10,345 research outputs found

    Alfv\'en wave-driven wind from RGB and AGB stars

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    We develop a magnetohydrodynamical model of Alfv\'en wave-driven wind in open magnetic flux tubes piercing the stellar surface of Red Giant Branch (RGB) and Asymptotic Giant Branch (AGB) stars, and investigate the physical properties of the winds. The model simulations are carried out along the evolutionary tracks of stars with initial mass in the range of 1.5 to 3.0 MM_{\odot} and initial metallicity ZiniZ_{\rm ini}=0.02. The surface magnetic field strength being set to be 1G, we find that the wind during the evolution of star can be classified into the following four types; the first is the wind with the velocity higher than 80 km s1^{-1} in the RGB and early AGB (E-AGB) phases; the second is the wind with outflow velocity less than 10 km s1^{-1} seen around the tip of RGB or in the E-AGB phase; the third is the unstable wind in the E-AGB and thermally pulsing AGB (TP-AGB) phases; the fourth is the stable massive and slow wind with the mass-loss rate higher than 107M^{-7} M_{\odot} yr1^{-1} and the outflow velocity lower than 20 km s1^{-1} in the TP-AGB phase. The mass-loss rates in the first and second types of wind are two or three orders of magnitude lower than the values evaluated by an empirical formula. The presence of massive and slow wind of the fourth type suggests the possibility that the massive outflow observed in TP-AGB stars could be attributed to the Alfv\'en wave-driven wind.Comment: 17 pages, 15 figures, accepted for publication in Ap

    Sensitivity of T2KK to the non-standard interaction in propagation

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    Assuming only the non-zero electron and tau neutrino components ϵee\epsilon_{ee}, ϵeτ\epsilon_{e\tau}, ϵττ\epsilon_{\tau\tau} of the non-standard matter effect and postulating the atmospheric neutrino constraint ϵττ=ϵeτ2/(1+ϵee)\epsilon_{\tau\tau}=|\epsilon_{e\tau}|^2/(1+\epsilon_{ee}), we study the sensitivity to the non-standard interaction in neutrino propagation of the T2KK neutrino long-baseline experiment. It is shown that T2KK can constrain the parameters ϵee1|\epsilon_{ee}|\lesssim 1, ϵeτ0.2|\epsilon_{e\tau}|\lesssim 0.2. It is also shown that if ϵeτ|\epsilon_{e\tau}| and θ13\theta_{13} are large, then T2KK can determine the Dirac phase and the phase of ϵeτ\epsilon_{e\tau} separately, due to the information at the two baselines. We also provide an argument that the components ϵαμ|\epsilon_{\alpha\mu}| (α=e,μ,τ)(\alpha=e,\mu,\tau) must be small for the disappearance oscillation probability to be consistent with high-energy atmospheric neutrino data, which justifies our premise that these quantities are negligible.Comment: 29 pages, 25 figures, uses revtex4-1. Several places including typos revised. New references adde

    A Study Of Surface Dynamics Of Polymers. II. Investigation By Plasma Surface Implantation Of Fluorine–containing Moieties

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    Macromolecules at the surface of a polymeric solid have considerable mobility, and the specific arrangement of functional groups of macromolecules at the surface is dictated by the environmental conditions in which the surface is placed. Consequently, the change of environmental conditions, such as immersion in water or placement in a biological surrounding, could cause a considerable degree of change in the surface characteristics of a polymer from those evaluated in the laboratory against ambient air. The mobile nature of a polymer surface can be investigated by surface‐implanting fluorine‐containing moieties, mainly—CF3, by the plasma implantation technique and following the disappearance and reappearance of fluorine atoms on the surface. The disappearance rates (based on the immersion time in water at room temperature) of ESCA F1s signals, the decay rates of (advancing) contact angle of water, and the recovery of these values on heat treatment of water‐immersed samples were measured as a function of crystallinity of polymer samples (at three levels of crystallinity) for poly (ethylene terephthalate) and nylon 6. Copyright © 1988 John Wiley & Sons, Inc

