228 research outputs found

    Jagged blue frontiers: The police and the policing of boundaries in South Africa

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    Social and territorial boundaries have been fundamental to the approaches and practices of policing bodies in South Africa for centuries, from the mounted colonial paramilitary forces of the 1800s to the 21st century professional police. Boundaries have not only been a central mechanism that the police have consistently used to control and regulate the general population, but have also been catalysts for change in terms of operational policing strategies and tactics. This has typically been the case when a threat has been ascribed to a bounded area and/or populations that reside within the confines of the boundary, or on the other side of the boundary. The nature of the such a threat is considered to be even more severe when communities within the bounded space, or on the other side of the boundary, acquire significant quantities of firearms and ammunition, as this provides such populations with the lethal technology to defy and contest the police's coercive authority and ability to conserve boundaries relating to the maintenance of order and the enforcement of laws. South Africa is a distinctly relevant case study for an examination of the relationship between boundaries and the police as for the past three and a half centuries South Africa's diverse policing history has been profoundly framed by territorial, social and political boundaries. The police and the proto-police have been at the sharp edge of the application of authority by assorted forms of government, and have often acted to safeguard the interests of economic and political elites. That is, the police and formal policing bodies have been required to subdue and suppress groups and individuals that resisted or threatened the process of state building and resource extraction. The police were also regularly deployed to protect the territorial borders of South Africa from menacing others. By means of this historical analysis of South Africa, this thesis introduces a new concept, 'police frontierism', which illuminates the nature of the relationships between the police, policing and boundaries, and can potentially be used for future case study research. It is an alternative way of conceptualising policing, one in which police work is fundamentally framed by social and territorial boundaries. Such boundaries delineate perceived safe or 'civilised' spaces from dangerous or 'uncivilised' ones. The police tend to concentrate their resources in the frontier zone immediately adjacent to the boundary in order to preserve or extend the boundary of safety and 'civilisation', and restrict, subdue or eliminate those individuals, groups or circumstances from the 'uncivilised' spaces that a government authority or elites have deemed to be a threat to order and peace. An essential dynamic of this policing approach is that the boundary and the adjoining frontier zone strongly influence police practices and behaviour in this context. In particular, territorial and social delineations amplify and distort existing police prejudices against those communities on the other side of the boundary. The police often engage in othering, where the communities of interest are viewed negatively, and are predominantly seen as agents of disorder and law breaking. This othering may lead to an intensification of aggressive police behaviour towards the targeted communities

    X-Ray Spectra of Z Sources

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    A simple, physically consistent model has been proposed that seeks to explain in a unified way the X-ray spectra and rapid X-ray variability of the so-called Z sources and other accreting neutron stars in low-mass systems. Here we summarize the results of detailed numerical calculations of the X-ray spectra of the Z sources predicted by this model. Our computations show that in the Z sources, photons are produced primarily by electron cyclotron emission in the neutron star magnetosphere. Comptonization of these photons by the hot central corona and radial inflow produces X-ray spectra, color-color tracks, and countrate variations like those observed in the Z sources.Comment: 6 pages, 2 Postscript figures in 4 files, uses aas2pp4.sty, submitted to ApJ (Letters) 1995 May 3

    Unidirectional Propagation of an Ultra-Short Electromagnetic Pulse in a Resonant Medium with High Frequency Stark Shift

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    We consider in the unidirectional approximation the propagation of an ultra short electromagnetic pulse in a resonant medium consisting of molecules characterized by a transition operator with both diagonal and non-diagonal matrix elements. We find the zero-curvature representation of the reduced Maxwell-Bloch equations in the sharp line limit. This can be used to develop the inverse scattering transform method to solve these equations. Finally we obtain two types of exact traveling pulse solutions, one with the usual exponential decay and another with an algebraic decay.Comment: Latex, 10 pages, no figure

    Mass killings and calculated measures: The impact of police massacres on police reform in South Africa

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    Over the past two centuries, the police have perpetrated massacres in response to protest action in numerous countries. Available scholarly literature has typically focused on the circumstances that contributed to such mass killings, but rarely has there been consideration of the impact that such massacres subsequently may have had on the police organisation. Hence, this article will explore the relationship between massacres perpetrated by the police and police reform, with a particular focus on South Africa. The article concludes that, in the context of public order policing, massacres perpetuated by the police can contribute towards relatively immediate police reforms, particularly in terms of police strategies and tactics. In some circumstances, massacres have even led to some restructuring of the police organisation. The nature of the government and the policing environment appeared to be key determinants of the types of police reforms, post-massacre

