17,001 research outputs found
Enrollee Mix, Treatment Intensity, and Cost in Competing Indemnity and HMO Plans
We examine why managed care plans are less expensive than traditional indemnity insurance plans. Our database consists of the insurance experiences of over 200,000 state and local employees in Massachusetts and their families, who are insured in a single pool. Within this group, average HMO costs are 40 percent below those of the indemnity plan. We evaluate cost differences for 8 conditions representing over 10 percent of total health expenditures. They are: heart attacks, cancers (breast, cervical, colon, prostate), diabetes (type I and II), and live births. For each condition, we identify the portions of the cost differential arising from differences in treatment intensity, enrollee mix, and prices paid for the same treatment. Surprisingly, treatment intensity differs hardly at all between the HMOs and the indemnity plan. That is, relative to their fee-for-service competitor, HMOs do not curb the use of expensive treatments. Across the 8 conditions, roughly half of the HMO cost savings is due to the lower incidence of the diseases in the HMOs. Virtually all of the remaining savings come because HMOs pay lower prices for the same treatment.
Quench dynamics and non equilibrium phase diagram of the Bose-Hubbard model
We investigate the time evolution of correlations in the Bose-Hubbard model
following a quench from the superfluid to the Mott insulating phase. For large
values of the final interaction strength the system approaches a distinctly
non-equilibrium steady state that bears strong memory of the initial
conditions. In contrast, when the final interaction strength is comparable to
the hopping, the correlations are rather well approximated by those at thermal
equilibrium. The existence of two distinct non-equilibrium regimes is
surprising given the non-integrability of the Bose-Hubbard model. We relate
this phenomena to the role of quasi-particle interactions in the Mott
insulating state
Dynamical instability of a spin spiral in an interacting Fermi gas as a probe of the Stoner transition
We propose an experiment to probe ferromagnetic phenomena in an ultracold
Fermi gas, while alleviating the sensitivity to three-body loss and competing
many-body instabilities. The system is initialized in a small pitch spin
spiral, which becomes unstable in the presence of repulsive interactions. To
linear order the exponentially growing collective modes exhibit critical
slowing down close to the Stoner transition point. Also, to this order, the
dynamics are identical on the paramagnetic and ferromagnetic sides of the
transition. However, we show that scattering off the exponentially growing
modes qualitatively alters the collective mode structure. The critical slowing
down is eliminated and in its place a new unstable branch develops at large
wave vectors. Furthermore, long-wavelength instabilities are quenched on the
paramagnetic side of the transition. We study the experimental observation of
the instabilities, specifically addressing the trapping geometry and how
phase-contrast imaging will reveal the emerging domain structure. These probes
of the dynamical phenomena could allow experiments to detect the transition
point and distinguish between the paramagnetic and ferromagnetic regimes
Household food security status in South Africa
The Human Sciences Research Council has established a policy research initiative to monitor household food security and to identify and evaluate policy options. In this special edition, a selection of articles from this project is assembled. While deep chronic hunger has fallen with the expansion of the social grants, under-nutrition is a very serious and widespread challenge. This special edition draws together the best available evidence on household food security with the aim of stimulating wider debate.food security, social grants, smallholder and subsistence production, poverty, Consumer/Household Economics,
Decay of superfluid currents in a moving system of strongly interacting bosons
We analyze the stability and decay of supercurrents of strongly interacting bosons on optical lattices. At the mean-field level, the system undergoes an irreversible dynamic phase transition, whereby the current decays beyond a critical phase gradient that depends on the interaction strength. At commensurate filling the transition line smoothly interpolates between the classical modulational instability of weakly interacting bosons and the equilibrium Mott transition at zero current. Below the mean-field instability, the current can decay due to quantum and thermal phase slips. We derive asymptotic expressions of the decay rate near the critical current. In a three-dimensional optical lattice this leads to very weak broadening of the transition. In one and two dimensions the broadening leads to significant current decay well below the mean-field critical current. We show that the temperature scale below which quantum phase slips dominate the decay of supercurrents is easily within experimental reach.Accepted manuscrip
The Status of Disability Studies in SDS and its Impact on Disability Policy
Produced by The Center on Disability Studies, University of Hawai'i at Manoa, Honolulu, Hawai'i, The Frank Sawyer School of Management, Suffolk University, Boston, Massachusetts and The School of Social Sciences, The University of Texas at Dallas, for the Society for Disability Studies
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