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In mammals, there is a central clock that regulates both physiological and behavioral circadian rhythms. This clock is situated within the suprachiasmatic nucleus (SCN), which consists of two nuclei in the mammalian brain. Each nucleus has two subgroups, i.e., the ventral-lateral (VL) part and the dorsal-medial (DM) part, so that a total of four subgroups are within the SCN. Thus far, the connection structures of the four subgroups has not been explored in the experiment due to the lack of technology. In this study, based on the Poincaré model, we examined the effect of the connection structures on the synchronization between the subgroups, which is important for the robust rhythms of the SCN, under constant darkness. Comparing seven structures, we found that the connection of the VL in one nucleus to the DM in another is more conducive to the synchronization, but the connection between the two VL subgroups or between the two DM subgroups across the different nuclei reduces the synchronization degree. Our findings illuminate the influence of the connection structures of the four subgroups on the SCN function. [ABSTRACT FROM AUTHOR]

The Master Stability Function (MSF) is a crucial tool for understanding the synchronization behavior of coupled nonlinear oscillators. In recent years, the field of fractional calculus and its applications in nonlinear dynamics gained significant attention, leading to an expanded focus on the network dynamics of such systems. This study aims to explore this emerging area by deriving the MSF for coupled fractional-order nonlinear oscillators and investigating their relationship with coupling strength and fractional order. To provide a comprehensive comparison, we utilize the well-known nonlinear oscillators to study the differences and similarities between integer-order and fractional-order MSFs. Our analysis reveals that, similar to integer-order systems, fractional-order coupled nonlinear oscillators exhibit MSFs that can be characterized by the presence of negative values within a finite interval of the normalized coupling parameter. This negative region is crucial as it indicates stable synchronization. Furthermore, we categorize the fractional-order MSFs using the same classifications applied to integer-order MSFs. This classification helps in systematically understanding and comparing the synchronization properties of both types of systems. Our findings are supported by extensive numerical simulations, which demonstrate that the majority of fractional-order coupled oscillators exhibit higher classes of MSF. This higher classification suggests that fractional-order systems have a superior ability to achieve synchronization compared to their integer-order counterparts. In summary, this study underscores the significance of fractional calculus in enhancing our understanding of synchronization in complex systems. The derived MSF for fractional-order nonlinear oscillators provides valuable insights into their dynamic behavior and opens new avenues for research in various scientific and engineering disciplines. [ABSTRACT FROM AUTHOR]

In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis of structure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectric coupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulations are used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely (1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weakly coupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially strongly coupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation for the two types of coupling, respectively. Numerical examples using a piezoelectric energy harvester, which is a typical structure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most cost-effective algorithm. [ABSTRACT FROM AUTHOR]

Photon-magnon coupling (PMC) integrates microwave or optical photons with magnons, aiming to exploit their distinct strengths in a unified hybrid quantum system, for potential applications in quantum information science and technology. By utilizing numerical simulations, we design a planar hybrid system comprising a hexagonal-ring resonator (HRR) and yttrium iron garnet (YIG) thin film to explore the interaction between microwave photons and magnons. The anti-crossing effects between the HRR's photon mode and the YIG's magnon modes were observed in |S21|-frequency plots under various externally applied magnetic fields. An equivalent theoretical model, based on coupled oscillators, accurately replicated the observed anti-crossing effect and provided estimates for the PMC strength. Furthermore, we explored the behavior of the photon-magnon interaction by altering the position of the YIG film on the HRR's track width, allowing for a more reliable control of the PMC strength variable within the range of 38.78 to 126.6 MHz (nearly 200%) in the planar-geometry HRR/YIG hybrid system. This study opens avenues for designing novel hybrid systems with effective control over the strength of PMC in a planar geometry. [ABSTRACT FROM AUTHOR]

This study presents a planar hybrid system consisting of an electric-field-coupled resonator (ELCR) and yttrium iron garnet (YIG) film, designed to investigate the interaction between photons and magnons at room temperature. This hybrid system has been designed and simulated using the commercial electromagnetic full-wave simulator CST Microwave Studio. The phenomenon of anti-crossing between the photon mode of the ELCR and the magnon modes of the YIG was observed by analyzing the |S21|-versus-frequency spectrum under varying strengths of bias magnetic fields. We present a comprehensive theoretical framework that explains the observed anti-crossing effect resulting from photon-magnon coupling (PMC) and provide estimations for the strength of PMC (Δ). Additionally, the interaction between photons and magnons was manipulated through two distinct methods: by adjusting the thickness (tYIG) of the YIG film and by positioning the YIG films along the microstripline. For the ELCR (for tYIG = 25 μm), Δ comes to 58 MHz, while changing tYIG from 2 μm to 50 μm, enabling more precise control of the Δ parameter across the span of 17 MHz to 84 MHz. Similarly, the YIG positioning at a different location along the microstripline allowed manipulation of Δ from 5 to 50 MHz. The resultant PMC can be significantly tuned by 400% to 900% in a planar-geometry ELCR-YIG hybrid system. This research offers avenues for developing innovative hybrid systems that afford greater control over the magnitude of PMC in a planar configuration, representing a promising direction for future advancements in hybrid magnonic systems.

