Search results for "Exponent"
showing 10 items of 896 documents
Repetition times for Gibbsian sources
1999
In this paper we consider the class of stochastic stationary sources induced by one-dimensional Gibbs states, with Holder continuous potentials. We show that the time elapsed before the source repeats its first n symbols, when suitably renormalized, converges in law either to a log-normal distribution or to a finite mixture of exponential random variables. In the first case we also prove a large deviation result.
Poincaré inequalities and Steiner symmetrization
1996
A complete geometric characterization for a general Steiner symmetric domain Ω ⊂ Rn to satisfy the Poincare inequality with exponent p > n−1 is obtained and it is shown that this range of exponents is best possible. In the case where the Steiner symmetric domain is determined by revolving the graph of a Lipschitz continuous function, it is shown that the preceding characterization works for all p > 1 and furthermore for such domains a geometric characterization for a more general Sobolev–Poincare inequality to hold is given. Although the operation of Steiner symmetrization need not always preserve a Poincare inequality, a general class of domains is given for which Poincare inequalities are…
Floquet theory: exponential perturbative treatment
2001
We develop a Magnus expansion well suited for Floquet theory of linear ordinary differential equations with periodic coefficients. We build up a recursive scheme to obtain the terms in the new expansion and give an explicit sufficient condition for its convergence. The method and formulae are applied to an illustrative example from quantum mechanics.
Flow resistance in gravel-bed channels with large-scale roughness
2003
A previously published mixing length (ML) model for evaluating the Darcy–Weisbach friction factor for a large-scale roughness condition (depth to sediment height ratio ranging from 1 to 4) is briefly reviewed and modified (MML). Then the MML model and a modified drag (MD) model are experimentally tested using laboratory measurements carried out for gravel-bed channels and large-scale roughness condition. This analysis showed that the MML gives accurate estimates of the Darcy–Weisbach coefficient and for Froude number values greater than 0·5 the MML model coincides with the ML one. Testing of the MD model shows limited accuracy in estimating flow resistance. Finally, the MML and MD models are com…
Cracking behavior of zeolites with connected 12- and 10-member ring channels: The influence of pore structure on product distribution
1997
n-Heptane has been cracked on a CIT-1 zeolite which has connected 12- and 10-member ring (MR) channels, and its behavior was compared with that of MCM-22 with nonconnected 12- and 10-MR channels, and SSZ-24 and BETA with unidirectional and tridirectional 12-MR channels, respectively. The kinetic rate constant is highest for CIT-1, and the decay constant is lowest. From the selectivity point of view, its behavior can be better represented by a system with large cavities (the intersections between the 12- and 10-MR) connected by windows. This gives a behavior typical of that of large pore zeolites. CIT-1 produces a remarkably high selectivity toi-C4, and specially to isobutane. This zeolite s…
Separate regression modelling of the Gaussian and Exponential components of an EMG response from respiratory physiology.
2014
If Y1 \sim N(\mu ;\sigma^2) and Y2 \sim Exp(\nu), with Y1 independent of Y2, then their sum Y = Y1 +Y2 follows an Exponentially Modified Gaussian (EMG) distribution. In many applications it is of interest to model the two components separately, in order to investigate their (possibly) different important predictors. We show how this can be done through a GAMLSS with EMG response, and apply this separate regression modelling strategy to a dataset on lung function variables from the SAPALDIA cohort study.
Enhancerless Cytomegalovirus Is Capable of Establishing a Low-Level Maintenance Infection in Severely Immunodeficient Host Tissues but Fails in Expon…
2010
ABSTRACT Major immediate-early transcriptional enhancers are genetic control elements that act, through docking with host transcription factors, as a decisive regulatory unit for efficient initiation of the productive virus cycle. Animal models are required for studying the function of enhancers paradigmatically in host organs. Here, we have sought to quantitatively assess the establishment, maintenance, and level of in vivo growth of enhancerless mutants of murine cytomegalovirus in comparison with those of an enhancer-bearing counterpart in models of the immunocompromised or immunologically immature host. Evidence is presented showing that enhancerless viruses are capable of forming restr…
Motif patterns in 2D
2008
AbstractMotif patterns consisting of sequences of intermixed solid and don’t-care characters have been introduced and studied in connection with pattern discovery problems of computational biology and other domains. In order to alleviate the exponential growth of such motifs, notions of maximal saturation and irredundancy have been formulated, whereby more or less compact subsets of the set of all motifs can be extracted, that are capable of expressing all others by suitable combinations. In this paper, we introduce the notion of maximal irredundant motifs in a two-dimensional array and develop initial properties and a combinatorial argument that poses a linear bound on the total number of …
Low-cost approximate reconstructing of heterogeneous microstructures
2016
We propose an approximate reconstruction of random heterogeneous microstructures using the two-exponent power-law (TEPL). This rule originates from the entropic descriptor (ED) that is a multi-scale measure of spatial inhomogeneity for a given microstructure. A digitized target sample is a cube of linear size L in voxels. Then, a number of trial configurations can be generated by a model of overlapping spheres of a fixed radius, which are randomly distributed on a regular lattice. The TEPL describes the averaged maximum of the ED as a function of the phase concentration and the radius. Thus, it can be used to determine the radius. The suggested approach is tested on surrogate samples of cer…
Classifying G-graded algebras of exponent two
2019
Let F be a field of characteristic zero and let $$\mathcal{V}$$ be a variety of associative F-algebras graded by a finite abelian group G. If $$\mathcal{V}$$ satisfies an ordinary non-trivial identity, then the sequence $$c_n^G(\mathcal{V})$$ of G-codimensions is exponentially bounded. In [2, 3, 8], the authors captured such exponential growth by proving that the limit $$^G(\mathcal{V}) = {\rm{lim}}_{n \to \infty} \sqrt[n]{{c_n^G(\mathcal{V})}}$$ exists and it is an integer, called the G-exponent of $$\mathcal{V}$$ . The purpose of this paper is to characterize the varieties of G-graded algebras of exponent greater than 2. As a consequence, we find a characterization for the varieties with …