881 research outputs found
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
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
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
Human-animal relationships and interactions during the Covid-19 lockdown phase in the UK: Investigating links with mental health and loneliness
BACKGROUND: The Covid-19 pandemic raises questions about the role that relationships and interactions between humans and animals play in the context of widespread social distancing and isolation measures. We aimed to investigate links between mental health and loneliness, companion animal ownership, the human-animal bond, and human-animal interactions; and to explore animal owners' perceptions related to the role of their animals during lockdown. METHODS: A cross-sectional online survey of UK residents over 18 years of age was conducted between April and June 2020. The questionnaire included validated and bespoke items measuring demographics; exposures and outcomes related to mental health, wellbeing and loneliness; the human-animal bond and human-animal interactions. RESULTS: Of 5,926 participants, 5,323 (89.8%) had at least one companion animal. Most perceived their animals to be a source of considerable support, but concerns were reported related to various practical aspects of providing care during lockdown. Strength of the human-animal bond did not differ significantly between species. Poorer mental health pre-lockdown was associated with a stronger reported human-animal bond (b = -.014, 95% CI [-.023 - -.005], p = .002). Animal ownership compared with non-ownership was associated with smaller decreases in mental health (b = .267, 95% CI [.079 - .455], p = .005) and smaller increases in loneliness (b = -.302, 95% CI [-.461 - -.144], p = .001) since lockdown. CONCLUSION: The human-animal bond is a construct that may be linked to mental health vulnerability in animal owners. Strength of the human-animal bond in terms of emotional closeness or intimacy dimensions appears to be independent of animal species. Animal ownership seemed to mitigate some of the detrimental psychological effects of Covid-19 lockdown. Further targeted investigation of the role of human-animal relationships and interactions for human health, including testing of the social buffering hypothesis and the development of instruments suited for use across animal species, is required
Sliding Phases in XY-Models, Crystals, and Cationic Lipid-DNA Complexes
We predict the existence of a totally new class of phases in weakly coupled,
three-dimensional stacks of two-dimensional (2D) XY-models. These ``sliding
phases'' behave essentially like decoupled, independent 2D XY-models with
precisely zero free energy cost associated with rotating spins in one layer
relative to those in neighboring layers. As a result, the two-point spin
correlation function decays algebraically with in-plane separation. Our
results, which contradict past studies because we include higher-gradient
couplings between layers, also apply to crystals and may explain recently
observed behavior in cationic lipid-DNA complexes.Comment: 4 pages of double column text in REVTEX format and 1 postscript
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A variational study of the random-field XY model
A disorder-dependent Gaussian variational approach is applied to the
-dimensional ferromagnetic XY model in a random field. The randomness yields
a non extensive contribution to the variational free energy, implying a random
mass term in correlation functions. The Imry-Ma low temperature result,
concerning the existence () or absence () of long-range order is
obtained in a transparent way. The physical picture which emerges below
is that of a marginally stable mixture of domains. We also calculate within
this variational scheme, disorder dependent correlation functions, as well as
the probability distribution of the Imry-Ma domain size.Comment: 14 pages, latex fil
Squeezing superfluid from a stone: Coupling superfluidity and elasticity in a supersolid
In this work we start from the assumption that normal solid to supersolid
(NS-SS) phase transition is continuous, and develop a phenomenological Landau
theory of the transition in which superfluidity is coupled to the elasticity of
the crystalline He lattice. We find that the elasticity does not affect the
universal properties of the superfluid transition, so that in an unstressed
crystal the well-known -anomaly in the heat capacity of the superfluid
transition should also appear at the NS-SS transition. We also find that the
onset of supersolidity leads to anomalies in the elastic constants near the
transition; conversely, inhomogeneous strains in the lattice can induce local
variations of the superfluid transition temperature, leading to a broadened
transition.Comment: 4 page
Elastic Theory of pinned flux lattices
The pinning of flux lattices by weak impurity disorder is studied in the
absence of free dislocations using both the gaussian variational method and, to
, the functional renormalization group. We find universal
logarithmic growth of displacements for : and persistence of algebraic quasi-long range
translational order. When the two methods can be compared they agree within
on the value of . We compute the function describing the crossover
between the ``random manifold'' regime and the logarithmic regime. This
crossover should be observable in present decoration experiments.Comment: 12 pages, Revtex 3.
Iterated Moire Maps and Braiding of Chiral Polymer Crystals
In the hexagonal columnar phase of chiral polymers a bias towards cholesteric
twist competes with braiding along an average direction. When the chirality is
strong, screw dislocations proliferate, leading to either a tilt grain boundary
phase or a new "moire state" with twisted bond order. Polymer trajectories in
the plane perpendicular to their average direction are described by iterated
moire maps of remarkable complexity.Comment: 10 pages (plain tex) 3 figures uufiled and appende
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