Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues,which is closely related to both normal brain activity and abnormal neural activity such as epileptic ...Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues,which is closely related to both normal brain activity and abnormal neural activity such as epileptic discharge. However, the propagation mechanism behind this coexistence phenomenon remains unclear. In this paper, a three-dimensional electric field coupled hippocampal neural network is established to investigate generation of coexisting spontaneous fast and slow traveling waves. This model captures two types of dendritic traveling waves propagating in both transverse and longitude directions: the N-methyl-D-aspartate(NMDA)-dependent wave with a speed of about 0.1 m/s and the Ca-dependent wave with a speed of about 0.009 m/s. These traveling waves are synaptic-independent and could be conducted only by the electric fields generated by neighboring neurons, which are basically consistent with the in vitro data measured experiments. It is also found that the slow Ca wave could trigger generation of fast NMDA waves in the propagation path of slow waves whereas fast NMDA waves cannot affect the propagation of slow Ca waves. These results suggest that dendritic Ca waves could acted as the source of the coexistence fast and slow waves. Furthermore, we also confirm the impact of cellular spacing heterogeneity on the onset of coexisting fast and slow waves. The local region with decreasing distances among neighbor neurons is more liable to promote the onset of spontaneous slow waves which, as sources, excite propagation of fast waves. These modeling studies provide possible biophysical mechanisms underlying the neural dynamics of spontaneous traveling waves in brain tissues.展开更多
A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ di...A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed.展开更多
Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ^4 model are presented. Simultaneously, inspired by the new solutions of the famous φ^4 model recently proposed by J...Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ^4 model are presented. Simultaneously, inspired by the new solutions of the famous φ^4 model recently proposed by Jia, Huang and Lou, five kinds of new localized excitations of the nonlinear coupled scaiar field （NCSF） system are obtained.展开更多
LiNbO3 has been found attractive for lateral field excitation （LFE） applications due to its high piezoelectric coupling. In this paper, bulk acoustic wave propagation properties for LiNbO3 single crystal excited by ...LiNbO3 has been found attractive for lateral field excitation （LFE） applications due to its high piezoelectric coupling. In this paper, bulk acoustic wave propagation properties for LiNbO3 single crystal excited by a lateral electric field have been investigated using the extended Christoffel Bechmann method. It is found that the LFE piezoelectric coupling factor for c mode reaches its maximum value of 95.46% when ψ = 0° for both （yxl）-58° and （yxwl）±60°/58° LiNbO3. The acoustic wave phase velocity of c mode TSM （thickness shear mode） changes from 3456 m/s to 3983 m/s as a function of ψ. Here ψ represents the angle between the lateral electric field and the crystallographic X-axis in the substrate major surface. A 5 MHz LFE device of （yxl）-58° LiNbO3 with ψ = 0° was designed and tested in air. A major resonance peak was observed with the motional resistance as low as 17 Ω and the Q-factor value up to 10353. The test result is well in agreement with the theoretical analysis, and suggests that the LFE LiNbO3 device can be a good platform for high performance resonator or sensor applications.展开更多
This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and met...This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and metal wires. The square ring acts as the “bright state” and the metal wire acts as the “dark state”. The destructive interference between the bright state and the dark state produces an EIT-like effect. In the simulation results, a transparent window centered at 4.00 GHz can be observed in the transmission spectrum. By studying the phase change of the transparent window, it is found that the group delay of the metamaterial structure can reach 0.39 ns at 4.00 GHz. This paper </span><span>also studies the influence of the refractive index of the medium on the</span><span> EIT-like effect. Numerical simulations show that such metamaterial is very sensitive to the refractive index of the medium, and the sensitivity is 15 mm/RIU. Our design can be extended to other frequency bands and may have potential applications in filtering, sensing, slow-light devices, and nonlinear optics.展开更多
This paper is devoted to the study of the solitary wave solutions for the delayed coupled Higgs field equation{vtt-uxx-αu+βf*u|u|^(2)-2uv-τu(|u|^(2))x=0 vtt+vxx-β(|u|^(x))xx=0.We first establish the existence of s...This paper is devoted to the study of the solitary wave solutions for the delayed coupled Higgs field equation{vtt-uxx-αu+βf*u|u|^(2)-2uv-τu(|u|^(2))x=0 vtt+vxx-β(|u|^(x))xx=0.We first establish the existence of solitary wave solutions for the corresponding equation without delay and perturbation by using the Hamiltonian system method.Then we consider the persistence of solitary wave solutions of the delayed coupled Higgs field equation by using the method of dynamical system,especially the geometric singular perturbation theory,invariant manifold theory and Fredholm theory.According to the relationship between solitary wave and homoclinic orbit,the coupled Higgs field equation is transformed into the ordinary differential equations with fast variables by using the variable substitution.It is proved that the equations with perturbation also possess homoclinic orbit,and thus we obtain the existence of solitary wave solutions of the delayed coupled Higgs field equation.展开更多
基金supported in part by the National Natural Science Foundation of China (Grant Nos. 62171312 and 61771330)the Tianjin Municipal Education Commission Scientific Research Project (Grant No. 2020KJ114)。
文摘Coexistence of fast and slow traveling waves without synaptic transmission has been found in hhhippocampal tissues,which is closely related to both normal brain activity and abnormal neural activity such as epileptic discharge. However, the propagation mechanism behind this coexistence phenomenon remains unclear. In this paper, a three-dimensional electric field coupled hippocampal neural network is established to investigate generation of coexisting spontaneous fast and slow traveling waves. This model captures two types of dendritic traveling waves propagating in both transverse and longitude directions: the N-methyl-D-aspartate(NMDA)-dependent wave with a speed of about 0.1 m/s and the Ca-dependent wave with a speed of about 0.009 m/s. These traveling waves are synaptic-independent and could be conducted only by the electric fields generated by neighboring neurons, which are basically consistent with the in vitro data measured experiments. It is also found that the slow Ca wave could trigger generation of fast NMDA waves in the propagation path of slow waves whereas fast NMDA waves cannot affect the propagation of slow Ca waves. These results suggest that dendritic Ca waves could acted as the source of the coexistence fast and slow waves. Furthermore, we also confirm the impact of cellular spacing heterogeneity on the onset of coexisting fast and slow waves. The local region with decreasing distances among neighbor neurons is more liable to promote the onset of spontaneous slow waves which, as sources, excite propagation of fast waves. These modeling studies provide possible biophysical mechanisms underlying the neural dynamics of spontaneous traveling waves in brain tissues.
