27,191 research outputs found

    The great divide: regional differences in education and training

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    While regional disparities in the overall rate of participation in further education and training among young people are relatively small, marked differences persist in the pattern of investment across the regions. The proportion of young people continuing in full-time further education in the northern regions continues to lag far behind that in the south. This paper analyses the sources of this 'north-south' divide and the role played by differences in the educational and socio-economic composition of the regions. The results indicate that differences in schooling and levels of educational attainment play a modest role in determining such regional disparities. Further, eliminating all compositional differences across the regions - not only in terms of educational attainment, but also social and ethnic background and local labour market factors - would leave a significant north-south gap in participation in further education. These results point to continuing differences in underlying attitudes to further education and training, and these appear to be particularly marked among young women.

    Ethics and geographical equity in health care

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    Important variations in access to health care and health outcomes are associated with geography, giving rise to profound ethical concerns. This paper discusses the consequences of such concerns for the allocation of health care finance to geographical regions. Specifically, it examines the ethical drivers underlying capitation systems, which have become the principal method of allocating health care finance to regions in most countries. Although most capitation systems are based on empirical models of health care expenditure, there is much debate about which needs factors to include in (or exclude from) such models. This concern with legitimate and illegitimate drivers of health care expenditure reflects the ethical concerns underlying the geographical distribution of health care finance

    Viruses disrupt functions of human lymphocytes. Effects of measles virus and influenza virus on lymphocyte-mediated killing and antibody production.

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    We present experimental data that offer, in part, a better understanding of the immunosuppression that accompanies measles virus infection. We note that measles virus "silently" infects human lymphocytes and that the infection does not alter lymphocyte survival in vitro. Yet such infected lymphocytes fail to generate natural killer (NK) cell activity or synthesize immunoglobulins (Ig). Thus, the presence of virus within lymphocytes impairs their specific immune functions in the absence of cytolysis. Influenza virus also infects human lymphocytes. In contrast to measles virus infection of resting lymphocytes in which viral antigen is rarely expressed, influenza virus infection of these cells yields viral antigens expressed in the cytoplasm and on the cell surface. Influenza virus-infected lymphocytes have normal NK cell activity but fail to synthesize IgG or IgM

    Enhanced Spontaneous Emission Into The Mode Of A Cavity QED System

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    We study the light generated by spontaneous emission into a mode of a cavity QED system under weak excitation of the orthogonally polarized mode. Operating in the intermediate regime of cavity QED with comparable coherent and decoherent coupling constants, we find an enhancement of the emission into the undriven cavity mode by more than a factor of 18.5 over that expected by the solid angle subtended by the mode. A model that incorporates three atomic levels and two polarization modes quantitatively explains the observations.Comment: 9 pages, 2 figures, to appear in May 2007 Optics Letter

    Engineering an all-optical route to ultracold molecules in their vibronic ground state

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    We propose an improved photoassociation scheme to produce ultracold molecules in their vibronic ground state for the generic case where non-adiabatic effects facilitating transfer to deeply bound levels are absent. Formation of molecules is achieved by short laser pulses in a Raman-like pump-dump process where an additional near-infrared laser field couples the excited state to an auxiliary state. The coupling due to the additional field effectively changes the shape of the excited state potential and allows for efficient population transfer to low-lying vibrational levels of the electronic ground state. Repetition of many pump-dump sequences together with collisional relaxation allows for accumulation of molecules in v=0.Comment: Phys. Rev. A, in pres

    Study of different membrane spargers used in waste water treatment : characterisation and performance

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    In urban waste water treatment, a novel gas sparger based on flexible rubber membrane has been used for the last ten years. The objective of this present work is to compare two flexible membranes (the new membrane and the old membrane provided by ONDEO-DEGREMONT group) used in waste water treatment. For this purpose, the different membrane properties (hole diameter, pressure drop, critical pressure, deflection at the centerline and elasticity) have been characterized. The bubble generation at the membranes with a single orifice and with four orifices have been studied and their performances have been compared in terms of interfacial area and power consumption. From the experimental and theoretical approach, the new membrane is less elastic (or more rigid) than the old membrane. The bubble diameters generated from the new membrane remain constant with the gas velocity through the orifice, whereas they increase logarithmically for the old membrane. The inverse behaviours are observed in terms of the bubble formation frequency. Moreover, the bubbles generated from the new membrane have significantly larger sizes and lower formation frequencies than those obtained with the old one. From these results, it can be noted that the new membrane has a behaviour comparable to a rigid orifice. No coalescence phenomenon at the bubble formation is observed from the new and the old membranes with four orifices. The interfacial area and the power consumption are evaluated and show slight differences between the interfacial area provided by the old and the new membranes for one value of power consumption

    Landau-Fermi liquid analysis of the 2D t-t' Hubbard model

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    We calculate the Landau interaction function f(k,k') for the two-dimensional t-t' Hubbard model on the square lattice using second and higher order perturbation theory. Within the Landau-Fermi liquid framework we discuss the behavior of spin and charge susceptibilities as function of the onsite interaction and band filling. In particular we analyze the role of elastic umklapp processes as driving force for the anisotropic reduction of the compressibility on parts of the Fermi surface.Comment: 10 pages, 16 figure

    Spectral properties of the planar t-J model

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    The single-particle spectral functions A(k,ω)A({\bf k},\omega) and self-energies Σ(k,ω)\Sigma({\bf k},\omega) are calculated within the tJt-J model using the finite-temperature Lanczos method for small systems. A remarkable asymmetry between the electron and hole part is found. The hole (photoemission) spectra are overdamped, with ImΣω{\rm Im} \Sigma \propto \omega in a wide energy range, consistent with the marginal Fermi liquid scenario, and in good agreement with experiments on cuprates. In contrast, the quasiparticles in the electron part of the spectrum show weak damping.Comment: 4 pages, RevTeX, 4 Postscript figure

    Development of a thermal storage module using modified anhydrous sodium hydroxide

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    The laboratory scale testing of a modified anhydrous NaOH latent heat storage concept for small solar thermal power systems such as total energy systems utilizing organic Rankine systems is discussed. A diagnostic test on the thermal energy storage module and an investigation of alternative heat transfer fluids and heat exchange concepts are specifically addressed. A previously developed computer simulation model is modified to predict the performance of the module in a solar total energy system environment. In addition, the computer model is expanded to investigate parametrically the incorporation of a second heat exchange inside the module which will vaporize and superheat the Rankine cycle power fluid
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