The inherent complexities of excitable cardiac,nervous,and skeletal muscle tissues pose great challenges in constructing artificial counterparts that closely resemble their natural bioelectrical,structural,and mechani...The inherent complexities of excitable cardiac,nervous,and skeletal muscle tissues pose great challenges in constructing artificial counterparts that closely resemble their natural bioelectrical,structural,and mechanical properties.Recent advances have increasingly revealed the beneficial impact of bioelectrical microenvironments on cellular behaviors,tissue regeneration,and therapeutic efficacy for excitable tissues.This review aims to unveil the mechanisms by which electrical microenvironments enhance the regeneration and functionality of excitable cells and tissues,considering both endogenous electrical cues from electroactive biomaterials and exogenous electrical stimuli from external electronic systems.We explore the synergistic effects of these electrical microenvironments,combined with structural and mechanical guidance,on the regeneration of excitable tissues using tissue engineering scaffolds.Additionally,the emergence of micro/nanoscale bioelectronics has significantly broadened this field,facilitating intimate interactions between implantable bioelectronics and excitable tissues across cellular,tissue,and organ levels.These interactions enable precise data acquisition and localized modulation of cell and tissue functionalities through intricately designed electronic components according to physiological needs.The integration of tissue engineering and bioelectronics promises optimal outcomes,highlighting a growing trend in developing living tissue construct-bioelectronic hybrids for restoring and monitoring damaged excitable tissues.Furthermore,we envision critical challenges in engineering the next-generation hybrids,focusing on integrated fabrication strategies,the development of ionic conductive biomaterials,and their convergence with biosensors.展开更多
The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI ...The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI with NIR-II window excitation (1064nm/other wavelength beyond 1000nm) can afford deeper tissue penetration depth with high clarity due to the merits of suppressed photon scattering and diminished autofluorescence. In this review, we have summarized NIR-II window excitable/emissive organic/polymeric fluorophores recently developed. The characteristics of these fluorophores such as chemical structures and photophysical properties have also been critically discussed. Furthermore, the latest development of noninvasive in vivo FLI with NIR-II excitation was highlighted. The ideal imaging results emphasized the importance of NIR-II excitation of these fluorophores in enabling deep tissue penetration and high-resolution imaging. Finally, a perspective on the challenges and prospects of NIR-II excitable/emissive organic/polymeric fluorophores was also discussed. We expected this review will be served as a source of inspiration for researchers, stimulating the creation of novel NIR-II excitable fluorophores and fostering the development of bioimaging applications.展开更多
Neuronomodulation refers to the modulation of neural conduction and synaptic transmission(i.e.,the conduction process involved in synaptic transmission)of excitable neurons via changes in the membrane potential in res...Neuronomodulation refers to the modulation of neural conduction and synaptic transmission(i.e.,the conduction process involved in synaptic transmission)of excitable neurons via changes in the membrane potential in response to chemical substances,from spillover neuro-transmitters to paracrine or endocrine hormones circulating in the blood.Neuronomodulation can be direct or indirect,depending on the transduction pathways from the ligand binding site to the ion pore,either on the same molecule,i.e.the ion channel,or through an intermediate step on different molecules.The major players in direct neurono-modulation are ligand-gated or voltage-gated ion channels.The key process of direct neuronomodulation is the binding and chemoactivation of ligand-gated or voltage-gated ion channels,either orthosterically or allosterically,by various ligands.Indirect neuronomodulation involves metabotropic receptor-mediated slow potentials,where steroid hormones,cytokines,and chemokines can implement these actions.Elucidating neuronomodulation is of great significance for understanding the physiological mechanisms of brain function,and the occurrence and treatment of diseases.展开更多
The synchronization and asynchronization of two coupled excitable systems are investigated. The two systems with different initial configurations, which are separately a single spiral wave (or a travel wave) and the r...The synchronization and asynchronization of two coupled excitable systems are investigated. The two systems with different initial configurations, which are separately a single spiral wave (or a travel wave) and the rest state, can be developed to the synchronizing state with the same spiral wave (or travel wave) in each system, when the coupling is very strong. Decreasing the coupling intensity, two rest states or two different configurations appear in the two systems. The qualitative analysis and interpretation are given.展开更多
