The Red Supergiant Content of M31

We investigate the red supergiant (RSG) population of M31, obtaining radial velocities of 255 stars. These data substantiate membership of our photometrically-selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B-V, V-R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar-metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 Mo stars, while the vast majority evolved from stars with initial masses of 20 Mo or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; i.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested.Comment: Accepted for publication in the Astronomical Journa

Enterprise development on the margins : Making markets work for the poor?

This thesis is about the quest to build effective strategies to support the development of enterprise on the margins of the economy, to create jobs and reduce poverty. A core part of this challenge includes grappling with the role of markets in development, and of markets as a critical part of the context in which enterprise development in rural and peri-urban areas can either provide a path out of poverty – or instead serve to lock people into poverty. The thesis explores these issues by tracking the experience of the Mineworkers Development Agency (MDA) as it attempted to grapple with this challenge. MDA is the development wing of South Africa’s National Union of Mineworkers (NUM) , and was set up to create jobs and support enterprise development for communities affected by the loss of jobs on the mines. The thesis covers a fourteen-year period in MDA’s history, from its inception in 1988 until 2002. It tracks the learning process across several phases in the development of MDA’s approach. These included the development of worker co-operatives, the establishment of business service centres, value-chain work in the craft sector, and the commercialization of a juice product from the indigenous marula berry. In the process, MDA engaged with an emergent paradigm in the development sector called ‘Making Markets Work for the Poor’. Can markets really be made to work for the poor? Or even just made to work ‘better’ for the poor? Or is the process of inclusion in markets inexorably and inevitably one of making the poor work for markets? The thesis explores these issues in the context of MDA’s experience, locating this within a wider set of theoretical concerns over the role of markets in society, and the ways in which societies have protected themselves from the negative impacts of the development of market economies. It draws on wider political economy approaches to argue that markets are institutions that are socially constructed, and explores what scope there might therefore be to construct them differently. While recognising the importance of social protection, the thesis argues that there is a need to go beyond defensive strategies aimed at protecting society from markets, to identify new terms of engagement within markets to shape markets, and to harness their wealth-creating potential in ways that have different distributional consequences, as part of a long-term agenda of eradicating poverty

Reviews

Martin Oliver (ed.), Innovation in the Evaluation of Learning Technology, London: University of North London, 1998. ISBN: 1–85377–256–9. Softback, 242 pages, £15.00

Fast and frugal framing effects?

Three experiments examine whether simple pair-wise comparison judgments, involving the “recognition heuristic” (Goldstein & Gigerenzer, 2002), are sensitive to implicit cues to the nature of the comparison required. Experiments 1 & 2 show that participants frequently choose the recognized option of a pair if asked to make “larger” judgments but are significantly less likely to choose the unrecognized option when asked to make “smaller” judgments. Experiment 3 demonstrates that, overall, participants consider recognition to be a more reliable guide to judgments of a magnitude criterion than lack of recognition and that this intuition drives the framing effect. These results support the idea that, when making pair-wise comparison judgments, inferring that the recognized item is large is simpler than inferring that the unrecognized item is small

Producer co-operatives in South Africa: their economic and political limits and potential

The social and political effects of mass unemployment in South Africa mean there is an urgent need for strategies of job- creation. In this context, the Congress of SA Trade Unions (Cosatu), the South African Youth Congress (SAYCO), and the National Unemployed Workers' Co-ordinating Committee (NUWCC) have all expressed support for producer co-operatives, which are not only seen to have the potential to create jobs, but at the same time, are seen as providing a democratic alternative to capitalist enterprises. Thus firstly, this dissertation is exploring the potential for producer co-ops to fulfil these roles. However, for co-ops to make any contribution at all, they have to be economically viable. Thus this dissertation also attempts to analyse the terms on which this may be possible. In Chapter One, I analyse the roots of mass unemployment in South Africa, locate the problem and its effects within the framework of the current economic and political crisis, and analyse state strategies for overcoming this problem. I then turn to analysing the social and psychological effects of unemployment, and the implications of this for the growth of democratic organisation in the factories and township communities. I look at the strategies emerging for organising the unemployed, and conclude that the potential to organise the unemployed hinges largely around the extent to which unemployed workers' organisation manages to create jobs. In this regard, co-ops are a strategy of job creation that allows the unemployed to take the initiative in creating their own jobs, and on terms that build different forms of work organisation. On the basis of the priorities defined by the NUWCC, I then turn to analysing the limits and possibilities of co-op production. In Chapter Two, I address the theoretical issues that have emerged in relation to co-ops in capitalist society internationally, and attempt to analyse the reasons for their widespread economic failure, and for their tendency to degenerate into capitalist enterprises. From this, I draw out the potential terms on which collapse and/or degeneration can be countered, and refer to Mondragon in Spain and Lega in Italy as case studies. I then look at the potential political role co-ops can play, and conclude this chapter by focussing the issues discussed onto South African questions. In Chapter Three, I attempt a typology of co-op development in South Africa today, highlighting the extent to which a broad range of social forces see co-ops serving their own interests. Then, on the basis of a list of production co-ops in Addendum A, I analyse some of the overall features of the democratic co-ops that do exist at present, and point to the existence of degenerative tendencies in the South African context, with specific reference to Thusanang. I then focus on three case studies - the Pfananani co-ops, a carpentry co-op, and Nonthutuzelo. Each of these co-ops has arisen under different conditions, and they illustrate different aspects of the issues co-ops in SA will have to address if they are to survive. Chapter Four focusses on the production co-ops of the Sarmcol Workers Co-op (SAWCO), particularly the t-shirt co-op. The analysis of SAWCO constitutes the main case study of this dissertation. I have prioritised SAWCO because at the time I began the research, it was the only co-op with structural links to a Cosatu union; it is a co-op that arose out of the context of a workers' struggle, and contains important lessons for the establishment of co-ops with a clear relationship to democratic organisation. Furthermore, it relies on the 'solidarity' market to sell its products, and highlights certain important features and contradictions within this market. Finally, it highlights key issues in relation to the structures of ownership and control in democratic co-ops. In my conclusion, I attempt to draw together the material in the dissertation as a whole. I apply the theoretical discussion to the South African context, assess the implications of the nature of SA's economy for the development of co-ops, and attempt to provide some pointers to the terms on which democratic co-ops can be economically viable, thus creating jobs, at the same time as making a broader contribution to the extension of democracy in South Africa.Labour studies research report (University of the Witwatersrand); v

