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Oscillatory Activities in Regulatory Biological Networks and Hopf Bifurcation 总被引:1,自引:0,他引:1 下载免费PDF全文
Exploiting the nonlinear dynamics in the negative feedback loop, we propose a statistical signal-response model to describe the different oscillatory behaviour in a biological network motif. By choosing the delay as a bifurcation parameter, we discuss the existence of Hopf bifurcation and the stability of the periodic solutions of model equations with the centre manifold theorem and the normal form theory. It is shown that a periodic solution is born in a Hopf bifurcation beyond a critical time delay, and thus the bifurcation phenomenon may be important to elucidate the mechanism of oscillatory activities in regulatory biological networks. 相似文献
875.
An All-Solid-State Tunable Dual-Wavelength Ti:Sapphire Laser with Quasi-Continuous-Wave Outputs 下载免费PDF全文
A high power dual-wavelength Ti:sapphire laser system with wide turning range and high efficiency is described, which consists of two prism-dispersed resonators pumped by an a11-solid-state frequency-doubled Nd:YAG laser. Tunable dual-wavelength outputs, with one wavelength range from 750nm to 795nm and the other from 80Ohm to 850nm, have been demonstrated. With a pump power of 23 W at 532nm, a repetition rate of 6.5kHz and a pulse width of 67.6ns, the maximum dual-wavelength output power of 5.6 W at 785.3nm and 812.1 run, with a pulse width of 17.2ns and a line width of 2nm, has been achieved, leading to an optical-to-optical conversion efficiency of 24.4%. 相似文献
876.
A 2.048μm Tm,Ho:GdVO4 Laser Pumped Doubly Resonant Optical Parametric Oscillator Based on Periodically Poled Lithium LiNbO3 下载免费PDF全文
A multi-grating periodically poled LiNb03 (PPLN) doubly resonant optical parametric oscillator (DROPO) pumped by a 2-ttm laser is demonstrated experimentally. Employing acousto-optically Q-switched Tm,Ho:GdV04 laser with pump pulse of 25ns and repetition rate of lOkHz as pump sources firstly, the noncritically quasi- phase-matched (QPM) tunable mid-IR output in 3.87-4.43 μm is produced. Wavelength tuning is achieved with crystal temperature tuning from 50-180^o C. When the incident average pump power is 3 W at 2.048μm, the total OPO output power of 195mW at wavelength 3.88μm is obtained, corresponding to optical-to-optical conversion efficiency up to 6.5%. 相似文献
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We report a GaN metal-oxide-semiconductor high electron mobility transistor (MOS-HEMT) with atomic layer deposited (ALD) Al2O3 gate dielectric. Based on the previous work [Appl. Phys. Lett. 86 (2005) 063501] of Ye et al. by decreasing the thickness of the gate oxide to 3.5nm and optimizing the device fabrication process, the device with maximum transconductance of 150mS/mm is produced and discussed in comparison with the result of lOOmS/mm of Ye et al. The corresponding drain current density in the 0.8-μm-gate-length MOS-HEMT is 800mA/mm at the gate bias of 3.0 V. The gate leakage is two orders of magnitude lower than that of the conventional A1GaN/GaN HEMT. The excellent characteristics of this novel MOS-HEMT device structure with ALD Al2O3 gate dielectric are presented. 相似文献
878.
The difference in temporal structures of retinal ganglion cell spike trains between spontaneous activity and firing activity after contrast adaptation is investigated. The Lempel-Ziv complexity analysis reveals that the complexity of the neural spike train decreases after contrast adaptation. This implies that the behaviour of the neuron becomes ordered, which may carry relevant information about the external stimulus. Thus, during the neuron activity after contrast adaptation, external information could be encoded in forms of some certain patterns in the temporal structure of spike train that is significantly different, compared to that of the spike train during spontaneous activity, although the firing rates in spontaneous activity and firing activity after contrast adaptation are sometime similar. 相似文献
879.
依据最弱受约束电子势模型理论,计算了铕原子4f76snd6D9/2(n≥13)、4f76snd8D9/2(n≥17)、4f76snd8D5/2(n≥15)和4f76snd8D3/2(n≥21)里德堡系列能级.计算结果与实验值的最大相对误差为4×10-5,最大绝对误差是1.91cm-1,达到了较高精度,这表明文中的外推数据是可信的. 相似文献
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