Condom use by South African construction workers

Consistent and proper condom use is pivotal in preventing HIV infection. HIV prevalence in South Africa is among the highest in the world, with the construction industry especially affected, yet little is known about condom use by construction workers and the determinants thereof. Data were gathered from 512 site-based workers in the Western Cape. A theoretical model explaining condom use as a function of demographic factors, HIV knowledge, substance usage and risky sexual behaviour (excluding condom use) was proposed and tested using regression and structural equations modelling. The findings indicated that age, gender and level of education were indirect determinants of condom use, with higher levels of education predicting better AIDS-related knowledge. Higher levels of risky sexual behaviour were associated with more frequent use of condoms, suggesting greater awareness of risk. Condom use was adversely affected by greater alcohol and drug use, probably as a result of diminished capacity to assess risk. Finally, lower and not higher levels of AIDS-related knowledge were associated with better condom use, suggesting that improved knowledge of HIV transmission may work contrary to safe sex practice if it lulls the person into a false sense of confidence. Recommendations for targeted workplace interventions are proposed.     

Easing the implementation and change of manufacturing software systems

The software systems that underpin contemporary manufacturing enterprises can become the single most inflexible part of an enterprise, constraining a business that has to evolve. This paper describes an approach to manufacturing software system creation which supports system evolution. It is based on the notion that raising the level of the computing infrastructure through the use of a domain machine, can remove the need to transform the clear abstractions and decomposition identified during design into the incomprehensible maze of programming language constructs which prove difficult to maintain.

The paper provides a comparison between two implementations of a system to control a printed circuit board manufacturing line, one based on a conventional approach and the other based on the authors manufacturing domain machine. Ease of change enabled by the domain machine is illustrated through measuring the degree of modification required to each system when incorporating a new solder paste print machine in the production line.     

Images of native Americans

Abstract

This interesting volume explores the photographic environment and output of four Anglo women who had extended photographic relationships with Native American people: Kate Cory, an artist and collector who lived with the Hopi people for many years; Mary Shaffer; who travelled amongst the Stoney and Metis of Alberta, Canada; Jane Gay, who assisted ethnographer Alice Fletcher and documented land allotment and the effects of the Dawes Act on the Nez Percé people; Grace Nicholson, who set up commercial enterprises trading in art and cultural objects. None of the women was primarily a photographer. Their photographic work was always an adjunct to other purposes, to record encounters commercial, artistic or ethnographic, but at the same time the work functioned as a key articulation of their relationships with Native peoples. All four women, in their different ways, looked to Native American peoples as a way of defining and experiencing their own identities and spirituality and all four shared a commitment to and engagement with these peoples.     

Conference news

RESOURCES: ENVIRONMENT AND POLICY, by John Fernie and Alan Pitkethly, Harper and Row, London, 1985, 338 pp. (#bp12.95, paperback)

THE ECONOMICS OF FORESTRY AND NATURAL RESOURCES, by Per‐Olov Johansson and Karl‐Gustaf Lofgren, Basil Blackwell, Oxford, 1985, 292 pp. (#bp29.50, hardback only)

ENVIRONMENTAL PROTECTION: STANDARDS, COMPLIANCE AND COSTS, edited by T. J. Lack, J. Wiley &; Son, Chichester, 1984, 329 pp. (#bp30, hardback)

ENVIRONMENT AND ENFORCEMENT: REGULATION AND THE SOCIAL DEFINITION OF POLLUTION, by K. Hawkins, Clarendon Press, Oxford, 1984, 253 pp. (#bp15 hardback; #bp6.95, paperback)

ENVIRONMENTAL POLICY, VOLUME 1: ELEMENTS OF ENVIRONMENTAL ANALYSIS, by George Tolley, Philip Graves and Glenn Blomquist, Ballinger, Cambridge, Mass, and Harper and Row, London, 1981. (#bp27.50, hardback)

ENVIRONMENTAL POLICY, VOLUME 4: SOLID WASTES, by George Tolley, Jospeh Havlicek and Robert Fabian, Ballinger, Cambridge, Mass. and Harper and Row, London, 1985. (#bp44.00, hardback)

World Health Organisation, ENVIRONMENTAL POLLUTION CONTROL IN RELATION TO DEVELOPMENT, World Health Organisation, Geneva, Technical Report Series, 718, 1985, 63 pp.

