7,375 research outputs found
Infinite families of superintegrable systems separable in subgroup coordinates
A method is presented that makes it possible to embed a subgroup separable
superintegrable system into an infinite family of systems that are integrable
and exactly-solvable. It is shown that in two dimensional Euclidean or
pseudo-Euclidean spaces the method also preserves superintegrability. Two
infinite families of classical and quantum superintegrable systems are obtained
in two-dimensional pseudo-Euclidean space whose classical trajectories and
quantum eigenfunctions are investigated. In particular, the wave-functions are
expressed in terms of Laguerre and generalized Bessel polynomials.Comment: 19 pages, 6 figure
An infinite family of superintegrable Hamiltonians with reflection in the plane
We introduce a new infinite class of superintegrable quantum systems in the
plane. Their Hamiltonians involve reflection operators. The associated
Schr\"odinger equations admit separation of variables in polar coordinates and
are exactly solvable. The angular part of the wave function is expressed in
terms of little -1 Jacobi polynomials. The spectra exhibit "accidental"
degeneracies. The superintegrability of the model is proved using the
recurrence relation approach. The (higher-order) constants of motion are
constructed and the structure equations of the symmetry algebra obtained.Comment: 19 page
Unit hydrograph characterization of flow regimes leading to a streamflow estimation in ungauged catchments (regionalization)
Corrections to Sirlin's Theorem in Chiral Perturbation Theory
We present the results of the first two-loop calculation of a form factor in
full Chiral Perturbation Theory. We choose a specific
linear combination of and form factors (the one
appearing in Sirlin's theorem) which does not get contributions from order
operators with unknown constants. For the charge radii, the correction to
the previous one-loop result turns out to be significant, but still there is no
agreement with the present data due to large experimental uncertainties in the
kaon charge radii.Comment: 6 pages, Latex, 2 LaTeX figure
Families of superintegrable Hamiltonians constructed from exceptional polynomials
We introduce a family of exactly-solvable two-dimensional Hamiltonians whose
wave functions are given in terms of Laguerre and exceptional Jacobi
polynomials. The Hamiltonians contain purely quantum terms which vanish in the
classical limit leaving only a previously known family of superintegrable
systems. Additional, higher-order integrals of motion are constructed from
ladder operators for the considered orthogonal polynomials proving the quantum
system to be superintegrable
Operator ordering in Two-dimensional N=1 supersymmetry with curved manifold
We investigate an operator ordering problem in two-dimensional N=1
supersymmetric model which consists of n real superfields. There arises an
operator ordering problem when the target space is curved. We have to fix the
ordering in quantum operator properly to obtain the correct supersymmetry
algebra. We demonstrate that the super-Poincar\'{e} algebra fixes the correct
operator ordering. We obtain a supercurrent with correct operator ordering and
a central extension of supersymmetry algebra.Comment: 7 page
Pion and Kaon Electromagnetic Form Factors
We study the electromagnetic form factor of the pion and kaons at
low-energies with the use of Chiral Perturbation Theory. The analysis is
performed within the three flavour framework and at next-to-next-to-leading
order. We explain carefully all the relevant consistency checks on the
expressions, present full analytical results for the pion form factor and
describe all the assumptions in the analysis. From the phenomenological point
of view we make use of our expression and the available data to obtain the
charge radius of the pion obtaining , as well
as the low-energy constant . We also obtain
experimental values for 3 combinations of order constants.Comment: 50 page
Convergence of resonances on thin branched quantum wave guides
We prove an abstract criterion stating resolvent convergence in the case of
operators acting in different Hilbert spaces. This result is then applied to
the case of Laplacians on a family X_\eps of branched quantum waveguides.
Combining it with an exterior complex scaling we show, in particular, that the
resonances on X_\eps approximate those of the Laplacian with ``free''
boundary conditions on , the skeleton graph of X_\eps.Comment: 48 pages, 1 figur
Crohn's disease activity index and Vienna classification - Is it worthwhile to calculate before surgery?
Background: Crohn's disease (CD) patients with increased disease activity may reveal an increased risk for perioperative complications. The `Crohn's disease activity index' (CDAI) and the `Vienna classification' (VC) were developed for standardized disease activity estimations. The significance of these scores to predict extent, type and early outcome of surgery in CD patients was analyzed. Methods: In 179 surgically treated CD patients, the CDAI and VC were assessed from a prospective database. Relations of the scores with CD risk factors, type, number, location and complications of surgery were analyzed. Results: VC behavior and location subtypes were associated with distinct types of surgery (i.e. `strictureplasty' in `stricturing disease', `colon surgery' in `colon involvement'), but not with surgery type and extent or outcome. Surgery extent (i.e. with 5 vs. 3 `surgical sites' 425 +/- 25 vs. 223.3 +/- 25) and complications (357.1 +/- 36.9 (with) vs. 244.4 +/- 13 (without)) were associated with elevated CDAI levels; however, nicotine abuse remained the only significant risk factor for perioperative complications after multiple logistic regression. Conclusion: The significance of VC or CDAI for predicting the extent of surgery or complications is limited. None of the tested variables except preoperative nicotine abuse influenced the likelihood for perioperative complications. Copyright (c) 2006 S. Karger AG, Base
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