ossikovski Razvigor , Zeng Xianglong , Poumellec Bertrand , Lancry Matthieu
Published: June 2023

Polarization plays a crucial role in light–matter interactions; hence its overall manipulation is an essential key to unlock the versatility of light manufacturing, especially in femtosecond laser direct writing. Existing polarization-shaping techniques, however, only focus on their manipulation in the transverse plane of light beams, i.e., two-dimensional control. In this paper, we propose a novel passive strategy that exploits a class of femtosecond laser written space varying birefringent elements to shape the polarization state along the optical path. As a demonstration, we generate a three-dimensional structured Bessel beam whose linear polarization state slowly evolves along the focus (typ. 90° within 60λ). Such a “helically polarized” Bessel beam allows imprinting “twisted nanogratings” in SiO2 glass which result in an extrinsic optical chirality at a micrometric scale and own a high optical rotation. Our work provides new perspectives for three-dimensional polarization manipulation and insights into applications in structured light, light–matter interaction, and chiral device fabrication.
Changes in the photoluminescence of ultra-weak interlayer coupled MoSe2/PbI2 van der Waals heterostructures
Authors: Wu Di , Li Junzi , Hao Qiaoyan , Zhou Wenzhe , Wang Zhuo , Liu Jidong , Tu Yudi , Jiang Junjie , Qi Dianyu , Li Peng , Wang Zixuan , Gan Haibo , Hong Guo , Liu Fei , He Tingchao , Ouyang Fangping , Zhang Wenjing
Published: June 2023

Photo-generated dynamics have been extensively studied in two-dimensional (2D) heterostructures, such as MoSe2/WSe2 and MoSe2/MoS2. Here, we fabricate few-layer PbI2 and monolayer MoSe2 van der Waals (vdW) heterostructures. The excited-wavelength dependent measurements of photoluminescence (PL) and transient dynamic absorption spectra show that there is almost no photo-generated charge transfer between PbI2 and MoSe2. PL changes of MoSe2 are rather dominated by the Fermi level (EF) modulation through the interlayer charge transfer. Density functional theory calculation shows that binding energies in the heterostructures of MoSe2/WSe2 or MoSe2/MoS2 are 2–3 times higher than that of the MoSe2/PbI2 heterostructure, suggesting the weaker interlayer coupling between MoSe2 and PbI2. We propose that the weak interlayer vdW coupling cannot drive the photo-generated interlayer charge transfer while the EF modulation can be achieved through the interlayer charge transfer. The findings will be helpful to fundamental research and applications for novel optoelectronic devices based on 2D material vdW heterostructures.
Resonant escape induced by a finite time harmonic excitation
Authors: Kravetc Pavel , Gendelman Oleg , Fidlin Alexander
Published: June 2023

The purpose of this paper is twofold. First, we obtain the critical forcing needed for a resonant escape in finite time in the presence of damping. Second, we adapt the isolated resonance approximation (AIR) method to find the escaping time and analyze the escape in finite time. Approximations of the escape time on both the phase and the parameter planes were obtained. In particular, a peculiar fractal-like boundary of the finite-time escape region was revealed. This discovery helps to better understand the limitations of AIR and explains the sensitivity of the numerical experiments to the integration time.
Resetting induced multimodality
Authors: Pogorzelec Przemysław , Dybiec Bartłomiej
Published: June 2023

Properties of stochastic systems are defined by the noise type and deterministic forces acting on the system. In out-of-equilibrium setups, e.g., for motions under action of Lévy noises, the existence of the stationary state is not only determined by the potential but also by the noise. Potential wells need to be steeper than parabolic in order to assure the existence of stationary states. The existence of stationary states, in sub-harmonic potential wells, can be restored by stochastic resetting, which is the protocol of starting over at random times. Herein, we demonstrate that the combined action of Lévy noise and Poissonian stochastic resetting can result in the phase transition between non-equilibrium stationary states of various multimodality in the overdamped system in super-harmonic potentials. Fine-tuned resetting rates can increase the modality of stationary states, while for high resetting rates, the multimodality is destroyed as the stochastic resetting limits the spread of particles.
Attractor–repeller collision and the heterodimensional dynamics
Authors: Chigarev Vladimir , Kazakov Alexey , Pikovsky Arkady
Published: June 2023