In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis of structure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectric coupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulations are used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely (1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weakly coupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially strongly coupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation for the two types of coupling, respectively. Numerical examples using a piezoelectric energy harvester, which is a typical structure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most cost-effective algorithm. [ABSTRACT FROM AUTHOR]

Heat waves (HWs) can pose a serious threat to human health and natural ecosystems. Meanwhile, the mid-lower reaches of the Yangtze River are known as one of the most vulnerable regions suffering such disasters. At the mention of their potential drivers, the western North Pacific subtropical high (WNPSH) has been widely accepted as the key atmospheric circulation regulating these high-temperature extremes. Although considerable studies have proved the importance of the WNPSH, not enough work pays attention to the HWs which are not caused by the anomalous WNPSH. This study utilizes the instantaneous co-recurrence ratio α based on the Dynamical System (DS) method to quantify the forcing strength from the WNPSH to HWs, and classify HWs into four types according to their value of α and spatial pattern of the 500 hPa geopotential height, as high-α1, 2 and low-α1, 2. Results show that coverage by the WNPSH is not a necessary condition for the formation of HWs, which may also result from the anomalous South Asian high (SAH) and tropical cyclones (TCs), and the value of α can indicate whether the HWs are coupled with the WNPSH or not. Furthermore, the mechanisms behind these anomalous atmospheric systems are also different. The eastward-extended SAH in high-α HWs is associated with the latent heat of local condensation induced by the abnormal rainfall, while accompanied by an eastward-propagating wave train in low-α1. The intensification of the WNPSH in high-α HWs are attributed to both meridional and zonal wave trains originating from the maritime Continent and Western Europe, respectively, and the anomalous TCs in low-α2 are mainly due to the warmer sea surface temperature over the basin-wide equatorial Pacific, which may heat the bottom atmosphere and provide the convective instability. [ABSTRACT FROM AUTHOR]

We investigate the synchronizability of multilayer star-ring networks. Two types of multilayer networks, including aggregated coupling and divergent coupling, are established based on the connections between the hub node and the leaf nodes in the subnetwork. The eigenvalue spectrum of the two types of multilayer networks is strictly derived, and the correlation between topological parameters and synchronizability is analyzed by the master stability function framework. Moreover, the variable coupling strength has been investigated, revealing that it is significantly related to the synchronizability of the aggregated coupling while having no influence on the divergent coupling. Furthermore, the validity of the synchronizability analysis is obtained by implementing adaptive control on the multilayer star-ring networks previously mentioned. Calculations and comparisons show that the differences caused by the sizes of multilayer networks and interlayer coupling strength are not negligible. Finally, numerical examples are also provided to validate the effectiveness of the theoretical analysis.

We investigate the synchronizability of multilayer star-ring networks. Two types of multilayer networks, including aggregated coupling and divergent coupling, are established based on the connections between the hub node and the leaf nodes in the subnetwork. The eigenvalue spectrum of the two types of multilayer networks is strictly derived, and the correlation between topological parameters and synchronizability is analyzed by the master stability function framework. Moreover, the variable coupling strength has been investigated, revealing that it is significantly related to the synchronizability of the aggregated coupling while having no influence on the divergent coupling. Furthermore, the validity of the synchronizability analysis is obtained by implementing adaptive control on the multilayer star-ring networks previously mentioned. Calculations and comparisons show that the differences caused by the sizes of multilayer networks and interlayer coupling strength are not negligible. Finally, numerical examples are also provided to validate the effectiveness of the theoretical analysis. [ABSTRACT FROM AUTHOR]

The mammalian circadian clock is located in the suprachiasmatic nucleus (SCN) and consists of a network of coupled neurons, which are entrained to the environmental light-dark cycle. The phase coherence of the neurons is plastic and driven by the duration of daylight. With aging, the capacity to behaviorally adapt to seasonal changes in photoperiod reduces. The mechanisms underlying photoperiodic adaptation are largely unknown, but are important to unravel for the development of novel interventions to improve the quality of life of the elderly. We analyzed the phase coherence of single-cell PERIOD2::LUCIFERASE (PER2::LUC) expression rhythms in the SCN of young and old mice entrained to either long or short photoperiod. The phase coherence was used as input to a 2-community noisy Kuramoto model to estimate the coupling strength between and within neuronal subpopulations. The model revealed a correlation between coupling strength and photoperiod-induced changes in the phase relationship among neurons, suggesting a functional link. We found that the SCN of young mice adapts in coupling strength over a large range, with weak coupling in long photoperiod (LP) and strong coupling in short photoperiod (SP). In aged mice, we also found weak coupling in LP, but a reduced capacity to reach strong coupling in SP. The inability to respond with an increase in coupling strength suggests that manipulation of photoperiod is not a suitable strategy to enhance clock function with aging. We conclude that the inability of aged mice to reach strong coupling contributes to deficits in behavioral adaptation to seasonal changes in photoperiod. [ABSTRACT FROM AUTHOR]

Hot extremes impose severe effects on human health and the ecosystem, especially when high-temperature extremes sequentially occur in both daytime and nighttime within 1 day, known as Compound Hot Extremes (CHEs). Although a number of studies have focused on independent hot extremes, not enough work is devoted to compound ones, not to mention the coupling strength in covariations between the two variables (daytime and nighttime extreme temperature: Tmax and Tmin) over a given region. The instantaneous coupling strength can be derived by Dynamical System (DS) approach from covariations between Tmax and Tmin over a given region, and used to classify CHEs into coupled and decoupled types. Results show that more frequent coupled CHEs tend to be more intense with prolonged duration and extensive spatial extent compared with decoupled CHEs. Also, the mechanisms behind these two types of CHEs are largely different. Coupled CHEs are accompanied by a significant intensification and westward extension of the western North Pacific subtropical high (WNPSH), and the extremely high-temperature is mainly caused by receiving more solar radiation under the corresponding anticyclone. It is found that barotropic structure, weak jet stream and developing La Niña are conducive to the enhancement and persistence of WNPSH, in favor of the occurrence of long-lasting CHEs. Decoupled CHEs are associated with strong sea-land breeze (SLB), whose diurnal cycle could weaken the persistent large-scale circulation and suppress covariations between Tmax and Tmin. This kind of decoupled hot extremes are attributed to the combined effect of receiving more solar radiation during the day and trapping more long-wave radiation at night, where moisture and cloud cover play an important role. [ABSTRACT FROM AUTHOR]

