4,602 research outputs found
Strengthening Indigenous Social Work in the Academy
This paper provides an account of the development of an Indigenous Social Work program in Sudbury, Ontario and how it was conceived, developed and implemented. It describes the transformational approaches that Aboriginal faculty, communities and academic allies engaged in to create a rightful space for Indigenous social work in mainstream academia. In its 25th year, this program has provided many transformational opportunities for students, faculty and Aboriginal communities. Incorporating resistance and proactive momentum, the program has become pivotal in expanding the visibility and legitimacy for Indigenous social work in practice, theory, research and pedagogies. This program is an example of how community-faculty collaborations can sustain a robust Indigenous social work program
Collective Excitations, NMR, and Phase Transitions in Skyrme Crystals
At Landau level filling factors near nu =1, quantum Hall ferromagnets form a
Skyrme crystal state with quasi-long-range translational and non-collinear
magnetic order. We develop an effective low energy theory which explains the
presence in these systems of magnetic excitations at low energies below the
Larmor gap (Delta) and which predicts a dramatic enhancement of the nuclear
spin relaxation rate by a factor of 1000. The effective theory predicts a rich
set of quantum and classical phase transitions. Based in part on accurate
time-dependent Hartree-Fock calculations of the ordered state collective
excitation spectrum, we discuss aspects of the T-nu-Delta crystal phase
diagram.Comment: 4 pages REVTEX file and 3 postscript figure
Photoassociative spectroscopy at long range in ultracold strontium
We report photoassociative spectroscopy of Sr in a magneto-optical
trap operating on the intercombination line at 689 nm.
Photoassociative transitions are driven with a laser red-detuned by 600-2400
MHz from the atomic resonance at 461 nm. Photoassociation
takes place at extremely large internuclear separation, and the
photoassociative spectrum is strongly affected by relativistic retardation. A
fit of the transition frequencies determines the atomic lifetime
( ns) and resolves a discrepancy between experiment and
recent theoretical calculations.Comment: 4 pages, 4 figures, submitte
Numerical Investigation on Asymmetric Bilayer System at Integer Filling Factor
Deformation of the easy-axis ferromagnetic state in asymmetric bilayer
systems are investigated numerically. Using the exact diagonalization the
easy-axis to easy-plane ferromagnetic transition at total filling factor 3 or 4
is investigated. At still higher filling, novel stripe state in which stripes
are aligned in the vertical direction occurs. The Hartree-Fock energies of
relevant ordered states are calculated and compared.Comment: 4 pages, 6 figures, Proceedings of EP2DS-15, to appear in Physica
A Magnetically Torqued Disk Model for Be Stars
Despite extensive study, the mechanisms by which Be star disks acquire high
densities and angular momentum while displaying variability on many time scales
are still far from clear. In this paper, we discuss how magnetic torquing may
help explain disk formation with the observed quasi-Keplerian (as opposed to
expanding) velocity structure and their variability. We focus on the effects of
the rapid rotation of Be stars, considering the regime where centrifugal forces
provide the dominant radial support of the disk material. Using a kinematic
description of the angular velocity, vphi(r), in the disk and a parametric
model of an aligned field with a strength B(r) we develop analytic expressions
for the disk properties that allow us to estimate the stellar surface field
strength necessary to create such a disk for a range of stars on the
main-sequence. The model explains why disks are most common for main-sequence
stars at about spectral class B2 V. The earlier type stars with very fast and
high density winds would require unacceptably strong surface fields (> 10^3
Gauss) to form torqued disks, while the late B stars (with their low mass loss
rates) tend to form disks that produce only small fluxes in the dominant Be
diagnostics. For stars at B2 V the average surface field required is about 300
Gauss. The predicted disks provide an intrinsic polarization and a flux at
Halpha comparable to observations. We also discuss whether the effect on field
containment of the time dependent accumulation of matter in the flux tubes/disk
can help explain some of the observed variability of Be star disks.Comment: ApJ, in press. 46 pages, 12 figure
The Chandra ACIS Survey of M33 (ChASeM33): Transient X-ray Sources Discovered in M33
The Chandra ACIS Survey of M33 (ChASeM33) has acquired 7 fields of ACIS data
covering M33 with 200 ks of exposure in each field. A catalog from the first 10
months of data, along with archival Chandra observations dating back to the
year 2000, is currently available. We have searched these data for transient
sources that are measured to have a 0.35-8.0 keV unabsorbed luminosity of at
least 4 erg s in one epoch and are not detected in
another epoch. This set of the survey data has yielded seven such sources,
including one previously-known supersoft source. We analyzed XMM-Newton data
from the archive distributed over the years 2000 to 2003 to search for
recurrent outbursts and to get a spectrum for the supersoft transient. We find
only one recurrent transient in our sample. The X-ray spectra, light curves,
and optical counterpart candidates of two of the other sources suggest that
they are high-mass X-ray binaries. Archival Spitzer photometry and high X-ray
absorption suggest that one of the sources is a highly variable background
active galactic nucleus. The other three sources are more difficult to
classify. The bright transient population of M33 appears to contain a large
fraction of high-mass X-ray binaries compared with the transient populations of
M31 and the Galaxy, reflecting the later morphology of M33.Comment: 33 pages, 2 tables, 10 figures, accepted for publication in Ap
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