Space/time practices and the production of space and time: an introduction

This introduction to the HSR Special Issue Space/Time Practices outlines some main aspects of the discussion of space and time in social and cultural studies. Three main epistemic problems are sketched: 1) Space and time have often acquired a transcendental character, which continues to be especially true of time. 2) To this day, a distinct field of research on temporality in cultural studies is still in nascent form. 3) Space and time are often set in “binary oppositions” to one another, thereby inhibiting their combined analysis. The present volume, which is the result of discussions by the SpaceTime research group at the University of Erfurt (Erfurter RaumZeit-Forschung, ERZ), takes this set of problems as its starting point. The contributions share the presupposition that spatiality and temporality are inseparable in their lived and everyday worlds. Discussing concepts of permanences (Whitehead), of Space/ Time Practices and forms of production of time and space, the introduction proposes a constructivist, actor-and praxis-centered approach to space and time that enables an inter- and multidisciplinary platform for different questions about two central facets of human life

Urban Phenomena in São Paulo’s Nineteenth and Twentieth Centuries: Appropriating Local Spatio-Temporalities

O artigo investiga fenômenos urbanos na São Paulo dos séculos XIX e XX lançando mão do conceito de apropriação de Henri Lefebvre. Assim, enfoco as relações entre espaço(s) urbano(s) e seus habitantes, e a análise da cidade – usualmente percebida como espaço – se torna análise espacio-temporal e relacional de práticas, conflitos etc. dinâmicos, entendidos como fenômenos urbanos. Como os habitantes se apropriaram de São Paulo? É possível aferir formas especiais via          comparação com outras cidades latino-americanas de tempos mais antigos? Como os (i)migrantes chegados no final do século XIX modificaram formas antigas de se viver na cidade? Concluo com observações e críticas à potencialidade de se usar o conceito de apropriação nos estudos urbanos.The article seeks to investigate urban phenomena in São Paulo’s 19th and 20th centuries by utilizing Henri Lefebvre’s concept of appropriation. Thus I focus on the relations between urban space(s) and its inhabitants, and the analysis of the city – usually perceived as space – becomes a spatio-temporal and relational analysis regarding dynamic practices, conflicts, etc. understood as urban phenomena. How did the inhabitants appropriate São Paulo? May we state special forms by comparing it to other Latin American cities of former times? How did the migrants arriving at the end of 19th century change old forms of living in the city? I conclude with remarks and critics on the potential of using the concept of appropriation in urban studies

On the Sound Financial Valuation of Flexibility in Information Systems

Flexibility often represents the key area of value added by investing into an information system (IS) but also carries significant costs. Therefore, its quantitative financial valuation is of vital importance to make economically informed decisions about flexibility. This is challenging due to varying flexibility definitions and the complexity of the flexibility construct in itself. To address this challenge, this paper analyzes the scientific literature concerned with the financial valuation of flexibility in information systems (FIS). In the first part, it introduces fundamental requirements for a proper financial valuation, discusses the characteristics of FIS that are driving its economic value and identifies suitable financial valuation approaches. In the second part, a structured review of literature focusing on the application of FIS valuation analyzes to what extend the existing literature supports economically informed decisions within flexibility design. Further research is indicated with regard to dependencies between flexibility and the existing IS landscape as well as to a more structured and comprehensive approach to examine all interacting features of an IS enabling flexibility in the first place. In summary, joining the theoretical basis and the application of FIS valuation, this paper gathers all necessary fundamentals for a sound financial valuation of FIS and reveals the need for further development within this stream of BISE research

Gate control, g-factors and spin orbit energy of p-type GaSb nanowire quantum dot devices

Proposals for quantum information applications are frequently based on the coherent manipulation of spins confined to quantum dots. For these applications, p-type III-V material systems promise a reduction of the hyperfine interaction while maintaining large $g$-factors and strong spin-orbit interaction. In this work, we study bottom-gated device architectures to realize single and serial multi-quantum dot systems in Schottky contacted p-type GaSb nanowires. We find that the effect of potentials applied to gate electrodes on the nanowire is highly localized to the immediate vicinity of the gate electrode only, which prevents the formation of double quantum dots with commonly used device architectures. We further study the transport properties of a single quantum dot induced by bottom-gating, find large gate-voltage dependent variations of the $g^*$-factors up to $8.1\pm 0.2$ as well as spin-orbit energies between $110$-$230\,\mu$eV.Comment: 7 pages, 4 figure

Sub-stellar companions of intermediate-mass stars with CoRoT: CoRoT–34b, CoRoT–35b, and CoRoT–36b

Theories of planet formation give contradicting results of how frequent close-in giant planets of intermediate mass stars (IMSs; 1.3≤M⋆≤3.2M⊙⁠) are. Some theories predict a high rate of IMSs with close-in gas giants, while others predict a very low rate. Thus, determining the frequency of close-in giant planets of IMSs is an important test for theories of planet formation. We use the CoRoT survey to determine the absolute frequency of IMSs that harbour at least one close-in giant planet and compare it to that of solar-like stars. The CoRoT transit survey is ideal for this purpose, because of its completeness for gas-giant planets with orbital periods of less than 10 d and its large sample of main-sequence IMSs. We present a high precision radial velocity follow-up programme and conclude on 17 promising transit candidates of IMSs, observed with CoRoT. We report the detection of CoRoT–34b, a brown dwarf close to the hydrogen burning limit, orbiting a 1.1 Gyr A-type main-sequence star. We also confirm two inflated giant planets, CoRoT–35b, part of a possible planetary system around a metal-poor star, and CoRoT–36b on a misaligned orbit. We find that 0.12±0.10 per cent of IMSs between 1.3≤M⋆≤1.6M⊙ observed by CoRoT do harbour at least one close-in giant planet. This is significantly lower than the frequency (⁠0.70±0.16 per cent⁠) for solar-mass stars, as well as the frequency of IMSs harbouring long-period planets (⁠∼8 per cent⁠)