All dynamic complex networks have two important aspects, pattern dynamics and network topology. Discovering different types of pattern dynamics and exploring how these dynamics depend or/network topologies are tasks o...All dynamic complex networks have two important aspects, pattern dynamics and network topology. Discovering different types of pattern dynamics and exploring how these dynamics depend or/network topologies are tasks of both great theoretical importance and broad practical significance. In this paper we study the oscillatory behaviors of excitable complex networks （ECNs） and find some interesting dynamic behaviors of ECNs in oscillatory probability, the multiplicity of oscillatory attractors, period distribution, and different types of oscillatory patterns （e.g., periodic, quasiperiodic, and chaotic）. In these aspects, we further explore strikingly sharp differences among network dynamics induced by different topologies （random or scale-free topologies） and different interaction structures （symmetric or asymmetric couplings）. The mechanisms behind these differences are explained physically.展开更多
We studied synchronization behaviours of spiral waves in a two-layer coupled inhomogeneous excitable system. It was found that phase synchronization can be observed under weak coupling strength. By increasing the coup...We studied synchronization behaviours of spiral waves in a two-layer coupled inhomogeneous excitable system. It was found that phase synchronization can be observed under weak coupling strength. By increasing the coupling strength, the synchronization is broken down. With the further increase of the coupling strength, complete synchronization and phase synchronization occur again. We also found that the inhomogeneity in excitable systems is helpful to the synchronization.展开更多
Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation...Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation and analysis lead to the conclusions that, the number of refractory states does not influence the wave-front speed; the wave- front speed decreases as the excitation threshold increases and increases as the neighbor radius increases; the period of target waves is equal to the number of cell states; the excitation condition for target waves is that the wave-front speed must be bigger than half of the neighbor radius.展开更多
We study the firing synchronization behavior of the inhomogeneous excitable media. Phase synchronizationof neuron firings is observed with increasing the coupling, while the phases of neurons are different (out-of-pha...We study the firing synchronization behavior of the inhomogeneous excitable media. Phase synchronizationof neuron firings is observed with increasing the coupling, while the phases of neurons are different (out-of-phase synchronization). We found the synchronization of bursts can be greatly enhanced by applying an external forcing (in-phasesynchronization). The external forcing can be either a periodic or just homogeneous thermal noise. The mechanismresponsible for this enhancement is discussed.PACS numbers: 05.45.-a, 87.10.展开更多
The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear...The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear law are derived for untwisted organization center. These results have explicit physical meaning and are in good agreement with experiments.展开更多
We investigate the collective dynamics of network-organized identical excitable nodes. We theoretically analyze the stability of the rest state and propose that there are two different transition paths： the stationar...We investigate the collective dynamics of network-organized identical excitable nodes. We theoretically analyze the stability of the rest state and propose that there are two different transition paths： the stationary path and the oscillatory path. We find that, although the onset of collective dynamics strongly depend on the network topology, the local dynamics and how local nodes interact with each other decide the transition path and the involved bifurcation.展开更多
Depending on the excitability of the medium, a propagating wave segment will either contract or expand to fill the medium with spiral waves. This paper aims to introduce a simple mechanism of feedback control to stabi...Depending on the excitability of the medium, a propagating wave segment will either contract or expand to fill the medium with spiral waves. This paper aims to introduce a simple mechanism of feedback control to stabilize such an expansion or contraction. To do this, we lay out a feedback control system in a block diagram and reduce it into a bare, universal formula. Analytical and experimental findings are compared through a series of numerical simulations of the Barkley model.展开更多
Studies of sustained oscillations on complex networks with excitable node dynamics received much interest in recent years.Although an individual unit is non-oscillatory,they may organize to form various collective osc...Studies of sustained oscillations on complex networks with excitable node dynamics received much interest in recent years.Although an individual unit is non-oscillatory,they may organize to form various collective oscillatory patterns through networked connections.An excitable network usually possesses a number of oscillatory modes dominated by different Winfree loops and numerous spatiotemporal patterns organized by different propagation path distributions.The traditional approach of the so-called dominant phase-advanced drive method has been well applied to the study of stationary oscillation patterns on a network.In this paper,we develop the functional-weight approach that has been successfully used in studies of sustained oscillations in gene-regulated networks by an extension to the high-dimensional node dynamics.This approach can be well applied to the study of sustained oscillations in coupled excitable units.We tested this scheme for different networks,such as homogeneous random networks,small-world networks,and scale-free networks and found it can accurately dig out the oscillation source and the propagation path.The present approach is believed to have the potential in studies competitive non-stationary dynamics.展开更多
