2,865 research outputs found

    Migration To Rural Communities In The Midwest: Economic Wellbeing And Women At The Household Level

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    Migration patterns are changing from large metropolis to rural towns. Rather than temporary migration of male heads of households the patterns are now for families to migrate in various stages. Rural Missouri towns have attracted newcomers. Foreign born Hispanics in non metro Missouri have low income earnings, and education, mobility and being woman have a negative effect on income earnings, as regression results show. The livelihoods of rural newcomers are vulnerable, with low income, multiple adults working in the households and with limited English proficiency. This is consistent with the life stories of women in a small town near a meat processing plant in Missouri.Community/Rural/Urban Development, Consumer/Household Economics,

    Quantum oscillations of rectified dc voltage as a function of magnetic field in an "almost" symmetric superconducting ring

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    Periodic quantum oscillations of a rectified dc voltage Vdc(B) vs the perpendicular magnetic field B were measured near the critical temperature Tc in a single superconducting aluminum almost symmetric ring (without specially created circular asymmetry) biased by alternating current with a zero dc component. With varying bias current and temperature, these Vdc(B) oscillations behave like the Vdc(B) oscillations observed in a circular-asymmetric ring but are of smaller amplitude. The Fourier spectra of the Vdc(B) functions exhibit a fundamental frequency, corresponding to the ring area, and its higher harmonics. Unexpectedly, satellite frequencies depending on the structure geometry and external parameters were found next to the fundamental frequency and around its higher harmonics.Comment: author english version, 2 pages, 3 figires, Proc. of the XXXIV Conference on Low-Temperature Physics "NT-34" (Russia, 2006

    Oscillatory decay of a two-component Bose-Einstein condensate

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    We study the decay of a two-component Bose-Einstein condensate with negative effective interaction energy. With a decreasing atom number due to losses, the atom-atom interaction becomes less important and the system undergoes a transition from a bistable Josephson regime to the monostable Rabi regime, displaying oscillations in phase and number. We study the equations of motion and derive an analytical expression for the oscillation amplitude. A quantum trajectory simulation reveals that the classical description fails for low emission rates, as expected from analytical considerations. Observation of the proposed effect will provide evidence for negative effective interaction.Comment: 4 pages, 3 figue

    Uso de comederos: ventajas y desventajas

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    Decaying neutralino dark matter in anomalous U(1)HU(1)_H models

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    In supersymmetric models extended with an anomalous U(1)HU(1)_H different R-parity violating couplings can yield an unstable neutralino. We show that in this context astrophysical and cosmological constraints on neutralino decaying dark matter forbid bilinear R-parity breaking neutralino decays and lead to a class of purely trilinear R-parity violating scenarios in which the neutralino is stable on cosmological scales. We have found that among the resulting models some of them become suitable to explain the observed anomalies in cosmic-ray electron/positron fluxes.Comment: 19 pages, 3 figures. References added, typos corrected, accepted version in Phys Rev

    Precision stellar radial velocity measurements with FIDEOS at the ESO 1-m telescope of La Silla

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    We present results from the commissioning and early science programs of FIDEOS, the new high-resolution echelle spectrograph developed at the Centre of Astro Engineering of Pontificia Universidad Catolica de Chile, and recently installed at the ESO 1m telescope of La Silla. The instrument provides spectral resolution R = 43,000 in the visible spectral range 420-800 nm, reaching a limiting magnitude of 11 in V band. Precision in the measurement of radial velocity is guaranteed by light feeding with an octagonal optical fibre, suitable mechanical isolation, thermal stabilisation, and simultaneous wavelength calibration. Currently the instrument reaches radial velocity stability of = 8 m/s over several consecutive nights of observation

    Periodic Quantum Tunneling and Parametric Resonance with Cigar-Shaped Bose-Einstein Condensates

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    We study the tunneling properties of a cigar-shaped Bose-Einstein condensate by using an effective 1D nonpolynomial nonlinear Schr\"odinger equation (NPSE). First we investigate a mechanism to generate periodic pulses of coherent matter by means of a Bose condensate confined in a potential well with an oscillating height of the energy barrier. We show that is possible to control the periodic emission of matter waves and the tunneling fraction of the Bose condensate. We find that the number of emitted particles strongly increases if the period of oscillation of the height of the energy barrier is in parametric resonance with the period of oscillation of the center of mass of the condensate inside the potential well. Then we use NPSE to analyze the periodic tunneling of a Bose-Einstein condensate in a double-well potential which has an oscillating energy barrier. We show that the dynamics of the Bose condensate critically depends on the frequency of the oscillating energy barrier. The macroscopic quantum self-trapping (MQST) of the condensate can be suppressed under the condition of parametric resonance between the frequency of the energy barrier and the frequency of oscillation through the barrier of the very small fraction of particles which remain untrapped during MQST.Comment: latex, 23 pages, 10 figures, to be published in J. Phys. B (Atom. Mol.), related papers can be found at http://www.mi.infm.it/salasnich/tdqg.htm
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