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991.
The traffic of molecular motors through open tube-like compartments is studied using lattice models. These models exhibit boundary-induced phase transitions related to those of the asymmetric simple exclusion process (ASEP) in one dimension. The location of the transition lines depends on the boundary conditions at the two ends of the tubes. Three types of boundary conditions are studied: (A) Periodic boundary conditions which correspond to a closed torus-like tube. (B) Fixed motor densities at the two tube ends where radial equilibrium holds locally; and (C) Diffusive motor injection at one end and diffusive motor extraction at the other end. In addition to the phase diagrams, we also determine the profiles for the bound and unbound motor densities using mean field approximations and Monte Carlo simulations. Our theoretical predictions are accessible to experiments. 相似文献
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995.
Ferdinand Hofer Peter Warbichler Per Björn Anderson Reinhard Pitonak 《Mikrochimica acta》1990,101(1-6):243-249
Multi-layer coatings on cemented carbide substrates have been investigated by analytical electron microscopy (AEM). The samples were taken from cross-sections through the coating thus enabling a study of individual layers and interfaces. Various phenomena are shown: (1) tungsten diffusion and graphite inclusions in TiC layers, (2) oxygen impurities in Ti(C, N) coatings and (3) the occurrence of titanium oxinitrides in the interface between the Al2O3 and TiN-layers.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday 相似文献
996.
In this paper we describe the algorithm OPTCON which has been developed for the optimal control of nonlinear stochastic models. It can be applied to obtain approximate numerical solutions of control problems where the objective function is quadratic and the dynamic system is nonlinear. In addition to the usual additive uncertainty, some or all of the parameters of the model may be stochastic variables. The optimal values of the control variables are computed in an iterative fashion: First, the time-invariant nonlinear system is linearized around a reference path and approximated by a time-varying linear system. Second, this new problem is solved by applying Bellman's principle of optimality. The resulting feedback equations are used to project expected optimal state and control variables. These projections then serve as a new reference path, and the two steps are repeated until convergence is reached. The algorithm has been implemented in the statistical programming system GAUSS. We derive some mathematical results needed for the algorithm and give an overview of the structure of OPTCON. Moreover, we report on some tentative applications of OPTCON to two small macroeconometric models for Austria. 相似文献
997.
Milan Soukup Teodor Luk
Reinhard Zell Felix Roessler Kurt Steiner Erich Widmer 《Helvetica chimica acta》1989,72(2):365-369
A New Access to 2,6,6-Trimethylcyclohexa-2,4-dienone from 4-Oxoisophorone 2,6,6-Trimethylcyclohexa-2,4-dienone ( 1 ), a versatile starting material for the preparation of some carotenoids and several natural products, was efficiently (73% yield) prepared from oxoisophorone 3 . After conversion of 3 to the alcohol 4 or the acetate 5 , H2O was eliminated ( 4→1 ) under acidic distillative conditions, whereas AcOH could be eliminated ( 5→l ) under Pd(O) catalysis. 相似文献
998.
Reinhard Diestel 《Journal of Graph Theory》1987,11(1):43-52
Every planar triangulation G has the property that each induced cycle C of length at least 4 in G separates G, but no proper subgraph of C does. This property is trivially shared by all chordal graphs since these contain no such cycles at all. We ask to what extent maximally planar graphs and chordal graphs are unique with this property — or how much larger the class of graphs is that it determines. The answer is given in the form of a characterization of this class in terms of the simplicial decompositions of its elements. The theory of simplicial decompositions appears to be a very interesting, but still largely unexploited, method of characterization in graph theory, which seems tailor-made for problems like the one discussed. 相似文献
999.
A short derivation of the local harmonic approach and ATDHF is given which elucidates the formal similirity between them. The conditions for the validity of the approaches are studied. We show first, that they are related to deviation forces within second order RPA which drive the system out of the collective mode, and second, that the local harmonic approach is more restricted than ATDHF. 相似文献
1000.
The dynamic behavior of transient EPR nutation signals during the first 100 ns after N2-laser excitation or molecular triplet states in single crystals has been investigated. The onset of the signal is found to depend on the inhomogeneous width and form of the cw EPR line With phenazine (in fluorene) a time resolution of 15 ns could be demonstrated. 相似文献