2,433 research outputs found
OA07.02. Naturopathic medicine for the prevention of cardiovascular disease: a pragmatic randomized clinical trial
Resonances of the Frobenius-Perron Operator for a Hamiltonian Map with a Mixed Phase Space
Resonances of the (Frobenius-Perron) evolution operator P for phase-space
densities have recently attracted considerable attention, in the context of
interrelations between classical and quantum dynamics. We determine these
resonances as well as eigenvalues of P for Hamiltonian systems with a mixed
phase space, by truncating P to finite size in a Hilbert space of phase-space
functions and then diagonalizing. The corresponding eigenfunctions are
localized on unstable manifolds of hyperbolic periodic orbits for resonances
and on islands of regular motion for eigenvalues. Using information drawn from
the eigenfunctions we reproduce the resonances found by diagonalization through
a variant of the cycle expansion of periodic-orbit theory and as rates of
correlation decay.Comment: 18 pages, 7 figure
Electrical and thermoelectrical transport in Dirac fermions through a quantum dot
We investigate the conductance and thermopower of massless Dirac fermions
through a quantum dot using a pseudogap Anderson model in the non-crossing
approximation. When the Fermi level is at the Dirac point, the conductance has
a cusp where the thermopower changes its sign. When the Fermi level is away
from the Dirac point, the Kondo temperature illustrates a quantum impurity
transition between an asymmetric strong coupling Kondo state and a localized
moment state. The conductance shows a peak near this transition and reaches the
unitary limit at low temperatures. The magnitude of the thermopower exceeds
, and the thermoelectric figure of merit exceeds unity.Comment: 5 pages, 4 figure
The galaxy-halo connection from a joint lensing, clustering and abundance analysis in the CFHTLenS/VIPERS field
We present new constraints on the relationship between galaxies and their
host dark matter halos, measured from the location of the peak of the
stellar-to-halo mass ratio (SHMR), up to the most massive galaxy clusters at
redshift and over a volume of nearly 0.1~Gpc. We use a unique
combination of deep observations in the CFHTLenS/VIPERS field from the near-UV
to the near-IR, supplemented by secure spectroscopic redshifts,
analysing galaxy clustering, galaxy-galaxy lensing and the stellar mass
function. We interpret our measurements within the halo occupation distribution
(HOD) framework, separating the contributions from central and satellite
galaxies. We find that the SHMR for the central galaxies peaks at with an amplitude of ,
which decreases to for massive halos (). Compared to central galaxies only, the total SHMR (including
satellites) is boosted by a factor 10 in the high-mass regime (cluster-size
halos), a result consistent with cluster analyses from the literature based on
fully independent methods. After properly accounting for differences in
modelling, we have compared our results with a large number of results from the
literature up to : we find good general agreement, independently of the
method used, within the typical stellar-mass systematic errors at low to
intermediate mass () and the statistical
errors above. We have also compared our SHMR results to semi-analytic
simulations and found that the SHMR is tilted compared to our measurements in
such a way that they over- (under-) predict star formation efficiency in
central (satellite) galaxies.Comment: 31 pages, 18 figures, 4 table. Accepted for publication in MNRAS.
Online material available at http://www.cfhtlens.or
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The Distance To The Hyades Cluster Based On Hubble Space Telescope Fine Guidance Sensor Parallaxes
Trigonometric parallax observations made with the Hubble Space Telescope (HST) Fine Guidance Sensor (FGS) 3 of seven Hyades members in six fields of view have been analyzed along with their proper motions to determine the distance to the cluster. Knowledge of the convergent point and mean proper motion of the Hyades is critical to the derivation of the distance to the center of the cluster. Depending on the choice of the proper-motion system, the derived cluster center distance varies by 9%. Adopting a reference distance of 46.1 pc or m - M = 3.32, which is derived from the ground-based parallaxes in the General Catalogue of Trigonometric Stellar Parallaxes (1995 edition), the FK5/PPM proper-motion system yields a distance 4% larger, while the Hanson system yields a distance 2% smaller. The HST FGS parallaxes reported here yield either a 14% or 5% larger distance, depending on the choice of the proper-motion system. Orbital parallaxes (Torres et al.) yield an average distance 4% larger than the reference distance. The variation in the distance derived from the HST data illustrates the importance of the proper-motion system and the individual proper motions to the derivation of the distance to the Hyades center; therefore, a full utilization of the HST FGS parallaxes awaits the establishment of an accurate and consistent proper-motion system.NASA HST GTO, HF-1042.01-93A, HF-1046.01-93A, NAS526555Astronom
Human Galectins Induce Conversion of Dermal Fibroblasts into Myofibroblasts and Production of Extracellular Matrix: Potential Application in Tissue Engineering and Wound Repair