In this study, we have analyzed the role of the initialization in the forecast of the monsoon onset phase beyond 10 days lead time (i.e., in the extended range) to understand the impact of displacement or shift in initial conditions in the extended‐range forecast. Two displacement errors are considered: (a) the initial error arising due to a change in land surface initial conditions and (b) the initial error arising due to a change in the number of observations. For the first part (a), we have analyzed and compared the difference in prediction skills in the United Kingdom Met Office (UKMO) GloSea5 forecasts run with two different land surface initial conditions (IC) configurations. In one configuration, the IC is prepared using a monthly land surface climatology; in the other configuration, it is based on daily land surface reanalysis. In the other part (b), we used the Indian Institute of Tropical Meteorology's Climate Forecast System (IITM_CFS) model with two different ICs (NCEP and NCMRWF differing in the number of observations over the Indian land region). Both runs indicate a shift in the initial condition, which manifests as displacement error. UKMO and IITM_CFS runs have the same land surface model when the corresponding twin experiments are compared in (a) and (b). Analysis of the initial displacement errors from these runs indicates that improving the realism in the land surface initial conditions can effectively modulate or change the surface meteorological fields in the prediction model during the onset phase. The result shows that the rotational and divergence components of the surface winds differ in the two sets of runs. Results also indicate that the difference in surface initialization manifests as differences in rotational and divergent kinetic energy. This could lead to a difference in the forecast of monsoon onset rain. Further analysis also suggests that the local land surface initial condition error, in addition to an error in large‐scale teleconnections, affects the monsoon onset forecast and its prediction skill in the extended‐range time‐scale. [ABSTRACT FROM AUTHOR]

A dipole emitter (analogous to organic molecules) placed near any dielectric or metal nanoparticles, based on their spatially constrained location and orientation, vividly emulate optical nanoantennas. Herein, we have extensively simulated the single dipole emitter interaction with spherical homodimers of noble metal gold and silver nanoparticles for different positional dependent orientations, exemplifying systematically the hybridization (Rabi splitting), quenching and diffuse non‐radiative energy transfer effects. The blue‐shifted scattering spectra of the coupled dipole emitter with individual Ag and Au homodimers quantify and corroborate the corresponding quantum yield/efficiency estimations. Such spatially oriented emitter interaction further distinctly reveals the enhanced near‐field and far‐field effects of the plasmonic dimer system in terms of dipolar and quadrupolar resonances, arising due to the induced polarization by respective incident electric and opto‐magnetic field components. Understanding the surface‐enhanced behavior of organic molecules that are either incorporated or randomly attached (experimentally) on the surface of metal nanoparticles will benefit greatly from the present comprehensive data analysis. [ABSTRACT FROM AUTHOR]

Bimetallic electrocatalysts with its superior performance has a broad application prospect in oxygen evolution reaction (OER), but the fundamental understanding of the mechanism of synergistic effect is still limited since there lacks a practical way to decouple the influence factors on the intrinsic activity of active sites from others. Herein, a series of bimetallic Co−Ni two‐dimensional polymer (2DP) model OER catalysts with well‐defined architecture, monolayer characteristic, were designed and synthesized to explore the influence of the coupling strength between metal centers on OER performance. The coupling strength was regulated by adjusting the spacing between metal centers or the conjugation degree of bridge skeleton. Among the examined 2DPs, CoTAPP‐Ni‐MF‐2DP, which has the strongest coupling strength between metal centers exhibited the best OER performance. These model systems can help to explore the precise structure‐performance relationships, which is important for the rational catalyst design at the atomic/molecular levels. [ABSTRACT FROM AUTHOR]

Nonlinear markers of coupling strength are often utilized to typify cardiorespiratory and cerebrovascular regulations. The computation of these indices requires techniques describing nonlinear interactions between respiration (R) and heart period (HP) and between mean arterial pressure (MAP) and mean cerebral blood velocity (MCBv). We compared two model-free methods for the assessment of dynamic HP–R and MCBv–MAP interactions, namely the cross-sample entropy (CSampEn) and k-nearest-neighbor cross-unpredictability (KNNCUP). Comparison was carried out first over simulations generated by linear and nonlinear unidirectional causal, bidirectional linear causal, and lag-zero linear noncausal models, and then over experimental data acquired from 19 subjects at supine rest during spontaneous breathing and controlled respiration at 10, 15, and 20 b r e a t h s · m i n u t e − 1 as well as from 13 subjects at supine rest and during 60° head-up tilt. Linear markers were computed for comparison. We found that: (i) over simulations, CSampEn and KNNCUP exhibit different abilities in evaluating coupling strength; (ii) KNNCUP is more reliable than CSampEn when interactions occur according to a causal structure, while performances are similar in noncausal models; (iii) in healthy subjects, KNNCUP is more powerful in characterizing cardiorespiratory and cerebrovascular variability interactions than CSampEn and linear markers. We recommend KNNCUP for quantifying cardiorespiratory and cerebrovascular coupling. [ABSTRACT FROM AUTHOR]

A characteristic equation for the frequencies of the T‐shaped and overhang‐shaped cantilevers is derived for the first time. We show that there are optimum values of the overhang lengths and widths that maximize the frequency and the number of maxima is corresponding to the mode number. The frequency of higher‐order modes could be tuned by changing the overhang dimensions. Especially, a semi‐empirical formula for the coupling strength κ between cantilevers in an array is proposed where the strength presents a cubic decrease with the overhang width ξ and a linear increase with the overhang length η, κ=η/ξ3. There is a very good agreement between the proposed formula and the values obtained in recent experiments by other researchers. [ABSTRACT FROM AUTHOR]

Strong coupling between light and matter forms hybrid states, such as exciton-polaritons, which are crucial for advancements in quantum science and technology. Plasmonic metal nanoparticles, with their ultrasmall mode volumes, are effective for generating these states, but the coupling strength is often limited by surface saturation of excitonic materials. Additionally, cubic nanoparticles, which can generate strong local fields, have not been systematically explored. This study investigates strong coupling in Au nanocubes (AuNCs) coupled with J-aggregates, observing spectral splitting in both extinction and scattering spectra. Our findings suggest that smaller AuNCs, with higher-quality resonances and reduced mode volumes, achieve stronger coupling. Furthermore, a layer-by-layer (LBL) coating of J-aggregates on AuNCs results in a ∼21% increase in coupling strength. Simulations reveal the mechanism behind the enhanced coupling and confirm that the layering method effectively increases coupling, surpassing the limitations of the finite surface area of nanoparticles.

