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41.
We model the motion of a receptor on the membrane surface of a synapse as free Brownian motion in a planar domain with intermittent trappings in and escapes out of corrals with narrow openings. We compute the mean confinement time of the Brownian particle in the asymptotic limit of a narrow opening and calculate the probability to exit through a given small opening, when the boundary contains more than one. Using this approach, it is possible to describe the Brownian motion of a random particle in an environment containing domains with small openings by a coarse grained diffusion process. We use the results to estimate the confinement time as a function of the parameters and also the time it takes for a diffusing receptor to be anchored at its final destination on the postsynaptic membrane, after it is inserted in the membrane. This approach provides a framework for the theoretical study of receptor trafficking on membranes. This process underlies synaptic plasticity, which relates to learning and memory. In particular, it is believed that the memory state in the brain is stored primarily in the pattern of synaptic weight values, which are controlled by neuronal activity. At a molecular level, the synaptic weight is determined by the number and properties of protein channels (receptors) on the synapse. The synaptic receptors are trafficked in and out of synapses by a diffusion process. Following their synthesis in the endoplasmic reticulum, receptors are trafficked to their postsynaptic sites on dendrites and axons. In this model the receptors are first inserted into the extrasynaptic plasma membrane and then random walk in and out of corrals through narrow openings on their way to their final destination. 相似文献
42.
Ghulam Mustafa 《数学研究及应用》2003,23(3):413-421
本文引入了一种满足更一般的收缩不等式的多重函数类,并证明了属于该类的可测多重函数对的一些随机重合点定理。 相似文献
43.
Here we prove a limit theorem in the sense of the weak convergence of probability measures in the space of meromorphic functions
for a general Dirichlet series. The explicit form of the limit measure in this theorem is given.
Partially supported by Lithuanian Foundation of Studies and Science 相似文献
44.
设{Xni:1≤i≤n,n≥1}为行间独立的B值r.v.阵列,g(z)是指数为1/p的正则变化函数,r>0,{ani 1≤t≤n,n≥1}为实数阵列,本文得到了使(?)成立的条件,推广并改进了Stout及Sung等的著名结论. 相似文献
45.
This paper is about algorithms that schedule tasks to be performed in a distributed failure‐prone environment, when processors communicate by message‐passing, and when tasks are independent and of unit length. The processors work under synchrony and may fail by crashing. Failure patterns are imposed by adversaries. Linearly‐bounded adversaries may fail up to a constant fraction of the processors. Weakly‐adaptive adversaries have to select, prior to the start of an execution, a subset of processors to be failure‐prone, and then may fail only the selected processors, at arbitrary steps, in the course of the execution. Strongly adaptive adversaries have a total number of failures as the only restriction on failure patterns. The measures of complexity are work, measured as the available processor steps, and communication, measured as the number of point‐to‐point messages. A randomized algorithm is developed, that attains both ??(n log*n) expected work and ??(n log*n) expected communication, against weakly‐adaptive linearly‐bounded adversaries, in the case when the numbers of tasks and processors are both equal to n. This is in contrast with performance of algorithms against strongly‐adaptive linearly‐bounded adversaries, which has to be Ω(n log n/log log n) in terms of work. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 2004 相似文献
46.
可交换随机变量序列的随机极限定理 总被引:1,自引:0,他引:1
本文讨论了可交换随机变量序列{Xn:n≥1}的极限定理,得到了可交换随机变量序列的随机强大数律及加权和定理,并推广了文[4]中的结果. 相似文献
47.
就如何在4英寸热氧化硅衬底上沉积高质量的磁性隧道结纳米多层薄膜材料和如何利用光刻方法微加工制备均匀性较好的磁性隧道结方面做了初步研究,并对磁性隧 道结的磁电性质及其工作特性进行了初步测量和讨论.利用现有的光刻设备和工艺条 件在4英寸热氧化硅衬底上直接制备出的磁性隧道结,其结电阻与面积的积 矢的绝对误差在10% 以内,隧穿磁电阻的绝对误差在7% 以内,样品的磁性隧道结性质具有较好的均匀性和一致性,可以满足研制磁随机存储器存储单元演示器件的基本要求.
关键词:
磁性隧道结
隧穿磁电阻
磁随机存储器
4英寸热氧化硅衬底 相似文献
48.
Suppose that attached to each site z ∈ ? is a coin with bias θ(z), and only finitely many of these coins have nonzero bias. Allow a simple random walker to generate observations by tossing, at each move, the coin attached to its current position. Then we can determine the biases {θ(z)}z∈?, using only the outcomes of these coin tosses and no information about the path of the random walker, up to a shift and reflection of ?. This generalizes a result of Harris and Keane. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004 相似文献
49.
The load-carrying capacity of circular plates made of a fiber-reinforced composite and loaded with axisymmetric transverse forces under axisymmetric boundary conditions is investigated. The plates can be freely supported or clamped along their contour. To the known yield condition used, in the plane of main bending moments, there correspond irregular hexagons, which depend on the mechanical properties of composite constituents and some characteristic geometrical parameters. It is shown that, depending on the ratio of ultimate radial and circumferential bending moments, in the plastic state, the circular plates (the central part of the clamped plates) take the form of a cone or a frustum of cone. For each of the cases, the limit load is found, which is a function of the above-mentioned mechanical parameters. The statically allowable fields of bending moments and the corresponding allowable fields of deflection rates are determined. The solutions found are exact. Special cases for the freely supported plates are analyzed, and the results obtained are presented in the form of graphs.__________Translated from Mekhanika Kompozitnykh Materialov, Vol. 41, No. 2, pp. 177–192, March–April, 2005. 相似文献
50.
Alvaro P. Raposo Hans J. Weber David E. Alvarez-Castillo Mariana Kirchbach 《Central European Journal of Physics》2007,5(3):253-284
We briefly review the five possible real polynomial solutions of hypergeometric differential equations. Three of them are
the well known classical orthogonal polynomials, but the other two are different with respect to their orthogonality properties.
We then focus on the family of polynomials which exhibits a finite orthogonality. This family, to be referred to as the Romanovski
polynomials, is required in exact solutions of several physics problems ranging from quantum mechanics and quark physics to
random matrix theory. It appears timely to draw attention to it by the present study. Our survey also includes several new
observations on the orthogonality properties of the Romanovski polynomials and new developments from their Rodrigues formula. 相似文献