Members of the galectin family of endogenous lectins are potent adhesion/growth-regulatory effectors. Their multi-functionality opens possibilities for their use in bioapplications. We studied whether human galectins induce the conversion of human dermal fibroblasts into myofibroblasts (MFBs) and the production of a bioactive extracellular matrix scaffold is suitable for cell culture. Testing a panel of galectins of all three subgroups, including natural and engineered variants, we detected activity for the proto-type galectin-1 and galectin-7, the chimera-type galectin-3 and the tandem-repeat-type galectin-4. The activity of galectin-1 required the integrity of the carbohydrate recognition domain. It was independent of the presence of TGF-beta 1, but it yielded an additive effect. The resulting MFBs, relevant, for example, for tumor progression, generated a matrix scaffold rich in fibronectin and galectin-1 that supported keratinocyte culture without feeder cells. Of note, keratinocytes cultured on this substratum presented a stem-like cell phenotype with small size and keratin-19 expression. In vivo in rats, galectin-1 had a positive effect on skin wound closure 21 days after surgery. In conclusion, we describe the differential potential of certain human galectins to induce the conversion of dermal fibroblasts into MFBs and the generation of a bioactive cell culture substratum. Copyright (C) 2011 S. Karger AG, Base
Self-Consistent Relativistic Calculation of Nucleon Mean Free Path
We present a fully self-consistent and relativistic calculation of the
nucleon mean free path in nuclear matter and finite nuclei. Starting from the
Bonn potential, the Dirac-Brueckner-Hartree-Fock results for nuclear matter are
parametrized in terms of an effective - Lagrangian suitable for
the relativistic density-dependent Hartree-Fock (RDHF) approximation. The
nucleon mean free path in nuclear matter is derived from this effective
Lagrangian taking diagrams up to fourth-order into account. For the nucleon
mean free path in finite nuclei, we make use of the density determined by the
RDHF calculation in the local density approximation. Our microscopic results
are in good agreement with the empirical data and predictions by Dirac
phenomenology.Comment: 16 pages RevTex and 6 figures (paper, available upon request from
[email protected]) UI-NTH-931
The VIMOS Public Extragalactic Redshift Survey (VIPERS): On the correct recovery of the count-in-cell probability distribution function
We compare three methods to measure the count-in-cell probability density
function of galaxies in a spectroscopic redshift survey. From this comparison
we found that when the sampling is low (the average number of object per cell
is around unity) it is necessary to use a parametric method to model the galaxy
distribution. We used a set of mock catalogues of VIPERS, in order to verify if
we were able to reconstruct the cell-count probability distribution once the
observational strategy is applied. We find that in the simulated catalogues,
the probability distribution of galaxies is better represented by a Gamma
expansion than a Skewed Log-Normal. Finally, we correct the cell-count
probability distribution function from the angular selection effect of the
VIMOS instrument and study the redshift and absolute magnitude dependency of
the underlying galaxy density function in VIPERS from redshift to .
We found very weak evolution of the probability density distribution function
and that it is well approximated, independently from the chosen tracers, by a
Gamma distribution.Comment: 14 pages, 11 figures, 2 table
CLASH: Photometric redshifts with 16 HST bands in galaxy cluster fields
The Cluster Lensing And Supernovae survey with Hubble (CLASH) is an Hubble
Space Telescope (HST) Multi-Cycle Treasury program observing 25 massive galaxy
clusters. CLASH observations are carried out in 16 bands from UV to NIR to
derive accurate and reliable estimates of photometric redshifts. We present the
CLASH photometric redshifts and study the photometric redshift accuracy of the
arcs in more detail for the case of MACS1206.2-0847. We use the publicly
available Le Phare and BPZ photometric redshift codes on 17 CLASH galaxy
clusters. Using Le Phare code for objects with StoN>=10, we reach a precision
of 3%(1+z) for the strong lensing arcs, which is reduced to 2.4%(1+z) after
removing outliers. For galaxies in the cluster field the corresponding values
are 4%(1+z) and 3%(1+z). Using mock galaxy catalogues, we show that 3%(1+z)
precision is what one would expect from the CLASH photometry when taking into
account extinction from dust, emission lines and the finite range of SEDs
included in the photo-z template library. We study photo-z results for
different aperture photometry and find that the SExtractor isophotal photometry
works best. Le Phare and BPZ give similar photo-z results for the strong
lensing arcs as well as galaxies of the cluster field. Results are improved
when optimizing the photometric aperture shape showing an optimal aperture size
around 1" radius giving results which are equivalent to isophotal photometry.
Tailored photometry of the arcs improve the photo-z results.Comment: Accepted in A&A on nov 201
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Galaxy clustering and redshift-space distortions at z=0.8 in the first data release
We present in this paper the general real- and redshift-space clustering
properties of galaxies as measured in the first data release of the VIPERS
survey. VIPERS is a large redshift survey designed to probe the distant
Universe and its large-scale structure at 0.5 < z < 1.2. We describe in this
analysis the global properties of the sample and discuss the survey
completeness and associated corrections. This sample allows us to measure the
galaxy clustering with an unprecedented accuracy at these redshifts. From the
redshift-space distortions observed in the galaxy clustering pattern we provide
a first measurement of the growth rate of structure at z = 0.8: f\sigma_8 =
0.47 +/- 0.08. This is completely consistent with the predictions of standard
cosmological models based on Einstein gravity, although this measurement alone
does not discriminate between different gravity models.Comment: 19 pages, 19 figures, accepted for publication in A&
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