31,692 research outputs found
The boundary of the first order chiral phase transition in the m_pi-m_K--plane with a linear sigma model
Tree-level and complete one-loop parametrisation of the linear sigma model
(LSM) is performed and the phase boundary between first order and crossover
transition regions of the m_pi-m_K-plane is determined using the optimised
perturbation theory (OPT) as a resummation tool of perturbative series. Away
from the physical point the parameters of the model were determined by making
use of chiral perturbation theory (ChPT). The location of the phase boundary
for m_pi=m_K and of the tricritical point (TCP) on the m_pi=0 were estimated.Comment: 4 pages, 1 figure, uses espcrc1.sty; to appear in the proceedings of
Strong and Electroweak Matter 2006 (SEWM06), BNL, May 200
A curvature-driven effective attraction in multicomponent membranes
We study closed liquid membranes that segregate into three phases due to
differences in the chemical and physical properties of its components. The
shape and in-plane membrane arrangement of the phases are coupled through
phase-specific bending energies and line tensions. We use simulated annealing
Monte Carlo simulations to find low-energy structures, allowing both phase
arrangement and membrane shape to relax. The three-phase system is the simplest
one in which there are multiple interface pairs, allowing us to analyze
interfacial preferences and pairwise distinct line tensions. We observe the
system's preference for interface pairs that maximize differences in
spontaneous curvature. From a pattern selection perspective, this acts as an
effective attraction between phases of most disparate spontaneous curvature. We
show that this effective attraction is robust enough to persist even when the
interface between these phases is the most penalized by line tension. This
effect is driven by geometry and not by any explicit component-component
interaction.Comment: 6 pages, 6 figures, submitted to Phys. Rev. E, revised version
includes improvements of the simulation method and additional reference
Are polymer melts "ideal"?
It is commonly accepted that in concentrated solutions or melts
high-molecular weight polymers display random-walk conformational properties
without long-range correlations between subsequent bonds. This absence of
memory means, for instance, that the bond-bond correlation function, , of
two bonds separated by monomers along the chain should exponentially decay
with . Presenting numerical results and theoretical arguments for both
monodisperse chains and self-assembled (essentially Flory size-distributed)
equilibrium polymers we demonstrate that some long-range correlations remain
due to self-interactions of the chains caused by the chain connectivity and the
incompressibility of the melt. Suggesting a profound analogy with the
well-known long-range velocity correlations in liquids we find, for instance,
to decay algebraically as . Our study suggests a precise
method for obtaining the statistical segment length \bstar in a computer
experiment.Comment: 4 pages, 3 figure
Comment on: a two-stage fourth-order âalmostâ P-stable method for oscillatory problems
AbstractIn Chawla and Al-Zanaidi (J. Comput. Appl. Math. 89 (1997) 115â118) a fourth-order âalmostâ P-stable method for yâł=f(x,y) is proposed. We claim that it is possible to retrieve this combination of multistep methods by means of the theory of parameterized Runge-Kutta-Nyström (RKN) methods and moreover to generalize the method discussed by Chawla and Al-Zanaidi (J. Comput. Appl. Math. 89 (1997) 115â118)
Information dynamics: patterns of expectation and surprise in the perception of music
This is a postprint of an article submitted for consideration in Connection Science © 2009 [copyright Taylor & Francis]; Connection Science is available online at:http://www.tandfonline.com/openurl?genre=article&issn=0954-0091&volume=21&issue=2-3&spage=8
Energy efficiency (EE) and cost-effective means to increase EE and to mitigate the climate change of pork and broiler meat production in five European countries
Production of pork and broiler meat in the European Union (EU) has increased by 7.8
and 16.1%, respectively, in the period of 2001 â 2011. At that time pork and broiler
meat produced, amounted together to over four times the cattle meat. Meat is an important
protein source in human diet, but on the other hand, livestock uses globally
30% of ice-free terrestrial land and produces 18% of global greenhouse gas (GHG)
emissions. This exceeds the global emissions of the transport sector. Furthermore,
energy ratio (output/input) for meat production is less than 1.0 in general and it is
much lower than that of plant production. This paper presents cost-effectiveness of
EE measures in pork and broiler meat production and it is based on the results of the
Agriculture and Energy Efficiency Project (www.AGREE.aua.gr).
