775 research outputs found

    The Morality of Moral Education

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    The Background - Moral Education as the Traditional Source of Personal Development. One of the abiding interests of moral philosophy is how some measure of competence at existence can not only be attained, but attained to an excellent degree. The idea that man is born imperfect but may so order his life that he approaches a more complete state of perfection has been echoed in the words and deeds of men through the ages. It is reflected in our willingness to revere those men and women who in their lives neared the condition of existential entelechy. Throughout the ages, for instance, humankind has sought out heroes and martyrs who by virtue of their superior conduct and more impressive virtues have become the models upon which lesser men and women model their own lives

    Lymphocyte reactivity in patients with carcinoma of the breast and large bowel.

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    The reactivity of lymphocytes from patients with either carcinoma of the breast or large bowel has been studied using the human to mouse normal lymphocyte transfer (NLT) reaction. It was found that, in the case of breast cancer, there was a direct correlation between the clinical stage and a reduced NLT reaction. Only patients with regional lymph node or generalized metastases showed significantly reduced lymphocyte reactivity. However, in the case of large bowel cancer there was a generalized reduction in NLT reactivity which was independent of the clinical stage. Incubation of lymphocytes from individuals without neoplastic disease in serum or plasma from breast cancer patients, showing reduced NLT reactivity, resulted in a reduced NLT reaction. This appears to be indicative of the presence of circulating "blocking factor" in such patients

    Laser-wakefield accelerators as hard x-ray sources for 3D medical imaging of human bone

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    A bright μm-sized source of hard synchrotron x-rays (critical energy Ecrit > 30 keV) based on the betatron oscillations of laser wakefield accelerated electrons has been developed. The potential of this source for medical imaging was demonstrated by performing micro-computed tomography of a human femoral trabecular bone sample, allowing full 3D reconstruction to a resolution below 50 μm. The use of a 1 cm long wakefield accelerator means that the length of the beamline (excluding the laser) is dominated by the x-ray imaging distances rather than the electron acceleration distances. The source possesses high peak brightness, which allows each image to be recorded with a single exposure and reduces the time required for a full tomographic scan. These properties make this an interesting laboratory source for many tomographic imaging applications

    Bright X-ray radiation from plasma bubbles in an evolving laser wakefield accelerator

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    We show that the properties of the electron beam and bright x-rays produced by a laser wakefield accelerator can be predicted if the distance over which the laser self-focuses and compresses prior to self-injection is taken into account. A model based on oscillations of the beam inside a plasma bubble shows that performance is optimised when the plasma length is matched to the laser depletion length. With a 200~TW laser pulse this results in an x-ray beam with median photon energy of \unit[20]{keV}, >6×108> 6\times 10^{8} photons above \unit[1]{keV} per shot and a peak brightness of \unit[3 \times 10^{22}]{photons~s^{-1}mrad^{-2}mm^{-2} (0.1\% BW)^{-1}}.Comment: 5 pages, 4 figure

    Ultra-high brilliance multi-MeV γ\gamma-ray beam from non-linear Thomson scattering

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    We report on the generation of a narrow divergence (θ≈2.5\theta\approx 2.5 mrad), multi-MeV (EMAX=18E_\text{MAX} = 18 MeV) and ultra-high brilliance (≈2×1019\approx 2\times10^{19} photons s−1^{-1} mm−2^{-2} mrad −2^{-2} 0.1\% BW) γ\gamma-ray beam from the scattering of an ultra-relativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude a0≈2a_0\approx2). The spectrum of the generated γ\gamma-ray beam is measured, with MeV resolution, seamlessly from 6 MeV to 18 MeV, giving clear evidence of the onset of non-linear Thomson scattering. The photon source has the highest brilliance in the multi-MeV regime ever reported in the literature

    X-Ray Generation from Metal Targets Coated with Wavelength-Scale Spheres

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    X-ray yield measurements from targets coated with wavelength-scale spheres are compared with measurements from polished targets. Evidence for a hotter resonant electron temperature due to field enhancements from Mie resonances in the spheres is investigated
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