Street sociology and pavement politics: aspects of youth/student resistance in Cape Town,1985.

Paper presented at the Wits History Workshop: The Making of Class, 9-14 February, 198

Migrantes, refugiados, historia y precedentes

Hay mucho material sobre otras crisis migratorias anteriores que los legisladores europeos actuales podrían recuperar y aprovechar

The Union, The Nation, and the Talking Crow: The ideology and tactics of the Independent ICU in East London

African Studies Seminar series. Paper presented March,1985In January 1930 a meeting was held at Headman Koliwe's location in Kentani district, Transkei. It was addressed by Elias Mabodla (or Agitator No. 53 as he was identified in a police report) who had come "to preach ICU amongst you people". He recounted how nine trade union leaders had been arrested in East London where they had called a strike. Their plight evoked strong sympathy in Kentani, especially as one of those arrested was a local man, Dorrington Mqayi. Headman Nkonki summed up the mood of the meeting: "It is for us to see into this matter as our blood is amongst those people in the gaol at East London." Fifty years later, during our research on rural popular movements we encountered Mqayi in his identity as an ICU "agitator" in Kentani. We then retraced his footsteps. In an archival echo of his journeys between the Transkei and the harbour city, we moved from the boxes holding the records of the Kentani magistracy to those of the East London Town Clerk. We had no way of knowing whether Mqayi would resurface in the East London documents, but began our search for him in speculative optimism. We did meet Mqayi again - but not him alone. Mqayi in East London was not the leading actor that he might have been on the smaller stage of Kentani; rather, he had a modest speaking part in a vibrant urban drama - a drama recorded in the vivid and detailed police records* of ICU activity in the Town Clerk's files

The low frequency of dual AGNs versus the high merger rate of galaxies: A phenomenological model

Dual AGNs are natural byproducts of hierarchical mergers of galaxies in the LambdaCDM cosmogony. Recent observations have shown that only a small fraction (~ 0.1%-1%) of AGNs at redshift z<~ 0.3 are dual with kpc-scale separations, which is rather low compared to the high merger rate of galaxies. Here we construct a phenomenological model to estimate the number density of dual AGNs and its evolution according to the observationally-estimated major merger rates of galaxies and various scaling relations on the properties of galaxies and their central massive black holes. We show that our model reproduces the observed frequency and separation distribution of dual AGNs provided that significant nuclear activities are triggered only in gas-rich progenitor galaxies with central massive black holes and only when the nuclei of these galaxies are roughly within the half-light radii of their companion galaxies. Under these constraints, the observed low dual AGN frequency is consistent with the relatively high merger rate of galaxies and supports the hypothesis that major mergers lead to AGN/QSO activities. We also predict that the number of kpc-scale dual AGNs decreases with increasing redshift and only about 0.02%--0.06% of AGNs are dual AGNs with double-peaked narrow line features at redshifts of z 0.5-1.2. Future observations of high-redshift dual AGNs would provide a solid test for this prediction.Comment: 8 pages, 3 figure

Black Holes in the Early Universe

The existence of massive black holes was postulated in the sixties, when the first quasars were discovered. In the late nineties their reality was proven beyond doubt, in the Milky way and a handful nearby galaxies. Since then, enormous theoretical and observational efforts have been made to understand the astrophysics of massive black holes. We have discovered that some of the most massive black holes known, weighing billions of solar masses, powered luminous quasars within the first billion years of the Universe. The first massive black holes must therefore have formed around the time the first stars and galaxies formed. Dynamical evidence also indicates that black holes with masses of millions to billions of solar masses ordinarily dwell in the centers of today's galaxies. Massive black holes populate galaxy centers today, and shone as quasars in the past; the quiescent black holes that we detect now in nearby bulges are the dormant remnants of this fiery past. In this review we report on basic, but critical, questions regarding the cosmological significance of massive black holes. What physical mechanisms lead to the formation of the first massive black holes? How massive were the initial massive black hole seeds? When and where did they form? How is the growth of black holes linked to that of their host galaxy? Answers to most of these questions are work in progress, in the spirit of these Reports on Progress in Physics.Comment: Reports on Progress in Physics, in pres

Cryogenic detector preamplifer developments at the ANU

We present a summary of the cryogenic detector preamplifier development programme under way at the ANU. Cryogenic preamplifiers have been demonstrated for both near-infrared detectors (Teledyne H1RG and Leonardo SAPHIRA eAPD as part of development for the GMTIFS instrument) and optical CCDs (e2v CCD231-84 for use with the AAT/Veloce spectrograph). This approach to detector signal conditioning allows low-noise instrument amplifiers to be placed very close to an infra-red detector or optical CCD, isolating the readout path from external interference noise sources. Laboratory results demonstrate effective isolation of the readout path from external interference noise sources. Recent progress has focussed on the first on-sky deployment of four cryogenic preamp channels for the Veloce Rosso precision radial velocity spectrograph. We also outline future evolution of the current design, allowing higher speeds and further enhanced performance for the demanding applications required for the on instrument wavefront sensor on the Giant Magellan Integral Field Spectrograph (GMTIFS).This research was supported under Australian Research Council's Linkage Project funding scheme (LP150100620) in partnership with the Australian National University and Giant Magellan Telescope Organisation