1,656 research outputs found
AMPing Racial Attitudes: Comparing the Power of Explicit and Implicit Racism Measures in 2008
In 2008, ANES included for the first time—along with standard explicit measures of old-fashioned and symbolic racism—the Affect Misattribution Procedure (AMP), a relatively new implicit measure of racial attitudes. This article examines the extent to which four different measures of racial prejudice (three explicit and one implicit) predict public opinion during and after the 2008 election, including Americans' views towards several racial policy issues, their evaluations of, and feelings toward, Barack Obama, and their attitudes toward a Black president in general. Oversamples of African American and Latino respondents in the 2008 ANES enable us to broaden our tests of these measures beyond traditional White samples. We find that racial prejudice played an important role for all racial/ethnic groups but that the traditional explicit measures of racism are by far the stronger predictors for all of our dependent variables (compared to the new implicit measure) for both White and Black respondents. Surprisingly, the AMP adds clear explanatory power only to models in the Latino sample
On the cross-section of Dark Matter using substructure infall into galaxy clusters
We develop a statistical method to measure the interaction cross-section of
Dark Matter, exploiting the continuous minor merger events in which small
substructures fall into galaxy clusters. We find that by taking the ratio of
the distances between the galaxies and Dark Matter, and galaxies and gas in
accreting sub-halos, we form a quantity that can be statistically averaged over
a large sample of systems whilst removing any inherent line-of-sight
projections. In order to interpret this ratio as a cross-section of Dark Matter
we derive an analytical description of sub-halo infall which encompasses; the
force of the main cluster potential, the drag on a gas sub-halo, a model for
Dark Matter self-interactions and the resulting sub-halo drag, the force on the
gas and galaxies due to the Dark Matter sub-halo potential, and finally the
buoyancy on the gas and Dark Matter. We create mock observations from
cosmological simulations of structure formation and find that collisionless
Dark Matter becomes physically separated from X-ray gas by up to 20h^-1 kpc.
Adding realistic levels of noise, we are able to predict achievable constraints
from observational data. Current archival data should be able to detect a
difference in the dynamical behaviour of Dark Matter and standard model
particles at 6 sigma, and measure the total interaction cross-section sigma/m
with 68% confidence limits of +/- 1cm2g^-1. We note that this method is not
restricted by the limited number of major merging events and is easily extended
to large samples of clusters from future surveys which could potentially push
statistical errors to 0.1cm^2g^-1.Comment: 14 pages, 11 figure
Sparse spectral-tau method for the three-dimensional helically reduced wave equation on two-center domains
We describe a multidomain spectral-tau method for solving the
three-dimensional helically reduced wave equation on the type of two-center
domain that arises when modeling compact binary objects in astrophysical
applications. A global two-center domain may arise as the union of Cartesian
blocks, cylindrical shells, and inner and outer spherical shells. For each such
subdomain, our key objective is to realize certain (differential and
multiplication) physical-space operators as matrices acting on the
corresponding set of modal coefficients. We achieve sparse banded realizations
through the integration "preconditioning" of Coutsias, Hagstrom, Hesthaven, and
Torres. Since ours is the first three-dimensional multidomain implementation of
the technique, we focus on the issue of convergence for the global solver, here
the alternating Schwarz method accelerated by GMRES. Our methods may prove
relevant for numerical solution of other mixed-type or elliptic problems, and
in particular for the generation of initial data in general relativity.Comment: 37 pages, 3 figures, 12 table
Kinetics, dynamics, and bioavailability of bumetanide in healthy subjects and patients with chronic renal failure
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109801/1/cptclpt1986112.pd
Multidomain Spectral Method for the Helically Reduced Wave Equation
We consider the 2+1 and 3+1 scalar wave equations reduced via a helical
Killing field, respectively referred to as the 2-dimensional and 3-dimensional
helically reduced wave equation (HRWE). The HRWE serves as the fundamental
