Photofoams: remote control of foam destabilization by exposure to light using an azobenzene surfactant.

We report evidence for photocontrolled stability and breakage of aqueous foams made from solutions of a cationic azobenzene-containing surfactant over a wide range of concentrations. Exposure to UV or visible lights results in shape and polarity switches in the surfactant molecule, which in turn affects several properties including critical micelle concentration, equilibrium surface tension, and the air-water interfacial composition (cis isomers are displaced by trans ones). We demonstrate that the trans isomer stabilizes foams, whereas the cis isomer forms unstable foams, a property that does not correlate with effects of light on surface tension, nor with total surfactant concentration. Achieving in situ breakage of foam is accordingly ascribed to the remote control of the dynamics of adsorption/desorption of the surfactant, accompanied by gradients of concentrations out of equilibrium. Photomodulation of adsorption kinetics and/or diffusion dynamics on interfaces is reached here by a noninvasive clean trigger, bringing a new tool for the study of foams.

[The three-dimensional spiral scanner and volume rendering technique: importance in craniofacial traumatology and reconstructive surgery]. / Le scanner spiralé 3 D avec traitement de l'image en rendu de volume.

There are two reconstruction methods for 3D imaging with a helical scanner: a surface rendering process providing a 3D-SSD (Surface Shaded Display) image that looks like a plaster cast skull and 3D-VRD (Volume Rendering Technique) which is more precise and gives 3D images similar to radiographs. We review briefly the techniques used to acquire these images and present 3D volume-rendering scanners, pointing out its usefulness in craniomaxillofacial traumatology and reconstructive surgery.

Summary of track D: social science: research, policy and action.

SCOPE: This review summarizes the main issues discussed during Track D, which examined the societal impact of HIV/AIDS, and responses to the epidemic by individuals, families, communities and societies worldwide. Micro- and macrolevel issues addressed included the development, implementation and evaluation of programmes for prevention and care; policy development and implementation; structural issues such as the impact of gender relations, development and migration on the development of the epidemic; and the social and economic impact of HIV/AIDS on affected societies and communities. RECURRENT THEMES: Presentations provided strong evidence that peer-led, community-based programmes offer particularly effective ways of working, and that participatory research involving affected communities provides useful results for the design and evaluation of programmes and policies. This is the case across settings, issues, populations and countries. FUTURE DIRECTIONS: Emerging needs include how best to ensure sustainability of national and international responses, how best to scale up successful interventions for wider reach, and how best to work with systematically marginalized, neglected groups and populations. Research priorities include the characterization of the multiple determinants of HIV-related vulnerability, and the evaluation of interventions that take these complex determinants as their starting point. A more coherent and strategic response requires less separation between the different constituencies involved in AIDS work, and the more sustained involvement of people living with HIV/AIDS themselves.

AIDS, children, families: how to respond?

PIP: As more and more children become orphans due to the AIDS-related deaths of their parents and/or guardians, many people think that placing orphans in orphanages may be the solution to the problem. While this focus upon orphans is understandable, one must also not forget that children suffer from a diminished standard of living due to AIDS morbidity long before their parents die and HIV affects all social and economic dependents of an infected person, not just the children. The Paris-based International Children's Center (ICC) followed 120 AIDS-affected families for several years to study the socioeconomic destiny of the children and families overall. It was subsequently concluded that appropriate and lasting support programs must take into account and build upon the coping responses of the families and communities themselves. Thirty nongovernmental organization representatives from eight eastern and southern African countries attending a workshop in Lusaka, Zambia, February 1994 developed the following recommendations: orphanages should be used in only emergency situations and on a temporary basis, access to education must be maintained for children affected by the epidemic, cash donations should be made to needy families in only extreme cases in the interest of promoting self-sufficiency, and the rights of dependent survivors must be respected, especially with regard to inheritance.^ieng