Miss Linda Dekker and co-workers from the UCL Eastman Oral Institute, University College London presented the work to the Society for General Microbiology’s conference at Harrogate . Photodynamic therapy uses antimicrobial brokers, in this instance tin chlorin e6 , which produce free of charge radicals and an unstable type of oxygen called singlet oxygen if they face light at the right wavelength. These harm and kill bacteria.This one was particularly difficult. It not only had the usual problem of finding the least data about the areas where the problem was likely to be greatest – – specifically, low-income countries in Africa and Asia – – but it also had to establish ‘disability,’ which is a fluid idea that depends not only on the physiological state of a person but the barriers to activity. ‘The big message here’s that folks are facing barriers and that is what the main problem is,’ said Krug. ‘Disability can be an interaction between your impairment and the barriers put up by culture and the surroundings.’ Disability is further complicated simply by definition, as was evident in two surveys done in Ireland in the past decade.