二维格子神经元网络中螺旋波的鲁棒性和破裂

研究了二维格子神经元网络中螺旋波的鲁棒性和破裂问题．小世界网络连接被分解为局部规则连接和一定概率的长程连接,实际的生物神经元网络的长程连接概率可能是变化的．因此,用局部规则连接和可变的长程连接概率则更能恰当地研究网络对实际生物系统螺旋波的演化,可变的长程连接概率对螺旋波的影响简化为乘性噪声效应．首先选择恰当的初始值和参数值并在无流边界条件下在神经元网络内诱导出稳定旋转的螺旋波,再考虑网络对螺旋波演化的影响．研究发现当乘性噪声强度小于一定闽值时螺旋波保持很好的鲁棒性,进一步增加乘性噪声强度则发现螺旋波破裂．定义了一类统计同步因子,并通过观察同步因子曲线上临界点参数（如噪声强度和刺激电流强度等）对应的所有格点神经元膜点位来研究螺旋波的相变问题．首先研究了Hindmarsh-Rose耦合神经元网络中螺旋波的鲁棒性和破裂,为验证结论与模型无关则进一步研究了在通道噪声下Hodgkin-Huxley神经元网络螺旋波的破裂和鲁棒性问题,发现在通道噪声下乘性噪声更容易引起螺旋波的破裂．     

A mathematical model of a P53 oscillation network triggered by DNA damage

Taking the interaction between a DNA damage repair module, an ATM module, and a P53--MDM2 oscillation module into account, this paper presents a mathematical model of a P53 oscillation network triggered by a DNA damage signal in individual cells. The effects of the DNA damage signal and the delay time of P53-induced MDM2 expression on the behaviours of the P53 oscillation network are studied. In the oscillatory state of the P53--MDM2 oscillator, it is found that the pulse number of P53--P oscillation increases with the increase of the initial DNA damage signal, whereas the amplitude and the period of P53--P oscillation are fixed for different initial DNA damage signals, and the period numbers of P53--P oscillations decrease with the increase of time delay of MDM2 expression induced by P53. These theoretical predictions are consistent with previous experimental results. The combined negative feedback of P53--MDM2 with the time delay of P53-induced MDM2 expression causes oscillation behaviour in the P53 network.     

Synergy and Redundancy in a Signaling Cascade with Different Feedback Mechanisms

Feedback plays an important role in various biological signal transmission systems. In this paper, a signaling cascade system(including three layers: input(S), intermediate(V), output(X) components) is employed to study the fluctuations and net synergy in information transmission, in which the V component is regulated by itself or the X component, and each feedback on V is either positive or negative. The Fano factor, the net synergy, and the signalto-noise ratio(SNR) of signaling cascade with the four possible feedback types are theoretically derived by using linear noise approximation of the master equation, and the ability of information transmission through the signaling cascade is characterized by using the partial information decomposition of information theory. It is found that the signaling cascade exhibits different responses to the four feedback mechanisms, which depend on the relationships between degradation rates of components. Our results not only clarify the dependence of the Fano factor, net synergy, and SNR on the feedback regulations with the varying of degradation rates of components, but also imply that living cells could utilize different feedback mechanisms to adapt to the external fluctuating environments.     

A Quantitative Analysis of Modulation of the Fast Excitatory Postsynaptic Potential of Neurons in Rat Sympathetic Ganglia by a Low-Intensity Laser

We propose a mathematical model which can quantitatively describe the kinetics of postsynaptic membrane potential modulated by a low intensity laser. By virtue of the numerical computation, it is found that the height of peak of fast excitatory postsynaptic potential （f-EPSP） for intermediate laser power density （around 2mW/cm^2） is higher than that for both small and large laser power densities, that is, of the f-EPSP peak height changes with the increasing laser power density （up to 5 m W/cm^2） in non-monotonic behaviour. The theoretical results are qualitatively consistent with the previous experimental data.     

Breakup of Spiral Waves in Coupled Hindmarsh--Rose Neurons

Breakup of spiral wave in the Hindmarsh-Rose neurons with nearest-neighbour couplings is reported. Appropriate initial values and parameter regions are selected to develop a stable spiral wave and then the Gaussian coloured noise with different intensities and correlation times is imposed on all neurons to study the breakup of spiral wave, respectively. Based on the mean field theory, the statistical factor of synchronization is defined to analyse the evolution of spiral wave. It is found that the stable rotating spiral wave encounters breakup with increasing intensity of Gaussian coloured noise or decreasing correlation time to certain threshold.     

生物钟基因网络中分子噪声诱导的日夜节律振荡及相干共振

研究了果蝇细胞内生物钟基因调节网络的分子噪声，特别讨论了生物钟系统处于略微远离振荡区域的稳态时分子噪声对于时钟蛋白的日夜节律振荡的影响.结果表明：(1)虽然时钟蛋白合成或者衰减的生化反应事件是在随机的时间间隔里随机发生的，但系统可以依赖自身固有的调节机理诱导出明显的日夜节律振荡；(2)分子噪声诱导的日夜节律振荡的相干性可以在合适的分子噪声水平下到达最佳，说明了相干共振现象的发生.     

浅析网络环境下图书馆的功能

网络环境下图书馆的功能是虚拟图书馆和实体图书馆功能的总和。介绍了网络环境下图书馆的基本特征和功能。提出了完善服务模式、强化文献资源共建共享、建立特色馆藏文献、提高图书馆专业人员素质等网络环境下图书馆的发展对策。     

两个双态噪声驱动系统的近似几率密度研究

研究了由两个双态噪声驱动的随机系统。给出了该随机系统的几率密度方程组，借助几率密度的随机刘维方程和对双态噪声变换，求得了近似几率密度方程。运用这种方法导出了随机的化学反应系统的近似几率密度方程。利用“Ｈａｎｇｇｉ－ｌｉｋｅａｎｓａｔｚ”求得了此化学反应的近似Ｆｏｋｋｅｒ－ｐｌａｎｃｋ方程及其定态解。     

FitzHugh-Nagumo神经模型中的噪声诱导相变

报道了对称六齿配体Ｎ,Ｎ,Ｎ’－四（２’－苯并咪唑甲基）乙二胺（ＥＤＴＢ）的两种含镍（Ⅱ）配合物「ｉ（ＥＤＴＢ）」（ＣｌＯ４）２．３Ｈ２Ｏ和「Ｎｉ（ＥＤＴＢ）」Ｃｌ２．２Ｈ２Ｏ．３Ｃ２Ｈ５ＯＨ的合成、表征及其对尿素水解的影响。根据配合物元素分析、摩尔电导、紫外－可见（ＵＶ－Ｖｉｓ）、红外（ＩＲ）、ＥＳＲ谱和循环伏安（ＣＶ）等性质与已测Ｘ－射线单晶结构的同种配体含铜（Ⅱ）单核配合物比较,推测此两种配