• Two different FBG line-by-line apodization techniques called as the edge-weak-coupling inscription technique are proposed. • The superiority of the edge-weak-coupling methods in the FBG apodization is demonstrated theoretically and experimentally. • The experiment data visually demonstrates the influence of the coupling strength profile on the apodized FBG performance. The apodization profiles have a great influence on the performance of apodized fiber Bragg gratings (AFBGs). Different apodization profiles can significantly affect the side lobe suppression ratio (SLSR) of AFBGs. In this work, we demonstrate theoretically and experimentally that the reduction of the local coupling strength of Gaussian AFBG edges can promote the side lobe suppression of the AFBG. Compared to the femtosecond laser line-by-line (LbL) inscription method of tailoring the track length, the two proposed different edge-weak-coupling LbL inscription methods improve the SLSR of the AFBGs by about 2.4 dB and 7.2 dB owing to the different reductions of the edge local coupling strength in the Gaussian apodization profiles. The SLSR of the direct-writing AFBG is expected to be improved further by optimizing the coupling strength profile. [ABSTRACT FROM AUTHOR]

Fold-and-thrust belts (FTBs) evolve over a mechanically weak basal décollement that separates the overlying intensely deformed rocks from the underlying less deformed ones. Although deformation structures in FTBs commonly show lateral continuity, a closer inspection reveals distinctive variations in structural style (e.g., fold style) along and across mountain belts. This study uses laboratory-scale viscous models to investigate the influence of lateral décollement strength variations on the spatio-temporal evolution of strain patterns in FTBs. These experiments, simulating crustal-scale deformation, show notable changes in the mode of tectonic wedge growth, including the topographic evolution and ductile strain pattern distribution. For example, the deformation front propagates faster over weakly coupled décollement than the laterally adjacent strongly coupled segment, leading to along-strike variations of the topographic slope and curved outline of the deformation front. Constrictional strain, characteristic of regions of weak coupling, is transient and replaced by flattening strain beyond ∼20 % bulk shortening. The latter prevails in regions over strong décollement, whereas complex strain histories mark the transition zone between weak and strong décollements. Based on our modelling results, we propose that variations in décollement strength may cause the segmentation of deformation processes and the development of transverse faults in FTBs. • We use laboratory models to explain the widespread deformation heterogeneity in fold-and-thrust belts. • Along-strike décollement strength variations in FTBs cause structural segmentation and formation of curved deformation front. • Orogen-transverse faults possibly represent a transition zone between weakly and strongly coupled décollements. • Multiple surface slope breaks in orogenic wedges may result from across-strike variations in décollement strength. [ABSTRACT FROM AUTHOR]

Nonlinear markers of coupling strength are often utilized to typify cardiorespiratory and cerebrovascular regulations. The computation of these indices requires techniques describing nonlinear interactions between respiration (R) and heart period (HP) and between mean arterial pressure (MAP) and mean cerebral blood velocity (MCBv). We compared two model-free methods for the assessment of dynamic HP–R and MCBv–MAP interactions, namely the cross-sample entropy (CSampEn) and k-nearest-neighbor cross-unpredictability (KNNCUP). Comparison was carried out first over simulations generated by linear and nonlinear unidirectional causal, bidirectional linear causal, and lag-zero linear noncausal models, and then over experimental data acquired from 19 subjects at supine rest during spontaneous breathing and controlled respiration at 10, 15, and 20 breaths·minute−1 as well as from 13 subjects at supine rest and during 60° head-up tilt. Linear markers were computed for comparison. We found that: (i) over simulations, CSampEn and KNNCUP exhibit different abilities in evaluating coupling strength; (ii) KNNCUP is more reliable than CSampEn when interactions occur according to a causal structure, while performances are similar in noncausal models; (iii) in healthy subjects, KNNCUP is more powerful in characterizing cardiorespiratory and cerebrovascular variability interactions than CSampEn and linear markers. We recommend KNNCUP for quantifying cardiorespiratory and cerebrovascular coupling.

This brief studies the cluster synchronization problem for networks of linearly coupled systems where the dynamical system models in different clusters are nonidentical. To ensure scalability and reconfigurability of networks, a distributed adaptive law is proposed to update the intra-cluster coupling strengths. Concretely, each system is required to update its own coupling strength with its cluster members, instead of using a common strength for all systems. The adaptive updating law applied by each system depends on relative states with respective to connected cluster members which are locally available information. Moreover, the parameters involved in the adaptive law of each system allow decentralized off-line computations. Both generic linear systems which are partial-state coupled and nonlinear oscillators which are full-state coupled are considered, respectively. [ABSTRACT FROM AUTHOR]

