1,784 research outputs found
Aspects of the Noisy Burgers Equation
The noisy Burgers equation describing for example the growth of an interface
subject to noise is one of the simplest model governing an intrinsically
nonequilibrium problem. In one dimension this equation is analyzed by means of
the Martin-Siggia-Rose technique. In a canonical formulation the morphology and
scaling behavior are accessed by a principle of least action in the weak noise
limit. The growth morphology is characterized by a dilute gas of nonlinear
soliton modes with gapless dispersion law with exponent z=3/2 and a superposed
gas of diffusive modes with a gap. The scaling exponents and a heuristic
expression for the scaling function follow from a spectral representation.Comment: 23 pages,LAMUPHYS LaTeX-file (Springer), 13 figures, and 1 table, to
appear in the Proceedings of the XI Max Born Symposium on "Anomalous
Diffusion: From Basics to Applications", May 20-24, 1998, Ladek Zdroj, Polan
Solitons in the noisy Burgers equation
We investigate numerically the coupled diffusion-advective type field
equations originating from the canonical phase space approach to the noisy
Burgers equation or the equivalent Kardar-Parisi-Zhang equation in one spatial
dimension. The equations support stable right hand and left hand solitons and
in the low viscosity limit a long-lived soliton pair excitation. We find that
two identical pair excitations scatter transparently subject to a size
dependent phase shift and that identical solitons scatter on a static soliton
transparently without a phase shift. The soliton pair excitation and the
scattering configurations are interpreted in terms of growing step and
nucleation events in the interface growth profile. In the asymmetrical case the
soliton scattering modes are unstable presumably toward multi soliton
production and extended diffusive modes, signalling the general
non-integrability of the coupled field equations. Finally, we have shown that
growing steps perform anomalous random walk with dynamic exponent z=3/2 and
that the nucleation of a tip is stochastically suppressed with respect to
plateau formation.Comment: 11 pages Revtex file, including 15 postscript-figure
Damped finite-time-singularity driven by noise
We consider the combined influence of linear damping and noise on a dynamical
finite-time-singularity model for a single degree of freedom. We find that the
noise effectively resolves the finite-time-singularity and replaces it by a
first-passage-time or absorbing state distribution with a peak at the
singularity and a long time tail. The damping introduces a characteristic
cross-over time. In the early time regime the probability distribution and
first-passage-time distribution show a power law behavior with scaling exponent
depending on the ratio of the non linear coupling strength to the noise
strength. In the late time regime the behavior is controlled by the damping.
The study might be of relevance in the context of hydrodynamics on a nanometer
scale, in material physics, and in biophysics.Comment: 9 pages, 4 eps-figures, revtex4 fil
Power laws and stretched exponentials in a noisy finite-time-singularity model
We discuss the influence of white noise on a generic dynamical
finite-time-singularity model for a single degree of freedom. We find that the
noise effectively resolves the finite-time-singularity and replaces it by a
first-passage-time or absorbing state distribution with a peak at the
singularity and a long time tail exhibiting power law or stretched exponential
behavior. The study might be of relevance in the context of hydrodynamics on a
nanometer scale, in material physics, and in biophysics.Comment: 10 pages revtex file, including 4 postscript-figures. References
added and a few typos correcte
Correlations, soliton modes, and non-Hermitian linear mode transmutation in the 1D noisy Burgers equation
Using the previously developed canonical phase space approach applied to the
noisy Burgers equation in one dimension, we discuss in detail the growth
morphology in terms of nonlinear soliton modes and superimposed linear modes.
We moreover analyze the non-Hermitian character of the linear mode spectrum and
the associated dynamical pinning and mode transmutation from diffusive to
propagating behavior induced by the solitons. We discuss the anomalous
diffusion of growth modes, switching and pathways, correlations in the
multi-soliton sector, and in detail the correlations and scaling properties in
the two-soliton sector.Comment: 50 pages, 15 figures, revtex4 fil
Book Reviews
Book Review 1Book Title: Ecotoxicology. The Study of Pollutants in Ecosystems. (Second edition)Book Author: F. MoriartyAcademic Press, 1988. 289 pages.Book Review 2Book Title: Ecology of Sandy ShoresBook Authors: A.C. Brown & A. McLachlanElsevier, 1990. 328 pages.Book Review 3Book Title: Ecology and Natural History of Tropical BeesBook Author: David W. RoubikCambridge University Press, Cambridge, 1989Book Review 4Book Title: The AntsBook Authors: Bert Hölldobler & Edward O. WilsonThe Belknap Press of Harvard University Press, Cambridge, Massachusetts,1990. 732 pages.Book Review 5Book Title: Social Insects: an evolutionary approach to castes and reproductionBook Author: Edited by W. EngelsSpringer Verlag, Berlin 1990. 265 pages.Book Review 6Book Title: Mathematical BiologyBook Author: J.D. MurraySpringer-Verlag, New York, 1989. 767 pages. Volume 19 in the Biomathematics series
The Simplest Little Higgs
We show that the SU(3) little Higgs model has a region of parameter space in
which electroweak symmetry breaking is natural and in which corrections to
precision electroweak observables are sufficiently small. The model is anomaly
free, generates a Higgs mass near 150 GeV, and predicts new gauge bosons and
fermions at 1 TeV.Comment: 13 pages + appendix, typos corrected, version to appear in JHE
Recommended from our members
The big green lab project
YesBeverley Lucas and her colleagues give us a big green welcome to the Ecoversity of Bradford
In 2005, the Higher Education Funding Council for England (Hefce) stated that âthe greatest contribution a university can make to sustainable development is through the education of their graduatesâ. The University of Bradford took up the gauntlet, embedding sustainable development in all areas of its campus whilst also transforming the curriculum across the university to educate for sustainable development. This led to them coining themselves an ecoversity.The authors would like to thank the National HE STEM Programme for funding this project
Synthetic studies with bacitracin A and preparation of analogues containing alternative zinc binding groups
Microbial Biotechnolog
Origin of Life
The evolution of life has been a big enigma despite rapid advancements in the
fields of biochemistry, astrobiology, and astrophysics in recent years. The
answer to this puzzle has been as mind-boggling as the riddle relating to
evolution of Universe itself. Despite the fact that panspermia has gained
considerable support as a viable explanation for origin of life on the Earth
and elsewhere in the Universe, the issue remains far from a tangible solution.
This paper examines the various prevailing hypotheses regarding origin of life
like abiogenesis, RNA World, Iron-sulphur World, and panspermia; and concludes
that delivery of life-bearing organic molecules by the comets in the early
epoch of the Earth alone possibly was not responsible for kick-starting the
process of evolution of life on our planet.Comment: 32 pages, 8 figures,invited review article, minor additio
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