铈和钆对体外培养正常二倍体细胞的作用

采用同位素示踪、细胞周期分析和组化等技术，研究Ｃｅ３＋和Ｇｄ３＋对动物正常二倍体细胞的生物学作用。结果表明，Ｃｅ３＋和Ｇｄ３＋仅在一个狭窄的剂量范围（１×１０－６～１×１０－５ｍｏｌ／Ｌ）可促进正常二倍体细胞增殖，有明显的剂量—效应关系。Ｃｅ３＋和Ｇｄ３＋在高浓度时（１×１０－３ｍｏｌ／Ｌ），对细胞具有毒性，可使细胞坏死、增殖缓慢并诱导细胞凋亡。     

具有时滞的细胞神经网络的全局指数稳定性

利用Liapunov函数方法,结合积分不等式技巧,分析了时滞细胞神经网络的平衡点存在的唯一性和全局指数稳定性,保证时滞细胞神经网络全局指数稳定的一个新的充分判据被得到.所得判据比已有文献具有更少的限制,为实际应用提供了方便.     

考虑公交港湾式停靠的多速混合城市交通流元胞自动机模型研究

在Nagel-Schreckenberg提出的元胞自动机模型基础上,建立了考虑公交车辆和港湾式公交停靠站的多速混合车辆单车道城市交通流元胞自动机模型.通过计算机模拟,给出了随机减速概率、混合车流密度、公交车辆平均停靠时间、公交车辆占有率和港湾式公交车站间距对混合车流速度和流量的影响图.对混合车流的特性进行了分析和讨论. 关键词： 元胞自动机 港湾式公交停靠站 混合交通流模型 计算机模拟     

The unstable behavior of cellular premixed flames induced by intrinsic instability

The unstable behavior of cellular premixed flames induced by intrinsic instability is studied by two-dimensional unsteady calculations of reactive flows. In the present numerical simulation, the compressible Navier–Stokes equation including a one-step irreversible chemical reaction is employed. We consider two basic types of phenomena to account for the intrinsic instability of premixed flames, i.e., hydrodynamic and diffusive-thermal effects. The hydrodynamic effect is caused by the thermal expansion through the flame front; the diffusive-thermal effect is caused by the preferential diffusion of mass versus heat. A disturbance with several wavelength components is superimposed on a planar flame, and the formation of a cellular flame induced by hydrodynamic and diffusive-thermal effects is numerically simulated. After the cellular-flame formation, the combination and division of cells are observed. The behavior of cellular-flame fronts becomes more unstable when the Lewis number is lower than unity, since the diffusive-thermal effect has a great influence on the unstable behavior. The cell size changes with time, and its average is greater than the critical wavelength and becomes smaller by decreasing the Lewis number. The flame velocity of cellular flames depends strongly on the length of computational domain in the direction tangential to the flame front. As the length of computational domain increases, the flame velocity becomes larger. This is because the long-wavelength components of disturbances play an important role in the shape of cellular flames, i.e., in the flame-surface area.     

Periodical cicadas: A minimal automaton model

The Magicicada spp. life cycles with its prime periods and highly synchronized emergence have defied reasonable scientific explanation since its discovery. During the last decade several models and explanations for this phenomenon appeared in the literature along with a great deal of discussion. Despite this considerable effort, there is no final conclusion about this long standing biological problem. Here, we construct a minimal automaton model without predation/parasitism which reproduces some of these aspects. Our results point towards competition between different strains with limited dispersal threshold as the main factor leading to the emergence of prime numbered life cycles.     

Cellular instabilities of expanding hydrogen/propane spherical flames at elevated pressures: theory and experiment

An experimental and theoretical investigation of the onset of cellular instabilities on spherically expanding flames in mixtures of hydrogen and propane in air at elevated pressures was conducted. Critical conditions for the onset of instability were measured and mapped out over a range of pressures and mixture compositions. An asymptotic theory of hydrodynamic and diffusional-thermal cell development on flames in mixtures comprised of two scarce fuels burning in air was also formulated. Predicted values of Peclet number, defined as the flame radius at the onset of instability normalized by the flame thickness, were shown to compare favorably with the experimentally measured values.     

Complexity of some natural problems in automatic structures

We prove that the automatic isomorphism problem for automatic structures, the automatic automorphism problem for an automatic structure, and the automatic embedding problem for automatic structures are $ \overset{\lower0.5em\hbox{$ \overset{\lower0.5em\hbox{ Matematicheski $ \overset{\lower0.5em\hbox{$ \overset{\lower0.5em\hbox{ Zhurnal, Vol. 46, No. 1, pp. 71–78, January–February, 2005.     

Critical points of two-dimensional bootstrap percolation-like cellular automata

Cellular automata in two dimensions that generalize the bootstrap percolation dynamics are considered, focusing on the thresholdp _c of the initial density for convergence to total occupancy to occur; these models are classified according top _c being 0, 1, or strictly between these extreme values. Explicit upper and lower bounds are provided in the third case.     

Lyapunov exponents for one-dimensional cellular automata

Summary In the paper we give a mathematical definition of the left and right Lyapunov exponents for a one-dimensional cellular automaton (CA). We establish an inequality between the Lyapunov exponents and entropies (spatial and temporal).     

Probabilistic properties of neuron spiking time-series obtained in vivo

Probabilistic properties of spiking time-series obtained in vivo from singular neurons belonging to Red Nucleus of brain are analyzed for two groups of rats: genetically defined rat model of depression (Flinders Sensitive Rat Line - FSL) and a control (healthy) group. The FSL group shows a distribution of interspike intervals with a much longer tail than that found for normal rats. The former distribution (for the FSL group) indicates a power-law with exponent α = - 1±0.1. A simple thermodynamic (noise) model is elaborated to explain obtained results. Received 13 May 2001 and Received in final form 20 September 2001