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281.
Yuval Peres 《Communications in Mathematical Physics》1996,177(2):417-434
We show that sample paths of Brownian motion (and other stable processes) intersect the same sets as certain random Cantor sets constructed by a branching process. With this approach, the classical result that two independent Brownian paths in four dimensions do not intersect reduces to the dying out of a critical branching process, and estimates due to Lawler (1982) for the long-range intersection probability of several random walk paths, reduce to Kolmogrov's 1938 law for the lifetime of a critical branching process. Extensions to random walks with long jumps and applications to Hausdorff dimension are also derived. 相似文献
282.
Claire Kenyon Yuval Rabani Alistair Sinclair 《Journal of Algorithms in Cognition, Informatics and Logic》1998,27(2):218-235
We study the average case performance of the Best Fit algorithm for on-line bin packing under the distributionU{j, k}, in which the item sizes are uniformly distributed in the discrete range {1/k, 2/k,…,j/k}. Our main result is that, in the casej = k − 2, the expected waste for an infinite stream of items remains bounded. This settles an open problem posed by Coffmanet al.[[4]]. It is also the first result which involves a detailed analysis of the infinite multidimensional Markov chain underlying the algorithm. 相似文献
283.
Boaz Ben-Moshe Matthew J. Katz Joseph S. B. Mitchell Yuval Nir 《Computational Geometry》2004,28(2-3):175-190
The terrain surface simplification problem has been studied extensively, as it has important applications in geographic information systems and computer graphics. The goal is to obtain a new surface that is combinatorially as simple as possible, while maintaining a prescribed degree of similarity with the original input surface. Generally, the approximation error is measured with respect to distance (e.g., Hausdorff) from the original or with respect to visual similarity. In this paper, we propose a new method of simplifying terrain surfaces, designed specifically to maximize a new measure of quality based on preserving inter-point visibility relationships. Our work is motivated by various problems of terrain analysis that rely on inter-point visibility relationships, such as optimal antenna placement.
We have implemented our new method and give experimental evidence of its effectiveness in simplifying terrains according to our quality measure. We experimentally compare its performance with that of other leading simplification methods. 相似文献
284.
For integers d > 1 and arbitrary 1 ? α ? d, α-products in d-fold Cartesian products are produced by probabilistic methods. Some explicit constructions are given by solutions of instances of the Turán problem for graphs. 相似文献
285.
286.
In this paper we deal with an approximation to the point process of exceedances over a higher threshold. We compute sharp bounds on the remainder terms when actual distributions of exceedances are replaced by appropriate generalized Pareto distributions (GPD). The bound will be formulated in terms of the von Mises function. The ultimate as well as the penultimate approximations are considered; in the latter case the shape parameter of the approximating GPD depends on the threshold. 相似文献
287.
Erez Y Presiado I Gepshtein R Huppert D 《The journal of physical chemistry. A》2011,115(40):10962-10971
Steady-state and time-resolved techniques were employed to study the nonradiative process of curcumin dissolved in ethanol and 1-propanol in a wide range of temperatures. We found that the nonradiative rate constants at temperatures between 175-250 K qualitatively follow the same trend as the dielectric relaxation times of both neat solvents. We attribute the nonradiative process to solvent-controlled proton transfer. We also found a kinetic isotope effect on the nonradiative process rate constant of ~2. We propose a model in which the excited-state proton transfer breaks the planar hexagonal structure of the keto-enol center of the molecule. This, in turn, enhances the nonradiative process driven by the twist angle between the two phenol moieties. 相似文献
288.
Amdursky N Gepshtein R Erez Y Koifman N Huppert D 《The journal of physical chemistry. A》2011,115(24):6481-6487
Time-resolved emission techniques were employed to study the nonradiative process of thioflavin-T (ThT) in 1-propanol, 1-butanol, and 1-pentanol as a function of the hydrostatic pressure. Elevated hydrostatic pressure increases the alcohol viscosity, which in turn strongly influences the nonradiative rate of ThT. A diamond-anvil cell was used to increase the pressure up to 2.4 GPa. We found that the nonradiative rate constant, k(nr), decreases with pressure. We further found a remarkable linear correlation between a decrease in k(nr) (increase in the nonradiative lifetime, τ(nr)) and an increase in the solvent viscosity. The viscosity was varied by a factor of 1000 and k(nr) was measured at high pressures, at which the nonradiative rate constant of the molecules decreased from (7 ps)(-1) to (13 ns)(-1), (13 ps)(-1) to (17 ns)(-1) and (17 ps)(-1) to (15 ns)(-1) for 1-propanol, 1-butanol, and 1-pentanol, respectively. The viscosity-dependence of k(nr) is explained by the excited-state rotation rate of the two-ring systems, with respect to each other. 相似文献
289.
Glass-Maujean M Jungen Ch Schmoranzer H Haar I Knie A Reiss P Ehresmann A 《The Journal of chemical physics》2011,135(14):144302
The energies, widths and absolute intensities of the P(1) v' = 0, J' = 1 absorption transitions of H(2) have been measured in the spectral range of 81-75 nm using monochromatized synchrotron radiation. This work completes and extends previous observations, in particular those of Herzberg and Jungen [J. Mol. Spectrosc. 41, 425 (1972)]. Ab initio multichannel quantum defect theory (MQDT) is used to corroborate the spectral analysis of the experimental data. Line intensities and decay widths are also calculated using MQDT. 相似文献
290.
A protocol employing weak values (WVs) to obtain ultrasensitive amplification of weak signals in the context of a solid-state setup is proposed. We consider an Aharonov-Bohm interferometer where both the orbital and the spin degrees of freedom are weakly affected by the presence of an external charge to be detected. The interplay between the spin and the orbital WVs leads to a significant amplification even in the presence of finite temperature, voltage, and external noise. 相似文献