With help of establishing the moving coordinate on the wave front surface and the perturbation analysis in the boundary layer,the structures of wave front and organization center in excitable media were studied. The e...With help of establishing the moving coordinate on the wave front surface and the perturbation analysis in the boundary layer,the structures of wave front and organization center in excitable media were studied. The eikonal equation of wave front surface and general equation of organization center were obtained. These eikonal equations reveal the wave front surfaces have structures of twisted scroll wave and Mbius band, the organization centers have structures of knotted and linked ring. These theoretical results not only explain the wave patterns of BZ(Belousov-Zhabotinskii) chemical reaction but also give several possibility structures of wave front surface and organization center in general excitable media.展开更多
Three-photon(3P)fluorescence imaging(FLI)utilizing excitation wavelengths within the near-infrared-Ⅲ (NIR-Ⅲ,1600-1870 nm)window has emerged as a transformative modality for intravital imaging,owing to its combined a...Three-photon(3P)fluorescence imaging(FLI)utilizing excitation wavelengths within the near-infrared-Ⅲ (NIR-Ⅲ,1600-1870 nm)window has emerged as a transformative modality for intravital imaging,owing to its combined advantages of excellent spatiotemporal resolution and remarkable tissue penetration.High-performance fluorescent probes are the cornerstone of highquality NIR-Ⅲ3P FLI.However,the construction of such probes is often hindered by inherent trade-offs in molecular design principles,posing significant challenges for their performance optimization and practical application.Here,we propose a straightforward and effective strategy based onπ-bridge manipulation to reconcile those competing molecular design parameters and substantially enhance 3P fluorescence properties.Leveraging this approach,a robust AIE-active small molecule,named TSSID,was developed,which exhibits bright NIR-I(700-950 nm)emission under 1665 nm NIR-Ⅲ3P excitation when formulated into nanoparticles(NPs).Remarkably,upon retro-orbital injection into mice following craniotomy,TSSID NPs achieved the best performance in deep-brain angiography among all reported organic 3P materials in terms of vascular imaging depth,signalto-background ratio,spatial resolution,and hemodynamic imaging depth.Additionally,TSSID NPs demonstrated outstanding biocompatibility through systematic biosafety evaluations.This study provides an excellent imaging agent and useful molecular design philosophy,facilitating the development of advanced organic 3P FLI probes.展开更多
The dynamics of coupled excitable FitzHugh Nagumo systems under external noisy driving is studied. Different from most of previous work focusing on the noise-induced regularity in the framework of coherence resonance,...The dynamics of coupled excitable FitzHugh Nagumo systems under external noisy driving is studied. Different from most of previous work focusing on the noise-induced regularity in the framework of coherence resonance, here the average frequency （or firing rate） of coupled excitable elements is of much more concern. We find that （i） their frequencies first increase and then decrease with the increase of the coupling, and there is a clear crossover from a rush increase to a smooth increase with the increase of noise strength, and （ii） for nonidentical cases, all elements transit to an identical frequency simultaneously only after a certain coupling strength is achieved. These first-increase-thendecrease non-monotonic frequency behavior and isochronous frequency synchronization are believed to be two basic behaviors in coupled noisy excitable systems.展开更多
The control effect of recycled noise,generated by the superposition of a primary Gaussian noise source and a secondary source with a constant delay,has been studied in an excitable FitzHugh-Nagumo system.We mainly foc...The control effect of recycled noise,generated by the superposition of a primary Gaussian noise source and a secondary source with a constant delay,has been studied in an excitable FitzHugh-Nagumo system.We mainly focus on the performance of noise-induced spike and coherence resonance in a parameter region sub-threshold to supercritical Hopf bifurcation.For fixed noise intensity,simulations show that the coherence(quantitatively measured by R,which is defined as the mean value of the spike interval time T normalized to its mean square root) and the emission velocity of the noise-induced spikes exhibit damped oscillations with the variation of delay time,demonstrating a new kind of multi-resonance phenomenon.Furthermore,the optimal delay times for resonance and the fast emission velocity are related to the inherent frequency of the system.It seems that there are some synchronization effects between the dynamic character of the system and the delay time of recycled noise.Our results give clear information about how one can control the coherence and emission velocity of the noise-induced spike in a rather effective way,by deliberately adjusting the delay time and the fraction of the secondary noise.展开更多