    Nuclear effects in Neutrino Nuclear Cross-sections

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    Nuclear effects in the quasielastic and inelastic scattering of neutrinos(antineutrinos) from nuclear targets have been studied. The calculations are done in the local density approximation which take into account the effect of nucleon motion as well as renormalisation of weak transition strengths in the nuclear medium. The inelastic reaction leading to production of pions is calculated in a Δ\Delta dominance model taking into account the renormalization of Δ\Delta properties in the nuclear medium.Comment: 4 pages,3 figures, Ninth International Workshop on Neutrino Factories, Superbeams and Betabeams (NuFact07), August 6-11, 2007, Okayama University, Okayama, Japa

    Field Induced Multiple Reentrant Quantum Phase Transitions in Randomly Dimerized Antiferromagnetic S=1/2 Heisenberg Chains

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    The multiple reentrant quantum phase transitions in the S=1/2S=1/2 antiferromagnetic Heisenberg chains with random bond alternation in the magnetic field are investigated by the density matrix renormalization group method combined with the interchain mean field approximation. It is assumed that the odd-th bond is antiferromagnetic with strength JJ and even-th bond can take the values {\JS} and {\JW} ({\JS} > J > {\JW} > 0) randomly with probability pp and 1p1-p, respectively. The pure version (p=0p=0 and p=1p=1) of this model has a spin gap but exhibits a field induced antiferromagnetism in the presence of interchain coupling if Zeeman energy due to the magnetic field exceeds the spin gap. For 0<p<10 < p < 1, the antiferromagnetism is induced by randomness at small field region where the ground state is disordered due to the spin gap in the pure case. At the same time, this model exhibits randomness induced plateaus at several values of magnetization. The antiferromagnetism is destroyed on the plateaus. As a consequence, we find a series of reentrant quantum phase transitions between the transverse antiferromagnetic phases and disordered plateau phases with the increase of the magnetic field for moderate strength of interchain coupling. Above the main plateaus, the magnetization curve consists of a series of small plateaus and the jumps between them, It is also found that the antiferromagnetism is induced by infinitesimal interchain coupling at the jumps between the small plateaus. We conclude that this antiferromagnetism is supported by the mixing of low lying excited states by the staggered interchain mean field even though the spin correlation function is short ranged in the ground state of each chain.Comment: 5 pages, 8 figure

    Plasma Polymerization Of Tetramethyldisiloxane By A Magnetron Glow Discharge

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    Plasma polymerization of tetramethyldisiloxane by a magnetron glow discharge was studied. The glow discharge was created between parallel electrodes with a 10 kHz electric power source with a superimposed magnetic field using permanent bar magnets. Polymers were deposited onto moving substrates placed on the surface of a rotating disc located in between the electrodes. The deposition rates were determined with a quartz crystal thickness monitor placed on the plane of the rotating disc and just outside the edge of the disc. The current-voltage relationship observed for plasma polymerization of the monomer depends on the monomer feed rate and the conditioning of the electrodes or the establishment of a steady state surface in the polymer-forming plasma, which also depends mainly on the monomer feed rate. Consequently, plasma polymerization cannot be correlated to single operational parameters such as the discharge current, the power or the monomer feed rate in a simple manner. However, when the deposition rate was expressed as Rp/FM, where Rp is the polymer deposition rate, F is the monomer feed rate and M is the molecular weight (FM is thus the monomer mass feed rate), it was found that Rp/FM is uniquely related to the parameter W/FM where W is the discharge power in Watts. It was shown that many polymer properties were also determined mainly by the same composite parameter. It was also found that the presence of O2 gas in the monomer feed reduced the carbon content in the polymer and made the surface more hydrophobic while O2 plasma treatment of the plasma polymer rendered the surface more hydrophilic. © 1983
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