8 research outputs found
A Tonnetz Model for pentachords
This article deals with the construction of surfaces that are suitable for
representing pentachords or 5-pitch segments that are in the same class.
It is a generalization of the well known \"Ottingen-Riemann torus for triads of
neo-Riemannian theories. Two pentachords are near if they differ by a
particular set of contextual inversions and the whole contextual group of
inversions produces a Tiling (Tessellation) by pentagons on the surfaces. A
description of the surfaces as coverings of a particular Tiling is given in the
twelve-tone enharmonic scale case.Comment: 27 pages, 12 figure
Shared decision making and antibiotic benefit-harm conversations: an observational study of consultations between general practitioners and patients with acute respiratory infections
Reconciling the statistics of spectral reflectance and colour
The spectral reflectance function of a surface specifies the fraction of the illumination
reflected by it at each wavelength. Jointly with the illumination spectral density, this function
determines the apparent colour of the surface. Models for the distribution of spectral reflectance
functions in the natural environment are considered. The realism of the models is
assessed in terms of the individual reflectance functions they generate, and in terms of the
overall distribution of colours which they give rise to. Both realism assessments are made in
comparison to empirical datasets. Previously described models (PCA- and fourier-based) of
reflectance function statistics are evaluated, as are improved versions; and also a novel
model, which synthesizes reflectance functions as a sum of sigmoid functions. Key model
features for realism are identified. The new sigmoid-sum model is shown to be the most realistic,
generating reflectance functions that are hard to distinguish from real ones, and
accounting for the majority of colours found in natural images with the exception of an abundance
of vegetation green and sky blue