1,290 research outputs found
Topology and Nematic Ordering II: Observable Critical Behavior
This paper is the second in a pair treating a new lattice model for nematic
media. In addition to the familiar isotropic (I) and nematically ordered (N)
phases, the phase diagram established in the previous paper (Paper I) contains
a new, topologically ordered phase (T) occuring at large suppression of
topological defects and weak nematic interactions. This paper (Paper II) is
concerned with the experimental signatures of the proposed phase diagram.
Specific heat, light scattering and magnetic susceptibility near both the N/T
and I/T transitions are studied, and critical behavior determined. The singular
dependences of the Frank constants (, , ) and the dielectric
tensor anisotropy () on temperature upon approaching the N/T
transition are also found.Comment: 10 pages, RevTeX 3.
The illusion of community ownership: community-based water management in Uchira, Kilimanjaro region
Water resource managementSocial participationWater users’ associationsWater policyWater shortagePricingWater costsWater supplyLabor
The illusion of community ownership: community-based water management in Uchira, Kilimanjaro region
Water resource managementWater governanceSocial participationWater users’ associationsWater policyWater shortagePricingWater costsWater supplyLabor
Authentic recipes from around the world
This general audience book is the outcome of the AHRC project "Consuming Authenticities: Time, Place and the Past in the Construction of Authentic Foods and Drinks." It addresses the temporal relationships and ideas that contribute to the construction of narratives of authenticity in relation to four foods and drinks: pulque (an alcoholic drink from Central Mexico), flaounes (celebration Easter pies from Cyprus), Welsh craft cider and acarajé (a street snack from Brazil)
Self-organization in systems of self-propelled particles
We investigate a discrete model consisting of self-propelled particles that
obey simple interaction rules. We show that this model can self-organize and
exhibit coherent localized solutions in one- and in two-dimensions.In
one-dimension, the self-organized solution is a localized flock of finite
extent in which the density abruptly drops to zero at the edges.In
two-dimensions, we focus on the vortex solution in which the particles rotate
around a common center and show that this solution can be obtained from random
initial conditions, even in the absence of a confining boundary. Furthermore,
we develop a continuum version of our discrete model and demonstrate that the
agreement between the discrete and the continuum model is excellent.Comment: 4 pages, 5 figure
Non-Ergodic Dynamics of the 2D Random-phase Sine-Gordon Model: Applications to Vortex-Glass Arrays and Disordered-Substrate Surfaces
The dynamics of the random-phase sine-Gordon model, which describes 2D
vortex-glass arrays and crystalline surfaces on disordered substrates, is
investigated using the self-consistent Hartree approximation. The
fluctuation-dissipation theorem is violated below the critical temperature T_c
for large time t>t* where t* diverges in the thermodynamic limit. While above
T_c the averaged autocorrelation function diverges as Tln(t), for T<T_c it
approaches a finite value q* proportional to 1/(T_c-T) as q(t) = q* -
c(t/t*)^{-\nu} (for t --> t*) where \nu is a temperature-dependent exponent. On
larger time scales t > t* the dynamics becomes non-ergodic. The static
correlations behave as Tln{x} for T>T_c and for T<T_c when x < \xi* with \xi*
proportional to exp{A/(T_c-T)}. For scales x > \xi*, they behave as (T/m)ln{x}
where m is approximately T/T_c near T_c, in general agreement with the
variational replica-symmetry breaking approach and with recent simulations of
the disordered-substrate surface. For strong- coupling the transition becomes
first-order.Comment: 12 pages in LaTeX, Figures available upon request, NSF-ITP 94-10
Ground state properties of solid-on-solid models with disordered substrates
We study the glassy super-rough phase of a class of solid-on-solid models
with a disordered substrate in the limit of vanishing temperature by means of
exact ground states, which we determine with a newly developed minimum cost
flow algorithm. Results for the height-height correlation function are compared
with analytical and numerical predictions. The domain wall energy of a boundary
induced step grows logarithmically with system size, indicating the marginal
stability of the ground state, and the fractal dimension of the step is
estimated. The sensibility of the ground state with respect to infinitesimal
variations of the quenched disorder is analyzed.Comment: 4 pages RevTeX, 3 eps-figures include
- …