TRANSPORT IS FOR PEOPLE: NINTH INTERNATIONAL SYMPOSIUM ON THEORY AND PRACTICE IN TRANSPORT ECONOMICS, European Conference of Ministers of Transport, 1983, Paris (#bp15.00)

RECREATION MANAGEMENT AND PRICING, by A. G. Bovaird, M. J. Tricker and R. Stoakes, Gower Press, Aldershot, 1984, 182 pp. (#bp15, hardback)

URBAN LAND AND SHELTER FOR THE POOR, by Patrick McAuslan, Earthscan#shInternational Institute for Environment and Development, London, 1985, 145 pp.

CARING FOR THE UNEMPLOYED. Prepared for the Association of Metro‐polital Authorities by Susan Balloch, Chris Hume, Brian Jones and Peter Westland. Publishers: Bedford Square Press, London, 1985, for the National Council for Voluntary Organisations.

THE LONG‐TERM UNEMPLOYED. ACTION FOR A FORGOTTEN MILLION, by Peter Ashby (Head, NVCO Policy Analysis Unit). An NCVO Policy Discussion document, Bedford Square Press, London (1985).

ANTHROPOGENIC COMPOUNDS: Volume 3 Part C of The Handbook of Environmental Chemistry, edited by O. Hutzinger, Springer‐Verlag, Germany, 248 pp. 1986. (DM 188.00)

HEAVY METALS IN NATURAL WATERS: APPLIED MONITORING AND IMPACT ASSESSMENT, by James W. Moore and S. Ramamoorthy, Springer‐Verlag, U.S.A. and Germany, viii #pl 268 pages, index, 1984. (DM 108.00)

DESTRUCTION AND DISPOSAL OF PCBs BY THERMAL AND NON‐THERMAL METHODS, by D. G. Ackerman, L. L. Scinto, P. S. Bakshi, R. G. Delumyea, R. J. Johnson, G. Richard, A. M. Takata and E. M. Sworzyn. Noyes Data Corporation, Park Ridge, New Jersey, 1983, xiv #pl 417 pages (no index). (#dl48.00)

ELECTROSTATIC PRECIPITATOR MANUAL (Pollution Technology Review No. 91), by Jack R. McDonald and Alan H. Dean, Noyes Data Corporation, U.S.A., 1982. (#dl48.00)

PATTY'S INDUSTRIAL HYGIENE AND TOXICOLOGY, edited by Lewis J. Cralley and Lester V. Cralley, Volume 3 (2nd Edition)—Theory and Rationale of Industrial Hygiene Practice: (i) Volume 3A—The Work Environment (#bp97.20); (ii) Volume 3B—Biological Responses (#bp92.00) J. Wiley and Sons Ltd., Chichester U.K. 1985.

SAFE DRINKING WATER. THE IMPACT OF CHEMICALS ON A LIMITED RESOURCE, edited by R. G. Rice, J. Wiley and Sons, Chichester, U.K., Lewis Publishers Inc. Chelsea MI, 1985. (#bp36.00)

PLANTS FOR ARID LANDS. (Proceedings of the Kew International Conference on Economic Plants for Arid Lands held in the Jodrell Laboratory, Royal Botanic Gardens, Kew, England, 23‐27 July 1984), edited by G. E. Wickens, J. R. Goodwin and D. V. Field. George Allen and Unwin, London, 1985. (#bp30.00)

REGULATED RIVERS, edited by A. Lillehammer and S. J. Saltveit, Univer‐sitetsforlaget AS, Oslo, 1984. (#bp47.50)

NUTRIENT CYCLING IN TROPICAL FOREST ECOSYSTEMS, by C. F. Jordan, Wiley, Chichester, 1985. (#bp13.45)     

Practices,barriers and benefits of risk management process in building services costs estimation: comment

This note is a comment on Mok, C.K., Rao Tummala, V.M. and Leung, H.M. (1997) Practices, barriers and benefits of risk management process in building services cost estimation, Construction Management and Economics, 15 (2), 161–75, which describes research into the risk perceptions and risk management practices of building services engineers in Hong Kong. The note questions statements made in the paper and parts of the research design and data analyses.     

