3,332 research outputs found

    Polarization properties and dispersion relations for spiral resonances of a dielectric rod

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    Dielectric microcavities based on cylindrical and deformed cylindrical shapes have been employed as resonators for microlasers. Such systems support spiral resonances with finite momentum along the cylinder axis. For such modes the boundary conditions do not separate and simple TM and TE polarization states do not exist. We formulate a theory for the dispersion relations and polarization properties of such resonances for an infinite dielectric rod of arbitrary cross-section and then solve for these quantities for the case of a circular cross-section (cylinder). Useful analytic formulas are obtained using the eikonal (Einstein-Brillouin-Keller) method which are shown to be excellent approximations to the exact results from the wave equation. The major finding is that the polarization of the radiation emitted into the far-field is linear up to a polarization critical angle (PCA) at which it changes to elliptical. The PCA always lies between the Brewster and total-internal-reflection angles for the dielectric, as is shown by an analysis based on the Jones matrices of the spiraling rays.Comment: submitted to JOSA

    Evaluating Greek equity funds using data envelopment analysis

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    This study assesses the relative performance of Greek equity funds employing a non-parametric method, specifically Data Envelopment Analysis (DEA). Using an original sample of cost and operational attributes we explore the e¤ect of each variable on funds' operational efficiency for an oligopolistic and bank-dominated fund industry. Our results have significant implications for the investors' fund selection process since we are able to identify potential sources of inefficiencies for the funds. The most striking result is that the percentage of assets under management affects performance negatively, a conclusion which may be related to the structure of the domestic stock market. Furthermore, we provide evidence against the notion of funds' mean-variance efficiency

    Lesão por pododermatite em frangos de corte alojados em diferentes densidades.

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    A criação avícola com uma maior densidade visa o aumento da produção, com o mínimo de investimentos em construções e otimização dos custos fixos. Em consequência, a pressão para redução dos custos na criação de frangos de corte levou ao aumento da densidade das aves que promove maior produção de peso vivo/m2 (2). Além disso, a piora na qualidade da cama, principalmente pela compactação decorrente de aumento de umidade, determina o aparecimento de lesões na pele, pododermatites, calo de peito e hematomas (4). As pododermatites de contato são lesões erosivas da pele, predominantes na superfície plantar das patas dos frangos de corte. A etiologia apresenta uma inflamação da pele devido a uma combinação de umidade e fatores cáusticos presentes na cama, sendo a excreta das aves, que é composta de ácido úrico, um agente importante na formação do problema (1). As pododermatites em frangos de corte passaram a ter maior relevância nos últimos anos devido à exportação dos pés dos frangos para os mercados da Ásia. Objetivou-se com este trabalho avaliar o efeito do aumento da densidade em aviário convencional sobre a frequência de lesões por pododermatite em frangos de corte

    The Equivalence Principle in the Non-baryonic Regime

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    We consider the empirical validity of the equivalence principle for non-baryonic matter. Working in the context of the TH\epsilon\mu formalism, we evaluate the constraints experiments place on parameters associated with violation of the equivalence principle (EVPs) over as wide a sector of the standard model as possible. Specific examples include new parameter constraints which arise from torsion balance experiments, gravitational red shift, variation of the fine structure constant, time-dilation measurements, and matter/antimatter experiments. We find several new bounds on EVPs in the leptonic and kaon sectors.Comment: 22 pages, late

    Quantum fluctuations for drag free geodesic motion

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    The drag free technique is used to force a proof mass to follow a geodesic motion. The mass is protected from perturbations by a cage, and the motion of the latter is actively controlled to follow the motion of the proof mass. We present a theoretical analysis of the effects of quantum fluctuations for this technique. We show that a perfect drag free operation is in principle possible at the quantum level, in spite of the back action exerted on the mass by the position sensor.Comment: 4 pages, 1 figure, RevTeX, minor change

    Recruitment strategies and rates of a multi-site behavioral intervention for adolescents and young adults with cancer

