12,110 research outputs found

    Magnetic field waves at Uranus

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    The proposed research efforts funded by the UDAP grant to the BRI involve the study of magnetic field waves associated with the Uranian bow shock. This is a collaborative venture bringing together investigators at the BRI, Southwest Research Institute (SwRI), and Goddard Space Flight Center (GSFC). In addition, other collaborations have been formed with investigators granted UDAP funds for similar studies and with investigators affiliated with other Voyager experiments. These investigations and the corresponding collaborations are included in the report. The proposed effort as originally conceived included an examination of waves downstream from the shock within the magnetosheath. However, the observations of unexpected complexity and diversity within the upstream region have necessitated that we confine our efforts to those observations recorded upstream of the bow shock on the inbound and outbound legs of the encounter by the Voyager 2 spacecraft

    A new mechanism for a naturally small Dirac neutrino mass

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    A mechanism is proposed in which a right-handed neutrino zero mode and a right-handed charged lepton zero mode can be localized at the same place along an extra compact dimension while having markedly different spreads in their wave functions: a relatively narrow one for the neutrino and a rather broad one for the charged lepton. In their overlaps with the wave function for the left-handed zero modes, this mechanism could produce a natural large hierarchy in the effective Yukawa couplings in four dimensions, and hence a large disparity in masses.Comment: 6 pages (2 with figures), twocolumn forma

    Dynamical coupled-channel model of kaon-hyperon interactions

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    The pi N --> KY and KY --> KY reactions are studied using a dynamical coupled-channel model of meson-baryon interactions at energies where the baryon resonances are strongly excited. The channels included are: pi N, K \Lambda, and K\Sigma. The resonances considered are: N^* [S_{11}(1650), P_{11}(1710), P_{13}(1720),D_{13}(1700)]; \Delta^* [S_{31}(1900), P_{31}(1910), P_{33}(1920)]; \Lambda ^* [S_{01}(1670), P_{01}(1810)] \Sigma^* [P_{11}(1660), D_{13}(1670)]; and K^*(892). The basic non-resonant \pi N --> KY and KY --> KY transition potentials are derived from effective Lagrangians using a unitary transformation method. The dynamical coupled-channel equations are simplified by parametrizing the pi N -->pi N amplitudes in terms of empirical pi N partial-wave amplitudes and a phenomenological off-shell function. Two models have been constructed. Model A is built by fixing all coupling constants and resonance parameters using SU(3) symmetry, the Particle Data Group values, and results from a constituent quark model. Model B is obtained by allowing most of the parameters to vary around the values of model A in fitting the data. Good fits to the available data for pi^- p to K^0 \Lambda, K^0 \Sigma^0 have been achieved. The investigated kinematics region in the center-of-mass frame goes from threshold to 2.5 GeV. The constructed models can be imbedded into associated dynamical coupled-channel studies of kaon photo- and electro-production reactions.Comment: 35 pages, 11 Figure

    A Study on Tourism Development Strategy of Kaohsiung City in Taiwan after Urban Style Regeneration

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    Urban tourism has gradually been emphasized in past years; especially, it is regarded as a savior of urban regeneration in old industrial cities. When losing the competitive advantages and getting declined, old industrial cities are facing the challenge of transformation. The development of urban tourism is considered as the opportunity of industrial cities in dark recession that they start to involve in the development of tourism. Analytic Hierarchy Process (AHP) is applied in this study to evaluate key success factors in the tourism development strategy of Kaohsiung City after the urban style regeneration. AHP is used for confirming the levels of various evaluation factors. The first hierarchy contains four evaluation dimensions, and 14 evaluation standards are covered in the second hierarchy. The results reveal the important sequence of four evaluation factors in the second hierarchy as (1) marketing activity, (2) management strategy, (3) recreational environment, and (4) infrastructure, where the importance of evaluation factors in the third hierarchy is sequenced as (1) urban attraction, (2) environmental facility maintenance, (3) celebrations, (4) local characteristics, and (5) natural landscape. The research results and suggestions in this study are expected to enhance the tourism development of Kaohsiung City in Taiwan after the urban style regeneration.     Keywords: urban style, tourism development strategy, key success factors, Delphi method, AH

    Poincar\'e gauge theory with even and odd parity dynamic connection modes: isotropic Bianchi cosmological models

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    The Poincar\'e gauge theory of gravity has a metric compatible connection with independent dynamics that is reflected in the torsion and curvature. The theory allows two good propagating spin-0 modes. Dynamical investigations using a simple expanding cosmological model found that the oscillation of the 0+^+ mode could account for an accelerating expansion similar to that presently observed. The model has been extended to include a 0−0^{-} mode and more recently cross parity couplings. We investigate the dynamics of this model in a situation which is simple, non-trivial, and yet may give physically interesting results that might be observable. We consider homogeneous cosmologies, more specifically, isotropic Bianchi class A models. We find an effective Lagrangian for our dynamical system, a system of first order equations, and present some typical dynamical evolution.Comment: 8 pages, 1 figures, submitted to IARD 2010 Conference Proceedings in {\em Journal of Physics: Conference Series}, eds. L. Horwitz and M. Land (2011

    Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions

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    Recently reported transverse momentum distributions of strange hadrons produced in Pb(158AGeV) on Pb collisions and corresponding results from the relativistic quantum molecular dynamics (RQMD) approach are examined. We argue that the experimental observations favor a scenario in which multi-strange hadrons are formed and decouple from the system rather early at large energy densities (around 1 GeV/fm3^3). The systematics of the strange and non-strange particle spectra indicate that the observed transverse flow develops mainly in the late hadronic stages of these reactions.Comment: 4 pages, 4 figure

    Electron tunneling in a strained n-type Si1−xGex/Si/Si1−xGex double-barrier structure

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    We report electrical measurements on an n-type Si1−xGex/Si/Si1−xGex double-barrier structure grown on a partially relaxed Si1−yGey buffer layer. Resonance tunneling of Δ4band electrons is demonstrated. This is attributed to the strain splitting in the SiGe buffer layer where the Δ4 band is lowest in energy at the electrode. Since the Δ4 band electrons have a much lighter effective mass along the direction of tunneling current in comparison with that of the Δ2 band electrons, this work presents an advantage over those SiGe resonant-tunneling diodes in which tunneling of Δ2 band electrons is employed
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