3,810 research outputs found
Eigenvectors in the Superintegrable Model I: sl_2 Generators
In order to calculate correlation functions of the chiral Potts model, one
only needs to study the eigenvectors of the superintegrable model. Here we
start this study by looking for eigenvectors of the transfer matrix of the
periodic tau_2(t)model which commutes with the chiral Potts transfer matrix. We
show that the degeneracy of the eigenspace of tau_2(t) in the Q=0 sector is
2^r, with r=(N-1)L/N when the size of the transfer matrix L is a multiple of N.
We introduce chiral Potts model operators, different from the more commonly
used generators of quantum group U-tilde_q(sl-hat(2)). From these we can form
the generators of a loop algebra L(sl(2)). For this algebra, we then use the
roots of the Drinfeld polynomial to give new explicit expressions for the
generators representing the loop algebra as the direct sum of r copies of the
simple algebra sl(2).Comment: LaTeX 2E document, 11 pages, 1 eps figure, using iopart.cls with
graphicx and iopams packages. v2: Appended text to title, added
acknowledgments and made several minor corrections v3: Added reference,
eliminated ambiguity, corrected a few misprint
An analysis of postdural puncture headache in obstetric patients: A study from Kano, Nigeria
Background: One of the complications of spinal anesthesia is postdural puncture headache. Many risk factors have been identified which when addressed could reduce the incidence.Objectives: This was a prospective study that analyzed the incidence, onset and severity of postdural puncture headache among pregnant women who had cesarean section under a subarachnoid block in Aminu Kano Teaching Hospital, Kano, Nigeria.Patients and Methods: Spinal anesthesia was performed on 146 patients using size 25‑ or 26‑gauge Quincke, Whitacre, or Sprotte needles. Patients were followed up to determine the incidence, onset, and severity of post spinal headache. The data were analyzed using Statistical Package for Social Sciences (SPSS) version 18.0 (SPSS Inc., SPSS Statistics for Windows, Chicago, IL, USA). Demographic variables were presented using tables while summary was done using means, standard deviation, and percentages. Test of association was done using Fisher’s Exact test. A P value < 0.05 was considered statistically significant.Results: The overall incidence of postdural puncture headache was 15.8% with all cases presenting within the first 24 hours. Most patients rated their headache as mild to moderate on a 10‑cm visual analogue scale.Conclusion: Traumatic Quincke spinal needle is associated with high incidence of postdural puncture headache and therefore we recommend the use of atraumatic pencil tip needle especially in obstetric anesthesia.Key words: Cesarean section; postdural puncture headache; spinal anesthesia
Factorized finite-size Ising model spin matrix elements from Separation of Variables
Using the Sklyanin-Kharchev-Lebedev method of Separation of Variables adapted
to the cyclic Baxter--Bazhanov--Stroganov or -model, we derive
factorized formulae for general finite-size Ising model spin matrix elements,
proving a recent conjecture by Bugrij and Lisovyy
Investigation of shock waves in the relativistic Riemann problem: A comparison of viscous fluid dynamics to kinetic theory
We solve the relativistic Riemann problem in viscous matter using the
relativistic Boltzmann equation and the relativistic causal dissipative
fluid-dynamical approach of Israel and Stewart. Comparisons between these two
approaches clarify and point out the regime of validity of second-order fluid
dynamics in relativistic shock phenomena. The transition from ideal to viscous
shocks is demonstrated by varying the shear viscosity to entropy density ratio
. We also find that a good agreement between these two approaches
requires a Knudsen number .Comment: Version as published in PRC 82, 024910 (2010); 16 pages, 16 figures,
typos correcte
A deformed analogue of Onsager's symmetry in the XXZ open spin chain
The XXZ open spin chain with general integrable boundary conditions is shown
to possess a q-deformed analogue of the Onsager's algebra as fundamental
non-abelian symmetry which ensures the integrability of the model. This
symmetry implies the existence of a finite set of independent mutually
commuting nonlocal operators which form an abelian subalgebra. The transfer
matrix and local conserved quantities, for instance the Hamiltonian, are
expressed in terms of these nonlocal operators. It follows that Onsager's
original approach of the planar Ising model can be extended to the XXZ open
spin chain.Comment: 12 pages; LaTeX file with amssymb; v2: typos corrected,
clarifications in the text; v3: minor changes in references, version to
appear in JSTA
Symmetries of Large N Matrix Models for Closed Strings
We obtain the symmetry algebra of multi-matrix models in the planar large N
limit. We use this algebra to associate these matrix models with quantum spin
chains. In particular, certain multi-matrix models are exactly solved by using
known results of solvable spin chain systems.Comment: 12 pages, 1 eps figure, RevTex, some minor typos in the publised
version are correcte
In memoriam two distinguished participants of the Bregenz Symmetries in Science Symposia: Marcos Moshinsky and Yurii Fedorovich Smirnov
Some particular facets of the numerous works by Marcos Moshinsky and Yurii
Fedorovich Smirnov are presented in these notes. The accent is put on some of
the common interests of Yurii and Marcos in physics, theoretical chemistry, and
mathematical physics. These notes also contain some more personal memories of
Yurii Smirnov.Comment: Submitted for publication in Journal of Physics: Conference Serie
Three-Dimensional Vertex Model in Statistical Mechanics, from Baxter-Bazhanov Model
We find that the Boltzmann weight of the three-dimensional Baxter-Bazhanov
model is dependent on four spin variables which are the linear combinations of
the spins on the corner sites of the cube and the Wu-Kadanoff duality between
the cube and vertex type tetrahedron equations is obtained explicitly for the
Baxter-Bazhanov model. Then a three-dimensional vertex model is obtained by
considering the symmetry property of the weight function, which is
corresponding to the three-dimensional Baxter-Bazhanov model. The vertex type
weight function is parametrized as the dihedral angles between the rapidity
planes connected with the cube. And we write down the symmetry relations of the
weight functions under the actions of the symmetry group of the cube. The
six angles with a constrained condition, appeared in the tetrahedron equation,
can be regarded as the six spectrums connected with the six spaces in which the
vertex type tetrahedron equation is defined.Comment: 29 pages, latex, 8 pasted figures (Page:22-29
Logarithmic perturbation theory for quasinormal modes
Logarithmic perturbation theory (LPT) is developed and applied to quasinormal
modes (QNMs) in open systems. QNMs often do not form a complete set, so LPT is
especially convenient because summation over a complete set of unperturbed
states is not required. Attention is paid to potentials with exponential tails,
and the example of a Poschl-Teller potential is briefly discussed. A numerical
method is developed that handles the exponentially large wavefunctions which
appear in dealing with QNMs.Comment: 24 pages, 4 Postscript figures, uses ioplppt.sty and epsfig.st
Semiclassical treatment of logarithmic perturbation theory
The explicit semiclassical treatment of logarithmic perturbation theory for
the nonrelativistic bound states problem is developed. Based upon
-expansions and suitable quantization conditions a new procedure for
deriving perturbation expansions for the one-dimensional anharmonic oscillator
is offered. Avoiding disadvantages of the standard approach, new handy
recursion formulae with the same simple form both for ground and exited states
have been obtained. As an example, the perturbation expansions for the energy
eigenvalues of the harmonic oscillator perturbed by are
considered.Comment: 6 pages, LATEX 2.09 using IOP style
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