Secondary stress in Brazilian Portuguese: the interplay between production and perception studies

This paper reports experiments on speech production showing that secondary stress in Brazilian Portuguese (BP) can be best described as phrase-initial prominence cued by greater duration and pitch accent excursion in initial position. It also reports a perception experiment in which clicks were associated to consecutive V-to-V positions in stress groups. Mean click detection RTs are gradient, but show no influence of initial lengthening. RTs near the phrasally stressed position are shorter and almost 60% of RT variance can be accounted for by produced timing patterns

Spacetime algebraic skeleton

The cosmological constant Lambda, which has seemingly dominated the primaeval Universe evolution and to which recent data attribute a significant present-time value, is shown to have an algebraic content: it is essentially an eigenvalue of a Casimir invariant of the Lorentz group which acts on every tangent space. This is found in the context of de Sitter spacetimes but, as every spacetime is a 4-manifold with Minkowski tangent spaces, the result suggests the existence of a "skeleton" algebraic structure underlying the geometry of general physical spacetimes. Different spacetimes come from the "fleshening" of that structure by different tetrad fields. Tetrad fields, which provide the interface between spacetime proper and its tangent spaces, exhibit to the most the fundamental role of the Lorentz group in Riemannian spacetimes, a role which is obscured in the more usual metric formalism.Comment: 13 page

Generalized Convolution Roots of Positive Definite Kernels on Complex Spheres

Convolution is an important tool in the construction of positive definite kernels on a manifold. This contribution provides conditions on an $L^2$-positive definite and zonal kernel on the unit sphere of $\mathbb{C}^q$ in order that the kernel can be recovered as a generalized convolution root of an equally positive definite and zonal kernel