181 resultados para Thomson, David, 1914-1988


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A Thomson scattering system has been installed at the Tokyo electron beam ion trap for probing characteristics of the electron beam. A YVO4 green laser beam was injected antiparallel to the electron beam. The image of the Thomson scattering light from the electron beam has been observed using a charged-coupled device camera. By using a combination of interference filters, the spectral distribution of the Thomson scattering light has been measured. The Doppler shift observed for the scattered light is consistent with the beam energy. The beam radius dependence was investigated as a function of the beam energy, the beam current, and the magnetic field at the trap region. The variation of the measured beam radius against the beam current and the magnetic field were similar to those in Herrmann's prediction. The beam radius as a function of the beam energy was also similar to Herrmann's prediction but seemed to become larger at low energy. (C) 2002 American Institute of Physics.

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Historians of Ireland have devoted considerable attention to the Presbyterian origins of modern Irish republicanism in the 1790s and their overwhelming support for the Union with Great Britain in the 1880s. On the one hand, it has been argued that conservative politics came to dominate nineteenth-century Presbyterianism in the form of Henry Cooke who combined conservative evangelical religion with support for the established order. On the other hand, historians have long acknowledged the continued importance of liberal and radical impulses amongst Presbyterians. Few historians of the nineteenth century have attempted to bring these two stories together and to describe the relationship between the religion and politics of Presbyterians along the lines suggested by scholars of Presbyterian radicalism in the last quarter of the eighteenth century. This article argues that a distinctive form of Presbyterian evangelicalism developed in the nineteenth century that sought to bring the denomination back to the theological and spiritual priorities of seventeenth-century Scottish and Irish Presbyterianism. By doing so, it encouraged many Presbyterians to get involved in movements for reform and liberal politics. Supporters of ‘Covenanter Politics’ utilised their denominational principles and traditions as the basis for political involvement and as a rhetoric of opposition to Anglican privilege and Catholic tyranny. These could be the prime cause of Presbyterian opposition to the infringement of their rights, such as the marriage controversy and the Disruption of the Church of Scotland in the early 1840s, and they could also be employed as a language of opposition in response to broader social and political developments, such as the demands for land reform stimulated by the agricultural depression that accompanied the Famine. Despite their opposition to ascendancy, however, the Covenanter Politics of Presbyterian Liberals predisposed them towards pan-protestant unionism against the threat of ‘Rome Rule’.

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We have carried out an optical Thomson scatter study of a KrF laser-ablated Mg plume. The evolution of the electron temperature and density at distances 2-5 mm from the target surface has been studied. We have observed that the electron density falls more rapidly than the atomic density and believe that this is a result of rapid dielectronic recombination. A comparison of the electron density profile and evolution with simple hydrodynamic modeling indicates that there is a strong absorption of the laser in the plasma vapor above the target, probably due to photoionization. We also conclude that an isothermal model of expansion better fits the data than an isentropic expansion model. Finally, we compared data obtained from Thomson scatter with those obtained by emission spectroscopy under similar conditions. The two sets of data have differences but are broadly consistent.

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Review essay on David Vann's Caribou Island

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