2,165 research outputs found
Random Matrix Theory and Classical Statistical Mechanics. I. Vertex Models
A connection between integrability properties and general statistical
properties of the spectra of symmetric transfer matrices of the asymmetric
eight-vertex model is studied using random matrix theory (eigenvalue spacing
distribution and spectral rigidity). For Yang-Baxter integrable cases,
including free-fermion solutions, we have found a Poissonian behavior, whereas
level repulsion close to the Wigner distribution is found for non-integrable
models. For the asymmetric eight-vertex model, however, the level repulsion can
also disappearand the Poisson distribution be recovered on (non Yang--Baxter
integrable) algebraic varieties, the so-called disorder varieties. We also
present an infinite set of algebraic varieties which are stable under the
action of an infinite discrete symmetry group of the parameter space. These
varieties are possible loci for free parafermions. Using our numerical
criterion we have tested the generic calculability of the model on these
algebraic varieties.Comment: 25 pages, 7 PostScript Figure
The diagonal Ising susceptibility
We use the recently derived form factor expansions of the diagonal two-point
correlation function of the square Ising model to study the susceptibility for
a magnetic field applied only to one diagonal of the lattice, for the isotropic
Ising model.
We exactly evaluate the one and two particle contributions
and of the corresponding susceptibility, and obtain linear
differential equations for the three and four particle contributions, as well
as the five particle contribution , but only modulo a given
prime. We use these exact linear differential equations to show that, not only
the russian-doll structure, but also the direct sum structure on the linear
differential operators for the -particle contributions are
quite directly inherited from the direct sum structure on the form factors .
We show that the particle contributions have their
singularities at roots of unity. These singularities become dense on the unit
circle as .Comment: 18 page
Analytical evidence for the absence of spin glass transition on self-dual lattices
We show strong evidence for the absence of a finite-temperature spin glass
transition for the random-bond Ising model on self-dual lattices. The analysis
is performed by an application of duality relations, which enables us to derive
a precise but approximate location of the multicritical point on the Nishimori
line. This method can be systematically improved to presumably give the exact
result asymptotically. The duality analysis, in conjunction with the
relationship between the multicritical point and the spin glass transition
point for the symmetric distribution function of randomness, leads to the
conclusion of the absence of a finite-temperature spin glass transition for the
case of symmetric distribution. The result is applicable to the random bond
Ising model with or Gaussian distribution and the Potts gauge glass on
the square, triangular and hexagonal lattices as well as the random three-body
Ising model on the triangular and the Union-Jack lattices and the four
dimensional random plaquette gauge model. This conclusion is exact provided
that the replica method is valid and the asymptotic limit of the duality
analysis yields the exact location of the multicritical pointComment: 11 Pages, 4 figures, 1 table. submitted to J. Phys. A Math. Theo
Symmetry, complexity and multicritical point of the two-dimensional spin glass
We analyze models of spin glasses on the two-dimensional square lattice by
exploiting symmetry arguments. The replicated partition functions of the Ising
and related spin glasses are shown to have many remarkable symmetry properties
as functions of the edge Boltzmann factors. It is shown that the applications
of homogeneous and Hadamard inverses to the edge Boltzmann matrix indicate
reduced complexities when the elements of the matrix satisfy certain
conditions, suggesting that the system has special simplicities under such
conditions. Using these duality and symmetry arguments we present a conjecture
on the exact location of the multicritical point in the phase diagram.Comment: 32 pages, 6 figures; a few typos corrected. To be published in J.
Phys.
Patient-reported healthcare expectations in inflammatory bowel diseases.
BACKGROUND: Patient-reported experience is an important component of a holistic approach to quality of care. Patients' expectations of treatments and global disease management may indicate their illness representations and their satisfaction and hopes regarding quality of care.
OBJECTIVE: To study expectations of patients with inflammatory bowel disease.
METHODS: Two focus groups were conducted with 14 patients to explore their expectations about treatments and disease management. From qualitative content analyses of focus group discussions, we built a 22-item expectations questionnaire that was sent to 1756 patients of the Swiss IBD cohort. Answers were collected on a visual analog scale from 0 to 100, and medians (interquartile range [IQR]) calculated. Factor analysis identified main expectation dimensions, and multivariate analyses were performed to describe associations with patient characteristics.
RESULTS: Of 1094 patients (62%) included in the study, 54% were female, 54% had Crohn's disease, 35% had tertiary education, and 72% were employed. Expectation dimensions comprised realistic, predictive, and ideal expectations and were linked to information, communication, daily care, and disease recognition. Half (11 of 22) of the expectations were ranked as very high (median score > 70), the 2 most important being good coordination between general practitioners and specialists (median score: 89, IQR: 71-96) and information on treatment adverse events (89, IQR: 71-96). Women had overall higher levels of expectations than did men. Expectations were not associated with psychosocial measures, except those related to disease recognition, and most of them were highly associated with increased concerns on disease constraints and uncertainty.
CONCLUSIONS: Patients have high expectations for information and communication among caregivers, the levels varying by gender and region. Patients also appear to request more active participation in their disease management
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