178 research outputs found
Are Medical Prices Declining?
We address long-standing problems in measuring health care prices by estimating two medical care price indices. The first, a Service Price Index, prices specific medical services, as does the current CPI. The second, a Cost of Living Index, measures the net valuation of treating a health problem. We apply these indices to heart attack treatment between 1983 and 1994. Because of technological change and increasing price discounts, the current CPI overstates a chain-weighted price index by three percentage points annually. For plausible values of an additional life-year, the real Cost of Living Index fell about 1 percent annually.
Pricing Heart Attack Treatments
In this paper, we estimate price indices for heart attack treatments, demonstrating the techniques that are currently used in official price indices and presenting some alternatives. We consider two types of price indices, a Service Price Index, which prices specific treatments provided, and a Cost of Living Index, which prices the health outcomes of patients. Both indices are complicated by price measurement issues: list prices and transactions prices are fundamentally different in the medical care field. The development of new or modified medical treatments further complicates the comparison of like' goods over time. And the Cost of Living Index is hampered by the need to determine how much of health improvement results from medical treatments in comparison to other factors. We describe methods to address each of these obstacles. We conclude that whereas traditional price indices when applied to heart attack treatments are rising at roughly 3 percent per year above general inflation, a corrected service price index is rising at perhaps 1 to 2 percent per year above general inflation, and the cost of living index is falling by 1 to 2 percent per year relative to general inflation. We discuss the implications of these results for official price index calculations.
Phasespace Correlations of Antideuterons in Heavy Ion Collisions
In the framework of the relativistic quantum molecular dynamics approach
({\small RQMD}) we investigate antideuteron () observables in
Au+Au collisions at 10.7~AGeV. The impact parameter dependence of the formation
ratios and is calculated. In central
collisions, the antideuteron formation ratio is predicted to be two orders of
magnitude lower than the deuteron formation ratio. The yield in
central Au+Au collisions is one order of magnitude lower than in Si+Al
collisions. In semicentral collisions different configuration space
distributions of 's and 's lead to a large
``squeeze--out'' effect for antideuterons, which is not predicted for the
's
Modeling Cluster Production at the AGS
Deuteron coalescence, during relativistic nucleus-nucleus collisions, is
carried out in a model incorporating a minimal quantal treatment of the
formation of the cluster from its individual nucleons by evaluating the overlap
of intial cascading nucleon wave packets with the final deuteron wave function.
In one approach the nucleon and deuteron center of mass wave packet sizes are
estimated dynamically for each coalescing pair using its past light-cone
history in the underlying cascade, a procedure which yields a parameter free
determination of the cluster yield. A modified version employing a global
estimate of the deuteron formation probability, is identical to a general
implementation of the Wigner function formalism but can differ from the most
frequent realisation of the latter. Comparison is made both with the extensive
existing E802 data for Si+Au at 14.6 GeV/c and with the Wigner formalism. A
globally consistent picture of the Si+Au measurements is achieved. In light of
the deuteron's evident fragility, information obtained from this analysis may
be useful in establishing freeze-out volumes and help in heralding the presence
of high-density phenomena in a baryon-rich environment.Comment: 31 pages REVTeX, 19 figures (4 oversized included as JPEG). For full
postscript figures (LARGE): contact [email protected]
Ab initio molecular dynamics using density based energy functionals: application to ground state geometries of some small clusters
The ground state geometries of some small clusters have been obtained via ab
initio molecular dynamical simulations by employing density based energy
functionals. The approximate kinetic energy functionals that have been employed
are the standard Thomas-Fermi along with the Weizsacker correction
and a combination . It is shown that the functional
involving gives superior charge densities and bondlengths over the
standard functional. Apart from dimers and trimers of Na, Mg, Al, Li, Si,
equilibrium geometries for and clusters have also
been reported. For all the clusters investigated, the method yields the ground
state geometries with the correct symmetries with bondlengths within 5\% when
compared with the corresponding results obtained via full orbital based
Kohn-Sham method. The method is fast and a promising one to study the ground
state geometries of large clusters.Comment: 15 pages, 3 PS figure
Out of Equilibrium Thermal Field Theories - Finite Time after Switching on the Interaction - Wigner Transforms of Projected Functions
We study out of equilibrium thermal field theories with switching on the
interaction occurring at finite time using the Wigner transforms (in relative
space-time) of two-point functions.
For two-point functions we define the concept of projected function: it is
zero if any of times refers to the time before switching on the interaction,
otherwise it depends only on the relative coordinates. This definition includes
bare propagators, one-loop self-energies, etc. For the infinite-average-time
limit of the Wigner transforms of projected functions we define the analyticity
assumptions: (1) The function of energy is analytic above (below) the real
axis. (2) The function goes to zero as the absolute value of energy approaches
infinity in the upper (lower) semiplane.
Without use of the gradient expansion, we obtain the convolution product of
projected functions. We sum the Schwinger-Dyson series in closed form. In the
calculation of the Keldysh component (both, resummed and single self-energy
insertion approximation) contributions appear which are not the Wigner
transforms of projected functions, signaling the limitations of the method.
