114 research outputs found
Peer Support: The Peer Support Movement and the Future of Mental Health Care
Research paper on the history of the peer support movement as related to mental heath beginning in 1908.https://digitalcommons.wou.edu/maurice/1005/thumbnail.jp
The GLAS Algorithm Theoretical Basis Document for Laser Footprint Location (Geolocation) and Surface Profiles
This ATBD summarizes (and links with other ATBDs) the elements used to obtain the geolocated GLAS laser spot location, with respect to the Earth Center of Mass. Because of the approach used, the reference frame used to express the geolocation is linked to the reference frame used for POD and PAD, which are related to the ITRF. The geolocated spot coordinates (which includes the elevation or height, with respect to an adopted reference ellipsoid) is the inferred position of the laser spot, since the spot location is not directly measured. This document also summarizes the GLAS operation time periods
Predictions for p+Pb at 4.4A TeV to Test Initial State Nuclear Shadowing at energies available at the CERN Large Hadron Collider
Collinear factorized perturbative QCD model predictions are compared for p+Pb
at 4.4A TeV to test nuclear shadowing of parton distribution at the Large
Hadron Collider (LHC). The nuclear modification factor (NMF),
R_{pPb}(y=0,p_T<20 GeV/c) = dn_{p Pb} /(N_{coll}(b)dn_{pp}), is computed with
electron-nucleus (e+A) global fit with different nuclear shadow distributions
and compared to fixed Q^2 shadow ansatz used in Monte Carlo Heavy Ion Jet
Interacting Generator (HIJING) type models. Due to rapid DGLAP reduction of
shadowing with increasing Q^2 used in e+A global fit, our results confirm that
no significant initial state suppression is expected (R_{pPb} (p_T) = 1 \pm
0.1) in the p_T range 5 to 20 GeV/ c. In contrast, the fixed Q^2 shadowing
models assumed in HIJING type models predict in the above p_T range a sizable
suppression, R_{pPb} (p_T) = 0.6-0.7 at mid-pseudorapidity that is similar to
the color glass condensate (CGC) model predictions. For central (N_{coll} = 12)
p+ Pb collisions and at forward pseudorapidity (\eta = 6) the HIJING type
models predict smaller values of nuclear modification factors (R_{pPb}(p_T))
than in minimum bias events at mid-pseudorapidity (\eta = 0). Observation of
R_{pPb}(p_T= 5-20 GeV/c) less than 0.6 for minimum bias p+A collisions would
pose a serious difficulty for separating initial from final state interactions
in Pb+Pb collisions at LHC energies.Comment: Revised version accepted for publication; Phys. Rev. C, in press, 16
pages, 4 figures, text modifications, added references, new figure 4, revtex
Reissner-Nordstrom and charged gas spheres
The main point of this paper is a suggestion about the proper treatment of
the photon gas in a theory of stellar structure and other plasmas. This problem
arises in the study of polytropic gas spheres, where we have already introduced
some innovations. The main idea, already advanced in the contextof neutral,
homogeneous, polytropic stellar models, is to base the theory firmly on a
variational principle. Another essential novelty is to let mass distribution
extend to infinity, the boundary between bulk and atmosphere being defined by
an abrupt change in the polytropic index, triggered by the density. The logical
next step in this program is to include the effect of radiation, which is a
very significant complication since a full treatment would have to include an
account of ionization, thus fieldsrepresenting electrons, ions, photons,
gravitons and neutral atoms as well. In way of preparation, we consider models
that are charged but homogeneous, involving only gravity, electromagnetism and
a single scalar field that represents both the mass and the electric charge; in
short, anon-neutral plasma. While this work only represents a stage in the
development of a theory of stars, without direct application to physical
systems, it does shed some light on the meaning of the Reissner-Nordstrom
solution of the modified Einstein-Maxwell equations., with an application to a
simple system.Comment: 19 pages, plain te
Gravitino perturbations in Schwarzschild black holes
We consider the time evolution of massless gravitino perturbations in
Schwarzschild black holes, and show that as in the case of fields of other
values of spin, the evolution comes in three stages, after an initial outburst
as a first stage, we observe the damped oscillations characteristic of the
quasinormal ringing stage, followed by long time tails. Using the sixth order
WKB method and Prony fitting of time domain data we determine the quasinormal
frequencies. There is a good correspondence between the results obtained by the
above two methods, and we obtain a considerable improvement with respect to the
previously obtained third order WKB results. We also show that the response of
a black hole depends crucially on the spin class of the perturbing field: the