We study the heterodimensional dynamics in a simple map on a three-dimensional torus. This map consists of a two-dimensional driving Anosov map and a one-dimensional driven Möbius map, and demonstrates the collision of a chaotic attractor with a chaotic repeller if parameters are varied. We explore this collision by following tangent bifurcations of the periodic orbits and establish a regime where periodic orbits with different numbers of unstable directions coexist in a chaotic set. For this situation, we construct a heterodimensional cycle connecting these periodic orbits. Furthermore, we discuss properties of the rotation number and of the nontrivial Lyapunov exponent at the collision and in the heterodimensional regime.
Electric field control of RKKY coupling through solid-state ionics
Authors: Ameziane Maria , Rosenkamp Roy , Flajšman Lukáš , van Dijken Sebastiaan , Mansell Rhodri
Published: June 2023

Placing a suitable spacer layer between two magnetic layers can lead to an interaction between the magnetic layers known as Ruderman–Kittel–Kasuya–Yosida (RKKY) coupling. Controlling RKKY coupling, particularly the ability to switch between ferromagnetic and antiferromagnetic coupling, would enable novel magnetic data storage devices. By combining solid-state Li ion battery technology with an out-of-plane magnetized Co/Pt-based stack coupled through a Ru interlayer, we investigate the effects of the insertion of Li ions on the magnetic properties of the stack. The RKKY coupling and its voltage dependence are measured as a function of the Ru interlayer thickness, along with the effects of repeated voltage cycling. The Li ions both change the amplitude of the RKKY coupling and its phase, leading to the ability to switch the RKKY coupling between ferromagnetic and antiferromagnetic with applied voltages.
Short-lived chimera states
Authors: Kong Ling-Wei , Lai Ying-Cheng
Published: June 2023

In the classic Kuramoto system of coupled two-dimensional rotators, chimera states characterized by the coexistence of synchronous and asynchronous groups of oscillators are long-lived because the average lifetime of these states increases exponentially with the system size. Recently, it was discovered that, when the rotators in the Kuramoto model are three-dimensional, the chimera states become short-lived in the sense that their lifetime scales with only the logarithm of the dimension-augmenting perturbation. We introduce transverse-stability analysis to understand the short-lived chimera states. In particular, on the unit sphere representing three-dimensional (3D) rotations, the long-lived chimera states in the classic Kuramoto system occur on the equator, to which latitudinal perturbations that make the rotations 3D are transverse. We demonstrate that the largest transverse Lyapunov exponent calculated with respect to these long-lived chimera states is typically positive, making them short-lived. The transverse-stability analysis turns the previous numerical scaling law of the transient lifetime into an exact formula: the “free” proportional constant in the original scaling law can now be precisely determined in terms of the largest transverse Lyapunov exponent. Our analysis reinforces the speculation that in physical systems, chimera states can be short-lived as they are vulnerable to any perturbations that have a component transverse to the invariant subspace in which they live.
Evolutionarily stable strategies to overcome Allee effect in predator–prey interaction
Authors: Biswas Saswati , Ghosh Dibakar
Published: June 2023

Every successful species invasion is facilitated by both ecological and evolutionary mechanisms. The evolution of population’s fitness related traits acts as functional adaptations to Allee effects. This trade-off increases predatory success at an expense of elevated death rate of potential predators. We address our queries employing an eco-evolutionary modeling approach that provides a means of circumventing inverse density-dependent effect. In the absence of evolution, the ecological system potentially exhibits multi-stable configurations under identical ecological conditions by allowing different bifurcation scenarios with the Allee effect. The model predicts a high risk of catastrophic extinction of interacting populations around different types of saddle-node bifurcations resulting from the increased Allee effect. We adopt the game-theoretic approach to derive the analytical conditions for the emergence of evolutionarily stable strategy (ESS) when the ecological system possesses asymptotically stable steady states as well as population cycles. We establish that ESSs occur at those values of adopted evolutionary strategies that are local optima of some functional forms of model parameters. Overall, our theoretical study provides important ecological insights in predicting successful biological invasions in the light of evolution.
Optical anisotropy and polarization selectivity in MoS2/Ta2NiSe5 van der Waals heterostructures
Authors: Wang Wenjia , Sun Yurun , Dai Pan , Gao Honglei , Du Changhui , Li Kuilong
Published: June 2023

