19,703 research outputs found
Asymptotic behaviour of zeros of bieberbach polynomials
AbstractLet Ω be a simply-connected domain in the complex plane and let πn denote the nth-degree Bieberbach polynomial approximation to the conformal map f of Ω onto a disc. In this paper we investigate the asymptotic behaviour (as n→σ) of the zeros of πn, πn′ and also of the zeroes of certain closely related rational approximants to f. Our result show that, in each case, the distribution of the zeros is governed by the location of the singularities of the mapping function f in C⧹ω, and we present numerical examples illustrating this
Constraints on a new alternative model to dark energy
The recent type Ia supernova data suggest that the universe is accelerating
now and decelerated in recent past. This may provide the evidence that the
standard Friedmann equation needs to be modified. We analyze in detail a new
model in the context of modified Friedmann equation using the supernova data
published by the High- Supernova Search Team and the Supernova Cosmology
Project. The new model explains recent acceleration and past deceleration.
Furthermore, the new model also gives a decelerated universe in the future.Comment: 12 pages, 5 figures, use ws-ijmpd, minor changes made. In the new
version, a detailed derivation of the model is give
Morphology of Graphene on SiC(000-1) Surfaces
Graphene is formed on SiC(000-1) surfaces (the so-called C-face of the
crystal) by annealing in vacuum, with the resulting films characterized by
atomic force microscopy, Auger electron spectroscopy, scanning Auger microscopy
and Raman spectroscopy. Morphology of these films is compared with the graphene
films grown on SiC(0001) surfaces (the Si-face). Graphene forms a terraced
morphology on the C-face, whereas it forms with a flatter morphology on the
Si-face. It is argued that this difference occurs because of differing
interface structures in the two cases. For certain SiC wafers, nanocrystalline
graphite is found to form on top of the graphene.Comment: Submitted to Applied Physics Letters; 9 pages, 3 figures; corrected
the stated location of Raman G line for NCG spectrum, to 1596 cm^-
Designing fuzzy rule based classifier using self-organizing feature map for analysis of multispectral satellite images
We propose a novel scheme for designing fuzzy rule based classifier. An SOFM
based method is used for generating a set of prototypes which is used to
generate a set of fuzzy rules. Each rule represents a region in the feature
space that we call the context of the rule. The rules are tuned with respect to
their context. We justified that the reasoning scheme may be different in
different context leading to context sensitive inferencing. To realize context
sensitive inferencing we used a softmin operator with a tunable parameter. The
proposed scheme is tested on several multispectral satellite image data sets
and the performance is found to be much better than the results reported in the
literature.Comment: 23 pages, 7 figure
Constraints on models for the initial collision geometry in ultra relativistic heavy ion collisions
Monte Carlo (MC) simulations are used to compute the centrality dependence of
the collision zone eccentricities (), for both spherical and
deformed ground state nuclei, for different model scenarios. Sizable model
dependent differences are observed. They indicate that measurements of the
and order Fourier flow coefficients ,
expressed as the ratio , can provide robust constraints
for distinguishing between different theoretical models for the initial-state
eccentricity. Such constraints could remove one of the largest impediments to a
more precise determination of the specific viscosity from precision
measurements at the Relativistic Heavy Ion Collider (RHIC).Comment: 4 pages, 3 figs - version accepted for publicatio
Energy loss for heavy quarks in relation to light partons; is radiative energy loss for heavy quarks anomalous?
The scaling properties of jet suppression measurements are compared for
non-photonic electrons () and neutral pions () in Au + Au
collisions at GeV. For a broad range of transverse momenta
and collision centralities, the comparison is consistent with jet quenching
dominated by radiative energy loss for both heavy and light partons. Less
quenching is indicated for heavy quarks via ; this gives an
independent estimate of the transport coefficient that agrees with
its magnitude obtained from quenching of light partons via 's.Comment: Published versio
Variability of Contact Process in Complex Networks
We study numerically how the structures of distinct networks influence the
epidemic dynamics in contact process. We first find that the variability
difference between homogeneous and heterogeneous networks is very narrow,
although the heterogeneous structures can induce the lighter prevalence.
Contrary to non-community networks, strong community structures can cause the
secondary outbreak of prevalence and two peaks of variability appeared.
Especially in the local community, the extraordinarily large variability in
early stage of the outbreak makes the prediction of epidemic spreading hard.
Importantly, the bridgeness plays a significant role in the predictability,
meaning the further distance of the initial seed to the bridgeness, the less
accurate the predictability is. Also, we investigate the effect of different
disease reaction mechanisms on variability, and find that the different
reaction mechanisms will result in the distinct variabilities at the end of
epidemic spreading.Comment: 6 pages, 4 figure
Formal and finite order equivalences
We show that two families of germs of real-analytic subsets in are
formally equivalent if and only if they are equivalent of any finite order. We
further apply the same technique to obtain analogous statements for
equivalences of real-analytic self-maps and vector fields under conjugations.
On the other hand, we provide an example of two sets of germs of smooth curves
that are equivalent of any finite order but not formally equivalent
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