1,777 research outputs found

    The Evolution of Federal Courts’ Healthcare Antitrust Analysis: Does the PPACA Spell the End to Hospital Mergers?

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    Traditionally, hospital mergers were seen as a benefit to consumers. That is no longer the case. After years of nonprofit hospitals engaging in price inflation and misreporting charity care, new hospital mergers will be more heavily scrutinized. Specifically, the United States government has implemented policies that are intended to shrink the relevant market, separate hospital services into individual lines, and require more than a good faith standard for evidence of proposed efficiencies. These policies were created as a response to the findings in antitrust court cases that hospital executives were increasing prices as a monopolist. These cases have worked to discredit previous studies supporting the notion that nonprofit hospitals exhibit a lower association between market share and price. The resurgence of hospital merger cases in the federal courts combined with the PPACA provisions—namely, ACO implementation and redefined charity-care standards—will subject mergers to heightened scrutiny. Some damage has already been done in the hospital merger setting, but it is certain that, going forward, nonprofit hospitals no longer enjoy the same deference as before

    Anode-Coupled Readout for Light Collection in Liquid Argon TPCs

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    This paper will discuss a new method of signal read-out from photon detectors in ultra-large, underground liquid argon time projection chambers. In this design, the signal from the light collection system is coupled via capacitive plates to the TPC wire-planes. This signal is then read out using the same cabling and electronics as the charge information. This greatly benefits light collection: it eliminates the need for an independent readout, substantially reducing cost; It reduces the number of cables in the vapor region of the TPC that can produce impurities; And it cuts down on the number of feed-throughs in the cryostat wall that can cause heat-leaks and potential points of failure. We present experimental results that demonstrate the sensitivity of a LArTPC wire plane to photon detector signals. We also simulate the effect of a 1 μ\mus shaping time and a 2 MHz sampling rate on these signals in the presence of noise, and find that a single photoelectron timing resolution of ∼\sim30 ns can be achieved.Comment: 16 pages, 15 figure

    Improved TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems

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    Scintillation light produced in liquid argon (LAr) must be shifted from 128 nm to visible wavelengths in light detection systems used for liquid argon time-projection chambers (LArTPCs). To date, LArTPC light collection systems have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we report on light guides with improved attenuation lengths above 100 cm when measured in air. This is an important step in the development of meter-scale light guides for future LArTPCs. Improvements come from using a new acrylic-based coating, diamond-polished cast UV transmitting acrylic bars, and a hand-dipping technique to coat the bars. We discuss a model for connecting bar response in air to response in liquid argon and compare this to data taken in liquid argon. The good agreement between the prediction of the model and the measured response in liquid argon demonstrates that characterization in air is sufficient for quality control of bar production. This model can be used in simulations of light guides for future experiments.Comment: 25 pages, 20 figure

    Spin Gap and Resonance at the Nesting Wavevector in Superconducting FeSe0.4Te0.6

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    Neutron scattering is used to probe magnetic excitations in FeSe_{0.4}Te_{0.6} (T_c=14 K). Low energy spin fluctuations are found with a characteristic wave vector (0.5,0.5,L)(0.5,0.5,L) that corresponds to Fermi surface nesting and differs from Q_m=(\delta,0,0.5) for magnetic ordering in Fe_{1+y}Te. A spin resonance with \hbar\Omega_0=6.5 meV \approx 5.3 k_BT_c and \hbar\Gamma=1.25 meV develops in the superconducting state from a normal state continuum. We show that the resonance is consistent with a bound state associated with s+/- superconductivity and imperfect quasi-2D Fermi surface nesting.Comment: 4 pages, 4 figures, Submitted to Phys. Rev. Let

    LINKIN, a new transmembrane protein necessary for cell adhesion

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    In epithelial collective migration, leader and follower cells migrate while maintaining cell-cell adhesion and tissue polarity. We have identified a conserved protein and interactors required for maintaining cell adhesion during a simple collective migration in the developing C. elegans male gonad. LINKIN is a previously uncharacterized, transmembrane protein conserved throughout Metazoa. We identified seven atypical FG-GAP domains in the extracellular domain, which potentially folds into a β-propeller structure resembling the α-integrin ligand-binding domain. C. elegans LNKN-1 localizes to the plasma membrane of all gonadal cells, with apical and lateral bias. We identified the LINKIN interactors RUVBL1, RUVBL2, and α-tubulin by using SILAC mass spectrometry on human HEK 293T cells and testing candidates for lnkn-1-like function in C. elegans male gonad. We propose that LINKIN promotes adhesion between neighboring cells through its extracellular domain and regulates microtubule dynamics through RUVBL proteins at its intracellular domain

    Modelling chemo-hydro-mechanical behaviour of unsaturated clays: a feasibility study

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    Effective capabilities of combined chemo-elasto-plastic and unsaturated soil models to simulate chemohydro-mechanical (CHM) behaviour of clays are examined in numerical simulations through selected boundary value problems. The objective is to investigate the feasibility of approaching such complex material behaviour numerically by combining two existing models. The chemo-mechanical effects are described using the concept of chemical softening consisting of reduction of the pre-consolidation pressure proposed originally by Hueckel (Can. Geotech. J. 1992; 29:1071-1086; Int. J. Numer. Anal. Methods Geomech. 1997; 21:43-72). An additional chemical softening mechanism is considered, consisting in a decrease of cohesion with an increase in contaminant concentration. The influence of partial saturation on the constitutive behaviour is modelled following Barcelona basic model (BBM) formulation (Geotech. 1990; 40(3):405-430; Can. Geotech. J. 1992; 29:1013-1032). The equilibrium equations combined with the CHM constitutive relations, and the governing equations for flow of fluids and contaminant transport, are solved numerically using finite element. The emphasis is laid on understanding the role that the individual chemical effects such as chemo-elastic swelling, or chemo-plastic consolidation, or finally, chemical loss of cohesion have in the overall response of the soil mass. The numerical problems analysed concern the chemical effects in response to wetting of a clay specimen with an organic liquid in rigid wall consolidometer, during biaxial loading up to failure, and in response to fresh water influx during tunnel excavation in swelling clay. Copyright (c) 2005 John WileyQualité et durabilité de la protection des nappes aquifères sous sites d’enfouissement technique avec barrières argileuses d’étanchéit

    Failure of the empirical OCT law in the Bi2Sr2CuO6+d compound

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    We have studied the evolution of the thermoelectric power S(T) with oxygen doping of single-layered Bi2Sr2CuO6+d thin films and ceramics in the overall superconducting (Tc, S290K) phase diagram. While the universal relation between the room-temperature thermopower S290K and the critical temperature is found to hold in the strongly overdoped region (d>0.14), a strong violation is observed in the underdoped part of the phase diagram. The observed behaviour is compared with other cuprates and the different scenarios are discussed.Comment: 7 pages, 5 figure

    Observational evidence of spin-induced precession in active galactic nuclei

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    We show that it is possible to explain the physical origin of jet precession in active galactic nuclei (AGNs) through the misalignment between the rotation axes of the accretion disk and of the Kerr black hole. We apply this scenario to quasars, Seyfert galaxies and also to the Galactic Center black hole Sgr A*, for which signatures of either jet or disk precession have been found. The formalism adopted is parameterized by the ratio of the precession period to the black hole mass and can be used to put constraints to the physical properties of the accretion disk as well as to the black hole spin in those systems.Comment: 10 pages, 1 figure, accepted for publication in ApJ Letter
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