The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(c...The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(cowmanure,corn stalk and Myriophyllum aquaticum)under three hydrothermal carbonization(HTC)temperatures(180,200 and 220°C)were evaluated.The results showed that the hydrochars had high dissolved organic carbon content(20.15 to 37.65 mg/g)and its content showed a gradual reduction as HTC temperature increased.Three fluorescent components including mixed substance of fulvic acid-like and humic acid-like substances(C1,30.92%-58.32%),UVA humic acid-like substance(C2,25.27%-29.94%)and protein-like substance(C3,11.74%-41.92%)were identified in hydrochar DOM by excitation emission matrix spectra coupled with parallel factor analysis.High HTC temperature increased the relative proportion of aromatic substances(C1+C2)and humification degree of hydrochar DOM from cow manure,while it presented adverse effects on the hydrochar DOM from corn stalk and Myriophyllum.aquaticum.The principal component analysis suggested that feedstock type and HTC temperature posed significant effects on the characteristics of hydrochar DOM.Additionally,seed germination test of all hydrochar DOM demonstrated that the root length was reduced by 8.88%-26.43%in contrast with control,and the germination index values were 73.57%-91.12%.These findings provided new insights into the potential environmental effects for hydrochar application in soil.展开更多
Self-sustained oscillations in complex networks consisting of long-standing interest in diverse oscillations in random networks natural and social systems nonoscillatory nodes have attracted We study the self-sustaine...Self-sustained oscillations in complex networks consisting of long-standing interest in diverse oscillations in random networks natural and social systems nonoscillatory nodes have attracted We study the self-sustained periodic consisting of excitable nodes. We reveal the underlying dynamic展开更多
Undoubtedly, the sensory organs of biological systems have been evolved to accurately detect and locate the external stimuli, even if they are very weak. However, the mechanism underlying this ability is still not ful...Undoubtedly, the sensory organs of biological systems have been evolved to accurately detect and locate the external stimuli, even if they are very weak. However, the mechanism underlying this ability is still not fully understood. Previously, it had been shown that stochastic resonance may be a good candidate to explain this ability, by which the response of a system to an external signal is amplified by the presence of noise. Recently, it is pointed out that the initial phase diversity in external signals can be also served as a simple and feasible mechanism for weak signal detection or amplification in excitable neurons. We here make a brief review on this progress. We will show that there are two kinds of effects of initial phase diversity: one is the phase disorder, i.e., the initial phases are different and static, and the other is the phase noise, i.e., the initial phases are time-varying like noise. Both cases show that initial phase diversity in subthreshold periodic signals can indeed play a constructive role in the emergence of sustained spiking activity. As initial phase diversity can mimic different arrival times from source signal to sensory organs, these findings may provide a cue for understanding the hunting behaviors of some biological systems.展开更多
The ultrafast excitation dynamics of atoms and molecules exposed to circularly polarized two-color(CPTC)laser fields constitute a fascinating topic in attosecond science. Although extensive research has established th...The ultrafast excitation dynamics of atoms and molecules exposed to circularly polarized two-color(CPTC)laser fields constitute a fascinating topic in attosecond science. Although extensive research has established the relationship between the Rydberg state excitation(RSE) yields and the CPTC field parameters, such as field amplitude ratios and helicity of two components, the role of the relative phase(φ) in modulating RSE efficiency remains unclear. In this work, we theoretically investigate the φ dependence of RSE and ionization yields in the co-rotating and counter-rotating circularly polarized two-color(CPTC) few-cycle laser fields by a semiclassical model. We find that, in co-rotating CPTC fields, both RSE and ionization yields display pronounced oscillations as a function of φ and these oscillations are significantly suppressed in the counter-rotating configuration, particularly for ionization yields. Moreover, the ratio of RSE to ionization yields exhibits an out-of-phase oscillatory pattern between low-and high-intensity regimes. These results can be comprehended by the unique feature of φ dependence of CPTC few-cycle fields, based on our semiclassical analysis. Our results demonstrate that phase-controlled CPTC fields offer a versatile tool for steering ultrafast ionization and RSE dynamics of atoms and molecules.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52125501,52405325)the Key Research Project of Shaanxi Province(Nos.2021LLRH-08,2024SF2-GJHX-34)+5 种基金the Program for Innovation Team of Shaanxi Province(No.2023-CX-TD17)the Postdoctoral Fellowship Program of CPSF(No.GZB20230573)the Postdoctoral Project of Shaanxi Province(No.2023BSHYDZZ30)the Basic Research Program of Natural Science in Shaanxi Province(No.2021JQ-906)the China Postdoctoral Science Foundationthe Fundamental Research Funds for the Central Universities。