In-plane anisotropy induced by a low-symmetric lattice structure in two-dimensional (2D) van der Waals (vdWs) materials has significantly promoted their applications in optoelectronic devices, especially in polarization photodetection. Given the mature preparation technology of transition metal dichalcogenides (TMDCs), introducing artificial anisotropy into symmetric TMDCs becomes a promising way to trigger more excellent functionalities beyond their intrinsic properties. Herein, monolayer MoS2 in the MoS2/Ta2NiSe5 vdWs heterostructure presents obvious anisotropic optical properties confirmed by polarized Raman and photoluminescence spectra, which is mainly ascribed to the uniaxial strain via strong interlayer couplings. Moreover, the MoS2/Ta2NiSe5 heterojunction endows unique orientation-selected polarized absorbance. In the visible region, the dominant polarized orientation is along the armchair axis while rotated to the perpendicular direction in the near-infrared spectrum, which is mainly ascribed to the intrinsic linear dichroism of Ta2NiSe5. The results suggest that the MoS2/Ta2NiSe5 heterostructure provides a promising platform for artificial regulation of the optoelectronic properties of symmetric MoS2 and integrated optical applications in the polarization-sensitive photodetection.
Rotating cantilever-based low-frequency double-fiber grating acceleration sensor
Authors: Hong Li , Mai Menglin , Zhang Ruilei , Luo Qingshan , Wang Xiaoyu
Published: June 2023

Acceleration sensors play an important role in bridges, dams, seismic monitoring, geological exploration, and more. Aiming at the problem that it is still difficult to accurately measure low-frequency vibration signals with low-frequency acceleration sensors, a high-sensitivity, wide-low-band fiber Bragg grating (FBG) acceleration sensor incorporating a rotating cantilever and springs was proposed. A sensor mechanics model was built, and its key parameters were analyzed theoretically and optimized in size. ANSYS Workbench was used for simulation analysis, and the physical sensor was developed while a low-frequency test platform was established for performance tests. The experimental results suggested that the natural frequency of the sensor was 78 Hz, the operating frequency band was 1–55 Hz, the sensitivity was 1127.2 pm/g, the transverse interference immunity was less than 5.45%, and the dynamic range was 86.45 dB. With high sensitivity, wide low frequency band, and excellent temperature compensation characteristics, the designed sensor could provide a reference for the design of like FBG acceleration sensors.
Beyond-band discrete soliton interaction in binary waveguide arrays
Authors: Tran Minh C. , Tran Truong X.
Published: June 2023

We investigate different scenarios of interaction between two beyond-band discrete solitons (BBDSs), which are a new class of solitons in binary waveguide arrays and have been investigated just recently. In the quasi-continuous regime when solitons intensity is low and, thus, solitons are broad, two BBDSs with the same envelope in binary waveguide arrays interact with each other practically like two well-known fundamental solitons governed by the nonlinear Schrödinger equation in a single optical fiber. However, this similarity disappears if the discrete nature of the system is enhanced by increasing the intensity of BBDSs. In that case, two initially in-phase BBDSs with the same detuning cannot periodically collide during propagation. We also show that single-peaked BBDSs are more robust and less mobile than double-peaked BBDSs with the same detuning. This robustness stops two identical single-peaked BBDSs from interaction even at initial separations when double-peaked BBDSs can still strongly interact with each other or with single-peaked BBDSs.
Constructive role of shot noise in the collective dynamics of neural networks
Authors: Klinshov V. V. , Smelov P. S. , Kirillov S. Yu.
Published: June 2023

Finite-size effects may significantly influence the collective dynamics of large populations of neurons. Recently, we have shown that in globally coupled networks these effects can be interpreted as additional common noise term, the so-called shot noise, to the macroscopic dynamics unfolding in the thermodynamic limit. Here, we continue to explore the role of the shot noise in the collective dynamics of globally coupled neural networks. Namely, we study the noise-induced switching between different macroscopic regimes. We show that shot noise can turn attractors of the infinitely large network into metastable states whose lifetimes smoothly depend on the system parameters. A surprising effect is that the shot noise modifies the region where a certain macroscopic regime exists compared to the thermodynamic limit. This may be interpreted as a constructive role of the shot noise since a certain macroscopic state appears in a parameter region where it does not exist in an infinite network.
Algae–water–silica interactions in low and high ionic strength environments
Authors: Azam Md. Shafiul , Lu Xinguo , Rathore Bhumika S. , Padhan Rakesh , Wan Zhijing , Hore Dennis K.
Published: June 2023

