32,858 research outputs found

    Carrier-interference ratios for frequency sharing between frequency-modulated amplitude-modulated-vestigial-sideband television systems

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    For just perceptible interference, an FM television signal interfering with another FM television signal must have an average signal power that is 26 to 37 db less than the wanted signal power. For an AM-VSB television signal interfering with an FM television signal, the AM-VSB television's sync peak average power must be 18 to 31 db below the FM television signal's average power. Also, when an FM television signal interferes with an AM-VSB signal, the average signal power of the FM signal should be 56 to 59 db below the sync peak average power of the AM-VSB television signal. The range of power ratios occur as a result of different TV scenes used in the tests and different FM-signal frequency deviations used. All tests were performed using 525 line, system M, color-television signals

    Current-spin coupling for ferromagnetic domain walls in fine wires

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    The coupling between a current and a domain wall is examined. In the presence of a finite current and the absence of a potential which breaks the translational symmetry, there is a perfect transfer of angular momentum from the conduction electrons to the wall. As a result, the ground state is in uniform motion. This remains the case when relaxation is accounted for. This is described by, appropriately modified, Landau-Lifshitz-Gilbert equations.Comment: 4 pqges, no figure

    Charmonium-Nucleon Dissociation Cross Sections in the Quark Model

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    Charmonium dissociation cross sections due to flavor-exchange charmonium-baryon scattering are computed in the constituent quark model. We present results for inelastic J/ψNJ/\psi N and ηcN\eta_c N scattering amplitudes and cross sections into 46 final channels, including final states composed of various combinations of DD, DD^*, Σc\Sigma_c, and Λc\Lambda_c. These results are relevant to experimental searches for the deconfined phase of quark matter, and may be useful in identifying the contribution of initial ccˉc\bar c production to the open-charm final states observed at RHIC through the characteristic flavor ratios of certain channels. These results are also of interest to possible charmonium-nucleon bound states.Comment: 10 pages, 5 eps figures, revte

    Bi-layer splitting in overdoped high TcT_{c} cuprates

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    Recent angle-resolved photoemission data for overdoped Bi2212 are explained. Of the peak-dip-hump structure, the peak corresponds the q=0\vec q =0 component of a hole condensate which appears at TcT_c. The fluctuating part of this same condensate produces the hump. The bilayer splitting is large enough to produce a bonding hole and an electron antibonding quasiparticle Fermi surface. Smaller bilayer splittings observed in some experiments reflect the interaction of the peak structure with quasiparticle states near, but not at, the Fermi surface.Comment: 4 pages with 2 figures - published versio

    The use of ICT in the assessment of modern languages: the English context and European viewpoints

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    The ever increasing explosion of highly attractive multimedia resources on offer has boosted the use of information and communication technology (ICT) in the teaching and learning of modern languages. The use of ICT to assess languages is less frequent, however, although online testing is starting to develop. This paper examines the national context for the assessment of modern foreign language proficiency in England, outlines the kinds of assessment currently available and the development of electronic forms of assessment and compares the above with the survey results of a European Union (EU) funded project on current good practice in online assessment of languages in other European countries. The findings indicate that speaking is inadequately served by online testing as tests currently focus primarily on receptive language skills. The implications for future successful online testing include the incorporation of interactive skills and effective formative feedback
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