文摘The inherent complexities of excitable cardiac,nervous,and skeletal muscle tissues pose great challenges in constructing artificial counterparts that closely resemble their natural bioelectrical,structural,and mechanical properties.Recent advances have increasingly revealed the beneficial impact of bioelectrical microenvironments on cellular behaviors,tissue regeneration,and therapeutic efficacy for excitable tissues.This review aims to unveil the mechanisms by which electrical microenvironments enhance the regeneration and functionality of excitable cells and tissues,considering both endogenous electrical cues from electroactive biomaterials and exogenous electrical stimuli from external electronic systems.We explore the synergistic effects of these electrical microenvironments,combined with structural and mechanical guidance,on the regeneration of excitable tissues using tissue engineering scaffolds.Additionally,the emergence of micro/nanoscale bioelectronics has significantly broadened this field,facilitating intimate interactions between implantable bioelectronics and excitable tissues across cellular,tissue,and organ levels.These interactions enable precise data acquisition and localized modulation of cell and tissue functionalities through intricately designed electronic components according to physiological needs.The integration of tissue engineering and bioelectronics promises optimal outcomes,highlighting a growing trend in developing living tissue construct-bioelectronic hybrids for restoring and monitoring damaged excitable tissues.Furthermore,we envision critical challenges in engineering the next-generation hybrids,focusing on integrated fabrication strategies,the development of ionic conductive biomaterials,and their convergence with biosensors.
基金supported by the National Nature Science Foundation of China(Nos.62075079,62305127,61975200)the Natural Science Foundation of Jilin Province(20230508135RC)the Science and Technology Development Foundation of Changchun City(23GZZ15).
文摘The fluorescence imaging (FLI) in the second near-infrared window (NIR-II, 1000–1700nm) has attracted considerable attention in the past decade. In contrast to conventional NIR-I window excitation (808nm/980nm), FLI with NIR-II window excitation (1064nm/other wavelength beyond 1000nm) can afford deeper tissue penetration depth with high clarity due to the merits of suppressed photon scattering and diminished autofluorescence. In this review, we have summarized NIR-II window excitable/emissive organic/polymeric fluorophores recently developed. The characteristics of these fluorophores such as chemical structures and photophysical properties have also been critically discussed. Furthermore, the latest development of noninvasive in vivo FLI with NIR-II excitation was highlighted. The ideal imaging results emphasized the importance of NIR-II excitation of these fluorophores in enabling deep tissue penetration and high-resolution imaging. Finally, a perspective on the challenges and prospects of NIR-II excitable/emissive organic/polymeric fluorophores was also discussed. We expected this review will be served as a source of inspiration for researchers, stimulating the creation of novel NIR-II excitable fluorophores and fostering the development of bioimaging applications.
基金supported by grants from the National Natural Science Foundation of China(31970913 and 32170957)the Natural Science Foundation of Guangdong Province(2021A1515012156)+1 种基金National Key Research and Development Program of China(2021ZD0201703)the Key-Area Research and Development Program of Guangdong Province(2019B030335001).
文摘Neuronomodulation refers to the modulation of neural conduction and synaptic transmission(i.e.,the conduction process involved in synaptic transmission)of excitable neurons via changes in the membrane potential in response to chemical substances,from spillover neuro-transmitters to paracrine or endocrine hormones circulating in the blood.Neuronomodulation can be direct or indirect,depending on the transduction pathways from the ligand binding site to the ion pore,either on the same molecule,i.e.the ion channel,or through an intermediate step on different molecules.The major players in direct neurono-modulation are ligand-gated or voltage-gated ion channels.The key process of direct neuronomodulation is the binding and chemoactivation of ligand-gated or voltage-gated ion channels,either orthosterically or allosterically,by various ligands.Indirect neuronomodulation involves metabotropic receptor-mediated slow potentials,where steroid hormones,cytokines,and chemokines can implement these actions.Elucidating neuronomodulation is of great significance for understanding the physiological mechanisms of brain function,and the occurrence and treatment of diseases.
