In this article we apply signal detection theory to qualitatively unify the intensity justnoticable difference (JND) and masking data of Wegel and Lane (1924), Fletcher and Munson (1933 – 1938), Miller (1947), and Egan and Hake (1950). We do this by treating the loudness as the first moment, and the intensity JND as the second moment, of the random variable we call the single-trial loudness. Fr...

The standard cold dark matter (CDM) model has recently been challenged by the claim that dwarf galaxies have dark matter haloes with constant density cores, whereas CDM predicts haloes with steeply cusped density distributions. Consequently, numerous alternative dark matter candidates have recently been proposed. In this paper, we scrutinize the observational evidence for the incongruity betwee...

In the euclidean plane, a regular curve can be defined through its intrinsic equation which relates its curvature k to the arc length s. Elastic plane curves were determined this way. If k(s) = 2α cosh(αs) , the curve is known by the name “la courbe des forçats”, introduced in 1729 by Giovanni Poleni in relation with the tractrix [9]. The above equation is yet meaningful on a surface if one int...

If one drops the unicity assumption, (C(D)) is the property of having constant diameter, which is in fact equivalent (for closed curves in the plane) to having constant width or constant breadth (for the definitions and the proof of the equivalence, see [8, chap. 25]). It is a surprise to many (including me !) that curves of constant diameter other that the circle do exist. The simplest example...

We use the tapering effect of Hα/[N II] rotation curves of spiral galaxies first noted by Goad & Roberts (1981) to investigate the internal extinction in disks. The scale length of exponential fits to the inner part of rotation curves depends strongly on the disk axial ratio. Preliminary modelling of the effect implies substantial opacity of the central parts of disks at a wavelength of 0.66 μ....