1,622 research outputs found
E-consultation: evaluating appropriate technologies and processes for citizens' participation in public policy
This report sets out to explore the reality of consultation as a form of citizen participation in policy development in Ireland, North and South. It investigates processes of consultation, the only form of participation that is a legal requirement of policy making, with a view to assessing
their value as supporting tools of citizen centric governance. In addition a key objective of the research was to support the development of citizen driven government by identifying how Information Communication Technologies could support, develop or deepen the participation of
citizens in policy development through that same consultation requirement. In particular, it was hoped to identify e-consultation processes and technologies that are most appropriate to the needs of diverse local communities and to find the best ways to apply these to support citizen
driven democracy.
The research team is both interdisciplinary and action orientated. The authors come from diverse academic backgrounds such as sociology, political science, information management, community development and even marketing! However, they at least share in common a
commitment to democratic experimentalism (Unger, ), which involves working with what we have on offer to enrich democratic institutional possibilities by finding and building the zone where there is overlap between the conditions of practical progress and the requirements of
individual development, where whatever is proposed responds to the felt needs and aspirations of ordinary citizens
Vortex nucleation in bose-einstein condensates due to effective magnetic fields
We investigate the rotational properties of a Bose-Einstein condensate (BEC) in an effective magnetic field. The corresponding gauge potential is optically generated, and based on the adiabatic motion of the atoms. We demonstrate that the nucleation of vortices is seeded by instabilities in surface excitations and show that this picture also holds when the applied effective magnetic field is not homogeneous. The eventual configuration of vortices in the cloud depends on the geometry of the applied field
Theory of Double-Sided Flux Decorations
A novel two-sided Bitter decoration technique was recently employed by Yao et
al. to study the structure of the magnetic vortex array in high-temperature
superconductors. Here we discuss the analysis of such experiments. We show that
two-sided decorations can be used to infer {\it quantitative} information about
the bulk properties of flux arrays, and discuss how a least squares analysis of
the local density differences can be used to bring the two sides into registry.
Information about the tilt, compressional and shear moduli of bulk vortex
configurations can be extracted from these measurements.Comment: 17 pages, 3 figures not included (to request send email to
[email protected]
Non-hermitean delocalization in an array of wells with variable-range widths
Nonhermitean hamiltonians of convection-diffusion type occur in the
description of vortex motion in the presence of a tilted magnetic field as well
as in models of driven population dynamics. We study such hamiltonians in the
case of rectangular barriers of variable size. We determine Lyapunov exponent
and wavenumber of the eigenfunctions within an adiabatic approach, allowing to
reduce the original d=2 phase space to a d=1 attractor. PACS
numbers:05.70.Ln,72.15Rn,74.60.GeComment: 20 pages,10 figure
Recommended from our members
Biogenic Versus Anthropogenic Sources of CO in the United States
Aircraft observations of carbon monoxide (CO) from the ICARTT campaign over the eastern United States in summer 2004 (July 1–August 15), interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem), show that the national anthropogenic emission inventory from the U.S. Environmental Protection Agency (93 Tg CO y−1) is too high by 60% in summer. Our best estimate of the CO anthropogenic source for the ICARTT period is 6.4 Tg CO, including 4.6 Tg from direct emission and 1.8 Tg CO from oxidation of anthropogenic volatile organic compounds (VOCs). The biogenic CO source for the same period from the oxidation of isoprene and other biogenic VOCs is 8.3 Tg CO, and is independently constrained by ICARTT observations of formaldehyde (HCHO). Anthropogenic emissions of CO in the U.S. have decreased to the point that they are now lower than the biogenic source in summer.Earth and Planetary SciencesEngineering and Applied Science
Enhanced stability of the square lattice of a classical bilayer Wigner crystal
The stability and melting transition of a single layer and a bilayer crystal
consisting of charged particles interacting through a Coulomb or a screened
Coulomb potential is studied using the Monte-Carlo technique. A new melting
criterion is formulated which we show to be universal for bilayer as well as
for single layer crystals in the case of (screened) Coulomb, Lennard--Jones and
1/r^{12} repulsive inter-particle interactions. The melting temperature for the
five different lattice structures of the bilayer Wigner crystal is obtained,
and a phase diagram is constructed as a function of the interlayer distance. We
found the surprising result that the square lattice has a substantial larger
melting temperature as compared to the other lattice structures. This is a
consequence of the specific topology of the defects which are created with
increasing temperature and which have a larger energy as compared to the
defects in e.g. a hexagonal lattice.Comment: Accepted for publication in Physical Review
Topological Defects, Orientational Order, and Depinning of the Electron Solid in a Random Potential
We report on the results of molecular dynamics simulation (MD) studies of the
classical two-dimensional electron crystal in the presence disorder. Our study
is motivated by recent experiments on this system in modulation doped
semiconductor systems in very strong magnetic fields, where the magnetic length
is much smaller than the average interelectron spacing , as well as by
recent studies of electrons on the surface of helium. We investigate the low
temperature state of this system using a simulated annealing method. We find
that the low temperature state of the system always has isolated dislocations,
even at the weakest disorder levels investigated. We also find evidence for a
transition from a hexatic glass to an isotropic glass as the disorder is
increased. The former is characterized by quasi-long range orientational order,
and the absence of disclination defects in the low temperature state, and the
latter by short range orientational order and the presence of these defects.
The threshold electric field is also studied as a function of the disorder
strength, and is shown to have a characteristic signature of the transition.
Finally, the qualitative behavior of the electron flow in the depinned state is
shown to change continuously from an elastic flow to a channel-like, plastic
flow as the disorder strength is increased.Comment: 31 pages, RevTex 3.0, 15 figures upon request, accepted for
publication in Phys. Rev. B., HAF94MD
Population Dynamics and Non-Hermitian Localization
We review localization with non-Hermitian time evolution as applied to simple
models of population biology with spatially varying growth profiles and
convection. Convection leads to a constant imaginary vector potential in the
Schroedinger-like operator which appears in linearized growth models. We
illustrate the basic ideas by reviewing how convection affects the evolution of
a population influenced by a simple square well growth profile. Results from
discrete lattice growth models in both one and two dimensions are presented. A
set of similarity transformations which lead to exact results for the spectrum
and winding numbers of eigenfunctions for random growth rates in one dimension
is described in detail. We discuss the influence of boundary conditions, and
argue that periodic boundary conditions lead to results which are in fact
typical of a broad class of growth problems with convection.Comment: 19 pages, 11 figure
Adaptation of Autocatalytic Fluctuations to Diffusive Noise
Evolution of a system of diffusing and proliferating mortal reactants is
analyzed in the presence of randomly moving catalysts. While the continuum
description of the problem predicts reactant extinction as the average growth
rate becomes negative, growth rate fluctuations induced by the discrete nature
of the agents are shown to allow for an active phase, where reactants
proliferate as their spatial configuration adapts to the fluctuations of the
catalysts density. The model is explored by employing field theoretical
techniques, numerical simulations and strong coupling analysis. For d<=2, the
system is shown to exhibits an active phase at any growth rate, while for d>2 a
kinetic phase transition is predicted. The applicability of this model as a
prototype for a host of phenomena which exhibit self organization is discussed.Comment: 6 pages 6 figur
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