6,154 research outputs found

    Composite pairing in a mixed valent two channel Anderson model

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    Using a two-channel Anderson model, we develop a theory of composite pairing in the 115 family of heavy fermion superconductors that incorporates the effects of f-electron valence fluctuations. Our calculations introduce "symplectic Hubbard operators": an extension of the slave boson Hubbard operators that preserves both spin rotation and time-reversal symmetry in a large N expansion, permitting a unified treatment of anisotropic singlet pairing and valence fluctuations. We find that the development of composite pairing in the presence of valence fluctuations manifests itself as a phase-coherent mixing of the empty and doubly occupied configurations of the mixed valent ion. This effect redistributes the f-electron charge within the unit cell. Our theory predicts a sharp superconducting shift in the nuclear quadrupole resonance frequency associated with this redistribution. We calculate the magnitude and sign of the predicted shift expected in CeCoIn_5.Comment: 13 pages, 5 figure

    Remarkably robust and correlated coherence and antiferromagnetism in (Ce1x_{1-x}Lax_x)Cu2_2Ge2_2

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    We present magnetic susceptibility, resistivity, specific heat, and thermoelectric power measurements on (Ce1x_{1-x}Lax_x)Cu2_2Ge2_2 single crystals (0 x\leq x\leq 1). With La substitution, the antiferromagnetic temperature TNT_N is suppressed in an almost linear fashion and moves below 0.36 K, the base temperature of our measurements for x>x> 0.8. Surprisingly, in addition to robust antiferromagnetism, the system also shows low temperature coherent scattering below TcohT_{coh} up to \sim 0.9 of La, indicating a small percolation limit \sim 9%\% of Ce that separates a coherent regime from a single-ion Kondo impurity regime. TcohT_{coh} as a function of magnetic field was found to have different behavior for xx 0.9. Remarkably, (Tcoh)2(T_{coh})^2 at HH = 0 was found to be linearly proportional to TNT_N. The jump in the magnetic specific heat δCm\delta C_{m} at TNT_N as a function of TK/TNT_K/T_N for (Ce1x_{1-x}Lax_x)Cu2_2Ge2_2 follows the theoretical prediction based on the molecular field calculation for the SS = 1/2 resonant level model

    Nominal Income Targeting with the Monetary Base as Instrument: An Evaluation of McCallum\u27s Rule

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    In this paper, we explore McCallum\u27s monetary base instrument rule in the context of several models. The first section uses two models, previously utilized by McCallum, to demonstrate the general properties of his rule and to update through 1992 the empirical support for the rule. The second section uses models that allow a significant role for interest rates in transmitting the effects of changes in the monetary base to aggregate demand. The analysis in these two sections makes two main points: (1) Shifts. or instabilities, in the structural relationship between the base and nominal GNP in the 1980s and 1990s raise questions about the efficacy of the proposed rule; and (2) The ability of McCallum\u27s base instrument rule to control nominal output depends on the response pattern of the target variable, nominal output, to changes in the base. In the sequence of models presented, we lay out these dynamic linkages in successively more detail and examine their ·implications for nominal income targeting

    "It's not an Obvious Issue is it?" Office-Based Employees' Perceptions of Prolonged Sitting at Work: A Qualitative Study.

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    OBJECTIVE: Current UK workplace health promotion guidance recommends that employers minimize sedentary behaviors, but understanding the issues relating to prolonged workplace sitting has received little empirical attention. This study aimed to explore employees' perceptions of sitting time. METHODS: Participants at a small to medium-sized UK company were invited to join one of five focus groups. A framework analysis approach was used. RESULTS: Self-reported mean estimate of occupational sitting time was 6.4 hours/day with a mean estimate of leisure time sitting 6.5 hours/nonwork days. The study highlighted employees' lack of appreciation of the health risks associated with sedentary behavior. CONCLUSION: This study has highlighted that in addition to personal determinants, the workplace environment and organizational culture have a key role in supporting employees' potential adoption of healthier sitting behavior in the workplace

    Quantum mechanics and geodesic deviation in the brane world

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    We investigate the induced geodesic deviation equations in the brane world models, in which all the matter forces except gravity are confined on the 3-brane. Also, the Newtonian limit of induced geodesic deviation equation is studied. We show that in the first Randall-Sundrum model the Bohr-Sommerfeld quantization rule is as a result of consistency between the geodesic and geodesic deviation equations. This indicates that the path of test particle is made up of integral multiples of a fundamental Compton-type unit of length h/mch/mc.Comment: 5 pages, no figure

    Notorious places: image, reputation, stigma: the role of newspapers in area reputations for social housing estates

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    This paper reviews work in several disciplines to distinguish between image, reputation and stigma. It also shows that there has been little research on the process by which area reputations are established and sustained through transmission processes. This paper reports on research into the portrayal of two social housing estates in the printed media over an extended period of time (14 years). It was found that negative and mixed coverage of the estates dominated, with the amount of positive coverage being very small. By examining the way in which dominant themes were used by newspapers in respect of each estate, questions are raised about the mode of operation of the press and the communities' collective right to challenge this. By identifying the way regeneration stories are covered and the nature of the content of positive stories, lessons are drawn for programmes of area transformation. The need for social regeneration activities is identified as an important ingredient for changing deprived-area reputations

    Polysaccharide utilization loci and nutritional specialization in a dominant group of butyrate-producing human colonic Firmicutes

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    Acknowledgements The Rowett Institute of Nutrition and Health (University of Aberdeen) receives financial support from the Scottish Government Rural and Environmental Sciences and Analytical Services (RESAS). POS is a PhD student supported by the Scottish Government (RESAS) and the Science Foundation Ireland, through a centre award to the APC Microbiome Institute, Cork, Ireland. Data Summary The high-quality draft genomes generated in this work were deposited at the European Nucleotide Archive under the following accession numbers: 1. Eubacterium rectale T1-815; CVRQ01000001–CVRQ0100 0090: http://www.ebi.ac.uk/ena/data/view/PRJEB9320 2. Roseburia faecis M72/1; CVRR01000001–CVRR010001 01: http://www.ebi.ac.uk/ena/data/view/PRJEB9321 3. Roseburia inulinivorans L1-83; CVRS01000001–CVRS0 100 0151: http://www.ebi.ac.uk/ena/data/view/PRJEB9322Peer reviewedPublisher PD
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