Quartering the city in discourse and bricks: Articulating urban change in a South African enclave

Focusing on the urban enclave in Cape Town known as De Waterkant, this paper examines the product and process of ‘quartering’ urban space—shaping urban space as the locus for the symbolic framing of culture. This paper advances recent studies of De Waterkant by applying the concept of quartering to understand urban change in an African context. Complicating existing research on De Waterkant, the findings show that the area has witnessed four distinct quartered identities including: an ethnic quartering which was dismantled under apartheid; a Bohemian quartering that changed racial dynamics and improved housing stock; a ‘gay village’ quartering that engaged sexual identity performance as a strategy for place-making; and most recently a consumer lifestyle quartering that exhibited new notions of citizenship and consumption. This paper advances theorization of how quartering as a process is articulated through the application of discursive and material tropes to the urban fabric of the city.International Bibliography of Social Science

Que(e)rying Cape Town: touring Africa’s gay capital with the pink map

Since 1999, Cape Town’s Pink Map has attempted to provide local and international visitors alike with a cartographic representation of the city’s queer landscape. This paper engages with the archive provided by more than a decade of the Map to trace the outlines of this ‘pink’ discourse while contributing to debates on the promotion of ‘pink’ tourism and the nature of South African queer communities. This paper will demonstrate that, in addition to being a commercial publication that locates gay- and gay friendly leisure venues, services, and shopping, the Pink Map also engages particular tropes of the body and gender to inscribe sexual and consumer citizenship in the city of Cape Town with specific emphasis on the urban quarter known as De Waterkant. The analysis will show how the journey one takes while holding the Pink Map is illustrative of events taking place on the urban landscape that the Map depicts. In the final analysis, this paper reveals how the Pink Map serves as an archive of a limited notion of queer visibility, new modes of consumption, the queer tourist gaze and the embodied shaping of destination space

Community as utopia: Reflections on De Waterkant

This paper will reflect on research currently in progress in Cape Town's De Waterkant neighbourhood—an area also known as Cape Town's 'gay village'. This paper engages the literature of utopia as a framework of analysis for interrogating the performance of community—while at the same time problematising the terms "community" and "utopia" upon which much geographical description of the area is based. This research argues that both 'comforting' and 'unsettling' relational achievements amongst the human and non-human actors in De Waterkant function as building blocks of real or imagined community and further recognises multiple tensions that affect the formation of community and the pursuit of utopia in the South African urban context

Shape mode analysis exposes movement patterns in biology: flagella and flatworms as case studies

We illustrate shape mode analysis as a simple, yet powerful technique to concisely describe complex biological shapes and their dynamics. We characterize undulatory bending waves of beating flagella and reconstruct a limit cycle of flagellar oscillations, paying particular attention to the periodicity of angular data. As a second example, we analyze non-convex boundary outlines of gliding flatworms, which allows us to expose stereotypic body postures that can be related to two different locomotion mechanisms. Further, shape mode analysis based on principal component analysis allows to discriminate different flatworm species, despite large motion-associated shape variability. Thus, complex shape dynamics is characterized by a small number of shape scores that change in time. We present this method using descriptive examples, explaining abstract mathematics in a graphic way.Comment: 20 pages, 6 figures, accepted for publication in PLoS On

Adsorption and desorption of hydrogen at nonpolar GaN(1-100) surfaces: Kinetics and impact on surface vibrational and electronic properties

The adsorption of hydrogen at nonpolar GaN(1-100) surfaces and its impact on the electronic and vibrational properties is investigated using surface electron spectroscopy in combination with density functional theory (DFT) calculations. For the surface mediated dissociation of H2 and the subsequent adsorption of H, an energy barrier of 0.55 eV has to be overcome. The calculated kinetic surface phase diagram indicates that the reaction is kinetically hindered at low pressures and low temperatures. At higher temperatures ab-initio thermodynamics show, that the H-free surface is energetically favored. To validate these theoretical predictions experiments at room temperature and under ultrahigh vacuum conditions were performed. They reveal that molecular hydrogen does not dissociatively adsorb at the GaN(1-100) surface. Only activated atomic hydrogen atoms attach to the surface. At temperatures above 820 K, the attached hydrogen gets desorbed. The adsorbed hydrogen atoms saturate the dangling bonds of the gallium and nitrogen surface atoms and result in an inversion of the Ga-N surface dimer buckling. The signatures of the Ga-H and N-H vibrational modes on the H-covered surface have experimentally been identified and are in good agreement with the DFT calculations of the surface phonon modes. Both theory and experiment show that H adsorption results in a removal of occupied and unoccupied intragap electron states of the clean GaN(1-100) surface and a reduction of the surface upward band bending by 0.4 eV. The latter mechanism largely reduces surface electron depletion