We propose a procedure suitable for automated synchrogram analysis for setting the threshold below which phase variability between two marker event series is of such a negligible amount that the null hypothesis of phase desynchronization can be rejected. The procedure exploits the principle of maximizing the likelihood of detecting phase synchronization epochs and it is grounded on a surrogate data approach testing the null hypothesis of phase uncoupling. The approach was applied to assess cardiorespiratory phase interactions between heartbeat and inspiratory onset in amateur cyclists before and after 11-week inspiratory muscle training (IMT) at different intensities and compared to a more traditional approach to set phase variability threshold. The proposed procedure was able to detect the decrease in cardiorespiratory phase locking strength during vagal withdrawal induced by the modification of posture from supine to standing. IMT had very limited effects on cardiorespiratory phase synchronization strength and this result held regardless of the training intensity. In amateur athletes training, the inspiratory muscles did not limit the decrease in cardiorespiratory phase synchronization observed in the upright position as a likely consequence of the modest impact of this respiratory exercise, regardless of its intensity, on cardiac vagal control. [ABSTRACT FROM AUTHOR]

Abstract This paper is devoted to the study of the global synchronization of multiple neural networks (MNNs) via impulsive coupling control. Compared to one-layer neural networks, MNNs have more complex dynamics behavior and greater practical significance. In this paper, two interconnected bidirection MNNs are constructed; for this type of neural network system, each node in their network will be affected by the corresponding node in another network, then the synchronization problem of unidirection MNNs is extended to bidirection MNNs. In order to achieve synchronization of the bidirection MNNs, we adopt the method of impulsive coupling control, and together with the appropriate Lyapunov function, we deduce the relationship of the synchronization error system at the adjacent two impulsive moments, through iteration, and we finally obtain sufficient conditions to realize the global synchronization of the two interconnected bidirection MNNs. We illustrate the effectiveness of the results by simulation.

Periodically arranged metallic nanowires on top of a waveguide layer show a strong coupling between the particle plasmon of the wires and the waveguide mode. By introducing a dielectric spacer layer between the metallic structures and the waveguide layer, this coupling can be reduced. Here, the thickness of this spacer layer is varied and the coupling strength is determined for each spacer layer thickness by fitting an effective energy matrix to the energy positions of the resonance peaks. It is found that the coupling strength can be very well described by the electric field amplitude of the waveguide mode at the location of the nanowires. We carried out experiments and found very good agreement with theory and our simple model. Using this method, we achieved experimentally an extremely small mode splitting as small as 25 meV leading to very sharp spectral features. Our pathway and design for tailoring the coupling strength of plasmonic Fano resonances will enable the design of highly sensitive plasmonic sensor devices and open the door for narrow plasmonic spectral features for nonlinear optics and slow light propagation.

The equatorial Pacific warm water volume (WWV) and western equatorial Pacific WWV (WWVw) are two important long‐lead time El Niño‐Southern Oscillation (ENSO) event precursors. Here, we utilize the recharge‐discharge oscillator framework to obtain the analytical solution of WWV and WWVw lead times to ENSO sea surface temperatures (SSTs). Both WWV and WWVw lead times show a strong dependence on the inherent ENSO periodicity, whereas WWV lead time is further modulated by the air‐sea coupling strength and ENSO SST spatial pattern. The derived solution is able to explain observed decadal variations in lead times of WWV to SST in terms of variations in ENSO periodicity and air‐sea coupling strength. Plain Language Summary: Predicting El Niño‐Southern Oscillation (ENSO) events in advance has profound socio‐economic benefits because of ENSO's impacts on global weather and climate. The basin‐wide equatorial Pacific heat content (also known as warm water volume, WWV) and western Pacific WWV (WWVw) are well‐known predictors of ENSO events several seasons ahead. In this study, we present an analytical expression of WWV and WWVw lead times to ENSO sea surface temperature (SST) anomalies. The analytical solution can explain the observed decadal changes in WWV lead times. We demonstrate that the recent shortened WWV lead time observed after the year 2000 can be largely explained by a decrease in the inherent ENSO periodicity, and second by an increase in the air‐sea coupling strength. The latter is associated with an ENSO SST spatial pattern change with more frequent occurrences of Central Pacific El Niño events in recent decades. Key Points: Theoretical lead times of basin‐wide warm water volume (WWV) and western Pacific WWV (WWVw) to El Niño‐Southern Oscillation (ENSO) events are validatedWWV lead time depends on both ENSO periodicity and the ENSO spatial pattern, whereas WWVw lead time depends solely on ENSO periodicityObserved decadal variations of WWV lead times result from variations in ENSO periodicity and air‐sea coupling strength [ABSTRACT FROM AUTHOR]

Configuration design is a process of composing customized product from a set of predefined component types with a set of well-defined rules which decide how items can be selected and combined. The configuration solving process is to instantiate all component types into instances. However, the configurator faces the problem of how to determine the instantiation order of component types in the configuration solving process. An unreasonable instantiation order may reduce the accuracy of the configuration result and extend the time required to finish the configuration. In response to the above problem, a heuristic configuration solving process planning method by imitating the crystal crystallization process (CCP) was proposed. According to the product configuration rules, the frequent itemset mining algorithm was used to mine the correlation between the attribute parameters of the product configuration unit. By imitating the CCP and utilizing the calculated coupling strength, the configurator will determine a suitable instantiation sequence for component types. This method has been applied in the GB10 elevator produced by Canny Elevator. It is found that the configuration accuracy has been improved and the consumption of time has been reduced. [ABSTRACT FROM AUTHOR]

