5,339 research outputs found
CHANGING ENVIRONMENT FOR FOOD RETAILING IN JAPAN AND SOUTH EAST ASIA
Agribusiness, International Relations/Trade,
AGRICULTURAL TRADE LIBERALIZATION-- IMPACTS ON PRODUCERS
International Relations/Trade,
Low-Income Subsidies for the Medicare Prescription Drug Benefit: The Impact of the Asset Test
Assesses the impact of the requirement that low-income individuals with Medicare meet an asset test in order to receive additional help paying premiums and cost sharing under the new Medicare drug benefit. Raises questions about the equity of the test
Multicanonical analysis of the plaquette-only gonihedric Ising model and its dual
The three-dimensional purely plaquette gonihedric Ising model and its dual
are investigated to resolve inconsistencies in the literature for the values of
the inverse transition temperature of the very strong temperature-driven
first-order phase transition that is apparent in the system. Multicanonical
simulations of this model allow us to measure system configurations that are
suppressed by more than 60 orders of magnitude compared to probable states.
With the resulting high-precision data, we find excellent agreement with our
recently proposed nonstandard finite-size scaling laws for models with a
macroscopic degeneracy of the low-temperature phase by challenging the
prefactors numerically. We find an overall consistent inverse transition
temperature of 0.551334(8) from the simulations of the original model both with
periodic and fixed boundary conditions, and the dual model with periodic
boundary conditions. For the original model with periodic boundary conditions,
we obtain the first reliable estimate of the interface tension, 0.12037(18),
using the statistics of suppressed configurations
Macroscopic Degeneracy and order in the 3d plaquette Ising model
The purely plaquette 3d Ising Hamiltonian with the spins living at the
vertices of a cubic lattice displays several interesting features. The
symmetries of the model lead to a macroscopic degeneracy of the low-temperature
phase and prevent the definition of a standard magnetic order parameter.
Consideration of the strongly anisotropic limit of the model suggests that a
layered, "fuki-nuke" order still exists and we confirm this with multicanonical
simulations. The macroscopic degeneracy of the low-temperature phase also
changes the finite-size scaling corrections at the first-order transition in
the model and we see this must be taken into account when analysing our
measurements.Comment: arXiv admin note: text overlap with arXiv:1412.442
Exact solutions to plaquette Ising models with free and periodic boundaries
An anisotropic limit of the 3d plaquette Ising model, in which the plaquette
couplings in one direction were set to zero, was solved for free boundary
conditions by Suzuki (Phys. Rev. Lett. 28 (1972) 507), who later dubbed it the
fuki-nuke, or "no-ceiling", model. Defining new spin variables as the product
of nearest-neighbour spins transforms the Hamiltonian into that of a stack of
(standard) 2d Ising models and reveals the planar nature of the magnetic order,
which is also present in the fully isotropic 3d plaquette model. More recently,
the solution of the fuki-nuke model was discussed for periodic boundary
conditions, which require a different approach to defining the product spin
transformation, by Castelnovo et al. (Phys. Rev. B 81 (2010) 184303).
We clarify the exact relation between partition functions with free and
periodic boundary conditions expressed in terms of original and product spin
variables for the 2d plaquette and 3d fuki-nuke models, noting that the
differences are already present in the 1d Ising model. In addition, we solve
the 2d plaquette Ising model with helical boundary conditions. The various
exactly solved examples illustrate how correlations can be induced in finite
systems as a consequence of the choice of boundary conditions.Comment: v5 - The title is changed to better reflect the contents and the
exposition is streamlined. Version accepted for publicatio
The Burden of Out-of-Pocket Health Spending Among Older Versus Younger Adults: Analysis from the Consumer Expenditure Survey, 1998-2003
Analyzes the extent to which health care spending as a share of income has differed among younger adults versus people ages 65 and older, both at a single point in time (2003) and over the six-year period from 1998 to 2003
A New and Unifying Approach to Spin Dynamics and Beam Polarization in Storage Rings
With this paper we extend our studies [1] on polarized beams by distilling
tools from the theory of principal bundles. Four major theorems are presented,
one which ties invariant fields with the notion of normal form, one which
allows one to compare different invariant fields, and two that relate the
existence of invariant fields to the existence of certain invariant sets and
relations between them. We then apply the theory to the dynamics of spin-1/2
and spin-1 particles and their density matrices describing statistically the
particle-spin content of bunches. Our approach thus unifies the spin-vector
dynamics from the T-BMT equation with the spin-tensor dynamics and other
dynamics. This unifying aspect of our approach relates the examples elegantly
and uncovers relations between the various underlying dynamical systems in a
transparent way
An Informal Summary of a New Formalism for Classifying Spin-Orbit Systems Using Tools Distilled from the Theory of Bundles
We give an informal summary of ongoing work which uses tools distilled from
the theory of fibre bundles to classify and connect invariant fields associated
with spin motion in storage rings. We mention four major theorems. One ties
invariant fields with the notion of normal form, the second allows comparison
of different invariant fields and the two others tie the existence of invariant
fields to the existence of certain invariant sets. We explain how the theorems
apply to the spin dynamics of spin- and spin- particles. Our approach
elegantly unifies the spin-vector dynamics from the T-BMT equation with the
spin-tensor dynamics and other dynamics and suggests an avenue for addressing
the question of the existence of the invariant spin field.Comment: Based on a presentation at Spin2014, The 21st International Symposium
on Spin Physics, Beijing, China, October 2014. To be published in the
International Journal of Modern Physics, Conference Serie
The Wrong Kind of Gravity
The KPZ formula shows that coupling central charge less than one spin models
to 2D quantum gravity dresses the conformal weights to get new critical
exponents, where the relation between the original and dressed weights depends
only on the central charge. At the discrete level the coupling to 2D gravity is
effected by putting the spin models on annealed ensembles of planar random
graphs or their dual triangulations, where the connectivity fluctuates on the
same time-scale as the spins.
Since the sole determining factor in the dressing is the central charge, one
could contemplate putting a spin model on a quenched ensemble of 2D gravity
graphs with the ``wrong'' central charge. We might then expect to see the
critical exponents appropriate to the central charge used in generating the
graphs. In such cases the KPZ formula could be interpreted as giving a
continuous line of critical exponents which depend on this central charge. We
note that rational exponents other than the KPZ values can be generated using
this procedure for the Ising, tricritical Ising and 3-state Potts models.Comment: 8 pages, no figure
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