软件技术在近红外光谱定量分析中的应用

为了更好地运用化学计量学方法提高近红外光谱定量分析的质量,全面研究了相关算法技术与软件工具的应用。根据近红外光谱定量分析的一般流程,依次探讨了光谱数据预处理、异常样本检测、样本集划分、波长选择、模型建立及其参数优化的常用算法,并给出了其中各种主流算法的基本步骤;然后介绍了OMNIC、OPUS、Origin、The Unscrambler X和MATLAB等软件工具的功能特点和主要用途,可为相关技术研究和分析检测工作提供参考。     

Noise-induced synchronous stochastic oscillations in small scale cultured heart-cell networks

This paper reports that the synchronous integer multiple oscillations of heart-cell networks or clusters are observed in the biology experiment.The behaviour of the integer multiple rhythm is a transition between super-and subthreshold oscillations,the stochastic mechanism of the transition is identified.The similar synchronized oscillations are theoretically reproduced in the stochastic network composed of heterogeneous cells whose behaviours are chosen as excitable or oscillatory states near a Hopf bifurcation point.The parameter regions of coupling strength and noise density that the complex oscillatory rhythms can be simulated are identified.The results show that the rhythm results from a simple stochastic alternating process between super-and sub-threshold oscillations.Studies on single heart cells forming these clusters reveal excitable or oscillatory state nearby a Hopf bifurcation point underpinning the stochastic alternation.In discussion,the results are related to some abnormal heartbeat rhythms such as the sinus arrest.     

第二届全国动力学与控制青年学者研讨会介绍

为了深入交流动力学与控制学科己取得的成果,探讨今后的发展趋势和面临的挑战,促进青年学者间的交流,加深青年学者对履行历史使命的责任感,由国家自然科学基金委员会数理科学部发起,国家自然科学基金委员会数理科学部和中国力学学会一般力学专业委员会联合主办,由陕两师范大学承办的"第二届仝围动力学与控制青年学者研讨会"于2008年9月20～23日在陕西西安召开,中国力学学会一般力学专业委员会主任委员张伟教授担任会议土席,陕两师范人学生命科学学院占华光副教授、任维教授等组织该次会议.     

实验性神经起步点自发放电的整数倍节律和随机自共振

本文介绍了实验中发现的无外界周期刺激的神经起步点放电节律随[Ca＋＋]。变化产生的整数倍节律，并用描写神经放电的理论模型（Chay模型）进行数值模拟。结果发现：在相应的参数区间，确定性模型为－Hopf分岔，无整数倍节律；在随机模型中，在Hopf分岔点附近，整数倍节律产生，该整数倍节律是通过随机自共振产生的。实验中与模型的整数倍节律处于桢的参数区间，位于周期1和阈下振荡之间：并且有相同的特征；其峰峰间期处于一个基本峰峰新时期的整数倍，峰峰间期出现频率随峰峰新时期增加呈现出指数降低。这提示，实验中的整数倍节律是通过随机自共振产生的。     

Interpreting a period-adding bifurcation scenario in neural bursting patterns using border-collision bifurcation in a discontinuous map of a slow control variable

<正>To further identify the dynamics of the period-adding bifurcation scenarios observed in both biological experiment and simulations with the differential Chay model,this paper fits a discontinuous map of a slow control variable of the Chay model based on simulation results.The procedure of period adding bifurcation scenario from period k to period k + 1 bursting(k = 1,2,3,4) involved in the period-adding cascades and the stochastic effect of noise near each bifurcation point is also reproduced in the discontinuous map.Moreover,dynamics of the border-collision bifurcation are identified in the discontinuous map,which is employed to understand the experimentally observed period increment sequence.The simple discontinuous map is of practical importance in the modeling of collective behaviours of neural populations like synchronization in large neural circuits.     

Stochastic Alternating Dynamics for Synchronous EAD-Like Beating Rhythms in Cultured Cardiac Myocytes

Dissolved cardiac myocytes can couple together and generate synchronous beatings in culture. We observed a synchronized early after-depolarization（EAD）-like rhythm in cultured cardiac myocytes and reproduced the experimental observation in a network mathematical model whose dynamics are close to a Hopf bifurcation. The mechanism for this EAD-like rhythm is attributed to noised-induced stochastic alternatings between the focus and the limit cycle. These results provide novel understandings for pathological heart rhythms like the early immature beatings.     

Intermittent Chaotic Neural Firing Characterized by Non-Smooth Features

A chaotic firing pattern, characterized by non-smooth features and generated through the routine of intermittency from period 3, is observed in biological experiments on a neural firing pacemaker and reproduced in simulations by using a theoretical neuronal model with multiple time scales. This chaotic activity exhibits a scale law very similar to those of both the type-Ⅰ intermitteney generated in smooth systems and the type-Ⅴ intermittency in non-smooth systems.     

Stochastic Signal Induced Multiple Spatial Coherence Resonances and Spiral Waves in Excitable Media

Multiple spatial coherence resonances and spiral waves with various temporal-spatial structures are simulated in a two-dimensional network of excitable cells driven by a stochastic signal. The relationship between the multiple resonances and correspondingly different transitions of the spiral wave are elucidated. The results further provide a possible approach of applications of stochastic signal to evoke pattern transitions in excitable media.     

Bifurcation diagram globally underpinning neuronal firing behaviors modified by SK conductance

Neurons in the brain utilize various firing trains to encode the input signals they have received.Firing behavior of one single neuron is thoroughly explained by using a bifurcation diagram from polarized resting to firing,and then to depolarized resting.This explanation provides an important theoretical principle for understanding neuronal biophysical behaviors.This paper reports the novel experimental and modeling results of the modification of such a bifurcation diagram by adjusting small conductance potassium(SK)channel.In experiments,changes in excitability and depolarization block in nucleus accumbens shell and medium-spiny projection neurons are explored by increasing the intensity of injected current and blocking the SK channels by apamin.A shift of bifurcation points is observed.Then,a Hodgkin–Huxley type model including the main electrophysiological processes of such neurons is developed to reproduce the experimental results.The reduction of SK channel conductance also shifts the bifurcations,which is in consistence with experiment.A global bifurcation paradigm of this shift is obtained by adjusting two parameters,intensity of injected current and SK channel conductance.This work reveals the dynamics underpinning modulation of neuronal firing behaviors by biologically important ionic conductance.The results indicate that small ionic conductance other than that responsible for spike generation can modify bifurcation points and shift the bifurcation diagram and,thus,change neuronal excitability and adaptation.