4,626 research outputs found
Ergodic Transport Theory, periodic maximizing probabilities and the twist condition
The present paper is a follow up of another one by A. O. Lopes, E. Oliveira
and P. Thieullen which analyze ergodic transport problems. Our main focus will
a more precise analysis of case where the maximizing probability is unique and
is also a periodic orbit.
Consider the shift T acting on the Bernoulli space \Sigma={1, 2, 3,..,
d}^\mathbb{N} A:\Sigma \to \mathbb{R} a Holder potential.
Denote m(A)=max_{\nu is an invariant probability for T} \int A(x) \; d\nu(x)
and, \mu_{\infty,A}, any probability which attains the maximum value. We assume
this probability is unique (a generic property). We denote \T the bilateral
shift. For a given potential Holder A:\Sigma \to \mathbb{R}, we say that a
Holder continuous function W: \hat{\Sigma} \to \mathbb{R} is a involution
kernel for A, if there is a Holder function A^*:\Sigma \to \mathbb{R}, such
that, A^*(w)= A\circ \T^{-1}(w,x)+ W \circ \T^{-1}(w,x) - W(w,x). We say that
A^* is a dual potential of A. It is true that m(A)=m(A^*). We denote by V the
calibrated subaction for A, and, V^* the one for A^*. We denote by I^* the
deviation function for the family of Gibbs states for \beta A, when \beta \to
\infty.
For each x we get one (more than one) w_x such attains the supremum above.
That is, solutions of V(x) = W(w_x,x) - V^* (w_x)- I^*(w_x).
A pair of the form (x,w_x) is called an optimal pair. If \T is the shift
acting on (x,w) \in {1, 2, 3,.., d}^\mathbb{Z}, then, the image by \T^{-1} of
an optimal pair is also an optimal pair.
Theorem - Generically, in the set of Holder potentials A that satisfy
(i) the twist condition,
(ii) uniqueness of maximizing probability which is supported in a periodic
orbit, the set of possible optimal w_x, when x covers the all range of possible
elements x in \in \Sigma, is finite
Toxoplasma gondii profilin does not stimulate an innate immune response through bovine or human TLR5
Toxoplasma gondii is responsible for one of the most prevalent infections in people. T. gondii profilin (TgPr) is a protein integral to parasite movement and cellular invasion. Murine TLR has been described to bind TgPr. Furthermore, more recently, human TLR5 has been described to recognise recombinant TgPr, as well as bacterial flagellin. In addition to infections in humans, T. gondii infects farm animals, but little information is available about its innate recognition. We aimed to investigate whether, similarly to their human orthologue, bovine and porcine TLR5 could also be stimulated by TgPr by using a combination of reporter cell lines expressing full length TLR5 from each species as well as primary cells. Although human and bovine TLR5-transfected cells responded to flagellin, no response was detected upon stimulation
with profilin. Furthermore, TgPr failed to elicit IL-6 secretion in human peripheral blood mononuclear cells and CD14þ monocytes. In contrast, exposure of RAW cells, known to express TLR11 to TgPr, slightly increased the IL-6 response. Our data cast doubts on the possibility that profilin is a specific ligand for human TLR5 and bovine TLR5. This leaves the immunogenic properties of this potential target antigen uncharacterised outside of the murine system
Hybrid paramagnon phonon modes at elevated temperatures in EuTiO3
EuTiO3 (ETO) has recently experienced an enormous revival of interest because
of its possible multiferroic properties which are currently in the focus of
research. Unfortunately ETO is an unlikely candidate for enlarged
multifunctionality since the mode softening - typical for ferroelectrics -
remains incomplete, and the antiferromagnetic properties appear at 5.5K only.
