10,310 research outputs found
Alfv\'en wave-driven wind from RGB and AGB stars
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 and initial
metallicity =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 s in the RGB and early AGB (E-AGB) phases; the second is the
wind with outflow velocity less than 10 km s 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 10 yr and
the outflow velocity lower than 20 km s 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
Assuming only the non-zero electron and tau neutrino components
, , of the non-standard
matter effect and postulating the atmospheric neutrino constraint
, 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 , . It is
also shown that if and are large, then T2KK
can determine the Dirac phase and the phase of separately,
due to the information at the two baselines. We also provide an argument that
the components 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
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
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 dominance model taking into
account the renormalization of 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
The multiple reentrant quantum phase transitions in the
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 and even-th bond
can take the values {\JS} and {\JW} ({\JS} > J > {\JW} > 0) randomly
with probability and , respectively. The pure version ( and
) 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 , 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
In situ imaging of microstructure formation in electronic interconnections
The development of microstructure during melting, reactive wetting and solidification of solder pastes on Cu-plated printed circuit boards has been studied by synchrotron radiography. Using Sn-3.0Ag-0.5Cu/Cu and Sn-0.7Cu/Cu as examples, we show that the interfacial Cu6Sn5 layer is present within 0.05 s of wetting, and explore the kinetics of flux void formation at the interface between the liquid and the Cu6Sn5 layer. Quantification of the nucleation locations and anisotropic growth kinetics of primary Cu6Sn5 crystals reveals a competition between the nucleation of Cu6Sn5 in the liquid versus growth of Cu6Sn5 from the existing Cu6Sn5 layer. Direct imaging confirms that the β-Sn nucleates at/near the Cu6Sn5 layer in Sn-3.0Ag-0.5Cu/Cu joints
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