15,231 research outputs found
Multiferroic behavior of Aurivillius Bi4Mn3O12 from first-principles
The multiferroic behavior of the hypothetical Aurivillius compound Bi4Mn3O12
has been explored on the basis of density functional calculations. We find that
the tetragonal paraelectric phase of this material is ferromagnetic, showing
ferroelectric and antiferrodistortive instabilities similar to the ones
observed in its ferroelectric parent compound Bi4Ti3O12 . Our results indicate,
however, that the presence of Mn+4 ions at the B-sites shrinks the cell volume
and consequently the unstable polar mode, associated with the ferroelectric
polarization, is overcame by an antiferrodistortive distortion. In this way,
Bi4Mn3O12 exhibits incipient ferroelectricity at its equilibrium volume. We
show that the ferroelectric state can be favored by strain or partial
substitution of Mn with Ti.Comment: 6 pages, 5 figure
From Cavendish to PLANCK: Constraining Newton's Gravitational Constant with CMB Temperature and Polarization Anisotropy
We present new constraints on cosmic variations of Newton's gravitational
constant by making use of the latest CMB data from WMAP, BOOMERANG, CBI and
ACBAR experiments and independent constraints coming from Big Bang
Nucleosynthesis. We found that current CMB data provide constraints at the 10%
level, that can be improved to 3% by including BBN data. We show that future
data expected from the Planck satellite could constrain G at the 1.5% level
while an ultimate, cosmic variance limited, CMB experiment could reach a
precision of about 0.4%, competitive with current laboratory measurements.Comment: 6 pages, 8 figures, corrected typos, added reference
The Morphology-Density-Relation: Impact on the Satellite Fraction
In the past years several authors studied the abundance of satellites around
galaxies in order to better estimate the halo masses of host galaxies. To
investigate this connection, we analyze galaxies with
from the hydrodynamical cosmological
simulation Magneticum. We find that the satellite fraction of centrals is
independent of their morphology. With the exception of very massive galaxies at
low redshift, our results do not support the assumption that the dark matter
(DM) haloes of spheroidal galaxies are significantly more massive than those of
disc galaxies at fixed . We show that the
density-morphology-relation starts to build up at and is independent
of the star-formation properties of central galaxies. We conclude that
environmental quenching is more important for satellites than for centrals. Our
simulations indicate that conformity is already in place at , where
formation redshift and current star-formation rate (SFR) of central and
satellite galaxies correlate. Centrals with low SFRs have formed earlier (at
fixed ) while centrals with high SFR formed later, with
typical formation redshifts well in agreement with observations. However, we
confirm the recent observations that the apparent number of satellites of
spheroidal galaxies is significantly larger than for disc galaxies. This
difference completely originates from the inclusion of companion galaxies, i.e.
galaxies that do not sit in the potential minimum of a DM halo. Thus, due to
the density-morphological-relation the number of satellites is not a good
tracer for the halo mass, unless samples are restricted to the central galaxies
of DM haloes.Comment: 17 pages, submitted to MNRAS, www.magneticum.or
CONSUMER PERCEPTION ON ALTERNATIVE POULTRY
Food Consumption/Nutrition/Food Safety, Livestock Production/Industries,
Understanding the performance of the low energy neutrino factory: the dependence on baseline distance and stored-muon energy
Motivated by recent hints of large {\theta}13 from the T2K, MINOS and Double
Chooz experiments, we study the physics reach of a Low Energy Neutrino Factory
(LENF) and its dependence on the chosen baseline distance, L, and stored-muon
energy, E_{\mu}, in order to ascertain the configuration of the optimal LENF.
In particular, we study the performance of the LENF over a range of baseline
distances from 1000 km to 4000 km and stored-muon energies from 4 GeV to 25
GeV, connecting the early studies of the LENF (1300 km, 4.5 GeV) to those of
the conventional, high-energy neutrino factory design (4000 km and 7000 km, 25
GeV). Three different magnetized detector options are considered: a
Totally-Active Scintillator Detector (TASD) and two models of a liquid-argon
detector distinguished by optimistic and conservative performance estimates. In
order to compare the sensitivity of each set-up, we compute the full
{\delta}-dependent discovery contours for the determination of non-zero
{\theta}13, CP-violating values of {\delta} and the mass hierarchy. In the case
of large {\theta}13 with sin^2(2*{\theta}13) = (few)*10^{-3}, the LENF provides
a strong discovery potential over the majority of the L-E_{\mu} parameter space
and is a promising candidate for the future generation of long baseline
experiments aimed at discovering CP-violation and the mass hierarchy, and at
making a precise determination of the oscillation parameters.Comment: 14 pages, 5 figure
Muscle Dysmorphia and its Associated Psychological Features in Three Groups of Recreational Athletes
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