基金Project supported by the National Natural Science Foundation of China(Grant No.11205162)
文摘A three-dimensional model of the double-slot coupled cavity slow-wave structure （CCSWS） with a solid round elec- tron beam for the beam-wave interaction is presented. Based on the ＂cold＂ dispersion, the ＂hot＂ dispersion equation is derived with the Maxwell equations by using the variable separation method and the field-matching method. Through numerical calculations, the effects of the electron beam parameters and the staggered angle between adjacent walls on the linear gain are analyzed.
基金National Natural Science Foundation of China under Grant Nos.10475055 and 90503006the Scientific Research Fund of the Education Department of Zhejiang Province under Grant No.20040969
文摘Some extended solution mapping relations of the nonlinear coupled scalar field and the well-known φ^4 model are presented. Simultaneously, inspired by the new solutions of the famous φ^4 model recently proposed by Jia, Huang and Lou, five kinds of new localized excitations of the nonlinear coupled scaiar field （NCSF） system are obtained.
基金supported by the National Natural Science Foundation of China (Grant No 60571014)
文摘LiNbO3 has been found attractive for lateral field excitation （LFE） applications due to its high piezoelectric coupling. In this paper, bulk acoustic wave propagation properties for LiNbO3 single crystal excited by a lateral electric field have been investigated using the extended Christoffel Bechmann method. It is found that the LFE piezoelectric coupling factor for c mode reaches its maximum value of 95.46% when ψ = 0° for both （yxl）-58° and （yxwl）±60°/58° LiNbO3. The acoustic wave phase velocity of c mode TSM （thickness shear mode） changes from 3456 m/s to 3983 m/s as a function of ψ. Here ψ represents the angle between the lateral electric field and the crystallographic X-axis in the substrate major surface. A 5 MHz LFE device of （yxl）-58° LiNbO3 with ψ = 0° was designed and tested in air. A major resonance peak was observed with the motional resistance as low as 17 Ω and the Q-factor value up to 10353. The test result is well in agreement with the theoretical analysis, and suggests that the LFE LiNbO3 device can be a good platform for high performance resonator or sensor applications.
文摘This paper proposes a new metamaterial design that can achieve electromagnetic induction transparency-like (EIT-like) effects in the microwave band. The unit structure of metamaterials consists of square rings and metal wires. The square ring acts as the “bright state” and the metal wire acts as the “dark state”. The destructive interference between the bright state and the dark state produces an EIT-like effect. In the simulation results, a transparent window centered at 4.00 GHz can be observed in the transmission spectrum. By studying the phase change of the transparent window, it is found that the group delay of the metamaterial structure can reach 0.39 ns at 4.00 GHz. This paper </span><span>also studies the influence of the refractive index of the medium on the</span><span> EIT-like effect. Numerical simulations show that such metamaterial is very sensitive to the refractive index of the medium, and the sensitivity is 15 mm/RIU. Our design can be extended to other frequency bands and may have potential applications in filtering, sensing, slow-light devices, and nonlinear optics.
基金Supported by NSFC(Grant Nos.12071065 and 11871140)the National Key Research and Development Program of China(Grant No.2020YFA0713602)。
文摘This paper is devoted to the study of the solitary wave solutions for the delayed coupled Higgs field equation{vtt-uxx-αu+βf*u|u|^(2)-2uv-τu(|u|^(2))x=0 vtt+vxx-β(|u|^(x))xx=0.We first establish the existence of solitary wave solutions for the corresponding equation without delay and perturbation by using the Hamiltonian system method.Then we consider the persistence of solitary wave solutions of the delayed coupled Higgs field equation by using the method of dynamical system,especially the geometric singular perturbation theory,invariant manifold theory and Fredholm theory.According to the relationship between solitary wave and homoclinic orbit,the coupled Higgs field equation is transformed into the ordinary differential equations with fast variables by using the variable substitution.It is proved that the equations with perturbation also possess homoclinic orbit,and thus we obtain the existence of solitary wave solutions of the delayed coupled Higgs field equation.
