26,131 research outputs found
Determination of the cross-field density structuring in coronal waveguides using the damping of transverse waves
Time and spatial damping of transverse magnetohydrodynamic (MHD) kink
oscillations is a source of information on the cross-field variation of the
plasma density in coronal waveguides. We show that a probabilistic approach to
the problem of determining the density structuring from the observed damping of
transverse oscillations enables us to obtain information on the two parameters
that characterise the cross-field density profile. The inference is performed
by computing the marginal posterior distributions for density contrast and
transverse inhomo- geneity length-scale using Bayesian analysis and damping
ratios for transverse oscillations under the assumption that damping is
produced by resonant absorption. The obtained distributions show that, for
damping times of a few oscillatory periods, low density contrasts and short
inho- mogeneity length scales are more plausible in explaining observations.
This means that valuable information on the cross-field density profile can be
obtained even if the inversion problem, with two unknowns and one observable,
is a mathematically ill-posed problem.Comment: 5 pages, 3 figures, accepte
Spin polarized neutron matte and magnetic susceptibility within the Brueckner-Hartree-Fock approximation
The Brueckner--Hartree--Fock formalism is applied to study spin polarized
neutron matter properties. Results of the total energy per particle as a
function of the spin polarization and density are presented for two modern
realistic nucleon-nucleon interactions, Nijmegen II and Reid93. We find that
the dependence of the energy on the spin polarization is practically parabolic
in the full range of polarizations. The magnetic susceptibility of the system
is computed. Our results show no indication of a ferromagnetic transition which
becomes even more difficult as the density increases.Comment: 15 pages, 4 figures (Submitted to PRC
Microscopic calculations of spin polarized neutron matter at finite temperature
The properties of spin polarized neutron matter are studied both at zero and
finite temperature within the framework of the Brueckner--Hartree--Fock
formalism, using the Argonne v18 nucleon-nucleon interaction. The free energy,
energy and entropy per particle are calculated for several values of the spin
polarization, densities and temperatures together with the magnetic
susceptibility of the system. The results show no indication of a ferromagnetic
transition at any density and temperature.Comment: 19 pages, 5 figure
Latina/o Conversion and Miracle-Seeking at a Buddhist Temple
The growing diversification of the US Latino religious’ experiences calls for scholarly attention beyond Protestant or Catholic categories. This study begins to answer this call. Using interview data with 26 Latinos collected over 2 years of observation at the True Lama Meditation Center (TLMC) in Houston, Texas, we describe how Latinos who convert to Buddhism or actively attend the temple while also continuing to attend Christian services (both Catholic and Protestant) see themselves and understand their religious identities and practices. We then explore the reasons for their conversion or changes in religious identities and practices through various theoretical lens. Although the majority of respondents now claim to be Buddhist, many did not switch religions but augmented or extended their religious identities and practices. Reasons for conversion to Buddhism or concurrent involvement at the temple and Buddhist faith practices include seeking material support and miracles and those seeking spiritual fulfillment they felt they were not getting in Christian faith practices
Influence of atomic polarization and horizontal illumination on the Stokes profiles of the He I 10830 multiplet
The polarization observed in the spectral lines of the He I 10830 multiplet
carries valuable information on the dynamical and magnetic properties of plasma
structures in the solar chromosphere and corona, such as spicules, prominences,
filaments, emerging magnetic flux regions, etc. Here we investigate the
influence of atomic level polarization on the emergent Stokes profiles for a
broad range of magnetic field strengths, in both 90 degree and forward
scattering geometry. We show that, contrary to a widespread belief, the
selective emission and absorption processes caused by the presence of atomic
level polarization may have an important influence on the emergent linear
polarization, even for magnetic field strengths as large as 1000 G.
Consequently, the modeling of the Stokes Q and U profiles should not be done by
taking only into account the contribution of the transverse Zeeman effect
within the framework of the Paschen-Back effect theory, unless the magnetic
field intensity of the observed plasma structure is sensibly larger than 1000
G. We point out also that in low-lying optically thick plasma structures, such
as those of active region filaments, the (horizontal) radiation field generated
by the structure itself may substantially reduce the positive contribution to
the anisotropy factor caused by the (vertical) radiation field coming from the
underlying solar photosphere, so that the amount of atomic level polarization
may turn out to be negligible. Only under such circumstances may the emergent
linear polarization of the He I 10830 multiplet in such regions of the solar
atmosphere be dominated by the contribution caused by the transverse Zeeman
effect.Comment: Accepted for publication in The Astrophysical Journal (It is
tentatively scheduled for the ApJ January 20, 2007 issue
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