1,076 research outputs found
Targeting accuracy and impact of a community-identified waiver card scheme for primary care user fees in Afghanistan
<p>Abstract</p> <p>Background</p> <p>User fees are a known common barrier to using health services, particularly among the poor. When fees are present, many facilities have waiver systems for poor patients to exempt them from paying. Targeting waivers to patients who need them most has been a challenge, especially in fragile states, where relevant data are limited and trust in institutions is low.</p> <p>Methods</p> <p>Community-based targeting of vulnerable households was piloted in Afghanistan and evaluated for its feasibility, accuracy and effect on care-seeking. Waiver cards were distributed to very poor and female-headed households in catchment areas of 26 facilities in 10 provinces of Afghanistan in 2005 as one component of a larger health financing study. Households were nominated by community leaders using general guidelines to support 15% of the poorest members. In most cases, waiver cards were pro-actively distributed to them. Targeting accuracy, perceptions, as well the cards' effects on utilization were evaluated in 2007 through household surveys, health facility data, and in-depth interviews and focus group discussions with facility staff and community leaders.</p> <p>Results</p> <p>The waiver system was implemented quickly at all but one facility charging fees. Facility staff and community leaders reported favorable perceptions of implementation and targeting accuracy.</p> <p>However, an analysis of the asset index of beneficiaries indicated that although targeting was progressive, significant leakage and high levels of under-coverage occurred; 42% of cards were used by people in the wealthiest three quintiles, and only 19% of people in the poorest quintile received a card. Households with waiver cards reported higher rates of care-seeking for recent illnesses compared to those without cards (p = 0.02).</p> <p>Conclusions</p> <p>Community identification of beneficiaries is feasible in a fragile state. Several recommendations are discussed to improve targeting accuracy of a waiver card system in the future, in light of this research and other international experiences.</p
Rules for Computing Symmetry, Density and Stoichiometry in a Quasi-Unit-Cell Model of Quasicrystals
The quasi-unit cell picture describes the atomic structure of quasicrystals
in terms of a single, repeating cluster which overlaps neighbors according to
specific overlap rules. In this paper, we discuss the precise relationship
between a general atomic decoration in the quasi-unit cell picture atomic
decorations in the Penrose tiling and in related tiling pictures. Using these
relations, we obtain a simple, practical method for determining the density,
stoichiometry and symmetry of a quasicrystal based on the atomic decoration of
the quasi-unit cell taking proper account of the sharing of atoms between
clusters.Comment: 14 pages, 8 figure
The cosmic gravitational wave background in a cyclic universe
Inflation predicts a primordial gravitational wave spectrum that is slightly
``red,'' i.e., nearly scale-invariant with slowly increasing power at longer
wavelengths. In this paper, we compute both the amplitude and spectral form of
the primordial tensor spectrum predicted by cyclic/ekpyrotic models. The
spectrum is blue and exponentially suppressed compared to inflation on long
wavelengths. The strongest observational constraint emerges from the
requirement that the energy density in gravitational waves should not exceed
around 10 per cent of the energy density at the time of nucleosynthesis.Comment: 4 pages, 3 figuer
Strong Brane Gravity and the Radion at Low Energies
For the 2-brane Randall-Sundrum model, we calculate the bulk geometry for
strong gravity, in the low matter density regime, for slowly varying matter
sources. This is relevant for astrophysical or cosmological applications. The
warped compactification means the radion can not be written as a homogeneous
mode in the orbifold coordinate, and we introduce it by extending the
coordinate patch approach of the linear theory to the non-linear case. The
negative tension brane is taken to be in vacuum. For conformally invariant
matter on the positive tension brane, we solve the bulk geometry as a
derivative expansion, formally summing the `Kaluza-Klein' contributions to all
orders. For general matter we compute the Einstein equations to leading order,
finding a scalar-tensor theory with ,
and geometrically interpret the radion. We comment that this radion scalar may
become large in the context of strong gravity with low density matter.
Equations of state allowing to be negative, can exhibit behavior
where the matter decreases the distance between the 2 branes, which we
illustrate numerically for static star solutions using an incompressible fluid.