Reviews

Mark Kerr, How to Promote your Web Site Effectively, London: Aslib/IMI, ISBN: 0–85142–424–4. Paperback, 87 pages, £13.99

A Runaway Red Supergiant in M31

A significant percentage of OB stars are runaways, so we can expect a similar percentage of their evolved descendants to also be runaways. However, recognizing such stars presents its own set of challenges, as these older, more evolved stars will have drifted farther from their birthplace, and thus their velocities might not be obviously peculiar. Several Galactic red supergiants (RSGs) have been described as likely runaways based on the existence of bow shocks, including Betelgeuse. Here we announce the discovery of a runaway RSG in M31 based on a 300 km s^(−1) discrepancy with M31's kinematics. The star is found about 21' (4.6 kpc) from the plane of the disk, but this separation is consistent with its velocity and likely age (~10 Myr). The star, J004330.06+405258.4, is an M2 I, with M_V = −5.7, logL/L_☉ = 4.76, an effective temperature of 3700 K, and an inferred mass of 12–15M_⊙. The star may be a high-mass analog of the hypervelocity stars, given that its peculiar space velocity is probably 400–450 km s^(−1), comparable to the escape speed from M31's disk

Adverse Effects of Heartwood on the Mechanical Properties of Wood-Wool Cement Boards Manufactured from Radiata Pine Wood

Wood-wool cement boards (WWCBs) that are manufactured commercially in Australia from radiata pine occasionally contain localized areas in which there is poor bonding between wood and cement. The cause of this defect, which leads to the rejection of boards before they arc sold, is not known, but it has been suggested that it may be due to the use of blue-stained wood or heartwood in the manufacture of boards. In this study, both wood types were tested for their effects on the hydration of Portland cement and the mechanical properties of WWCBs. Blue-stained sapwood slightly retarded the hydration of cement but had no significant (P < 0.05) effect on the mechanical properties of boards. In contrast, heartwood severely retarded cement hydration, and boards made from heartwood had little structural integrity. The appearance of such boards resembled the defective portions of commercially produced boards, and therefore it can be concluded that the defect arises from the inhibitory effect of heartwood on cement hydration. The problem could be eliminated by processing logs from young radiata pine trees, less than 12-15 years old, which will contain little or no heartwood

Reviews

Sally Brown, Steve Armstrong and Gail Thompson (eds.), Motivating Students, London: Kogan Page, 1998. ISBN: 0–7494–2494‐X. Paperback, 214 pages. £18.99

Manufacture of Wood-Cement Composites from Acacia Mangium. Part II. Use of Accelerators in the Manufacture of Wood-Wool Cement Boards from A. Mangium

In the second paper in this series, we test the hypothesis that cement-setting accelerators with the ability to chelate phenolic extractives will be more effective at improving the physical properties of wood-wool cement boards made from the heartwood of Acacia mangium than conventional accelerators. Furthermore, we assess whether the use of chelating accelerators will allow boards with acceptable properties to be manufactured from A. mangium wood-wool that has not been subjected to preliminary aqueous extraction to remove phenolic extractives. Batches of wood-wool from A. mangium containing approximately 75% heartwood were either soaked in water or used in their native form. The batches were then treated with an aqueous solution containing an inorganic compound (generally 0.05 or 0.1 M) selected for its ability to accelerate the hydration of Portland cement, and in the case of 5 of the 11 compounds tested, chelate phenolic extractives. Individual wood-wool cement boards were manufactured from each treated batch of wood-wool and tested for their dry and wet bending strength (MOR), stiffness (MOE), and water absorption properties. Boards made from untreated or water-soaked wood-wool acted as controls. The MOR and MOE of boards made from unsoaked A. mangium wood-wool and treated with the chelating accelerators tin or ferric chloride at 0.1 M concentration were 10.8 and 10.9 MPa and 2256 and 2178 MPa, respectively. These same boards showed less than 5% thickness swelling after 24-h immersion in water. In contrast most of the boards containing a conventional non-chelating accelerator had no structural integrity. The combination of a chelating accelerator and a conventional accelerator was particularly effective at improving the physical properties of boards made from unsoaked wood-wool. We conclude that wood-wool cement boards with acceptable physical properties can be manufactured from A. mangium heartwood by treating wood-wool with inorganic compounds that have the ability to chelate phenolic extractives and accelerate the hydration of Portland cement. Our findings could eliminate the need to pre-soak A. mangium wood-wool in water during the manufacture of wood-wool cement boards and may have broader relevance to the manufacture of wood-wool cement boards from other hardwood species containing phenolic extractives