674,952 research outputs found
Transfer Matrices and Partition-Function Zeros for Antiferromagnetic Potts Models. V. Further Results for the Square-Lattice Chromatic Polynomial
We derive some new structural results for the transfer matrix of
square-lattice Potts models with free and cylindrical boundary conditions. In
particular, we obtain explicit closed-form expressions for the dominant (at
large |q|) diagonal entry in the transfer matrix, for arbitrary widths m, as
the solution of a special one-dimensional polymer model. We also obtain the
large-q expansion of the bulk and surface (resp. corner) free energies for the
zero-temperature antiferromagnet (= chromatic polynomial) through order q^{-47}
(resp. q^{-46}). Finally, we compute chromatic roots for strips of widths 9 <=
m <= 12 with free boundary conditions and locate roughly the limiting curves.Comment: 111 pages (LaTeX2e). Includes tex file, three sty files, and 19
Postscript figures. Also included are Mathematica files data_CYL.m and
data_FREE.m. Many changes from version 1: new material on series expansions
and their analysis, and several proofs of previously conjectured results.
Final version to be published in J. Stat. Phy
On the shape of the light profiles of early-type galaxies
We have obtained the best fit to the light profiles of a luminosity limited
sample of elliptical and S0 galaxies with a power law \rn, letting the exponent
remain free rather than keeping it fixed at as in the well known \GV
formula. The introduction of a free parameter in the fitting formula (ranging
from for kpc to for kpc) is justified by
the existence of a good correlation between and the global galaxian
parameters, such as total luminosity and scale-radius. This result seems to be
in line with the segregation of properties between the `ordinary' and `bright'
families of early-type galaxies, and has consequence for the claimed
independence of the shape of galaxy profiles with respect to the Fundamental
Plane parameters.Comment: 10 pages, postscript file including figures, PADOVA (archived file
truncated during email transfer
Constrained annealing for spin glasses
The quenched free energy of spin glasses is estimated by means of annealed
averages where the frustration is constrained to its average value. We discuss
the case of d-dimensional Ising models with random nearest neighbour coupling,
and we introduce a new method to obtain constrained annealed averages without
recurring to Lagrange multipliers. It requires to perform quenched averages
either on small volumes in an analytic way, or on finite size strips via
products of random transfer matrices. We thus give a sequence of converging
lower bounds for the quenched free energy of 2d spin glasses.Comment: plane TeX file,24 pages. 6 figures may be requested to Paladin at
vxscaq.aquila.infn.i
A helicoidal transfer matrix model for inhomogeneous DNA melting
An inhomogeneous helicoidal nearest-neighbor model with continuous degrees of
freedom is shown to predict the same DNA melting properties as traditional
long-range Ising models, for free DNA molecules in solution, as well as
superhelically stressed DNA with a fixed linking number constraint. Without
loss of accuracy, the continuous degrees of freedom can be discretized using a
minimal number of discretization points, yielding an effective transfer matrix
model of modest dimension (d=36). The resulting algorithms to compute DNA
melting profiles are both simple and efficient.Comment: v3: Matlab toolbox included with source file; article unchanged, 12
pages, 11 figures, RevTe
ECONOMIC IMPLICATIONS OF THE FAIR ACT ON U.S. PEANUT PRODUCERS
This study analyzed the potential economic impacts of the FAIR Act under GATT and NAFTA on the U.S. peanut industry. Results indicate that the economic impacts of the new program combined with the trade agreements are profound on the peanut industry in both short and long terms. Changes of the peanut program could decrease peanut producers' farm income substantially, eliminate government financial costs related to excessive quotas, and transfer peanut growers' program benefits back to peanut consumers. Increasing imports of foreign peanuts due to free/reduced trade barrier agreements would transfer peanut producers' program benefits to domestic peanut importers and foreign exporters who sell peanuts to the U.S. Note: Tables 3 and 4 not included in machine readable file--contact authors for copies.economic impacts, FAIR Act, peanuts, quota, support price, Agricultural and Food Policy, Crop Production/Industries,
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