    Civil supremacy of the military in Namibia : an evolutionary perspective

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    Includes bibliographical references.The aim of this dissertation is to analyse the phenomenon of civil supremacy, and in particular how it evolves and is sustained over time. A theoretical case study of Namibia will be undertaken to achieve this objective, with three traditions of civil supremacy, namely colonial, revolutionary/insurgent and democratic (as well as the relevant mechanisms and techniques), being the focus. This dissertation seeks to determine how these traditions emerge and develop over time. Basically, civil supremacy rests on a set of ideas, institutions and behaviours. Together these practices limit the possibility of excessive military intervention in political affairs and provide a system that endows civilian officials with the authority and the machinery to exercise supremacy in military affairs

    Large Area Metasurface Lenses in the NIR Region

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    Metasurfaces have revolutionized the definition of compact optics. Using subwavelength periodic structures of nanostructured dielectrics, the refractive index and absorption properties of metasurfaces – which are 2D metamaterials – can manipulate light to a degree not possible with conventional bulk glasses and crystals. The phase, polarization, spin (for circularly polarized light), amplitude and wavelength of light can all be manipulated and crafted to user-specified values to mimic the action of a lens, which we refer to as a metalens (ML). MLs have four major advantages over traditional refractive lenses – superior resolution, lighter weight, miniaturization and cost. Many metasurfaces with useful functionalities have been proposed in recent years, yet although novel in their approach have few real-world applications. One such market is the use within infrared laser systems, such as laser designators. In this work, we demonstrate metasurface lenses working at a wavelength of λ = 1064 nm, with aperture d = 1 mm and four different Fnumbers (focal length f = 0.5, 1, 2 and 5 mm). The lenses are composed of 700nm high a-Si pillars – ranging from 70- 360 nm diameter – which are fabricated using electron beam lithography (EBL) and reactive ion etching processes, on top of a fused silica substrate. Such lenses are shown to have diffraction-limited performance, with focal spot-size agreeing with theoretical values of λ‧f/d. Furthermore, we have designed large area lenses with aperture d = 10 mm, where the number of pillars per lens exceeds 550 million. By using an efficient Python script, we are able to produce these 100 mm2 samples with just 14 hours of EBL writing time

    Living the life of floods: place-based learning in an Anthropocene harmscape

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    This article explores how place-based learning and the development of landscape literacies unfold in a place suffused with a complex set of risks resulting from inter-operating and intersecting sociohistorical, political and environmental factors. By analysing assemblages of images and accompanying texts produced through a photovoice process undertaken by co-researchers in an informal settlement in South Africa’s Cape Flats, we show that residents are embedded in an ongoing process of embodied place-connectedness that has extensive pedagogical impact. We suggest that the learning that takes place in this harmscape may enable residents’ survival at the cost of allowing for either hope or the possibility of transformative change

    Modulation of Wnt/β-catenin signaling and proliferation by a ferrous iron chelator with therapeutic efficacy in genetically engineered mouse models of cancer

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    Using a screen for Wnt/β-catenin inhibitors, a family of 8-hydroxyquinolone derivatives with in vivo anti-cancer properties was identified. Analysis of microarray data for the lead compound N-((8-hydroxy-7-quinolinyl) (4-methylphenyl)methyl)benzamide (HQBA) using the Connectivity Map database suggested that it is an iron chelator that mimics the hypoxic response. HQBA chelates Fe2+ with a dissociation constant of ∼10−19 , with much weaker binding to Fe3+ and other transition metals. HQBA inhibited proliferation of multiple cell lines in culture, and blocked the progression of established spontaneous cancers in two distinct genetically engineered mouse models of mammary cancer, MMTV-Wnt1 and MMTV-PyMT mice, without overt toxicity. HQBA may inhibit an iron-dependent factor that regulates cell-type-specific β-catenin-driven transcription. It inhibits cancer cell proliferation independently of its effect on β-catenin signaling, as it works equally well in MMTV-PyMT tumors and diverse β-catenin-independent cell lines. HQBA is a promising specific intracellular Fe2+ chelator with activity against spontaneous mouse mammary cancers
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