The symbolization of central approximants in the IPA

Approximants that can be considered weaker versions of voiced fricatives (termed here ‘frictionless continuants’) are poorly served by the IPA in terms of symbolization as compared to semi-vowel approximants. In this paper we survey the central approximants and the symbols and diacritics used to transcribe them; we focus on evidence for the use of non-rhotic frictionless continuants in both natural language (by which we mean non-clinical varieties) and disordered speech; and we suggest some possible unitary symbols for those that currently require the use of a hard-to-read lowering diacritic beneath the symbol for the corresponding voiced fricative.

Semiclassical complex angular momentum theory and Pade reconstruction for resonances, rainbows, and reaction thresholds

A semiclassical complex angular momentum theory, used to analyze atom-diatom reactive angular distributions, is applied to several well-known potential (one-particle) problems. Examples include resonance scattering, rainbow scattering, and the Eckart threshold model. Pade reconstruction of the corresponding matrix elements from the values at physical (integral) angular momenta and properties of the Pade approximants are discussed in detail.