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1.
2.
It is long known that the Fokker-Planck equation with prescribed constant coefficients of diffusion and linear friction describes
the ensemble average of the stochastic evolutions in velocity space of a Brownian test particle immersed in a heat bath of
fixed temperature. Apparently, it is not so well known that the same partial differential equation, but now with constant
coefficients which are functionals of the solution itself rather than being prescribed, describes the kinetic evolution (in
the N→∞ limit) of an
isolated
N-particle system with certain stochastic interactions. Here we discuss in detail this recently discovered interpretation.
An erratum to this article can be found at 相似文献
3.
Guido Wauters Jacques Dewaele Carlo Vandecasteele Richard Dams 《Mikrochimica acta》1989,98(4-6):157-162
Proton activation analysis was used for the determination of cadmium and lead in three sediment reference materials. The method is based on the111,112Cd(p, xn)111 In and the206,207,208Pb(p, xn)206Bi reactions.111In and206Bi were chemically separated by anion exchange. The results obtained were taken into account for the certification of the materials and are in the excellent agreement with the certified values. 相似文献
4.
5.
R. Pizzoferrato L. Lagonigro T. Ziller A. Di Carlo R. Paolesse F. Mandoj A. Ricci C. Lo Sterzo 《Chemical physics》2004,300(1-3):217-225
We study the infrared emission at 1.54 μm of an organolanthanide complex, Er(III)-tetraphenylporphyrin [Er(TPP)acac], both as a result of direct optical excitation and via energy transfer from host π-conjugate polymers of type poly(arylene–ethynylene) [PAE]. In the first case, the emission of the neat complex is characterized in inert transparent materials and a value of the quantum yield at 1.54 μm φIR=4×10−4 is measured. Then, fluorescence resonance transfer is investigated in blends of Er(TPP)acac with PAEs by monitoring the quenching of the polymer fluorescence along with the enhancement of both the visible emission of the ligand and the near-infrared band of Er3+. These different procedures allow a detailed analysis of the transfer efficiency within a specific implementation of the Förster model for polymeric donors. The experimental values of the critical radius R0, ranging from 1.3 to 2.5 nm for the different blends, are in good agreement with theory for a wide interval of the physical and spectroscopic parameters. This suggests that other mechanisms for excitation transfer do not play a significant role in these materials. 相似文献
6.
C. Boldrighini R.A. Minlos A. Pellegrinotti 《Communications in Mathematical Physics》1997,189(2):533-557
We consider a general model of directed polymers on the lattice , weakly coupled to a random environment. We prove that the central limit theorem holds almost surely for the discrete time
random walk X
T
associated to the polymer. Moreover we show that the random corrections to the cumulants of X
T
are finite, starting from some dimension depending on the index of the cumulants, and that there are corresponding random
corrections of order , , in the asymptotic expansion of the expectations of smooth functions of X
T
. Full proofs are carried out for the first two cumulants. We finally prove a kind of local theorem
showing that the ratio of the probabilities of the events to the corresponding probabilities with no randomness, in the region of “moderate” deviations from the average drift bT, are, for almost all choices of the environment, uniformly close, as , to a functional of the environment “as seen from (T,y)$”.
Received: 14 October 1996 / Accepted: 28 March 1997 相似文献
7.
8.
Peptidic aminopeptidase inhibitors, bestatin, phebestin and probestin have been prepared by stereo- and regiocontrolled reactions from a common α,β-epoxy ester precursor. 相似文献
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10.