The structure of the energy input appeared to be very similar in pork and broiler meat
production. Feed was found to be the major indirect energy input. Its contribution to
the total energy demand varied from 51% to 82% in pork production and from 55% to
94% in broiler meat production. The percentage of feed was the lowest in the Northern
European countries and the highest in the south. This difference was mainly attributable
to the demand for heating of animal houses during the winter period. Differences
could also be found in the absolute energy input of feed. It indicated that
there may be possibilities to improve feeding strategies or feed conversation rate of
animals. In pork production, the energy input of feed was 12.5 GJ t-1 (live weight) in
average and 8.6 GJ t-1 (live weight) in broiler production. The difference between pork
and broiler meat is a consequence of the higher feed conversation rate of broilers in
contrast to pigs. The category âOther energy useâ was the second highest energy input and it consisted of energy input for ventilation, illumination, feeding, and heating
of animal houses. In pork production, the input of this category was 4.7 GJ t-1 (live
weight) in average (25% from the total energy input) and 2.4 GJ t-1 (live weight) in
broiler meat production (22% from the total energy input). The specific energy input
in pork production was the lowest in The Netherlands ( 14.5 GJ t-1) and that of broiler
meat production in Germany (9.8 GJ t-1).
Case studies analysed in five participating countries demonstrated EE measures capable
to reduce costs, to increase EE, and to cut GHG emissions at the same time.
Proposed EE measures were related to ventilation, heating, feeding, animal bedding,
energy generation from manure, and feed production. As an example, an airtight
grain storage met all three goals at the same time. Investment costs were lower than
those for a grain dryer, no energy was needed for drying, and no GHG emissions
were generated because no gas or oil was needed for drying. All suggested EE
measures were not as successful. They might appear negative for costs but positive
for EE and GHG reduction, resulting in a trade-off situation. An approach like this
helps to rank potential EE measures in terms of their cost-effectiveness and capability
to cut GHG emissions
Origin of strong scarring of wavefunctions in quantum wells in a tilted magnetic field
The anomalously strong scarring of wavefunctions found in numerical studies
of quantum wells in a tilted magnetic field is shown to be due to special
properties of the classical dynamics of this system. A certain subset of
periodic orbits are identified which are nearly stable over a very large
interval of variation of the classical dynamics; only this subset are found to
exhibit strong scarring. Semiclassical arguments shed further light on why
these orbits dominate the experimentally observed tunneling spectra.Comment: RevTeX, 5 page
Hydrodynamics of polar liquid crystals
Starting from a microscopic definition of an alignment vector proportional to
the polarization, we discuss the hydrodynamics of polar liquid crystals with
local -symmetry. The free energy for polar liquid crystals
differs from that of nematic liquid crystals () in that it
contains terms violating the symmetry. First we show
that these -odd terms induce a general splay instability of a
uniform polarized state in a range of parameters. Next we use the general
Poisson-bracket formalism to derive the hydrodynamic equations of the system in
the polarized state. The structure of the linear hydrodynamic modes confirms
the existence of the splay instability.Comment: 9 pages, corrected typos, added references, revised content, to
appear in PR
A theorem on the absence of phase transitions in one-dimensional growth models with onsite periodic potentials
We rigorously prove that a wide class of one-dimensional growth models with
onsite periodic potential, such as the discrete sine-Gordon model, have no
phase transition at any temperature . The proof relies on the spectral
analysis of the transfer operator associated to the models. We show that this
operator is Hilbert-Schmidt and that its maximum eigenvalue is an analytic
function of temperature.Comment: 6 pages, no figures, submitted to J Phys A: Math Ge
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