Deforestation plays an essential role in land cover changes in tropical area. It resulted in changing surface biophysical characteristics such as albedo and surface roughness altering the climate, heat fluxes as well as CO2 fluxes. Thus, this study aims to analyse the biogeophysical and biogeochemical processes in forest, shrub, grass, and soybean. Also, the study analyses the coupling strength in the terrestrial segment. This analysis is conducted using the Community Land Model Version 5 (CLM5). The results showed that land-use changes alter surface heat fluxes. Forest changing into shrub, grass, and soybean decreased latent heat fluxes and increased sensible heat fluxes. Land-use changes also alter carbon uptake, although it did not necessarily reduce the net primary production (NPP) and efficiency. Forest changing into soybean will increase NPP, while its changes to grass and shrub will decrease NPP. Among all land covers, soybean had higher carbon use efficiency (CUE) due to the availability of water and soil nutrient supply. In comparison, the forest had lower CUE due to its high respiration to maintain its biomass. Coupling strength between soil moisture and latent heat fluxes in all land covers was positive, but the R-squared was relatively low. This result indicated that there was another factor impacting surface energy balance partition such as vegetation cover. [ABSTRACT FROM AUTHOR]

Local activity is regarded as the origin of complexity. In this study, a locally active memristor with coexisting two stable pinched hysteresis loops and two local activity regions is proposed. Its nonvolatile memory, as well as locally active characteristics, is validated by the power-off plot and DC V–I plot. Based on two-dimensional Hindmarsh–Rose and two-dimensional Fitzhugh–Nagumo neurons, a simple neural network is constructed by connecting the two neurons with the locally active memristor. Coexisting multiple firing patterns under different initial conditions are investigated by considering the coupling strength as a unique controlled parameter. The results suggest that the system exhibits coexisting periodic and chaotic bursting firing patterns as well as coexisting two periodic firing patterns with different topologies. Furthermore, state switching without parameters is also explored. In particular, phase synchronization of the memristor synapse-coupled neurons is discussed, which implies that two nonidentical neurons gradually become phase synchronized with the increase in the coupling strength. In order to confirm the effectiveness of numerical simulations, circuit simulations are included. [ABSTRACT FROM AUTHOR]

CdSe nanoplatelets (NPLs) are promising 2D semiconductors for optoelectronic applications, in which efficient charge transport properties are desirable. It is reported that thermal annealing constitutes an effective strategy to control the optical absorption and electrical properties of CdSe NPLs by tuning the inter-NPL distance. Combining optical absorption, transmission electron microscopy, and thermogravimetric analysis, it is revealed that the thermal decomposition of ligands (e.g., cadmium myristate) governs the inter-NPL distance and thus the inter-NPL electronic coupling strength. Employing ultrafast terahertz spectroscopy, it is shown that this enhanced electronic coupling increases both the free carrier generation efficiency and the short-range mobility in NPL solids. The results show a straightforward method of controlling the interfacial electronic coupling strength for developing functional optoelectronic devices through thermal treatments., (© 2023 The Authors. Small published by Wiley‐VCH GmbH.)

Synchronization is a ubiquitous feature in many natural systems and nonlinear science. This paper studies the synchronization in complete network consisting of n nodes. Each node is connected to all other nodes by linear coupling and represented by a reaction-diffusion system of FitzHugh-Nagumo type which can be obtained by simplifying the famous Hodgkin-Huxley model. From this complete network, the author seeks a sufficient condition on the coupling strength to achieve synchronization. The result shows that the more easily the nodes synchronize, the bigger the degrees of the networks. Based on this consequence, the author will test the theoretical result numerically to see if there is a compromise.

Abstract Three kinds of typical structures, hemi-/spherical nanoparticles/nanoparticle dimers on the substrate and spherical nanoparticles/nanoparticle dimers half-buried into the substrate, are used for FDTD simulation to theoretically discuss the influence of the substrate to the localized surface plasmon (LSP) coupling when the metal nanoparticles/nanoparticle dimers are locating near a substrate. Simulated results show that the dependencies between the LSP coupling wavelength and the refractive index of the substrate for different structures are not the same, which can be attributed to the different polarization field distributions of LSPs. When light is incident from different directions, the LSP coupling strength are not the same as well and the ratios of the scattering peak intensities depend on the position of the metal nanoparticles or nanoparticle dimers. These phenomenon can be explained by the difference of the local driving electric field intensities which is modulated by the interface between the air and the substrate.

Using a mean-field theory, a twist-bend nematic (NTB) phase has been described. In addition to second-order Legendre polynomial term, the chiral interaction potential includes third-order Legendre polynomial term also. It considers the coupling between a nematic director and a pitch axis of the NTB phase. The distortion free energy, order parameter for twist-bend nematic, and orientational distribution function in equilibrium state have been calculated. Based on the free energy minimization, we obtain that the inclusion of third-order Legendre polynomial term in interaction energy makes NTB phase more stable. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of the global synchronization of multiple neural networks (MNNs) via impulsive coupling control. Compared to one-layer neural networks, MNNs have more complex dynamics behavior and greater practical significance. In this paper, two interconnected bidirection MNNs are constructed; for this type of neural network system, each node in their network will be affected by the corresponding node in another network, then the synchronization problem of unidirection MNNs is extended to bidirection MNNs. In order to achieve synchronization of the bidirection MNNs, we adopt the method of impulsive coupling control, and together with the appropriate Lyapunov function, we deduce the relationship of the synchronization error system at the adjacent two impulsive moments, through iteration, and we finally obtain sufficient conditions to realize the global synchronization of the two interconnected bidirection MNNs. We illustrate the effectiveness of the results by simulation. [ABSTRACT FROM AUTHOR]

Nanostructure-based surface-enhanced infrared absorption (SEIRA) spectroscopy has attracted tremendous interest as an ultrasensitive detection tool that supplies chemical-fingerprint information. The interactions between molecular vibrations and plasmons lead to not only the enhancement of spectral intensity, but also the distortion of spectral Lorentzian lineshapes into asymmetric Fano-type or more complicated lineshapes in the SEIRA spectra; this effect hampers the correct readout of vibrational frequencies and intensities for an accurate interpretation of the measured spectra and quantitative analysis. In this work, we investigate the Fano interference between molecular vibrations and plasmons based on exact electrodynamic simulations and theoretical models. We report that, even if the molecular vibrational energy is equal to the plasmon resonant energy, the molecule–nanostructure distance-dependent dipole–dipole interactions, the plasmon-mediated coherent intermolecular interactions and the decay rates of plasmons have a significant impact on the SEIRA lineshapes. This study paves the way for controllable Fano interference at the nanoscale and more studies on plasmon-dressed molecular electronic or vibrational excited states. [ABSTRACT FROM AUTHOR]

