Scalable Overlay Multicast Tree Construction for QoS-Constrained Media Streaming

Overlay networks have become popular in recent times for content distribution and end-system multicasting of media streams. In the latter case, the motivation is based on the lack of widespread deployment of IP multicast and the ability to perform end-host processing. However, constructing routes between various end-hosts, so that data can be streamed from content publishers to many thousands of subscribers, each having their own QoS constraints, is still a challenging problem. First, any routes between end-hosts using trees built on top of overlay networks can increase stress on the underlying physical network, due to multiple instances of the same data traversing a given physical link. Second, because overlay routes between end-hosts may traverse physical network links more than once, they increase the end-to-end latency compared to IP-level routing. Third, algorithms for constructing efficient, large-scale trees that reduce link stress and latency are typically more complex. This paper therefore compares various methods to construct multicast trees between end-systems, that vary in terms of implementation costs and their ability to support per-subscriber QoS constraints. We describe several algorithms that make trade-offs between algorithmic complexity, physical link stress and latency. While no algorithm is best in all three cases we show how it is possible to efficiently build trees for several thousand subscribers with latencies within a factor of two of the optimal, and link stresses comparable to, or better than, existing technologies

An Underappreciated Radiation Hazard from High Voltage Electrodes in Vacuum

The use of high voltage (HV) electrodes in vacuum is commonplace in physics laboratories. In such systems, it has long been known that electron emission from an HV cathode can lead to bremsstrahlung X-rays; indeed, this is the basic principle behind the operation of standard X-ray sources. However, in laboratory setups where X-ray production is not the goal and no electron source is deliberately introduced, field-emitted electrons accelerated by HV can produce X-rays as an unintended hazardous byproduct. Both the level of hazard and the safe operating regimes for HV vacuum electrode systems are not widely appreciated, at least in university laboratories. A reinforced awareness of the radiation hazards associated with vacuum HV setups would be beneficial. We present a case study of a HV vacuum electrode device operated in a university atomic physics laboratory. We describe the characterisation of the observed X-ray radiation, its relation to the observed leakage current in the device, the steps taken to contain and mitigate the radiation hazard, and suggest safety guidelines.Comment: Submitted to Health Physic

Decolonial Post-Tribal Interpretation

This article reflects on the socio-economic and tribal dimensions of both 3 Reigns 12:24p-t and the post-1994 South African transition. Mahmood Mamdani’s recent book, Neither Settler nor Native, provides an analysis of political decolonisation in post-apartheid South Africa, in which he identifies two areas of failure within the significant gains made during South Africa’s transition from apartheid to democracy—socio-economic justice and tribalisation. These two areas are the unfinished business of our substantive decolonisation of the political. In this article, I use Mamdani’s analysis as an exegetical dialogue partner, probing the socio-economic and tribal dimensions of 3 Reigns 12:24p-t and identifying this text as a proto-tribal text which documents the emergence of tribal economics. Methodologically, this article establishes a to-and-fro tripolar movement between the contemporary South African context and the biblical text.   https://doi.org/10.17159/2312-3621/2023/v36n1a7

After the missionaries: historical and hermeneutical dimensions of African appropriations of the Bible in Sub-Saharan Africa

Peer reviewedWhile the Bible was produced in part in Mediterranean North Africa, Sub-Saharan Africa has had a very different engagement with the Bible. This article analyses the reception of the Bible in Sub-Saharan Africa, recognising its complicity in colonialism, then going on to reflect in detail on African agency in the appropriation of the Bible. The perspective of this article is both historical and hermeneutical, following a broadly chronological framework, but pausing regularly to analyse the hermeneutical contributions of particular historical moments.Research Institute for Theology and Religio

The legacy of liberation theologies in South Africa, with an emphasis on biblical hermeneutics

Peer reviewedThis article reflects on the historical and hermeneutical legacy of liberation theologies in South Africa. Beginning with an analysis of the hermeneutical contours of liberation theologies in general, the article then goes on to examine the shape and contributions of three significant liberation theologies in South Africa over the past thirty years: Black Theology, Contextual Theology, and African Women’s Theology.Research Institute for Theology and Religio

Exegesis seeking appropriation; appropriation seeking exegesis: Re-reading 2 Samuel 13:1−22 in search of redemptive masculinities

Exegesis in the traditional sense is concerned with generating as much (scientific) detail about a biblical text as possible. Whilst the two primary modes of biblical exegesis � socio-historical and literary-semiotic � do this differently, they share a common concern for the detail of the text as an ancient artefact. Critical distance is a key concept here, with the exegetes bracketing (for a moment) their own contexts and concerns. However, such bracketing is impossible to sustain, and so the exegetes� interests (shaped by their contexts and concerns) �leak� into the act of exegesis. Most exegetes today recognise this leakage, and whilst some still view such leakage as contaminating the exegesis, others, including the tradition of African biblical scholarship, actively identify the contextual concerns they bring to the task of exegesis, both respecting the detail of the text and desiring to be accountable to their contexts in which the Bible is a significant text. This article explored some of the dimensions of forms of exegesis that actively seek appropriation, using 2 Samuel 13:1�22 as an example. In this case, the article analysed the contextual shift from a focus on women as the victims of sexual violence to an emerging emphasis on masculinities. Reading the same text from these different contextual concerns �activates� particular details of the text, and so both draw on different elements of the text and thus guides the gaze of exegesis.</span

The Bible and/as the Lynching Tree: A South African Tribute to James H. Cone

In this tribute to James H. Cone I reflect on his biblical-theological hermeneutics, drawing on work that spans nearly fifty years, but concentrating on his most recent book, The Cross and the Lynching Tree. I identify in Cone’s work radical hermeneutics of reception, which I then bring into dialogue with Itumeleng Mosala’s radical hermeneutic of production. This dialogue, I argue, offers us significant biblical-theological capacities for a post-apartheid biblical hermeneutics of decolonisation, with specific reference to South Africa’s land expropriation debate

The beginning of African biblical interpretation: The bible among the Batlhaping.

Prior to the translation of the Bible in Africa, Africans were already engaging with the Bible, initially as an iconic object of power and then as an aural object. In the first section of this article I attempt to detect elements of the early reception of the Bible among the BaTlhaping people. The second section of the article then analyses the theology that lies behind Bible translation, for rendering the Bible into local vernaculars is not a self-evident impulse. The translation of the Bible into local languages must be understood as an aspect of a larger theological project. Finally, the third section of the article reflects on the capacity of the Bible ‘to speak for itself’, arguing that once the Bible has been translated into a local language it slips, at least partially, out of the grasp of those who translated it

An analysis of inter-industry earnings differentials in Canada, 1957, 1962 and 1969

Given that considerable inter-firm and inter-industry wage differentials in fact exist, much empirical work has been undertaken to discover the factors influencing earnings differentials. A majority of these studies have attempted to explain changes in these differentials over time rather than to explain the levels of these differentials as they existed at points in time

The ANC's deployment of religion in nation building : from Thabo Mbeki, to "The RDP of the Soul", to Jacob Zuma

Papers presented at the Forum for Religious Dialogue Symposium of the Research Institute for Theology and Religion held at the University of South Africa, Pretoria, 26-27 March 2009Research Institute for Theology and Religio