First order quantum corrections to the classical reflection factor of the sinh-Gordon model

The sinh-Gordon model is restricted to a half-line by boundary conditions maintaining integrability. A perturbative calculation of the reflection factor is given to one loop order in the bulk coupling and to first order in the difference of the two parameters introduced at the boundary, providing a further verification of Ghoshal's formula. The calculation is consistent with a conjecture for the general dependence of the reflection factor on the boundary parameters and the bulk coupling.Comment: 16 pages, 1 figur

Boundary breathers in the sinh-Gordon model

We present an investigation of the boundary breather states of the sinh-Gordon model restricted to a half-line. The classical boundary breathers are presented for a two parameter family of integrable boundary conditions. Restricting to the case of boundary conditions which preserve the \phi --> -\phi symmetry of the bulk theory, the energy spectrum of the boundary states is computed in two ways: firstly, by using the bootstrap technique and subsequently, by using a WKB approximation. Requiring that the two descriptions of the spectrum agree with each other allows a determination of the relationship between the boundary parameter, the bulk coupling constant, and the parameter appearing in the reflection factor derived by Ghoshal to describe the scattering of the sinh-Gordon particle from the boundary.Comment: 16 pages amslate

On duality and reflection factors for the sinh-Gordon model

The sinh-Gordon model with integrable boundary conditions is considered in low order perturbation theory. It is pointed out that results obtained by Ghoshal for the sine-Gordon breather reflection factors suggest an interesting dual relationship between models with different boundary conditions. Ghoshal's formula for the lightest breather is checked perturbatively to $O(\beta^2)$ in the special set of cases in which the $\phi\to -\phi$ symmetry is maintained. It is noted that the parametrisation of the boundary potential which is natural for the semi-classical approximation also provides a good parametrisation at the `free-fermion' point.Comment: 17 pages, harvmac(b

The eyes of suckermouth armoured catfish (Loricariidae, subfamily Hypostomus): pupil response, lenticular longitudinal spherical aberration and retinal topography

The dilated, round pupils of a species of suckermouth armoured catfish (Liposarcus pardalis) constrict slowly on illumination (over 35-40 min) to form crescent-shaped apertures. Ray tracing of He-Ne laser beams shows that the lenses of a related species (Pterygoplichthys etentaculus), which also has a crescent-shaped pupil, are well corrected for longitudinal spherical aberration, suggesting that the primary purpose of the irregular pupil in armoured catfish is not to correct such aberration. It is suggested that the iris operculum may serve to camouflage the pupil of these substrate-dwelling species. An examination of the catfish retina shows the photoreceptors to be exclusively single cones interspersed with elongate rods and demonstrates the presence of multiple optic nerve head papillae. Two areas of high ganglion cell density, each side of a vertically oriented falciform process, provide increased spatial resolving power along the axes examining the substrate in front of and behind the animal

Semiclassical analysis of defect sine-Gordon theory

The classical sine-Gordon model is a two-dimensional integrable field theory, with particle like solutions the so-called solitons. Using its integrability one can define its quantum version without the process of canonical quantization. This bootstrap method uses the fundamental propterties of the model and its quantum features in order to restrict the structure of the scattering matrix as far as possible. The classical model can be extended with integrable discontinuities, purely transmitting jump-defects. Then the quantum version of the extended model can be determined via the bootstrap method again. But the outcoming quantum theory contains the so-called CDD uncertainity. The aim of this article is to carry throw the semiclassical approximation in both the classical and the quantum side of the defect sine-Gordon theory. The CDD ambiguity can be restricted by comparing the two results. The relation between the classical and quantum parameters as well as the resoncances appeared in the spectrum are other objectives

Using handheld pocket computers in a wireless telemedicine system

Objectives: To see if senior emergency nurse practitioners can provide support to inexperienced ones in a Minor Injuries Unit by using a wireless LAN system of telemedicine transmitting images to a PDA when they were on duty. In addition, whether such a system could be sufficiently accurate to make clinical diagnoses with a high level of diagnostic confidence. This would permit an overall lower grade of nurse to be employed to manage most of the cases as they arrive with a proportionate lowering of costs. Methods: The wireless LAN equipment could roam in the Minor Injuries Unit and the experienced emergency Nurse practitioners could be at home, shopping or even at a considerable distance from the centre. Thirty pictorial images of patients who had been sent to the Review Clinic were transmitted to a PDA various distances of one to sixteen miles from the centre. Two senior emergency nurse practitioners viewed the images and opined on the diagnosis, their degree of confidence in the diagnosis and their opinion of the quality of the image. Results: the images of patients were sharp, clear, and of diagnostic quality. The image quality was only uncertain, as was the level of confidence of the diagnosis if the patient was very dark skinned. Conclusions: The wireless LAN system works with a remote PDA in this clinical situation. However there are question marks over the availability of enough experienced emergency nurse practitioners to staff a service that provides senior cover for longer parts of the day and at weekends

Boundary Reflection Matrix for D4(1)D_4^{(1)} Affine Toda Field Theory

We present one loop boundary reflection matrix for $d_4^{(1)}$ Toda field theory defined on a half line with the Neumann boundary condition. This result demonstrates a nontrivial cancellation of non-meromorphic terms which are present when the model has a particle spectrum with more than one mass. Using this result, we determine uniquely the exact boundary reflection matrix which turns out to be \lq non-minimal' if we assume the strong-weak coupling \lq duality'.Comment: 14 pages, Late

Quantum boundary currents for nonsimply-laced Toda theories

We study the quantum integrability of nonsimply--laced affine Toda theories defined on the half--plane and explicitly construct the first nontrivial higher--spin charges in specific examples. We find that, in contradistinction to the classical case, addition of total derivative terms to the "bulk" current plays a relevant role for the quantum boundary conservation.Comment: 11 pages, latex, no figure

Properties of non-BPS SU(3) monopoles

This paper is concerned with magnetic monopole solutions of SU(3) Yang-Mills-Higgs system beyond the Bogomol'nyi-Prasad-Sommerfield limit. The different SU(2) embeddings, which correspond to the fundamental monopoles, as well the embedding along composite root are studied. The interaction of two different fundamental monopoles is considered. Dissolution of a single fundamental non-BPS SU(3) monopole in the limit of the minimal symmetry breaking is analysed.Comment: 19 pages, 7 figures. Typos corrected, reference added. Final version published in Physica Script