The interaction between algae and solid surfaces is of direct interest for the optimization of biofuel production technologies. Silica is particularly relevant due the use of solgel matrices for enhanced growth and ease of processing, where ionic strength variation is an important consideration. Here, an inverted fluorescence experiment is used to perform measurements of the distance between a silica surface and algae in solution. At low ionic strength, the average algae–silica distance is approximately 90 nm but increases to roughly 130 nm at 1 M NaCl, contradicting the prediction based on simple electrical double layer interaction models. These findings illustrate the role of biochemical and electrostatic interactions at charged aqueous interfaces of relevance to biofuel production.
Charge states of nitrogen-vacancy centers in Fermi level controlled diamond n-i-n junctions
Authors: Shimizu M. , Makino T. , Kato H. , Fujiwara M. , Ogura M. , Mizuochi N. , Hatano M.
Published: June 2023

Control of the charge state of the nitrogen-vacancy (NV) center is crucial because of its instability and its transitions between the negative (NV–) and neutral (NV0) NV charge states under laser irradiation In this study, we fabricated an n-i-n junction, with an i-layer sandwiched between two phosphorus-doped n-layers; then, we measured the charge state of NV centers under steady state and laser irradiation in a known band structure where the Fermi energy changes gradually. The steady-state charge state measured by a nondestructive single shot exhibited stable NV– and NV0 signals when the Fermi level was even slightly above and below the transition level, respectively. This result indicates that the charge state can be significantly stabilized through band engineering. Both charge-state populations were observed only when the Fermi level was close to the transition level. Under continuous green laser irradiation, the ratio of NV– measured by the photoluminescence spectra changed gradually with the Fermi level in the depletion layer because of the balance between excitation from the laser and the supply of charge from the band. This outcome agrees reasonably with the calculated bands. Furthermore, we measured the PL spectra of the ensemble NV centers and discovered that their charge state can be well-controlled, as in the single NV center. The charge state of the i-layer at the interface can be stabilized by depositing a thin n-layer on the surface. These results would contribute significantly to improve sensor performance.
Tiered synchronization in Kuramoto oscillators with adaptive higher-order interactions
Authors: Rajwani Priyanka , Suman Ayushi , Jalan Sarika
Published: June 2023

Phase transitions widely occur in natural systems. Incorporation of higher-order interactions in coupled dynamics is known to cause first-order phase transition to synchronization in an otherwise smooth second-order in the presence of only pairwise interactions. Here, we discover that adaptation in higher-order interactions restores the second-order phase transition in the former setup and notably produces additional bifurcation referred as tiered synchronization as a consequence of combination of super-critical pitchfork and two saddle node bifurcations. The Ott–Antonsen manifold underlines the interplay of higher-order interactions and adaptation in instigating tiered synchronization, as well as provides complete description of all (un)stable states. These results would be important in comprehending dynamics of real-world systems with inherent higher-order interactions and adaptation through feedback coupling.
Increased habitat connectivity induces diversity via noise-induced symmetry breaking
Authors: Narang Arzoo , Banerjee Tanmoy , Sharathi Dutta Partha
Published: June 2023

Stochasticity or noise is omnipresent in ecosystems that mediates community dynamics. The beneficial role of stochasticity in enhancing species coexistence and, hence, in promoting biodiversity is well recognized. However, incorporating stochastic birth and death processes in excitable slow–fast ecological systems to study its response to biodiversity is largely unexplored. Considering an ecological network of excitable consumer–resource systems, we study the interplay of network structure and noise on species’ collective dynamics. We find that noise drives the system out of the excitable regime, and high habitat patch connectance in the ordered as well as random networks promotes species’ diversity by inducing new steady states via noise-induced symmetry breaking.
Solutions of the converging and diverging shock problem in a medium with varying density
Authors: Giron Itamar , Balberg Shmuel , Krief Menahem
Published: June 2023

We consider the solutions of the Guderley problem, consisting of a converging and diverging hydrodynamic shock wave in an ideal gas with a power law initial density profile. The self-similar solutions and specifically the reflected shock coefficient, which determines the path of the reflected shock, are studied in detail for cylindrical and spherical symmetries and for a wide range of values of the adiabatic index and the spatial density exponent. Finally, we perform a comprehensive comparison between the analytic solutions and Lagrangian hydrodynamic simulations by setting proper initial and boundary conditions. A very good agreement between the analytical solutions and the numerical simulations is obtained. This demonstrates the usefulness of the analytic solutions as a code verification test problem.
The influence of the selection of zero-crossing starting point on measurement accuracy of the absolute gravimeter
Authors: Mou Zonglei , Han Xiao , Hu Ruo , Li Zhenfei , Liu Chunhui
Published: June 2023