A vibratory erosion test rig is used to study the cavitation erosion of 6061 alloy. Some craters and material fracture are found on the specimen surface at the beginning of test. A cavitation model in an ultrasonic field is developed by applying the bubble–bubble interaction effect into Keller–Miksis equation to obtain the bubbles dynamic characteristics. The results reveal that the bubble cloud configuration is suitable for the explanation of cavitation erosion, and the erosion surfaces of the specimen were subjected to the effect of both massive bubbles collapsing, occurring in the thin liquid layer between the horn and the specimen. It is concluded that the optimal coupling strength of bubbles increases with the decrease of the bubble initial radius, and stable cavitation only occurs when the acoustic pressure amplitude is higher than a threshold value, which can well predict the experimental results. [ABSTRACT FROM AUTHOR]

Excessive neural synchronization in the cortico-basal ganglia-thalamocortical circuits in the beta (β) frequency range (12–35 Hz) is closely associated with dopamine depletion in Parkinson's disease (PD) and correlated with movement impairments, but the neural basis remains unclear. In this work, we establish a double-oscillator neural mass model for the cortico-basal ganglia-thalamocortical closed-loop system and explore the impacts of dopamine depletion induced changes in coupling connections within or between the two oscillators on neural activities within the loop. Spectral analysis of the neural mass activities revealed that the power and frequency of their principal components are greatly dependent on the coupling strengths between nuclei. We found that the increased intra-coupling in the basal ganglia-thalamic (BG-Th) oscillator contributes to increased oscillations in the lower β frequency band (12–25 Hz), while increased intra-coupling in the cortical oscillator mainly contributes to increased oscillations in the upper β frequency band (26–35 Hz). Interestingly, pathological upper β oscillations in the cortical oscillator may be another origin of the lower β oscillations in the BG-Th oscillator, in addition to increased intra-coupling strength within the BG-Th network. Lower β oscillations in the BG-Th oscillator can also change the dominant oscillation frequency of a cortical nucleus from the upper to the lower β band. Thus, this work may pave the way towards revealing a possible neural basis underlying the Parkinsonian state. • A two oscillator model is built to explore the Parkinsonian beta oscillations. • Intra- and inter-coupling have different roles in inducing the beta oscillations. • Cortical oscillator may also be the origin of the lower beta oscillations. [ABSTRACT FROM AUTHOR]

The analysis of land-atmosphere water and energy interactions requires reliable representation of soil moisture (SM) and evapotranspiration (ET) coupling strength (ρ). However, ρ in current land surface models (LSMs) is prone to bias and its error sources remain unclear. This study aims to identify error sources controlling LSM ρ biases. To this end, we first use a well-established algorithm to produce debiased reference ρ map based on multi-source remote sensing data. Then, ρ values from three LSMs (Variable Infiltration Capacity (VIC), Catchment Land Surface Model (CLSM), and Noah) in Global Land Data Assimilation System (GLDAS) are evaluated against our reference ρ map. Results show that all the three LSMs demonstrate strong ρ in the northern part of China (dominated by arid and semi-arid climates). In contrast, the biases of modeled ρ are marginal in the (relatively) humid southern part of China. Across the three LSMs, Noah and CLSM contain substantial positive biases in ρ representation, while VIC-based ρ estimates are significantly lower than the remotely sensed reference ρ values. Based on our analysis, it appears that the relative importance of transpiration and soil evaporation determines the overall magnitude of ρ and the inter-model ρ differences. However, the LSMs employ different schemes in land surface energy balance. Therefore, the exact process and/or parameter controlling the transpiration and soil evaporation partitioning may be model-specific. • The SM-ET coupling strengths of GLDAS LSMs are evaluated. • Large coupling differences exist between LSMs in arid and semi-arid climates. • Transpiration fraction dominates inter-model coupling differences. [ABSTRACT FROM AUTHOR]

The system model on synchronizability problem of complex networks with multi-layer structure is closer to the real network than the usual single-layer case. Based on the master stability equation (MSF), this paper studies the eigenvalue spectrum of two k-layer variable coupling windmill-type networks. In the case of bounded and unbounded synchronization domain, the relationships between the synchronizability of the layered windmill-type networks and network parameters, such as the numbers of nodes and layers, inter-layers coupling strength, are studied. The simulation of the synchronizability of the layered windmill-type networks are given, and they verify the theoretical results well. Finally, the optimization schemes of the synchronizability are given from the perspective of single-layer and multi-layer networks, and it was found that the synchronizability of the layered windmill-type networks can be improved by changing the parameters appropriately.

In wireless power transfer (WPT) systems, the energy transmission channel is established by the coupling relationship between transmitting coil and receiving coil, and the coupling strength is usually measured by coupling coefficient. Therefore, it is necessary to calculate the mutual inductance between transmitting coil and receiving coil when describing their coupling strength. Here, filamentary circular coils and cylindrical helix coils are taken as the object of study, and the formulas for mutual inductance of two coils with misalignment are derived based on Neumann's formula. In addition, the influence of multiple factors, such as axial distance, lateral distance and angle, on mutual inductance is analysed, and the calculated results are verified by experiments. The research results of this paper can be used to estimate the mutual inductance between the couplers in WPT systems, especially when there is misalignment.

