74 research outputs found
Stigma, identity and power:Managing stigmatized identities through discourse
We analyse how men incarcerated in Helsinki Prison managed, through talk, their stigmatized identities as prisoners. Three strategies are identified: âappropriationâ of the label âprisonerâ; claiming coveted social identities; and representing oneself as a âgoodâ person. The research contribution we make is to show how inmates dealt with their self-defined stigmatized identities through discourse, and how these strategies were effects of power. We argue that stigmatized identities are best theorized in relation to individualsâ repertoires of other (non-stigmatized) identities that they may draw on to make supportive self-claims. Prisoners, like other kinds of organizational participants, we argue, often have considerable scope for managing diverse, fragile, perhaps even contradictory, understandings of their selves.</jats:p
Growth Laws for Phase Ordering
We determine the characteristic length scale, , in phase ordering
kinetics for both scalar and vector fields, with either short- or long-range
interactions, and with or without conservation laws. We obtain
consistently by comparing the global rate of energy change to the energy
dissipation from the local evolution of the order parameter. We derive growth
laws for O(n) models, and our results can be applied to other systems with
similar defect structures.Comment: 12 pages, LaTeX, second tr
The Energy-Scaling Approach to Phase-Ordering Growth Laws
We present a simple, unified approach to determining the growth law for the
characteristic length scale, , in the phase ordering kinetics of a system
quenched from a disordered phase to within an ordered phase. This approach,
based on a scaling assumption for pair correlations, determines
self-consistently for purely dissipative dynamics by computing the
time-dependence of the energy in two ways. We derive growth laws for conserved
and non-conserved models, including two-dimensional XY models and
systems with textures. We demonstrate that the growth laws for other systems,
such as liquid-crystals and Potts models, are determined by the type of
topological defect in the order parameter field that dominates the energy. We
also obtain generalized Porod laws for systems with topological textures.Comment: LATeX 18 pages (REVTeX macros), one postscript figure appended,
REVISED --- rearranged and clarified, new paragraph on naive dimensional
analysis at end of section I
Phase ordering in bulk uniaxial nematic liquid crystals
The phase-ordering kinetics of a bulk uniaxial nematic liquid crystal is
addressed using techniques that have been successfully applied to describe
ordering in the O(n) model. The method involves constructing an appropriate
mapping between the order-parameter tensor and a Gaussian auxiliary field. The
mapping accounts both for the geometry of the director about the dominant
charge 1/2 string defects and biaxiality near the string cores. At late-times t
following a quench, there exists a scaling regime where the bulk nematic liquid
crystal and the three-dimensional O(2) model are found to be isomorphic, within
the Gaussian approximation. As a consequence, the scaling function for
order-parameter correlations in the nematic liquid crystal is exactly that of
the O(2) model, and the length characteristic of the strings grows as
. These results are in accord with experiment and simulation. Related
models dealing with thin films and monopole defects in the bulk are presented
and discussed.Comment: 21 pages, 3 figures, REVTeX, submitted to Phys. Rev.
Fluctuations and defect-defect correlations in the ordering kinetics of the O(2) model
The theory of phase ordering kinetics for the O(2) model using the gaussian
auxiliary field approach is reexamined from two points of view. The effects of
fluctuations about the ordering field are included and we organize the theory
such that the auxiliary field correlation function is analytic in the
short-scaled distance (x) expansion. These two points are connected and we find
in the refined theory that the divergence at the origin in the defect-defect
correlation function obtained in the original theory is removed.
Modifications to the order-parameter autocorrelation exponent are
computed.Comment: 29 pages, REVTeX, to be published in Phys. Rev. E. Minor
grammatical/syntax changes from the origina
Vortex annihilation in the ordering kinetics of the O(2) model
The vortex-vortex and vortex-antivortex correlation functions are determined
for the two-dimensional O(2) model undergoing phase ordering. We find
reasonably good agreement with simulation results for the vortex-vortex
correlation function where there is a short-scaled distance depletion zone due
to the repulsion of like-signed vortices. The vortex-antivortex correlation
function agrees well with simulation results for intermediate and long-scaled
distances. At short-scaled distances the simulations show a depletion zone not
seen in the theory.Comment: 28 pages, REVTeX, submitted to Phys. Rev.
Grain boundary pinning and glassy dynamics in stripe phases
We study numerically and analytically the coarsening of stripe phases in two
spatial dimensions, and show that transient configurations do not achieve long
ranged orientational order but rather evolve into glassy configurations with
very slow dynamics. In the absence of thermal fluctuations, defects such as
grain boundaries become pinned in an effective periodic potential that is
induced by the underlying periodicity of the stripe pattern itself. Pinning
arises without quenched disorder from the non-adiabatic coupling between the
slowly varying envelope of the order parameter around a defect, and its fast
variation over the stripe wavelength. The characteristic size of ordered
domains asymptotes to a finite value $R_g \sim \lambda_0\
\epsilon^{-1/2}\exp(|a|/\sqrt{\epsilon})\epsilon\ll 1\lambda_0a$ a constant of order unity. Random fluctuations allow defect motion to
resume until a new characteristic scale is reached, function of the intensity
of the fluctuations. We finally discuss the relationship between defect pinning
and the coarsening laws obtained in the intermediate time regime.Comment: 17 pages, 8 figures. Corrected version with one new figur
Breakdown of Scale Invariance in the Phase Ordering of Fractal Clusters
Our numerical simulations with the Cahn-Hilliard equation show that
coarsening of fractal clusters (FCs) is not a scale-invariant process. On the
other hand, a typical coarsening length scale and interfacial area of the FC
exhibit power laws in time, while the mass fractal dimension remains invariant.
The initial value of the lower cutoff is a relevant length scale. A
sharp-interface model is formulated that can follow the whole dynamics of a
diffusion controlled growth, coarsening, fragmentation and approach to
equilibrium in a system with conserved order parameter.Comment: 4 pages, 4 figures, RevTex, submitted to PR
Dynamics of orientational ordering in fluid membranes
We study the dynamics of orientational phase ordering in fluid membranes.
Through numerical simulation we find an unusually slow coarsening of
topological texture, which is limited by subdiffusive propagation of membrane
curvature. The growth of the orientational correlation length obeys a
power law with in the late stage. We also discuss
defect profiles and correlation patterns in terms of long-range interaction
mediated by curvature elasticity.Comment: 5 pages, 3 figures (1 in color); Eq.(9) correcte
Rocketborne instrument to search for infrared emission from baryonic dark matter in galactic halos
We describe the design and performance of the near IR telescope experiment (NITE), a rocket-borne instrument designed to search for IR emission from baryonic dark matter in the halos of nearby edge-on spiral galaxies. A 256 X 256 InSb array at the focus of a 16.5 cm liquid-helium- cooled telescope achieves near-background-limited sensitivity in a 3.5-5.5 micrometers waveband where the local foreground from zodiacal emission is at a minimum. This experiment represents the first scientific application of a low-background IR InSb array, a precursor to the InSb arrays intended for SIRTF, in a space-borne observation. We describe the flight performance of the instrument and preliminary scientific result from an observation of NGC 4565
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