Constraints on pseudo-Dirac neutrinos using high-energy neutrinos from NGC 1068

Neutrinos can be pseudo-Dirac in Nature - they can be Majorana fermions whilebehaving effectively as Dirac fermions. Such scenarios predict active-sterileneutrino oscillation driven by a tiny mass-squared difference $(\delta m^2)$,which is an outcome of soft-lepton number violation. Oscillations due to tiny$\delta m^2$ can take place only over astrophysical baselines and hence are notaccessible in terrestrial neutrino oscillation experiments. This implies thathigh-energy neutrinos coming from large distances can naturally be used to testthis scenario. We use the recent observation of high-energy neutrinos from theactive galactic nuclei NGC 1068 by the IceCube collaboration to constrain$\delta m^2 \leq 10^{-18}{\rm eV}^2$ at more than $90\%$ confidence level - oneof the strongest limits to date on the values of $\delta m^2$.<br

Spectral Properties of the Attractive Hubbard Model

Deviations from Fermi liquid behavior are well documented in the normal state of the cuprate superconductors, and some of these differences are possibly related to pre-formed pairs appearing at temperatures above T_c. In order to test these ideas we have investigated the attractive Hubbard model within a self-consistent, conserving ladder approximation. In this version of the theory, no feature is present which can be related to the pseudo gap found in the high-T_c materials. Further, the interactions between two-particle bound states change the physics of the superconducting instability in a profound fashion, and lead to a completely different phenomenology that one predicts based on the non-self-consistent version of the same theory.Comment: 4 pages including 2 figures, to appear in the proceedings of the SNS'9

Stem cells and fluid flow drive cyst formation in an invertebrate excretory organ.

Cystic kidney diseases (CKDs) affect millions of people worldwide. The defining pathological features are fluid-filled cysts developing from nephric tubules due to defective flow sensing, cell proliferation and differentiation. The underlying molecular mechanisms, however, remain poorly understood, and the derived excretory systems of established invertebrate models (Caenorhabditis elegans and Drosophila melanogaster) are unsuitable to model CKDs. Systematic structure/function comparisons revealed that the combination of ultrafiltration and flow-associated filtrate modification that is central to CKD etiology is remarkably conserved between the planarian excretory system and the vertebrate nephron. Consistently, both RNA-mediated genetic interference (RNAi) of planarian orthologues of human CKD genes and inhibition of tubule flow led to tubular cystogenesis that share many features with vertebrate CKDs, suggesting deep mechanistic conservation. Our results demonstrate a common evolutionary origin of animal excretory systems and establish planarians as a novel and experimentally accessible invertebrate model for the study of human kidney pathologies

Scaling and regeneration of self-organized patterns

Biological patterns generated during development and regeneration often scale with organism size. Some organisms, e.g., flatworms, can regenerate a rescaled body plan from tissue fragments of varying sizes. Inspired by these examples, we introduce a generalization of Turing patterns that is self-organized and self-scaling. A feedback loop involving diffusing expander molecules regulates the reaction rates of a Turing system, thereby adjusting pattern length scales proportional to system size. Our model captures essential features of body plan regeneration in flatworms as observed in experiments.Comment: 5 pages, 3 color figure

Studio della propagazione della frattura in polibutene per tubi

Il Polibutene-1 isotattico (i-PB1) è un materiale polimerico usato per la produzione di tubi per il trasporto di fluidi in pressione. In questo lavoro si sono studiati due tipi di i-PB1 prodotti da Basell che differiscono per grado di isotatticità. Si sono condotte prove di frattura a diverse temperature e velocità di spostamento imposte. Si è utilizzata una configurazione di flessione su provini con singolo intaglio (SENB) unitamente a quella di doppia trave a sbalzo (DCB), quest’ultima limitatamente allo studio della fase di propagazione. Al fine di individuare con precisione l’innesco della frattura e la velocità di propagazione della stessa si è fatto ricorso a metodi ottici. Dal punto di vista fenomenologico durante la propagazione si assiste alla formazione di zone in cui il materiale risulta fortemente stirato. La frattura in esse avanza con una lacerazione continua che si alterna a salti repentini in occasione del brusco cedimento di queste zone, associato a conseguenti cadute del carico. Questa parziale instabilità è stata osservata sui due materiali per entrambe le configurazioni di prova. I risultati ottenuti sono stati interpretati seguendo l’approccio della meccanica della frattura e applicando uno schema di riduzione di tipo tempo-temperatura che ha permesso di descrivere il comportamento viscoelastico del materiale su un intervallo temporale di diverse decadi. I risultati hanno permesso di applicare un modello analitico per la previsione della vita utile di tubi in pressione. Il modello si è mostrato in buon accordo con i dati sperimentali disponibili da prove condotte su tubi dello stesso materiale