An experiment to detect gravity at sub-mm scale with high-Q mechanical oscillators

Silicon double paddle oscillators are well suited for the detection of weak forces because of their high Q factor (about 10^5 at room temperature). We describe an experiment aimed at the detection of gravitational forces between masses at sub-mm distance using such an oscillator. Gravitational excitation is produced by a rotating aluminium disk with platinum segments. The force sensitivity of this apparatus is about 10 fN at room temperature for 1000 s averaging time at room temperature. The current limitations to detection of the gravitational force are mentioned.Comment: 19 pages, to appear in Proceedings of the Tenth Marcel Grossmann Meeting on General Relativity, edited by M. Novello, S. Perez-Bergliaffa and R. Ruffini, World Scientific. Revision: portable format and revised figure

Changing tune in Woodstock: Creative industries and local urban development in Cape Town, South Africa

Since the beginning of the new millennium, a plethora of works has been published on the making of the ‘creative city’ and the urban impact of the creative economy. So far, however, limited recognition has been given to how the development of cultural industries and the creative economy as a whole influences urban transformation in the rapidly urbanising Global South, especially in Africa. In Cape Town, a steadily growing number of creative industries and ‘culturepreneurs’ (Lange 2005) are carving out new spaces from the city’s highly contested urban setting. Over the past five years, the mixed-use, inner-city fringe area of Woodstock has seen the incessant arrival of creatives from various sectors. Travelling alongside is a property sector geared towards catering specifically for the creative industries’ spatial demands by turning old industrial structures – the remains of Woodstock’s former capacity as national hub for clothing, food processing and other light manufacturing – into creative centres hosting international film studios, leading galleries and designer ‘theatre retail spaces’. After setting the stage through a comprehensive introduction to the rise of the creative economy in South Africa and Cape Town, this article tunes into the current local development of Woodstock, based on extensive field research in the area. It traces ways and forms of conflict but also new social interfaces between the new creative tenants and the old established community, on the one hand pointing to problematic issues like lingering gentrification, sociospatial polarisation and lopsided cultural representation while also trying to flesh out some of the opportunities for finding the right frequency of engagement between creative industries and spaces of vernacular creativity within Cape Town’s post-apartheid urban realm. Keywords: Creative economy, creative city, Global South, urban regeneration, gentrification, vernacular creativit

Few-Body Physics in a Three-Component Fermi Gas

This thesis reports on the first production of a degenerate three-component Fermi gas in equilibrium. The sample consists of 6Li atoms in the three lowest Zeeman sublevels. Its production is enabled through the control of interactions by means of Feshbach resonances. For weak interactions the three-state mixture exhibits a remarkable stability with lifetimes exceeding 30 seconds. This represents an excellent starting point for future experiments. In the course of this thesis, we analyzed the collisional stability of such a threecomponent sample as a function of the magnetic field and thus also as a function of the interaction strength. In the region below 600 Gauss we observed a strongly varying three-body loss and found two loss resonances at about 127 Gauss and at 500 Gauss. The observed three-body loss coefficient varies over almost three orders of magnitude. We were able to explain this behavior with a model utilizing the universality of systems with large scattering lengths. In this model, the loss resonances are due to a universal three-body bound state that crosses the threeatom continuum twice. Additionally, further measurements could be performed in the region of unitary two-body interactions near the Feshbach resonances