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Parameter P (parameter + p)

Distribution by Scientific Domains

Mathematics and Statistics	50%

Selected Abstracts

The radial basis functions method for identifying an unknown parameter in a parabolic equation with overspecified data

NUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 5 2007
Mehdi Dehghan
Abstract Parabolic partial differential equations with overspecified data play a crucial role in applied mathematics and engineering, as they appear in various engineering models. In this work, the radial basis functions method is used for finding an unknown parameter p(t) in the inverse linear parabolic partial differential equation ut = uxx + p(t)u + ,, in [0,1] × (0,T], where u is unknown while the initial condition and boundary conditions are given. Also an additional condition ,01k(x)u(x,t)dx = E(t), 0 , t , T, for known functions E(t), k(x), is given as the integral overspecification over the spatial domain. The main approach is using the radial basis functions method. In this technique the exact solution is found without any mesh generation on the domain of the problem. We also discuss on the case that the overspecified condition is in the form ,0s(t)u(x,t)dx = E(t), 0 < t , T, 0 < s(t) < 1, where s and E are known functions. Some illustrative examples are presented to show efficiency of the proposed method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 [source]

Linear lower bounds for ,c(p) for a class of 2D self-destructive percolation models

RANDOM STRUCTURES AND ALGORITHMS, Issue 4 2009
J. van den Berg
Abstract The self-destructive percolation model is defined as follows: Consider percolation with parameter p > pc. Remove the infinite occupied cluster. Finally, give each vertex (or, for bond percolation, each edge) that at this stage is vacant, an extra chance , to become occupied. Let ,c(p) be the minimal value of ,, needed to obtain an infinite occupied cluster in the final configuration. This model was introduced by van den Berg and Brouwer. They showed, for the site model on the square lattice (and a few other 2D lattices satisfying a special technical condition) that ,c(p) , . In particular, ,c(p) is at least linear in p , pc. Although the arguments used by van den Berg and Brouwer look very lattice-specific, we show that they can be suitably modified to obtain similar linear lower bounds for ,c(p) (with p near pc) for a much larger class of 2D lattices, including bond percolation on the square and triangular lattices, and site percolation on the star lattice (or matching lattice) of the square lattice. © 2009 Wiley Periodicals, Inc. Random Struct. Alg., 2009 [source]

1-(,- d -Erythrofuranosyl)adenosine

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010
Paul C. Kline
The title compound, also known as ,-erythroadenosine, C9H11N5O3, (I), a derivative of ,-adenosine, (II), that lacks the C5, exocyclic hydroxymethyl (,CH2OH) substituent, crystallizes from hot ethanol with two independent molecules having different conformations, denoted (IA) and (IB). In (IA), the furanose conformation is OT1,E1 (C1,- exo, east), with pseudorotational parameters P and ,m of 114.4 and 42°, respectively. In contrast, the P and ,m values are 170.1 and 46°, respectively, in (IB), consistent with a 2E,2T3 (C2,- endo, south) conformation. The N -glycoside conformation is syn (+sc) in (IA) and anti (,ac) in (IB). The crystal structure, determined to a resolution of 2.0,Å, of a cocrystal of (I) bound to the enzyme 5,-fluorodeoxyadenosine synthase from Streptomyces cattleya shows the furanose ring in a near-ideal OE (east) conformation (P = 90° and ,m = 42°) and the base in an anti (,ac) conformation. [source]

Concentration dependence of the hopping mobility in disordered organic solids

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2004
O. Rubel
Abstract Traditionally the dependance of the drift mobility, ,, on the concentration of localized states, N, in disordered organic solids is plotted in the form , , exp[,C(N,3),p] with p = 1/3 and constant C. This representation cannot be correct, because transport in disordered organic solids is essentially a variablerange-hopping process with a weaker dependence ,(N). We study this dependence theoretically and show that both parameters p and C strongly depend on temperature and hence they are not universal. Only at very high temperatures the formula with p = 1/3 is valid. The result is significant in particular for a correct diagnostics of the localization length , from the measured dependence ,(N). (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]