3,829 research outputs found
Smooth Random Surfaces from Tight Immersions?
We investigate actions for dynamically triangulated random surfaces that
consist of a gaussian or area term plus the {\it modulus} of the gaussian
curvature and compare their behavior with both gaussian plus extrinsic
curvature and ``Steiner'' actions.Comment: 7 page
Crossover Between Weakly and Strongly Self-avoiding Random Surfaces
We investigate the crossover between weak and strong self-avoidance in a
simulation of random surfaces with extrinsic curvature. We consider both
dynamically triangulated and rigid surfaces with the two possible
discretizations of the extrinsic curvature term.Comment: 5 page
An Effective Model for Crumpling in Two Dimensions?
We investigate the crumpling transition for a dynamically triangulated random
surface embedded in two dimensions using an effective model in which the
disordering effect of the variables on the correlations of the normals is
replaced by a long-range ``antiferromagnetic'' term. We compare the results
from a Monte Carlo simulation with those obtained for the standard action which
retains the 's and discuss the nature of the phase transition.Comment: 5 page
Ising Model Coupled to Three-Dimensional Quantum Gravity
We have performed Monte Carlo simulations of the Ising model coupled to
three-dimensional quantum gravity based on a summation over dynamical
triangulations. These were done both in the microcanonical ensemble, with the
number of points in the triangulation and the number of Ising spins fixed, and
in the grand canoncal ensemble. We have investigated the two possible cases of
the spins living on the vertices of the triangulation (``diect'' case) and the
spins living in the middle of the tetrahedra (``dual'' case). We observed phase
transitions which are probably second order, and found that the dual
implementation more effectively couples the spins to the quantum gravity.Comment: 11 page
Person-centred oral hydration care for older people with dementia admitted to acute hospital wards: Empirical research qualitative.
To conduct an in-depth exploration of oral hydration care provided to people living with dementia in acute hospital wards, using a person-centred care framework. Oral hydration care is an important, yet rarely explored aspect of fundamental care for people with dementia admitted to acute hospitals. Using person-centred care as a conceptual framework we investigated how oral hydration care is delivered for people living with dementia in acute hospital wards. A qualitative, multiple-case study. The cases were three acute wards in one hospital. Direct observation of care for 13 people with dementia (132 h), semistructured interviews with ward staff (n = 28), ward leaders (n = 4), organisational leaders (n = 5), people with dementia (n = 6), their relatives (n = 5), documentary analysis of clinical inpatient records (n = 26) and relevant hospital policies. Data were analysed using framework analysis. Four themes were identified: (1) The acute hospital: oral hydration is obscured and not prioritised (2) Overshadowing of oral hydration at ward level (3) Siloed nature of hydration roles (4) Strategies for, and barriers to, delivering person-centred oral hydration care. This study combines the concept of person-centred care and oral hydration care for people living with dementia admitted to acute hospital wards, demonstrating that person-centred hydration care was complex and not prioritised. Nurses should consider means of improving prioritisation and cohesive delivery of person-centred hydration care in acute hospital wards. [Abstract copyright: © 2023 The Authors. Journal of Clinical Nursing published by John Wiley & Sons Ltd.
Thin absolute villains
We perform simulations of an absolute value version of the Villain model on phi3 and phi4 Feynman diagrams, ``thin'' 3-regular and 4-regular random graphs. The phi4 results are in excellent quantitative agreement with the exact calculations by Dorey and Kurzepa for an annealed ensemble of thin graphs, in spite of simulating only a single graph of each size. We also derive exact results for an annealed ensemble of phi3 graphs and again find excellent agreement with the numerical data for single phi3 graphs. The simulations confirm the picture of a mean field vortex transition which is suggested by the analytical results. Further simulations on phi5 and phi6 graphs and of the standard XY model on phi3 graphs confirm the universality of these results. The calculations of Dorey and Kurzepa were based on reinterpreting the large orders behaviour of the anharmonic oscillator in a statistical mechanical context so we also discuss briefly the interpretation of singularities in the large orders behaviour in other models as phase transitions
A Potts/Ising Correspondence on Thin Graphs
We note that it is possible to construct a bond vertex model that displays
q-state Potts criticality on an ensemble of phi3 random graphs of arbitrary
topology, which we denote as ``thin'' random graphs in contrast to the fat
graphs of the planar diagram expansion.
Since the four vertex model in question also serves to describe the critical
behaviour of the Ising model in field, the formulation reveals an isomorphism
between the Potts and Ising models on thin random graphs. On planar graphs a
similar correspondence is present only for q=1, the value associated with
percolation.Comment: 6 pages, 5 figure
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