基金国家重点基础研究发展计划(973计划)，国家自然科学基金，the Innovation Funds for Laser Technology，国家自然科学基金，the Science Foundation of the China Academy of Engineering Physics
文摘The synchronization and asynchronization of two coupled excitable systems are investigated. The two systems with different initial configurations, which are separately a single spiral wave (or a travel wave) and the rest state, can be developed to the synchronizing state with the same spiral wave (or travel wave) in each system, when the coupling is very strong. Decreasing the coupling intensity, two rest states or two different configurations appear in the two systems. The qualitative analysis and interpretation are given.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174034,11135001,11205041,and 11305112)the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20130282)
文摘All dynamic complex networks have two important aspects, pattern dynamics and network topology. Discovering different types of pattern dynamics and exploring how these dynamics depend or/network topologies are tasks of both great theoretical importance and broad practical significance. In this paper we study the oscillatory behaviors of excitable complex networks （ECNs） and find some interesting dynamic behaviors of ECNs in oscillatory probability, the multiplicity of oscillatory attractors, period distribution, and different types of oscillatory patterns （e.g., periodic, quasiperiodic, and chaotic）. In these aspects, we further explore strikingly sharp differences among network dynamics induced by different topologies （random or scale-free topologies） and different interaction structures （symmetric or asymmetric couplings）. The mechanisms behind these differences are explained physically.
基金Project supported by the National Natural Science Foundation of China (Grant No 10305005)the Fundamental Research Fund for Physics and Mathematics of Lanzhou University, China
文摘We studied synchronization behaviours of spiral waves in a two-layer coupled inhomogeneous excitable system. It was found that phase synchronization can be observed under weak coupling strength. By increasing the coupling strength, the synchronization is broken down. With the further increase of the coupling strength, complete synchronization and phase synchronization occur again. We also found that the inhomogeneity in excitable systems is helpful to the synchronization.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10562001 and 10765002
文摘Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation and analysis lead to the conclusions that, the number of refractory states does not influence the wave-front speed; the wave- front speed decreases as the excitation threshold increases and increases as the neighbor radius increases; the period of target waves is equal to the number of cell states; the excitation condition for target waves is that the wave-front speed must be bigger than half of the neighbor radius.
基金国家自然科学基金，国家重点基础研究发展计划(973计划)，教育部高校骨干教师资助计划，the TRAPOYT in Higher Education Institutions of MOE，教育部霍英东教育基金
文摘We study the firing synchronization behavior of the inhomogeneous excitable media. Phase synchronizationof neuron firings is observed with increasing the coupling, while the phases of neurons are different (out-of-phase synchronization). We found the synchronization of bursts can be greatly enhanced by applying an external forcing (in-phasesynchronization). The external forcing can be either a periodic or just homogeneous thermal noise. The mechanismresponsible for this enhancement is discussed.PACS numbers: 05.45.-a, 87.10.
文摘The motion of organization center of three_dimensional untwisted scroll waves in excitable media with single diffusion is studied by singular perturbation method in this paper. The relation of curvature and the linear law are derived for untwisted organization center. These results have explicit physical meaning and are in good agreement with experiments.
基金Supported by the National Natural Science Foundation of China under Grant No 71301012
文摘We investigate the collective dynamics of network-organized identical excitable nodes. We theoretically analyze the stability of the rest state and propose that there are two different transition paths： the stationary path and the oscillatory path. We find that, although the onset of collective dynamics strongly depend on the network topology, the local dynamics and how local nodes interact with each other decide the transition path and the involved bifurcation.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11105074 and 11005026)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (Grant Nos. 11KJB140004 and 11KJA110001)the Qing Lan Project of Jiangsu Province, China
文摘Depending on the excitability of the medium, a propagating wave segment will either contract or expand to fill the medium with spiral waves. This paper aims to introduce a simple mechanism of feedback control to stabilize such an expansion or contraction. To do this, we lay out a feedback control system in a block diagram and reduce it into a bare, universal formula. Analytical and experimental findings are compared through a series of numerical simulations of the Barkley model.
基金Project supported by the National Natural Science Foundation of China(Grant No.11875135).
文摘Studies of sustained oscillations on complex networks with excitable node dynamics received much interest in recent years.Although an individual unit is non-oscillatory,they may organize to form various collective oscillatory patterns through networked connections.An excitable network usually possesses a number of oscillatory modes dominated by different Winfree loops and numerous spatiotemporal patterns organized by different propagation path distributions.The traditional approach of the so-called dominant phase-advanced drive method has been well applied to the study of stationary oscillation patterns on a network.In this paper,we develop the functional-weight approach that has been successfully used in studies of sustained oscillations in gene-regulated networks by an extension to the high-dimensional node dynamics.This approach can be well applied to the study of sustained oscillations in coupled excitable units.We tested this scheme for different networks,such as homogeneous random networks,small-world networks,and scale-free networks and found it can accurately dig out the oscillation source and the propagation path.The present approach is believed to have the potential in studies competitive non-stationary dynamics.
