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排序方式: 共有6031条查询结果,搜索用时 31 毫秒
991.
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993.
Scaling behavior of earthquakes’ inter-events time series 总被引:1,自引:0,他引:1
Shahriar Shadkhoo Fakhteh Ghanbarnejad Gholam R. Jafari Mohammad R. R. Tabar 《Central European Journal of Physics》2009,7(3):620-623
In this paper, we investigate the statistical and scaling properties of the California earthquakes’ inter-events over a period
of the recent 40 years. To detect long-term correlations behavior, we apply detrended fluctuation analysis (DFA), which can
systematically detect and overcome nonstationarities in the data set at all time scales. We calculate for various earthquakes
with magnitudes larger than a given M. The results indicate that the Hurst exponent decreases with increasing M; characterized
by a Hurst exponent, which is given by, H = 0:34 + 1:53/M, indicating that for events with very large magnitudes M, the Hurst exponent decreases to 0:50, which is for independent
events.
相似文献
994.
Nicola Pizzolato Davide Valenti Dominique Persano Adorno Bernardo Spagnolo 《Central European Journal of Physics》2009,7(3):541-548
The evolutionary dynamics of a system of cancerous cells in a model of chronic myeloid leukemia (CML) is investigated by a
statistical approach. Cancer progression is explored by applying a Monte Carlo method to simulate the stochastic behavior
of cell reproduction and death in a population of blood cells which can experience genetic mutations. In CML front line therapy
is represented by the tyrosine kinase inhibitor imatinib which strongly affects the reproduction of leukemic cells only. In
this work, we analyze the effects of a targeted therapy on the evolutionary dynamics of normal, first-mutant and cancerous
cell populations. Several scenarios of the evolutionary dynamics of imatinib-treated leukemic cells are described as a consequence
of the efficacy of the different modelled therapies. We show how the patient response to the therapy changes when a high value
of the mutation rate from healthy to cancerous cells is present. Our results are in agreement with clinical observations.
Unfortunately, development of resistance to imatinib is observed in a fraction of patients, whose blood cells are characterized
by an increasing number of genetic alterations. We find that the occurrence of resistance to the therapy can be related to
a progressive increase of deleterious mutations.
相似文献
995.
The stochastic resonance (SR) phenomenon induced by a multiplicative periodic signal in a logistic growth model with correlated
noises is studied by using the theory of signal-to-noise ratio (SNR) in the adiabatic limit. The expressions of the SNR are obtained. The effects of multiplicative noise intensity α and additive noise intensity D, and correlated intensity λ on the SNR are discussed respectively. It is found that the existence of a maximum in the SNR is the identifying characteristic of the SR phenomena. In comparison with the SR induced by additive periodic signal, some
new features are found: (1) When SNR as a function of λ for fixed ratio of α and D, the varying of α can induce a stochastic multi-resonance, and can induce a re-entrant transition of the peaks in SNR vs λ; (2) There exhibits a doubly critical phenomenon for SNR vs D and λ, i.e., the increasing of D (or λ) can induce the critical phenomenon for SNR with respect to λ (or D); (3) The doubly stochastic resonance effect appears when α and D are simultaneously varying in SNR, i.e., the increment of one noise intensity can help the SR on another noise intensity come forth.
相似文献
996.
通过数值模拟方法, 研究了在具有稳定次阈值振荡特性的二维映射神经元体系中, 噪声对体系非线性动力学的调控作用. 通过计算发现了噪声诱导的动作电位和随机共振现象. 另外,还研究了体系的控制参数及输入信号的频率对体系动力学的影响, 发现了该体系中频率依赖的随机共振现象.
关键词:
二维映射神经元模型
次阈值振荡
高斯白噪声
随机共振 相似文献
997.
998.
999.
讨论了具有一般约束的全局优化问题,给出该问题的一个随机搜索算法,证明了该算法依概率1收敛到问题的全局最优解.数值结果显示该方法是有效的. 相似文献
1000.