For increasing stellar density, the branes become close before the upper mass
limit, but after violation of the dominant energy condition. This raises the
interesting question of whether astrophysically reasonable matter, and initial
data, could cause branes to collide at low energy, such as in dynamical
collapse.Comment: 24 pages, 3 figure
Brane Formation and Cosmological Constraint on the Number of Extra Dimensions
Special relativity is generalized to extra dimensions and quantized energy
levels of particles are obtained. By calculating the probability of particles'
motion in extra dimensions at high temperature of the early universe, it is
proposed that the branes may have not existed since the very beginning of the
universe, but formed later. Meanwhile, before the formation, particles of the
universe may have filled in the whole bulk, not just on the branes. This
scenario differs from that in the standard big bang cosmology in which all
particles are assumed to be in the 4D spacetime. So, in brane models, whether
our universe began from a 4D big bang singularity is questionable. A
cosmological constraint on the number of extra dimensions is also given which
favors .Comment: 11 pages, no figures. To appear in IJT
Metric Expansion from Microscopic Dynamics in an Inhomogeneous Universe
Theories with ingredients like the Higgs mechanism, gravitons, and inflaton
fields rejuvenate the idea that relativistic kinematics is dynamically
emergent. Eternal inflation treats the Hubble constant H as depending on
location. Microscopic dynamics implies that H is over much smaller lengths than
pocket universes to be understood as a local space reproduction rate. We
illustrate this via discussing that even exponential inflation in TeV-gravity
is slow on the relevant time scale. In our on small scales inhomogeneous
cosmos, a reproduction rate H depends on position. We therefore discuss
Einstein-Straus vacuoles and a Lindquist-Wheeler like lattice to connect the
local rate properly with the scaling of an expanding cosmos. Consistency allows
H to locally depend on Weyl curvature similar to vacuum polarization. We derive
a proportionality constant known from Kepler's third law and discuss the
implications for the finiteness of the cosmological constant.Comment: 23 pages, no figure
Using the Noether symmetry approach to probe the nature of dark energy
We propose to use a model-independent criterion based on first integrals of
motion, due to Noether symmetries of the equations of motion, in order to
classify the dark energy models in the context of scalar field (quintessence or
phantom) FLRW cosmologies. In general, the Noether symmetries play an important
role in physics because they can be used to simplify a given system of
differential equations as well as to determine the integrability of the system.
The Noether symmetries are computed for nine distinct accelerating cosmological
scenarios that contain a homogeneous scalar field associated with different
types of potentials. We verify that all the scalar field potentials, presented
here, admit the trivial first integral namely energy conservation, as they
should. We also find that the exponential potential inspired from scalar field
cosmology, as well as some types of hyperbolic potentials, include extra
Noether symmetries. This feature suggests that these potentials should be
preferred along the hierarchy of scalar field potentials. Finally, using the
latter potentials, in the framework of either quintessence or phantom scalar
field cosmologies that contain also a non-relativistic matter(dark matter)
component, we find that the main cosmological functions, such as the scale
factor of the universe, the scalar field, the Hubble expansion rate and the
metric of the FRLW space-time, are computed analytically. Interestingly, under
specific circumstances the predictions of the exponential and hyperbolic scalar
field models are equivalent to those of the CDM model, as far as the
global dynamics and the evolution of the scalar field are concerned. The
present analysis suggests that our technique appears to be very competitive to
other independent tests used to probe the functional form of a given potential
and thus the associated nature of dark energy.Comment: Accepted for publication in Physical Review D (13 pages
Double Field Inflation
We present an inflationary universe model which utilizes two coupled real
scalar fields. The inflation field experiences a first order phase
transition and its potential dominates the energy density of the Universe
during the inflationary epoch. This field is initially trapped in its
metastable minimum and must tunnel through a potential barrier to reach the
true vacuum. The second auxiliary field couples to the inflaton field
and serves as a catalyst to provide an abrupt end to the inflationary epoch;
i.e., the field produces a time-dependent nucleation rate for bubbles of
true vacuum. In this model, we find that bubbles of true vacuum can
indeed percolate and we argue that thermalization of the interiors can more
easily take place. The required degree of flatness (i.e., the fine tuning) in
the potential of the field is comparable to that of other models which
invoke slowly rolling fields. Pseudo Nambu-Goldstone bosons may naturally
provide the flat potential for the rolling field.Comment: 18 pages, 2 figures, This early paper is being placed on the archive
to make it more easily accessible in light of recent interest in reviving
tunneling inflationary models and as its results are used in an accompanying
submissio
Quantum state correction of relic gravitons from quantum gravity
The semiclassical approach to quantum gravity would yield the Schroedinger
formalism for the wave function of metric perturbations or gravitons plus
quantum gravity correcting terms in pure gravity; thus, in the inflationary
scenario, we should expect correcting effects to the relic graviton
(Zel'dovich) spectrum of the order (H/mPl)^2
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