Five-dimensional quasispin toward a complete classification of the isospin characteristics of shell-model states in the seniority scheme

A solution is proposed for the inner multiplicity problem associated with the five-dimensional quasispin description of shell-model states. A classification scheme, in terms of an orthonormal basis, leads to tractable results with definite symmetry properties under particle-hole conjugation. Explicit constructions are given for the R(5) irreducible representations for which the inner multiplicities are never greater than two. For states of seniority v = 2, reduced isospin t = 1, of a configuration jn general expressions are given for the matrix elements of an arbitrary two-body interaction, to determine their n, T dependence, and to isolate those features of the actual interaction among nucleons which are most effective in splitting the isospin degeneracy of such states.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32767/1/0000138.pd

Anterior corneal optical aberrations induced by photorefractive keratectomy for hyperopia

PURPOSE: Photorefractive keratectomy (PRK) for hyperopia requires both a steepening of the central cornea and a flattening of the mid-periphery to achieve its effect and is likely to affect the optical aberrations of the eye. METHODS: Nine patients underwent PRK to correct between +2.00 and +4.00 D of hyperopia (first eye treated for each patient) using the Summit Technology Apex Plus excimer laser, Anterior corneal aberrations for pupil diameters of 3, 5.5 and 7 mm were estimated from corneal topography data (TMS-I), assuming a uni-index, single surface cornea. Refractive error was assessed using retinoscopy and standard subjective tests. RESULTS: Apart from the intended change in refraction (mean spherical equivalent manifest refraction, +4.60 +/- 1.60 D before surgery and +0.70 +/- 1.60 D at 1 year after surgery), the most significant change was in spherical aberration. Anterior corneal spherical aberration was positive (+1.60 +/- 0.60 D for a 5.5-mm pupil) before surgery and became negative after surgery (-1.80 +/- 1.20 IP sat I year). The change in spherical aberration was related to the achieved change in refractive error. CONCLUSIONS: The large change (approximately 3.00 D) in spherical aberration (from positive to negative aberration) has implications for the optical performance of the whole eye, where the effects of lenticular aberration must also be considered