The absolute gravimeter is an important precision instrument for obtaining gravity acceleration in fields such as geophysics, resource survey, and national defense construction. It is greatly affected by its self-vibration during operation. If the self-vibration frequency exceeds the range of the sensor, it will not be effectively processed by the method of vibration compensation. To solve this problem, the effect of instrument self-vibration on the accuracy of gravity is analyzed through simulation and actual measurement data. Based on the calculation of the simulation data, the functional relationship between the self-vibration frequency of the instrument and the zero-crossing starting point is obtained. The Starting Point Mathematical Model is established to accurately calculate the zero-crossing starting point. Then, the zero-crossing starting point calculated by the model is taken as the time reference of the zero crossing for the least square fitting. The split and platform absolute gravity measurement systems are built, respectively, to test the measured data. The test results reveal that, compared with the traditional method using the initial falling time as the zero-crossing starting point, the proposed method can reduce the gravity deviation by 50 μGal and improve the accuracy by an average of 35.35% under split-type working conditions. Under platform-type working conditions, it can decrease the gravity deviation by 3 mGal and improve the accuracy by an average of 53.78%. The method proposed can reduce the fixed phase vibration interference caused by the instrument self-vibration and provide a reference for improving the measurement accuracy of the instrument under different working conditions.
Spin-velocity locking in a helical chain of atomic p± orbitals
Authors: Kashiwa Shinnosuke , Akera Hiroshi
Published: June 2023

Observations of a high spin selectivity in various helical structures, which is called the chirality-induced spin selectivity, suggest a common mechanism originating from the helical geometry. In this paper, we consider a helical chain of atomic p± orbitals having the tangential angular momentum l = ±1. We show in this model that the coupling of l and the spin gives rise to spin-velocity locking, i.e., directions of spin and group velocity are parallel or antiparallel depending on the chirality of the helix, and consequently, an almost perfect spin selectivity in a specific energy region in a wide range of the curvature and the torsion of the helix. We find that the present spin-velocity locking originates from the helical symmetry in which the Hamiltonian is invariant with respect to a combined operation of the rotation around the helix axis and the translation along the helix axis. Therefore, we expect that spin-velocity locking occurs in a wide variety of helical structures.
Experimental construction of force- and frequency-response curves of
nonlinear resonators
Authors: Elhady Alaaeldin , Alghamdi Majed S. , Abdel-Rahman Eihab
Published: June 2023

We present an experimental technique to construct the response of nonlinear resonators under harmonic excitation as a control parameter is swept. Our technique can resolve nonlinear features in the resonator response, such as bifurcations and hysteresis. To validate it, we construct the frequency response of a MEMS resonator while the excitation frequency is swept. The response is measured optically and recorded in the time domain. The root-mean-square of the response is calculated over a variable-size time-window. The sweep time, window size, and frequency step size were found to be limited by the quality factor of the resonator under test. We examine and describe those limitations in terms of the slew rate and sampling frequency. Although we used optical measurements to validate the technique, the methods described herein are applicable to any measured response signal.
Propagation of wave packets along large-scale background waves
Authors: Shaykin D. V. , Kamchatnov A. M.
Published: June 2023

We study propagation of high-frequency wave packets along a large-scale background wave, which evolves according to dispersionless hydrodynamic equations for two variables (fluid density and flow velocity). Influence of the wave packet on evolution of the background wave is neglected, so the large-scale evolution can be found independently of the wave packet's motion. At the same time, propagation of the packet depends in an essential way on the background wave, and it can be considered in a framework of the geometric optics approximation with the use of Hamilton equations for the carrier wave number and the mean co-ordinate of the packet. We derive equations for the carrier wave number as a function of the parameters, which describe the background wave. When they are solved, the path of the packet can be found by simple integration of the Hamilton equation. The theory is illustrated by its application to the problem of propagation of wave packets along expanding a large-scale wave, in which evolution is described by the shallow water equations. In particular, they correspond to the dispersionless limit of the defocusing nonlinear Schrödinger equation, and then the expanding wave can be considered as an expanding cloud of the Bose–Einstein condensate. Reflection of wave packets from upstream flows and their propagation along stationary flows are also discussed. The analytical solutions found for these particular cases agree very well with an exact numerical solution of the nonlinear Schrödinger equation.
Gravity currents of viscous fluids in a vertically widening and converging fracture
Authors: Longo S.
Published: June 2023

