For Lack of Evidence

Huhn and Morin discuss the quest for truth and the influence of uncertainty in an era where perception and thought are questioned. Fischer explains the state of current uncertainty by the absence of visual evidence in the contemporary world of electronics. Includes comments on works by six Canadian and European artists considering the relative nature of appearances and the current technological context. Biographical notes. 5 bibl. ref

Large-scale volumetric flow measurement in a pure thermal plume by dense tracking of helium-filled soap bubbles

We present a spatially and temporally highly resolved flow measurement covering a !arge volume (~o.6 m3) in a pure thermal plume in air. The thermal plume develops above an extended heat source and is characterized by moderate velocities (U~0.35 m/s) with a Reynolds number of Re~500 and a Rayleigh number of Ra~100000. We demonstrate the requirements and capa bilities of the measurement equipment and the particle tracking approach to be able to probe measurement volumes up to and beyond one cubic meter. The use of !arge tracer particles (300 µm), helium-filled soap bubbles (HFSBs), is crucial and yields high particle image quality over large-volume depths when illuminated with arrays of pulsed high-power LEDs. The experimental limitations of the HFSBs-their limited lifetime and their intensity loss over time-are quantified. The HFSBs' uniform particle images allows an accurate reconstruction of the flow using Shake-The-Box particle tracking with high partlcle concentrations up to 0.1 particles per pixel. This enables tracking of up to 275,000 HFSBs simultaneously. After interpolating the scattered data onto a regular grid with a Navier-Stokes regularization, the velocity field of the thermal plume reveals a multitude of vortices with a smooth temporal evolution and a remarkable coherence in time (see animation, supplementary data). Acceleration fields are also derived from interpolated particle tracks and complement the flow measurement. Additionally, the flow map, the basis of a !arge dass of Lagrangian coherent structures, is computed directly from observed particle tracks. We show entrainment regions and coherent vortices of the thermal plume in the flow map and compute fields of the finite-time Lyapunov exponent

Inside the Visible : An Elliptical Traverse of 20th Century Art in, of, and from the Feminine

This exhibition catalogue, edited by the curator, De Zheger, surveys the contribution of women to 20th century art through the work of 37 artists, splitting the contents into four thematic sections, each of which are divided into three periods: the 1930s-40s, the 1960s-70s, and the 1990s. The four sections address, respectively, feminine plurality and difference, the poetics of alterity, the interweaving of language and space, and finally, materiality and embodiment. Index, 4 p. List of works. Biographical notes. Bibliography 8 p. Circa 660 bibl. ref