Superconductivity is caused by the interaction between electrons by the exchange of bosonic excitations, however, this glue forming electron pairs is manifested itself by the coupling strength of the electrons to bosonic excitations. Here the doping and momentum dependence of the coupling strength of the electrons to spin excitations in cuprate superconductors is studied within the kinetic-energy-driven superconducting mechanism. The normal self-energy in the particle-hole channel and pairing self-energy in the particle-pariticle channel generated by the interaction between electrons by the exchange of spin excitation are employed to extract the coupling strengths of the electrons to spin excitations in the particle-hole and particle-particle channels, respectively. It is shown that below , both the coupling strengths in the particle-hole and particle-particle channels around the antinodes consist of two peaks, with a sharp low-energy peak located at 5 meV in the optimally doped regime, and a broad-band with a weak peak centred at 40 meV. In particular, this two-peak structure in the coupling strength in the particle-hole channel can persist into the normal-state, while the coupling strength in the particle-particle channel vanishes at the nodes. However, the positions of the peaks in the underdoped regime shift towards to higher energies with the increase of doping. More specifically, although the positions of the peaks move to lower energies from the antinode to the hot spot, the weights of the peaks decrease with the move of the momentum from the antinode to the hot spot, and fade away at the hot spots. [ABSTRACT FROM AUTHOR]

Phase-splitting and various arrhythmic behaviors have been observed in mammals. Although it is known that desynchronization of SCN neurons plays an important role, the exact mechanisms underlying this behavior are still not completely understood. A previous study suggested that phase-splitting behavior was explained by the SCN output signal feeding back to the SCN with a time delay of about 12 h. However, experimental evidence showed that the feedback is instantaneous and does not have a time delay. In the present study, a Kuramoto model with instant feedback is proposed to explain the mechanisms underlying phase splitting and arrhythmic behavior. Our results show that phase-splitting and arrhythmic behavior results from the feedback which is described by two key parameters, the strength of the feedback as well as the phase difference of the feedback to the SCN activity. Additionally, in accordance with experimental findings, we observe that the SCN period in the split state is equal to 24 h, while it is larger than 24 h for a state that has a robust circadian rhythm. Our study provides an alternative explanation for the phase-splitting and arrhythmic behavior and opens a window to understand how feedback influences the SCN, and consequently its behavior. [ABSTRACT FROM AUTHOR]

• A new formula for calculating bibliographic coupling strength is provided. • It is based on the TF-IDF formula as used in information retrieval. • A derived formula for similarity calculation between documents is provided. • The feasibility of these new formulae is shown on a large dataset. We propose a new method for computing the bibliographic coupling strength between two documents. This new method is based on the TF-IDF formula from the field of information retrieval. It is shown that this formula is a valid alternative for the original formula introduced by Kessler and is, from a probabilistic point of view, a correction of the Vladutz-Cook formula. We further define a cosine based similarity formula generalizing the Sen-Gan coupling angle formula. [ABSTRACT FROM AUTHOR]

In wireless power transfer (WPT) systems, the energy transmission channel is established by the coupling relationship between transmitting coil and receiving coil, and the coupling strength is usually measured by coupling coefficient. Therefore, it is necessary to calculate the mutual inductance between transmitting coil and receiving coil when describing their coupling strength. Here, filamentary circular coils and cylindrical helix coils are taken as the object of study, and the formulas for mutual inductance of two coils with misalignment are derived based on Neumann's formula. In addition, the influence of multiple factors, such as axial distance, lateral distance and angle, on mutual inductance is analysed, and the calculated results are verified by experiments. The research results of this paper can be used to estimate the mutual inductance between the couplers in WPT systems, especially when there is misalignment. [ABSTRACT FROM AUTHOR]

Abstract Recently, coupling between groups of neurons or different brain regions has been widely studied to provide insights into underlying mechanisms of brain functions. To comprehensively understand the effect of such coupling, it is necessary to accurately extract the coupling strength information among multivariate neural signals from the whole brain. This study proposed a new method named multivariate permutation conditional mutual information (MPCMI) to quantitatively estimate the coupling strength of multivariate neural signals (MNS). The performance of the MPCMI method was validated on the simulated MNS generated by multi-channel neural mass model (MNMM). The coupling strength feature of simulated MNS extracted by MPCMI showed better performance compared with standard methods, such as permutation conditional mutual information (PCMI), multivariate Granger causality (MVGC), and Granger causality analysis (GCA). Furthermore, the MPCMI was applied to estimate the coupling strengths of two-channel resting-state electroencephalographic (rsEEG) signals from different brain regions of 19 patients with amnestic mild cognitive impairment (aMCI) with type 2 diabetes mellitus (T2DM) and 20 normal control (NC) with T2DM in Alpha1 and Alpha2 frequency bands. Empirical results showed that the MPCMI could effectively extract the coupling strength features that were significantly different between the aMCI and the NC. Hence, the proposed MPCMI method could be an effective estimate of coupling strengths of MNS, and might be a viable biomarker for clinical applications. [ABSTRACT FROM AUTHOR]

This study considers the synchronisation of stochastic‐coupled systems with time‐varying delays and Lévy noise on networks without strong connectedness (SCSTLNC) through periodically intermittent control. Also, here, internal delays, coupling delay, white noise, and Lévy noise are considered in SCSTLNC. Then, to guarantee synchronisation of SCSTLNC, several useful criteria are obtained by applying some techniques of inequalities, such as a graph‐theoretic approach, a hierarchical approach, and the theory of asymptotically autonomous systems. The intensity of control is closely related to the coupling strength and the perturbed intensity of noise. In particular, the synchronisation of stochastic‐coupled oscillators with time‐varying delays and Lévy noise on networks without strong connectedness as a practical application of the authors' theoretical results are investigated. Finally, a numerical example of oscillator networks is provided to demonstrate the validity and feasibility of their analytical results. [ABSTRACT FROM AUTHOR]