We are investigating flows in the viscous-buoyancy balance regime in a converging channel with an upward increase in the width, with the gap of the channel varying according to a xkzr power function, being x and z the horizontal and vertical coordinate, respectively, and with 0<k<1 and 0<r<1 in order to be consistent with the model. The fluid rheology is described according to the Ostwald–de Waele model, with a power-law relationship between shear stress and shear rate and with application for shear-thinning, shear-thickening and, as a special case, Newtonian fluids. While for the case of flow in the direction of widening of the horizontal channel, a self-similar solution of the first kind can be expected, for flow toward the origin, with channel narrowing horizontally, the solution is self-similar of the second kind, with the space and a reduced time coupled in a self-similar independent variable but with an unknown parameter of the transformation group that makes the differential problem invariant. The solution is found in the phase plane by numerical integration of the paths connecting pairs of singular points, separately for the pre-closure phase, in which the current front advances invading the channel, and for the post-closure or leveling phase, in which the fluid has reached the origin and the front no longer propagates, while the level progressively increases canceling the pressure gradient. Integration is performed with a trial and error procedure by modifying the unknown parameter, generally named eigenvalue and specifically critical eigenvalue when the path has been successfully integrated. The overall effect of an increasing permeability upward is that of an increase in the front speed, with the current profile also becoming locally steeper. The effect of an increase in the fluid-behavior index is mixed, as it reduces the speed of the front but still increases the steepness of the local current profile. In any case, the model implies that the eigenvalue tends to infinity for k→1 even in the presence of an increase in the vertical permeability (r > 0).
Lubricant-infused iron palmitate surfaces with high durability and stable condensation heat transfer
Authors: Gulfam Raza
Published: June 2023

Slippery liquid-infused porous surfaces are vulnerable to lubricant depletion caused by three major factors encompassing, the evaporation, cloaking, and shearing. Herein, lubricant-infused iron palmitate surfaces (LI-IPSs) are presented addressing the challenges of (1) evaporation-driven lubricant depletion enabled by the immensely clustered micro-/nano-structures of iron palmitate surface (IPS), (2) completely suppressing the wetting ridge even with miscible water-oil combinations enabled by only the handful uptake of oil by IPS. The apparent contact angle θa and sliding angle α of water on LI-IPSs are 98° ± 2° and 3° ± 1°, respectively. Under evaporation-driven lubricant depletion analysis, the shelf-durability of LI-IPSs has been found to last for 10 days in partially open environment at the ambient temperature (25 °C). The heat fluxes and condensate fluxes have been determined. The highest condensate flux on LI-IPSs (14 kgh−1 m−2) is ascribed to the dropwise condensation mode with efficient droplet dynamics. However, the service durability of LI-IPSs has lasted only for 50 ± 5 min under rigorous condensation, which is further addressed by developing a LI-IPS prototype. Based on the excellent wicking capability of IPS, LI-IPS prototype is capable of maintaining the dropwise condensation unless the oil is available in the oil tub. The LI-IPS prototype has been subjected to open environment at ambient temperature for 168 h, and even after that, the stable dropwise condensation has been achieved with the same range of droplet speed as had been observed in the first hour. Meantime, the high condensation heat fluxes at various subcooling temperatures are obtained, justifying the promising ability of LI-IPS.
One-dimensional modeling of microvascular hemodynamics in the retina using multimodal imaging
Authors: Julien L. , Bonnin S. , Paques M. , Fullana J.-M.
Published: June 2023

Modeling techniques are an essential complement to clinical studies of the retina, as they provide access to non-measurable parameters throughout the network and enable the simulation of controlled disturbances or pathologies. In this work, we propose the development of a patient-specific one-dimensional model of the arterial circulation in the retina. Our model is based on conservation laws and utilizes morphometric and velocimetric data obtained through clinical multimodal imaging to construct the network topology and impose realistic boundary conditions. Specifically, our model simulates blood flow from the central retina artery to the terminal smallest arterioles. To validate our model, we perform a sensitivity analysis and compare its results to published data. Finally, we use our model to investigate the hemodynamic consequences of focal stenosis on retinal arteries. Overall, our model provides a valuable tool for exploring the complex dynamics of retinal blood flow and their potential clinical implications.