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    INTRODUCTION: To provide an overview of factors related to recruitment of adolescents and young adults (AYA) into research and recruitment rates and reasons for refusal from a multicenter study entitled "Stories and Music for Adolescent/Young Adult Resilience during Transplant" (SMART). METHODS: A randomized clinical trial study design was used. The settings included 9 hospitals. The sample included AYAs (aged 11-24 years) who were undergoing a stem cell transplant. Several instruments were used to measure symptom distress, coping, resilience, and quality of life in AYA with cancer. RESULTS: A total of 113 AYA were recruited (50%) for this study. Strategies were refined as the study continued to address challenges related to recruitment. We provide a description of recruitment strategies and an evaluation of our planning, implementing, and monitoring of recruitment rates for the SMART study. DISCUSSION: When designing a study, careful consideration must be given to factors influencing recruitment as well as special considerations for unique populations. Dissemination of strategies specific to unique populations will be helpful to the design of future research studies

    Testing the Principle of Equivalence by Solar Neutrinos

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    We discuss the possibility of testing the principle of equivalence with solar neutrinos. If there exists a violation of the equivalence principle quarks and leptons with different flavors may not universally couple with gravity. The method we discuss employs a quantum mechanical phenomenon of neutrino oscillation to probe into the non-universality of the gravitational couplings of neutrinos. We develop an appropriate formalism to deal with neutrino propagation under the weak gravitational fields of the sun in the presence of the flavor mixing. We point out that solar neutrino observation by the next generation water Cherenkov detectors can improve the existing bound on violation of the equivalence principle by 3-4 orders of magnitude if the nonadiabatic Mikheyev-Smirnov-Wolfenstein mechanism is the solution to the solar neutrino problem.Comment: Latex, 17 pages + 6 uuencoded postscript figures, KEK-TH-396, TMUP-HEL-9402 (unnecessary one reference was removed

    Nets, Spray or Both? The Effectiveness of Insecticide-Treated Nets and Indoor Residual Spraying in Reducing Malaria Morbidity and Child Mortality in sub-Saharan Africa.

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    Malaria control programmes currently face the challenge of maintaining, as well as accelerating, the progress made against malaria with fewer resources and uncertain funding. There is a critical need to determine what combination of malaria interventions confers the greatest protection against malaria morbidity and child mortality under routine conditions. This study assesses intervention effectiveness experienced by children under the age of five exposed to both insecticide-treated nets (ITNs) and indoor residual spraying (IRS), as compared to each intervention alone, based on nationally representative survey data collected from 17 countries in sub-Saharan Africa. Living in households with both ITNs and IRS was associated with a significant risk reduction against parasitaemia in medium and high transmission areas, 53% (95% CI 37% to 67%) and 31% (95% CI 11% to 47%) respectively. For medium transmission areas, an additional 36% (95% CI 7% to 53%) protection was garnered by having both interventions compared with exposure to only ITNs or only IRS. Having both ITNs and IRS was not significantly more protective against parasitaemia than either intervention alone in low and high malaria transmission areas. In rural and urban areas, exposure to both interventions provided significant protection against parasitaemia, 57% (95% CI 48% to 65%) and 39% (95% CI 10% to 61%) respectively; however, this effect was not significantly greater than having a singular intervention. Statistically, risk for all-cause child mortality was not significantly reduced by having both ITNs and IRS, and no additional protectiveness was detected for having dual intervention coverage over a singular intervention. These findings suggest that greater reductions in malaria morbidity and health gains for children may be achieved with ITNs and IRS combined beyond the protection offered by IRS or ITNs alone

    Senate called to order at 11:10 a.m. President pro Tempore Amodei presiding.

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    Lord, You have given us eyes to see and ears to hear. But, in our task of crafting legislation, often those gifts by themselves are not enough. Grant us vision and understanding as we seek how to best govern Your people. AMEN. Pledge of allegiance to the Flag. Senator Raggio moved that further reading of the Journal be dispensed with, and the President pro Tempore and Secretary be authorized to make the necessary corrections and additions. Motion carried. REPORTS OF COMMITTEE
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