quality factor becomes a decreasing function of the spin for boson
perturbations, whereas the opposite situation appears for fermion ones
QUALIDADE DE VIDA: A IMPORTÂNCIA DA ALIMENTAÇÃO SAUDÁVEL E HÁBITOS DE HIGIENE NA FORMAÇÃO INTEGRAL DO ALUNO DA EDUCAÇÃO BÁSICA
Ideal Stars and General Relativity
We study a system of differential equations that governs the distribution of
matter in the theory of General Relativity. The new element in this paper is
the use of a dynamical action principle that includes all the degrees of
freedom, matter as well as metric. The matter lagrangian defines a relativistic
version of non-viscous, isentropic hydrodynamics. The matter fields are a
scalar density and a velocity potential; the conventional, four-vector velocity
field is replaced by the gradient of the potential and its scale is fixed by
one of the eulerian equations of motion, an innovation that significantly
affects the imposition of boundary conditions. If the density is integrable at
infinity, then the metric approaches the Schwarzschild metric at large
distances. There are stars without boundary and with finite total mass; the
metric shows rapid variation in the neighbourhood of the Schwarzschild radius
and there is a very small core where a singularity indicates that the gas laws
break down. For stars with boundary there emerges a new, critical relation
between the radius and the gravitational mass, a consequence of the stronger
boundary conditions. Tentative applications are suggested, to certain Red
Giants, and to neutron stars, but the investigation reported here was limited
to polytropic equations of state. Comparison with the results of Oppenheimer
and Volkoff on neutron cores shows a close agreement of numerical results.
However, in the model the boundary of the star is fixed uniquely by the
required matching of the interior metric to the external Schwarzschild metric,
which is not the case in the traditional approach.Comment: 26 pages, 7 figure
The geodesic structure of the Schwarzschild Anti-de Sitter black hole
In the present work we found the geodesic structure of an AdS black hole. By
means of a detailed analyze of the corresponding effective potentials for
particles and photon, we found all the possible motions which are allowed by
the energy levels. Radial and non radial trajectories were exactly evaluated
for both geodesics. The founded orbits were plotted in order to have a direct
visualization of the allowed motions. We show that the geodesic structure of
this black hole presents new type of motions not allowed by the Schwarzschild
spacetime.Comment: 17 pages, 11 figure
Reducing the gravitational lensing scatter of Type Ia supernovae without introducing any extra bias
Magnification and de-magnification due to gravitational lensing will
contribute to the brightness scatter of Type Ia supernovae (SNe Ia). The
purpose of this paper is to investigate the possibility to decrease this
scatter by correcting individual SNe Ia using observations of galaxies in the
foreground, without introducing any extra bias. We simulate a large number of
SN Ia lines of sight populated by galaxies. For each line of sight the true
magnification factor and an estimate thereof are calculated. The estimated
magnification factor corresponds to what an observer would infer from a survey
like SNLS. Using the simulated data we investigate the possibility to estimate
the magnification of individual supernovae with enough precision to be able to
correct their brightness for gravitational lensing with negligible bias. Our
simulations show that the bias arising from gravitational lensing corrections
of individual SNe Ia is negligible for current and next generation surveys and
that the scatter from lensing can be reduced by approximately a factor 2. The
total scatter in the SN Ia magnitudes could be reduced by 4% for an intrinsic
dispersion of 0.13 mag. For an intrinsic dispersion of 0.09 mag, which might
not be to unrealistic for future surveys, the total scatter could be reduced by
6%. This will reduce the errors on cosmological parameters derived from
supernova data by 4-8%. The prospect of correcting for lensing is thus very
good.Comment: 7 pages, 7 figures, accepted by A&
Vacuum polarization effects on quasinormal modes in electrically charged black hole spacetimes
We investigate the influence of vacuum polarization of quantum massive fields
on the scalar sector of quasinormal modes in spherically symmetric black holes.
We consider the evolution of a massless scalar field on the spacetime
corresponding to a charged semiclassical black hole, consisting of the quantum
corrected geometry of a Reissner-Nordstr\"om black hole dressed by a quantum
massive scalar field in the large mass limit. Using a sixth order WKB approach
we find the shift in the quasinormal mode frequencies due to vacuum
polarization .Comment: 9 pages, 5 figures, typos added, references added and content change
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