511 research outputs found

    Wind energy

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    Existence of topological hairy dyons and dyonic black holes in anti-de Sitter SU(N) Einstein-Yang-Mills theory

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    We investigate dyonic black hole and dyon solutions of four-dimensional SU(N) Einstein-Yang-Mills theory with a negative cosmological constant. We derive a set of field equations in this case, and prove the existence of non-trivial solutions to these equations for any integer N, with 2N − 2 gauge degrees of freedom. We do this by showing that solutions exist locally at infinity, and at the event horizon for black holes and the origin for solitons. We then prove that we can patch these solutions together regularly into global solutions that can be integrated arbitrarily far into the asymptotic regime. Our main result is to show that dyonic solutions exist in open sets in the parameter space, and hence that we can find non-trivial dyonic solutions in a number of regimes whose magnetic gauge fields have no zeros, which is likely important to the stability of the solutions. Keywords : Dyons, Black holes, topological, SU(N), EYM, Existenc

    Nanoparticle ZnS:Ag/ 6 LiF—a new high count rate neutron scintillator with pulse shape discrimination

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    A neutron sensitive scintillator employing nanoparticles of ZnS:Ag has been developed for the first time. Pulse shape differences between neutron and gamma signals were observed in this material and neutron-gamma discrimination was applied. With initial signal processing parameters, gamma sensitivities of 8.5×10−6 to 60Co gammas were achieved. The average primary decay of neutron scintillation in nanoparticle ZnS:Ag/6LiF was measured to be 18ns, and afterglow was significantly suppressed in comparison to standard ZnS:Ag/6LiF scintillators that employ micron sized ZnS:Ag. Fast decay times and minimal afterglow indicate potential for use in high count rate capability applications. Prospective count rate capabilities were investigated here as proof of concept, with rates of 1.12Mcps measured for a single readout channel with less than 3.5% count loss. This is approximately 70 times greater than the count rate capability of the current standard ZnS:Ag/6LiF scintillation detectors. With improvements to signal processing and scintillator composition, nanoparticle ZnS:Ag/6LiF could be a promising candidate for future high rate capability neutron detectors

    Effects of Self-Heating on Planar Heterostructure Barrier Varactor Diodes

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    The conversion efficiency for planar Al0.7GaAs-GaAs heterostructure barrier varactor triplers is shown to be reduced from a theoretical efficiency of 10% to 3% due to self-heating. The reduction is in accordance with measurements on planar Al0.7GaAs-GaAs heterostructure barrier varactor (HBV) triplers to 261 GHz at room temperature and with low temperature tripler measurements to 255 GHz. The delivered maximum output power at 261 GHz is 2.0 mW. Future HBV designs should carefully consider and reduce the device thermal resistance and parasitic series resistance. Optimization of the RF circuit for a 10 ?m diameter device yielded a delivered output power of 3.6 mW (2.5% conversion efficiency) at 234 GH

    Migration and HIV risk: life histories of Mexican-born men living with HIV in North Carolina

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    Latino men in the Southeastern USA are disproportionately affected by HIV, but little is known about how the migration process influences HIV-related risk. In North Carolina (NC), a relatively new immigrant destination, Latino men are predominantly young and from Mexico. We conducted 31 iterative life history interviews with 15 Mexican-born men living with HIV. We used holistic content narrative analysis methods to examine HIV vulnerability in the context of migration and to identify important turning points. Major themes included the prominence of traumatic early life experiences, migration as an ongoing process rather than a finite event, and HIV diagnosis as a final turning point in migration trajectories. Findings provide a nuanced understanding of HIV vulnerability throughout the migration process and have implications including the need for bi-national HIV prevention approaches, improved outreach around early testing and linkage to care, and attention to mental health
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