Perceptions of HIV/AIDS policies and treatment programmes by Western Cape construction firms

The HIV/AIDS pandemic poses a substantial long‐term threat to economic development in South Africa. A questionnaire survey explored the perceptions of a sample of construction firms in the Western Cape regarding HIV/AIDS policy and treatment programmes. The findings show that there is no universal view about the long‐term threat of HIV/AIDS. Most organizations have awareness policies in place but prevention and treatment policies are less common. Treatment programmes are the least implemented of all intervention services due to insufficient resource capacity, the potential stigmatization of infected persons, and low take‐up rates. Despite an acknowledgement of the benefits flowing from mounting treatment programmes, doubt exists as to their financial viability.     

Colloidal Processing of Zirconium Diboride Ultra‐High Temperature Ceramics

Colloidal processing of the Ultra‐High Temperature Ceramic (UHTC) zirconium diboride (ZrB₂) to develop near?net‐shaping techniques has been investigated. The use of the colloidal processing technique produces higher particle packing that ultimately enables achieving greater densification at lower temperatures and pressures, even pressureless sintering. ZrB₂ suspension formulations have been optimized in terms of rheological behavior. Suspensions were shaped into green bodies (63% relative density) using slip casting. The densification was carried out at 1900°C, 2000°C, and 2100°C, using both hot pressing at 40 MPa and pressureless sintering. The colloidally processed materials were compared with materials prepared by a conventional dry processing route (cold pressed at 50 MPa) and subjected to the same densification procedures. Sintered densities for samples produced by the colloidal route are higher than produced by the dry route (up to 99.5% relative density by hot pressing), even when pressureless sintering is performed (more than 90% relative density). The promising results are considered as a starting point for the fabrication of complex‐shaped components that can be densified at lower sintering temperatures without pressure.     

Problems in using a comb sample as a stress-free reference for the determination of welding residual stress by diffraction

Precise measurement of a stress-free reference lattice parameter is vital in the determination of residual stress by diffraction techniques using θ/2θ-based analyses. For the evaluation of the residual strain profile in fusion-welded material, it is particularly important to correct the measured strain point-by-point by a stress-free reference for each spatial location across the weld. This is to take into account the compositional and microstructural variation across the weld caused by the thermal cycle of welding, as local changes in solute content of the parent alloy cause changes in the stress-free lattice parameter.Although ideally such measurements should be obtained from small cubes machined from the weld, the use of a comb sample has previously been proposed as a macro-stress-free reference, with the assumption that each finger of the comb is of insufficient dimension to hold a macro-stress field. This paper presents an approach towards analysis of the stress-free reference values using a comb sample extracted from a variable polarity plasma arc (VPPA) welded plate. It is shown that there is inter-granular stress and retained macro-stress within the comb teeth, and an experimental approach to deal with the problem is proposed.     

Receive antenna selection for MIMO systems over correlated fading channels

In this letter, we propose a novel receive antenna selection algorithm based on cross entropy optimization to maximize the capacity over spatially correlated channels in multiple-input multiple-output (MIMO) wireless systems. The performance of the proposed algorithm is investigated and compared with the existing schemes. Simulation results show that our low complexity algorithm can achieve near-optimal results that converge to within 99% of the optimal results obtained by exhaustive search. In addition, the proposed algorithm achieves near-optimal results irrespective of the mutual relationship between the number of transmit and receive antennas, the statistical properties of the channel and the operating signal-to-noise ratio.