文摘With help of establishing the moving coordinate on the wave front surface and the perturbation analysis in the boundary layer,the structures of wave front and organization center in excitable media were studied. The eikonal equation of wave front surface and general equation of organization center were obtained. These eikonal equations reveal the wave front surfaces have structures of twisted scroll wave and Mbius band, the organization centers have structures of knotted and linked ring. These theoretical results not only explain the wave patterns of BZ(Belousov-Zhabotinskii) chemical reaction but also give several possibility structures of wave front surface and organization center in general excitable media.
基金the financial support from the National Natural Science Foundation of China(22275124,22475134,62475160,T2421003,62075135)Shenzhen University 2035 Program for Excellent Research(868-000003011036)Start-up Grant from Shenzhen University(868-000001032113,868-000001032219).
文摘Three-photon(3P)fluorescence imaging(FLI)utilizing excitation wavelengths within the near-infrared-Ⅲ (NIR-Ⅲ,1600-1870 nm)window has emerged as a transformative modality for intravital imaging,owing to its combined advantages of excellent spatiotemporal resolution and remarkable tissue penetration.High-performance fluorescent probes are the cornerstone of highquality NIR-Ⅲ3P FLI.However,the construction of such probes is often hindered by inherent trade-offs in molecular design principles,posing significant challenges for their performance optimization and practical application.Here,we propose a straightforward and effective strategy based onπ-bridge manipulation to reconcile those competing molecular design parameters and substantially enhance 3P fluorescence properties.Leveraging this approach,a robust AIE-active small molecule,named TSSID,was developed,which exhibits bright NIR-I(700-950 nm)emission under 1665 nm NIR-Ⅲ3P excitation when formulated into nanoparticles(NPs).Remarkably,upon retro-orbital injection into mice following craniotomy,TSSID NPs achieved the best performance in deep-brain angiography among all reported organic 3P materials in terms of vascular imaging depth,signalto-background ratio,spatial resolution,and hemodynamic imaging depth.Additionally,TSSID NPs demonstrated outstanding biocompatibility through systematic biosafety evaluations.This study provides an excellent imaging agent and useful molecular design philosophy,facilitating the development of advanced organic 3P FLI probes.
文摘The dynamics of coupled excitable FitzHugh Nagumo systems under external noisy driving is studied. Different from most of previous work focusing on the noise-induced regularity in the framework of coherence resonance, here the average frequency （or firing rate） of coupled excitable elements is of much more concern. We find that （i） their frequencies first increase and then decrease with the increase of the coupling, and there is a clear crossover from a rush increase to a smooth increase with the increase of noise strength, and （ii） for nonidentical cases, all elements transit to an identical frequency simultaneously only after a certain coupling strength is achieved. These first-increase-thendecrease non-monotonic frequency behavior and isochronous frequency synchronization are believed to be two basic behaviors in coupled noisy excitable systems.
基金supported by the National Natural Science Foundation of China (21073232)the Fundamental Research Funds for the Central Universities (2010QNA16)the Research Fund of China University of Mining and Technology
文摘The control effect of recycled noise,generated by the superposition of a primary Gaussian noise source and a secondary source with a constant delay,has been studied in an excitable FitzHugh-Nagumo system.We mainly focus on the performance of noise-induced spike and coherence resonance in a parameter region sub-threshold to supercritical Hopf bifurcation.For fixed noise intensity,simulations show that the coherence(quantitatively measured by R,which is defined as the mean value of the spike interval time T normalized to its mean square root) and the emission velocity of the noise-induced spikes exhibit damped oscillations with the variation of delay time,demonstrating a new kind of multi-resonance phenomenon.Furthermore,the optimal delay times for resonance and the fast emission velocity are related to the inherent frequency of the system.It seems that there are some synchronization effects between the dynamic character of the system and the delay time of recycled noise.Our results give clear information about how one can control the coherence and emission velocity of the noise-induced spike in a rather effective way,by deliberately adjusting the delay time and the fraction of the secondary noise.
基金supported by the Director Fund Project provided by the Institute of Plant Nutrition,Resources and Environment,Beijing Academy of Agriculture and Forestry Sciences(No.YZS202101)the Youth Fund Project provided by Beijing Academy of Agriculture and Forestry Sciences(No.QNJJ202125)China Agriculture Research System of MOF and MARA.
