1,842 research outputs found
The Lee-Yang theory of equilibrium and nonequilibrium phase transitions
We present a pedagogical account of the Lee-Yang theory of equilibrium phase
transitions and review recent advances in applying this theory to
nonequilibrium systems. Through both general considerations and explicit
studies of specific models, we show that the Lee-Yang approach can be used to
locate and classify phase transitions in nonequilibrium steady states.Comment: 24 pages, 7 papers, invited paper for special issue of The Brazilian
Journal of Physic
Discontinuous Transition in a Boundary Driven Contact Process
The contact process is a stochastic process which exhibits a continuous,
absorbing-state phase transition in the Directed Percolation (DP) universality
class. In this work, we consider a contact process with a bias in conjunction
with an active wall. This model exhibits waves of activity emanating from the
active wall and, when the system is supercritical, propagating indefinitely as
travelling (Fisher) waves. In the subcritical phase the activity is localised
near the wall. We study the phase transition numerically and show that certain
properties of the system, notably the wave velocity, are discontinuous across
the transition. Using a modified Fisher equation to model the system we
elucidate the mechanism by which the the discontinuity arises. Furthermore we
establish relations between properties of the travelling wave and DP critical
exponents.Comment: 14 pages, 9 figure
Representing older people: towards meaningful images of the user in design scenarios
Designing for older people requires the consideration of a range of difficult and sometimes highly personal design problems. Issues such as fear, loneliness, dependency, and physical decline may be difficult to observe or discuss in interviews. Pastiche scenarios and pastiche personae are techniques that employ characters to create a space for the discussion of new technological developments and as a means to explore user experience. This paper argues that the use of such characters can help to overcome restrictive notions of older people by disrupting designers' prior assumptions.
In this paper, we reflect on our experiences using pastiche techniques in two separate technology design projects that sought to address the needs of older people. In the first case pastiche scenarios were developed by the designers of the system and used as discussion documents with users. In the second case, pastiche personae were used by groups of users themselves to generate scenarios which were scribed for later use by the design team. We explore how the use of fictional characters and settings can generate new ideas and undermine rhetorical devices within scenarios that attempt to fit characters to the technology, rather than vice versa.
To assist in future development of pastiche techniques in designing for older people, we provide an array of fictional older characters drawn from literary and popular culture.</p
Spatial fluctuations of a surviving particle in the trapping reaction
We consider the trapping reaction, , where and particles
have a diffusive dynamics characterized by diffusion constants and .
The interaction with particles can be formally incorporated in an effective
dynamics for one particle as was recently shown by Bray {\it et al}. [Phys.
Rev. E {\bf 67}, 060102 (2003)]. We use this method to compute, in space
dimension , the asymptotic behaviour of the spatial fluctuation,
, for a surviving particle in the perturbative regime,
, for the case of an initially uniform distribution of
particles. We show that, for , with
. By contrast, the fluctuations of paths constrained to return to
their starting point at time grow with the larger exponent 1/3. Numerical
tests are consistent with these predictions.Comment: 10 pages, 5 figure
Unconsciously motivated behavior : an assessment of Freud\u27s theory of the dynamic unconscious and the empirical and theoretical objections raised to it, with some preliminary implications for Christian psychology
https://place.asburyseminary.edu/ecommonsatsdissertations/1926/thumbnail.jp
Book Reviews: Clinical Experiences, Indoctrination and Education in Alcoholism
HEAVY DRINKING: THE MYTH OF ALCOHOLISM AS A DISEASE
Herbert Fingarette
Berkeley, University of California Press 1988, 166 page
Relaxation time in a non-conserving driven-diffusive system with parallel dynamics
We introduce a two-state non-conserving driven-diffusive system in
one-dimension under a discrete-time updating scheme. We show that the
steady-state of the system can be obtained using a matrix product approach. On
the other hand, the steady-state of the system can be expressed in terms of a
linear superposition Bernoulli shock measures with random walk dynamics. The
dynamics of a shock position is studied in detail. The spectrum of the transfer
matrix and the relaxation times to the steady-state have also been studied in
the large-system-size limit.Comment: 10 page
Noise-induced dynamical transition in systems with symmetric absorbing states
We investigate the effect of noise strength on the macroscopic ordering
dynamics of systems with symmetric absorbing states. Using an explicit
stochastic microscopic model, we present evidence for a phase transition in the
coarsening dynamics, from an Ising-like to a voter-like behavior, as the noise
strength is increased past a nontrivial critical value. By mapping to a thermal
diffusion process, we argue that the transition arises due to locally-absorbing
states being entered more readily in the high-noise regime, which in turn
prevents surface tension from driving the ordering process.Comment: v2 with improved introduction and figures, to appear in PRL. 4 pages,
4 figure
- …