12,846 research outputs found

    Medicaid 1915(c) home and community-based services waivers across the states.

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    This article provides State-level data on the Medicaid 1915(c) home and community-based services (HCBS) waivers program. Medicaid 1915(c) waiver participants were 32 percent of the Medicaid participants in institutional care in 1997. These data document wide interstate variation in organizational oversight and program policies for the waivers. Many structural barriers to HCBS waiver growth existed. Case management services, in some form, were normative for most HCBS waiver participants, but formal mechanisms to assess client satisfaction and service quality were less common. Substantial new growth in this program may require fundamental changes in HCBS waiver policies

    Studies of the nucler equation of state using numerical calculations of nuclear drop collisions

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    A numerical calculation for the full thermal dynamics of colliding nuclei was developed. Preliminary results are reported for the thermal fluid dynamics in such processes as Coulomb scattering, fusion, fusion-fission, bulk oscillations, compression with heating, and collisions of heated nuclei

    Evaluation of thallium-201 scanning for detection of latent coronary artery disease

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    The use of thallium imaging as a noninvasive method to accurately screen shuttle passengers for latent coronary artery disease was investigated. All radionuclide procedures were performed using an Anger type camera with a high resolution collimator. A minimum of 200,000 counts were collected for each image using a 20% window centered on the 69-83 keV X-rays. For the images obtained following injection with the patient at rest, the testing was begun 10 minutes after injection. Injections of TT during exercise were made at a point near the termination of the treadmill procedure as determined by either the appearance of ST segment changes on the electrocardiogram consistant with subendocardial ischemia, the appearance of angina-like chest pain in the patient or fatigue in the patient which required cessation of the test. The severity of heart disease was based on the medical history, physical exam, exercise electrocardiograms, chest X-rays and the coronary arteriogram

    Explaining Actual Causation via Reasoning About Actions and Change

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    In causality, an actual cause is often defined as an event responsible for bringing about a given outcome in a scenario. In practice, however, identifying this event alone is not always sufficient to provide a satisfactory explanation of how the outcome came to be. In this paper, we motivate this claim using well-known examples and present a novel framework for reasoning more deeply about actual causation. The framework reasons over a scenario and domain knowledge to identify additional events that helped to "set the stage" for the outcome. By leveraging techniques from Reasoning about Actions and Change, the approach supports reasoning over domains in which the evolution of the state of the world over time plays a critical role and enables one to identify and explain the circumstances that led to an outcome of interest. We utilize action language AL for defining the constructs of the framework. This language lends itself quite naturally to an automated translation to Answer Set Programming, using which, reasoning tasks of considerable complexity can be specified and executed. We speculate that a similar approach can also lead to the development of algorithms for our framework

    Impact of Electron-Phonon Coupling on Near-Field Optical Spectra

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    The finite momentum transfer (q\boldsymbol{q}) longitudinal optical response σL(q,ω)\sigma^L(\boldsymbol{q},\omega) of graphene has a peak at an energy ω=vFq\omega=\hbar v_F q. This corresponds directly to a quasiparticle peak in the spectral density at momentum relative to the Fermi momentum kFqk_F -q. Inclusion of coupling to a phonon mode at ωE\omega_E results, for ω<ωE\omega<|\omega_E|, in a constant electron-phonon renormalization of the bare bands by a mass enhancement factor (1+λ)(1+\lambda) and this is followed by a phonon kink at ωE\omega_E where additional broadening begins. Here we study the corresponding changes in the optical quasiparticle peaks which we find to continue to directly track the renormalized quasiparticle energies until qq is large enough that the optical transitions begin to sample the phonon kink region of the dispersion curves where linearity in momentum is lost in the renormalized Dirac Fermion dispersion curves and the correspondence to a single quasiparticle energy is lost. Nevertheless there remains in σL(q,ω)\sigma^L(\boldsymbol{q},\omega) features analogous to the phonon kinks of the dispersion curves which are observable through variation of qq and ω\omega.Comment: 6 pages, 5 figure

    Atomic microwave-to-optical signal transduction via magnetic-field coupling in a resonant microwave cavity

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    Atomic vapors offer many opportunities for manipulating electromagnetic signals across a broad range of the electromagnetic spectrum. Here, a microwave signal with an audio-frequency modulation encodes information in an optical signal by exploiting an atomic microwave-to-optical double resonance, and magnetic-field coupling that is amplified by a resonant high-Q microwave cavity. Using this approach, audio signals are encoded as amplitude or frequency modulations in a GHz carrier, transmitted through a cable or over free space, demodulated through cavity-enhanced atom-microwave interactions, and finally, optically detected to extract the original information. This atom-cavity signal transduction technique provides a powerful means by which to transfer information between microwave and optical fields, all using a relatively simple experimental setup without active electronics

    Gauge matters: Observing the vortex-nucleation transition in a Bose condensate

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    The order parameter of a quantum-coherent many-body system can include a phase degree of freedom, which, in the presence of an electromagnetic field, depends on the choice of gauge. Because of the relationship between the phase gradient and the velocity, time-of-flight measurements reveal this gradient. Here, we make such measurements using initially trapped Bose-Einstein condensates (BECs) subject to an artificial magnetic field. Vortices are nucleated in the BEC for artificial field strengths above a critical value, which represents a structural phase transition. By comparing to superfluid-hydrodynamic and Gross-Pitaevskii calculations, we confirmed that the transition from the vortex-free state gives rise to a shear in the released BEC's spatial distribution, representing a macroscopic method to measure this transition, distinct from direct measurements of vortex entry. Shear is also affected by an artificial electric field accompanying the artificial magnetic field turn-off, which depends on the details of the physical mechanism creating the artificial fields, and implies a natural choice of gauge. Measurements of this kind offer opportunities for studying phase in less-well-understood quantum gas systems.Comment: 5 pages, 4 figures + 2 pages supplementary dat

    Effect of magnetic field on the phase transition in a dusty plasma

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    The formation of self-consistent crystalline structure is a well-known phenomenon in complex plasmas. In most experiments the pressure and rf power are the main controlling parameters in determining the phase of the system. We have studied the effect of externally applied magnetic field on the configuration of plasma crystals, suspended in the sheath of a radio-frequency discharge using the Magnetized Dusty Plasma Experiment (MDPX) device. Experiments are performed at a fixed pressure and rf power where a crystalline structure is formed within a confining ring. The magnetic field is then increased from 0 to 1.28 T. We report on the breakdown of the crystalline structure with increasing magnetic field. The magnetic field affects the dynamics of the plasma particles and first leads to a rotation of the crystal. At higher magnetic field, there is a radial variation (shear) in the angular velocity of the moving particles which we believe leads to the melting of the crystal. This melting is confirmed by evaluating the variation of the pair correlation function as a function of magnetic field.Comment: 9 pages, 5 figure
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