In the Feynman diagrams there is no explicit energy conservation at vertices,
there is an overall energy-smearing factor taking care of the uncertainty
relations.
The relation between the theories with the Keldysh time path and with the
finite time path enables one to rederive the results, such as the cancellation
of pinching, collinear, and infrared singularities, hard thermal loop
resummation, etc.Comment: 23 pages + 1 figure, Latex, corrected version, improved presentation,
version accepted for publication in Phys. Rev.
Effect of hydrogen on ground state structures of small silicon clusters
We present results for ground state structures of small SiH (2 \leq
\emph{n} \leq 10) clusters using the Car-Parrinello molecular dynamics. In
particular, we focus on how the addition of a hydrogen atom affects the ground
state geometry, total energy and the first excited electronic level gap of an
Si cluster. We discuss the nature of bonding of hydrogen in these
clusters. We find that hydrogen bonds with two silicon atoms only in SiH,
SiH and SiH clusters, while in other clusters (i.e. SiH,
SiH, SiH, SiH, SiH and SiH) hydrogen is bonded
to only one silicon atom. Also in the case of a compact and closed silicon
cluster hydrogen bonds to the cluster from outside. We find that the first
excited electronic level gap of Si and SiH fluctuates as a function
of size and this may provide a first principles basis for the short-range
potential fluctuations in hydrogenated amorphous silicon. Our results show that
the addition of a single hydrogen can cause large changes in the electronic
structure of a silicon cluster, though the geometry is not much affected. Our
calculation of the lowest energy fragmentation products of SiH clusters
shows that hydrogen is easily removed from SiH clusters.Comment: one latex file named script.tex including table and figure caption.
Six postscript figure files. figure_1a.ps and figure_1b.ps are files
representing Fig. 1 in the main tex
Quantum Tunneling in the Wigner Representation
Time dependence for barrier penetration is considered in the phase space. An
asymptotic phase-space propagator for nonrelativistic scattering on a one -
dimensional barrier is constructed. The propagator has a form universal for
various initial state preparations and local potential barriers. It is
manifestly causal and includes time-lag effects and quantum spreading. Specific
features of quantum dynamics which disappear in the standard semi-classical
approximation are revealed. The propagator may be applied to calculation of the
final momentum and coordinate distributions, for particles transmitted through
or reflected from the potential barrier, as well as for elucidating the
tunneling time problem.Comment: 18 pages, LATEX, no figure
Nuclear Clusters as a Probe for Expansion Flow in Heavy Ion Reactions at 10-15AGeV
A phase space coalescence description based on the Wigner-function method for
cluster formation in relativistic nucleus-nucleus collisions is presented. The
momentum distributions of nuclear clusters d,t and He are predicted for central
Au(11.6AGeV)Au and Si(14.6AGeV)Si reactions in the framework of the RQMD
transport approach. Transverse expansion leads to a strong shoulder-arm shape
and different inverse slope parameters in the transverse spectra of nuclear
clusters deviating markedly from thermal distributions. A clear ``bounce-off''
event shape is seen: the averaged transverse flow velocities in the reaction
plane are for clusters larger than for protons. The cluster yields
--particularly at low at midrapidities-- and the in-plane (anti)flow of
clusters and pions change if suitably strong baryon potential interactions are
included. This allows to study the transient pressure at high density via the
event shape analysis of nucleons, nucleon clusters and other hadrons.Comment: 38 pages, 9 figures, LaTeX type, eps used, subm. to Phys. Rev.
Program for expectant and new mothers: a population-based study of participation
<p>Abstract</p> <p>Background</p> <p>The Manitoba Healthy Baby Program is aimed at promoting pre- and perinatal health and includes two components: 1) prenatal income supplement; 2) community support programs. The goal of this research was to determine the uptake of these components by target groups.</p> <p>Methods</p> <p>Data on participation in each of the two program components were linked to data on all hospital births in Manitoba between 2004/05 through 2007/08. Descriptive analyses of participation by maternal characteristics were produced. Logistic regression analyses were conducted to identify factors associated with participation in the two programs. Separate regressions were run for two groups of women giving birth during the study period: 1) total population; 2) those receiving provincial income assistance during the prenatal period.</p> <p>Results</p> <p>Almost 30% of women giving birth in Manitoba received the Healthy Baby prenatal income supplement, whereas only 12.6% participated in any community support programs. Over one quarter (26.4%) of pregnant women on income assistance did not apply for and receive the prenatal income supplement, despite all being eligible for it. Furthermore, 77.8% of women on income assistance did not participate in community support programs. Factors associated with both receipt of the prenatal benefit and participation in community support programs included lower SES, receipt of income assistance, obtaining adequate prenatal care, having completed high school and having depressive symptoms. Having more previous births was associated with higher odds of receiving the prenatal benefit, but lower odds of attending community support programs. Being married was associated with lower odds of receiving the prenatal benefit but higher odds of participating in community support programs.</p> <p>Conclusions</p> <p>Although uptake of the Healthy Baby program in Manitoba is greater for women in groups at risk for poorer perinatal outcomes, a substantial number of women eligible for this program are not receiving it; efforts to reach these women should be enhanced.</p
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