13,351 research outputs found

    Maverick Examples Of Coset Conformal Field Theories

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    We present coset conformal field theories whose spectrum is not determined by the identification current method. In these ``maverick'' cosets there is a larger symmetry identifying primary fields than under the identification current. We find an A-D-E classification of these mavericks. }Comment: 16pages , reportSWAT-93-0

    A renormalisation-group treatment of two-body scattering

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    Nonrelativistic two-body scattering by a short-ranged potential is studied using the renormalisation group. Two fixed points are identified: a trivial one and one describing systems with a bound state at zero energy. The eigenvalues of the linearised renormalisation group are used to assign a systematic power-counting to terms in the potential near each of these fixed points. The expansion around the nontrivial fixed point is shown to be equivalent to the effective-range expansion.Comment: 6 pages (RevTeX), 1 figure (epsf); picture of RG flow and more discussion of momentum dependence adde

    Anatomical Studies of Cca Penetration Associated With Conventional (Tooth) and With Micro (Needle) Incising

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    Individual tooth and needle incisions were made on radial and tangential surfaces of white spruce and jack pine heartwood test samples. The samples were pressure-treated with CCA preservative and then dissected in various planes to examine patterns of preservative penetration. Lateral movement of preservative from incisions was generally greater in the radial than in the tangential direction (average R/T ratio about 1.5). Longitudinal movement was in the range of 15 to 20 times that of lateral movement. Ray tissue facilitates movement in the radial plane, but difficulty is encountered in traversing latewood bands. An individual tooth incision resulted in a larger zone of treated wood but also in a greater amount of wood tissue damage than a needle incision. When compared as ratios of treated wood area to damaged wood area at a depth of 9 mm beneath the original treated surface, needle incisions were decidedly superior. For an equivalent degree of preservative treatment, conventional incising teeth damaged about ten times the amount of wood tissue as did incising needles

    Saturated gain spectrum of VECSELs determined by transient measurement of lasing onset

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    We describe time-resolved measurements of the evolution of the spectrum of radiation emitted by an optically-pumped continuous-wave InGaAs-GaAs quantum well laser, recorded as lasing builds up from noise to steady state. We extract a fitting parameter corresponding to the gain dispersion of the parabolic spectrum equal to ?79 ± 30 fs2 and ?36 ± 6 fs2 for a resonant and anti-resonant structure, respectively. Furthermore the recorded evolution of the spectrum allows for the calculation of an effective FWHM gain bandwidth for each structure, of 11 nm and 18 nm, respectively

    Variations of electrophotoluminescence phenomena with frequency of applied field

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    Luminescence is a general term which includes the many phenomena involving the absorption of energy by a substance and its re=emission as visible or near visible radiation. Photoluminescence implies excitation 7 by irradiation with electromagnetic radiation; cathodoluminescence implies excitation by electron bombardment; thermoluminescence or glow refers to additional excitation by heat of a phosphor previously irradiated at a low temperature; and electroluminescence implies excitation by an electric field. The most recently observed phenomena, and the subjects of this investigation are those included in the general term electrophotoluminescence which refers to the effect of an electric field on photoluminescence. Luminescence includes both fluorescence and phosphorescence. Fluoresgence refers-to the emission observed either during excitation or within 10^-8 sec after excitation has ceased. Phosphorescence refers to any omission observed later than 10^-8 sec after excitation has ceased. Most substances are not luminescent but dissipate absorbed energy in heat. A few substances dissipate absorbed energy in photoelectrons, or in other forms. This discussion will be concerned exclusively with that class of crystalline inorganic solids which exhibit phosphorescence due to controlled traces of impurity. These solids are known as phosphors

    Measurements at low energies of the polarization-transfer coefficient Kyy' for the reaction 3H(p,n)3He at 0 degrees

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    Measurements of the transverse polarization coefficient Kyy' for the reaction 3H(p,n)3He are reported for outgoing neutron energies of 1.94, 5.21, and 5.81 MeV. This reaction is important both as a source of polarized neutrons for nuclear physics experiments, and as a test of theoretical descriptions of the nuclear four-body system. Comparison is made to previous measurements, confirming the 3H(p,n)3He reaction can be used as a polarized neutron source with the polarization known to an accuracy of approximately 5%. Comparison to R-matrix theory suggests that the sign of the 3F3 phase-shift parameter is incorrect. Changing the sign of this parameter dramatically improves the agreement between theory and experiment.Comment: 12 pages, RevTeX, 5 eps figures, submitted to Phys. Rev.

    Employable knowledge: benchmarking education about standardization in the UK

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    For academics and students in the United Kingdom the main source of standards is via British Standards Institution (BSI). The research demonstrates that British, European and International Standards play a key role in many areas of education. In some disciplines their inclusion in the course is mandatory, e.g. in building construction and performing risk assessments of equipment. Where not a requirement, other courses successfully encourage students to understand and apply specific standards and principles from them, to their design and project work, in topic areas such as quality management and user-computer interface design. Assessment practice is a key part of learning and academics have indicated how this fitted into the learning activity, e.g. by expecting students to develop an understanding of standards and reference them in all assessed work. Likewise, students taking part in the survey also suggest that they were actively engaged with one or more standards and that their understanding was measured through an assessed activity. However, students also emphasised the importance of additional support, e.g. introduction to standards in the workplace or as part of work placements, by library staff as an information resource, and by presentations from BSI experts. Employers have also indicated the importance of students’ knowledge, understanding and appreciation of relevant standards in the right context, emphasising their desire for standards to be included more widely in the curriculum. The draft recommendations from this study were subject to International review and comment, the results from this review served to strengthen the recommendations of this work. This research was commissioned by British Standards Institution (BSI). This research was produced in association with the Department for Business, Innovation and Skills as part of its ongoing programme of support for standardization. Grateful thanks are due to all those who filled in the questionnaire or who attended the workshops

    The URBIS Partnership Proposal for Global Designation

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    The URBIS Partnership is proposing a designation process to recognize urban regions’ efforts to engage in participatory, inclusive, and comprehensive approaches in urban planning for sustainability. Through this process, sustainable management practices would be developed and then cataloged for sharing and dissemination as part of a site-based global knowledge network. The URBIS Partnership is inviting expertise in fields including urban ecology, environmental education, policy, and urban planning to develop this process. Currently, urban regions involved include Stockholm, Montreal, Shanghai, Cape Town, Chicago, Istanbul, New Orleans, and New York. This effort will culminate in the establishment of the URBIS Partnership with the CBD Global Partnership of Cities and Biodiversity and other collaborators at the City Biodiversity Summit at Nagoya, Japan, the 10th Conference of the Parties to the Convention on Biological Diversity
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