model for the mixed-type PDE arising in the periodic standing wave (PSW)
approximation to binary inspiral. We present a method for solving the equation
based on domain decomposition and spectral approximation. Beyond describing
such a numerical method for solving strictly linear HRWE, we also present
results for a nonlinear scalar model of binary inspiral. The PSW approximation
has already been theoretically and numerically studied in the context of the
post-Minkowskian gravitational field, with numerical simulations carried out
via the "eigenspectral method." Despite its name, the eigenspectral technique
does feature a finite-difference component, and is lower-order accurate. We
intend to apply the numerical method described here to the theoretically
well-developed post-Minkowski PSW formalism with the twin goals of spectral
accuracy and the coordinate flexibility afforded by global spectral
interpolation.Comment: 57 pages, 11 figures, uses elsart.cls. Final version includes
revisions based on referee reports and has two extra figure
Angular momentum and an invariant quasilocal energy in general relativity
Owing to its transformation property under local boosts, the Brown-York
quasilocal energy surface density is the analogue of E in the special
relativity formula: E^2-p^2=m^2. In this paper I will motivate the general
relativistic version of this formula, and thereby arrive at a geometrically
natural definition of an `invariant quasilocal energy', or IQE. In analogy with
the invariant mass m, the IQE is invariant under local boosts of the set of
observers on a given two-surface S in spacetime. A reference energy subtraction
procedure is required, but in contrast to the Brown-York procedure, S is
isometrically embedded into a four-dimensional reference spacetime. This
virtually eliminates the embeddability problem inherent in the use of a
three-dimensional reference space, but introduces a new one: such embeddings
are not unique, leading to an ambiguity in the reference IQE. However, in this
codimension-two setting there are two curvatures associated with S: the
curvatures of its tangent and normal bundles. Taking advantage of this fact, I
will suggest a possible way to resolve the embedding ambiguity, which at the
same time will be seen to incorporate angular momentum into the energy at the
quasilocal level. I will analyze the IQE in the following cases: both the
spatial and future null infinity limits of a large sphere in asymptotically
flat spacetimes; a small sphere shrinking toward a point along either spatial
or null directions; and finally, in asymptotically anti-de Sitter spacetimes.
The last case reveals a striking similarity between the reference IQE and a
certain counterterm energy recently proposed in the context of the conjectured
AdS/CFT correspondence.Comment: 54 pages LaTeX, no figures, includes brief summary of results,
submitted to Physical Review
X-ray modelling of galaxy cluster gas and mass profiles
We present a parametric analysis of the intracluster medium and gravitating
mass distribution of a statistical sample of 20 galaxy clusters using the
phenomenological cluster model of Ascasibar and Diego. We describe an effective
scheme for the estimation of errors on model parameters and derived quantities
using bootstrap resampling. We find that the model provides a good description
of the data in all cases and we quantify the mean fractional intrinsic scatter
about the best-fit density and temperature profiles, finding this to have
median values across the sample of 2 and 5 per cent, respectively. In addition,
we demonstrate good agreement between r500 determined directly from the model
and that estimated from a core-excluded global spectrum. We compare cool core
and non-cool core clusters in terms of the logarithmic slopes of their gas
density and temperature profiles and the distribution of model parameters and
conclude that the two categories are clearly separable. In particular, we
confirm the effectiveness of the logarithmic gradient of the gas density
profile measured at 0.04 r500 in differentiating between the two types of
cluster.Comment: 8 pages, 7 figures, accepted for publication in MNRA
A longitudinal, HIV care continuum: 10-year restricted mean time in each care continuum stage after enrollment in care, by history of IDU
We present a novel, patient-centric, longitudinal summary of patient progress through the HIV care continuum. Using this new approach, we compare person-time spent alive, in care, on antiretroviral therapy (ART) and virally suppressed among persons who inject drugs (PWID) and those who do not (non-IDU)
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