However, a strong coupling between lattice and Eu spins exists and leads to the
appearance of a magnon-phonon-hybrid mode at elevated temperatures as evidenced
by electron paramagnetic resonance (EPR), muon spin rotation ({\mu}SR)
experiments and model predictions based on a coupled spin-polarizability
Hamiltonian. This novel finding supports the notion of strong
magneto-dielectric (MD) effects being realized in ETO and opens new strategies
in material design and technological applications.Comment: 9 pages, 4 figure
Theory of Dynamic Stripe Induced Superconductivity
Since the recently reported giant isotope effect on T* [1] could be
consistently explained within an anharmonic spin-charge-phonon interaction
model, we consider here the role played by stripe formation on the
superconducting properties within the same model. This is a two-component
scenario and we recast its basic elements into a BCS effective Hamiltonian. We
find that the stripe formation is vital to high-Tc superconductivity since it
provides the glue between the two components to enhance Tc to the unexpectedly
large values observed experimentally.Comment: 7 pages, 2 figure
CMB Lensing Power Spectrum Biases from Galaxies and Clusters using High-angular Resolution Temperature Maps
The lensing power spectrum from cosmic microwave background (CMB) temperature
maps will be measured with unprecedented precision with upcoming experiments,
including upgrades to ACT and SPT. Achieving significant improvements in
cosmological parameter constraints, such as percent level errors on sigma_8 and
an uncertainty on the total neutrino mass of approximately 50 meV, requires
percent level measurements of the CMB lensing power. This necessitates tight
control of systematic biases. We study several types of biases to the
temperature-based lensing reconstruction signal from foreground sources such as
radio and infrared galaxies and the thermal Sunyaev-Zel'dovich effect from
galaxy clusters. These foregrounds bias the CMB lensing signal due to their
non-Gaussian nature. Using simulations as well as some analytical models we
find that these sources can substantially impact the measured signal if left
untreated. However, these biases can be brought to the percent level if one
masks galaxies with fluxes at 150 GHz above 1 mJy and galaxy clusters with
masses above M_vir = 10^14 M_sun. To achieve such percent level bias, we find
that only modes up to a maximum multipole of l_max ~ 2500 should be included in
the lensing reconstruction. We also discuss ways to minimize additional bias
induced by such aggressive foreground masking by, for example, exploring a
two-step masking and in-painting algorithm.Comment: 14 pages, 14 figures, to be submitted to Ap
The Impact of Halo Properties, Energy Feedback and Projection Effects on the Mass-SZ Flux Relation
We present a detailed analysis of the intrinsic scatter in the integrated SZ
effect - cluster mass (Y-M) relation, using semi-analytic and simulated cluster
samples. Specifically, we investigate the impact on the Y-M relation of energy
feedback, variations in the host halo concentration and substructure
populations, and projection effects due to unresolved clusters along the line
of sight (the SZ background). Furthermore, we investigate at what radius (or
overdensity) one should measure the integrated SZE and define cluster mass so
as to achieve the tightest possible scaling. We find that the measure of Y with
the least scatter is always obtained within a smaller radius than that at which
the mass is defined; e.g. for M_{200} (M_{500}) the scatter is least for
Y_{500} (Y_{1100}). The inclusion of energy feedback in the gas model
significantly increases the intrinsic scatter in the Y-M relation due to larger
variations in the gas mass fraction compared to models without feedback. We
also find that variations in halo concentration for clusters of a given mass
may partly explain why the integrated SZE provides a better mass proxy than the
central decrement. Substructure is found to account for approximately 20% of
the observed scatter in the Y-M relation. Above M_{200} = 2x10^{14} h^{-1}
msun, the SZ background does not significantly effect cluster mass
measurements; below this mass, variations in the background signal reduce the
optimal angular radius within which one should measure Y to achieve the
tightest scaling with M_{200}.Comment: 12 pages, 6 figures, to be submitted to Ap
Experimental approaches for 100 TeV gamma-ray astronomy
The high energy end of gamma-ray source spectra might provide important clues
regarding the nature of the processes involved in gamma-ray emission. Several
galactic sources with hard emission spectra extending up to more than 30TeV
have already been reported. Measurements around 100TeV and above should be an
important goal for the next generation of high energy gamma-ray astronomy
experiments. Here we present several techniques providing the required exposure
(100 km^2.h). We focus our study on three Imaging Atmospheric Cherenkov
Technique (IACT) based approaches: low elevation observations, large field of
view telescopes, and large telescope arrays. We comment on the advantages and
disadvantages of each approach and report simulation based estimates of their
energy ranges and sensitivities.Comment: 3 pages 1 figure. Proceedings of TeV particle astrophysics 2,
Madison, August 2006.
http://www.icecube.wisc.edu/TeV/presentations/colin_poster.pd
Predictions of the causal entropic principle for environmental conditions of the universe
The causal entropic principle has been proposed as a superior alternative to
the anthropic principle for understanding the magnitude of the cosmological
constant. In this approach, the probability to create observers is assumed to
be proportional to the entropy production \Delta S in a maximal causally
connected region -- the causal diamond. We improve on the original treatment by
better quantifying the entropy production due to stars, using an analytic model
for the star formation history which accurately accounts for changes in
cosmological parameters. We calculate the dependence of \Delta S on the density
contrast Q=\delta\rho/\rho, and find that our universe is much closer to the
most probable value of Q than in the usual anthropic approach and that
probabilities are relatively weakly dependent on this amplitude. In addition,
we make first estimates of the dependence of \Delta S on the baryon fraction
and overall matter abundance. Finally, we also explore the possibility that
decays of dark matter, suggested by various observed gamma ray excesses, might
produce a comparable amount of entropy to stars.Comment: RevTeX4, 13pp, 10 figures; v2. clarified introduction, added ref
The polarizability model for ferroelectricity in perovskite oxides
This article reviews the polarizability model and its applications to
ferroelectric perovskite oxides. The motivation for the introduction of the
model is discussed and nonlinear oxygen ion polarizability effects and their
lattice dynamical implementation outlined. While a large part of this work is
dedicated to results obtained within the self-consistent-phonon approximation
(SPA), also nonlinear solutions of the model are handled which are of interest
to the physics of relaxor ferroelectrics, domain wall motions, incommensurate
phase transitions. The main emphasis is to compare the results of the model
with experimental data and to predict novel phenomena.Comment: 55 pages, 35 figure
- …