文摘The dissolved organic matter(DOM)with high mobility and reactivity plays a crucial role in soil.In this study,the characteristics and phytotoxicity ofDOMreleased fromthe hydrochars prepared from different feedstocks(cowmanure,corn stalk and Myriophyllum aquaticum)under three hydrothermal carbonization(HTC)temperatures(180,200 and 220°C)were evaluated.The results showed that the hydrochars had high dissolved organic carbon content(20.15 to 37.65 mg/g)and its content showed a gradual reduction as HTC temperature increased.Three fluorescent components including mixed substance of fulvic acid-like and humic acid-like substances(C1,30.92%-58.32%),UVA humic acid-like substance(C2,25.27%-29.94%)and protein-like substance(C3,11.74%-41.92%)were identified in hydrochar DOM by excitation emission matrix spectra coupled with parallel factor analysis.High HTC temperature increased the relative proportion of aromatic substances(C1+C2)and humification degree of hydrochar DOM from cow manure,while it presented adverse effects on the hydrochar DOM from corn stalk and Myriophyllum.aquaticum.The principal component analysis suggested that feedstock type and HTC temperature posed significant effects on the characteristics of hydrochar DOM.Additionally,seed germination test of all hydrochar DOM demonstrated that the root length was reduced by 8.88%-26.43%in contrast with control,and the germination index values were 73.57%-91.12%.These findings provided new insights into the potential environmental effects for hydrochar application in soil.
基金Acknowledgements This work was supported by the National Natural Science Foundation of China （Grant Nos. 10675020 and 10975015）, and the National Basic Research Program of China （973 Program） （Grant No. 2007CB814800）.
文摘Self-sustained oscillations in complex networks consisting of long-standing interest in diverse oscillations in random networks natural and social systems nonoscillatory nodes have attracted We study the self-sustained periodic consisting of excitable nodes. We reveal the underlying dynamic
基金supported by the National Natural Science Foundation of China(Grant No.11305078)
文摘Undoubtedly, the sensory organs of biological systems have been evolved to accurately detect and locate the external stimuli, even if they are very weak. However, the mechanism underlying this ability is still not fully understood. Previously, it had been shown that stochastic resonance may be a good candidate to explain this ability, by which the response of a system to an external signal is amplified by the presence of noise. Recently, it is pointed out that the initial phase diversity in external signals can be also served as a simple and feasible mechanism for weak signal detection or amplification in excitable neurons. We here make a brief review on this progress. We will show that there are two kinds of effects of initial phase diversity: one is the phase disorder, i.e., the initial phases are different and static, and the other is the phase noise, i.e., the initial phases are time-varying like noise. Both cases show that initial phase diversity in subthreshold periodic signals can indeed play a constructive role in the emergence of sustained spiking activity. As initial phase diversity can mimic different arrival times from source signal to sensory organs, these findings may provide a cue for understanding the hunting behaviors of some biological systems.
基金supported by the National Natural Science Foundation of China (Nos. 12121004, 12274273, and 12450402)the Science and Technology Department of Hubei Province (No. 2020CFA029)+1 种基金CAS Project for Young Scientists in Basic Research (No. YSBR-091)the Youth Innovation Promotion Association CAS (No. 2021328)。
文摘The ultrafast excitation dynamics of atoms and molecules exposed to circularly polarized two-color(CPTC)laser fields constitute a fascinating topic in attosecond science. Although extensive research has established the relationship between the Rydberg state excitation(RSE) yields and the CPTC field parameters, such as field amplitude ratios and helicity of two components, the role of the relative phase(φ) in modulating RSE efficiency remains unclear. In this work, we theoretically investigate the φ dependence of RSE and ionization yields in the co-rotating and counter-rotating circularly polarized two-color(CPTC) few-cycle laser fields by a semiclassical model. We find that, in co-rotating CPTC fields, both RSE and ionization yields display pronounced oscillations as a function of φ and these oscillations are significantly suppressed in the counter-rotating configuration, particularly for ionization yields. Moreover, the ratio of RSE to ionization yields exhibits an out-of-phase oscillatory pattern between low-and high-intensity regimes. These results can be comprehended by the unique feature of φ dependence of CPTC few-cycle fields, based on our semiclassical analysis. Our results demonstrate that phase-controlled CPTC fields offer a versatile tool for steering ultrafast ionization and RSE dynamics of atoms and molecules.
