553 research outputs found

    Autoregulation of the Escherichia coli melR promoter: repression involves four molecules of MelR

    Get PDF
    The Escherichia coli MelR protein is a transcription activator that autoregulates its own promoter by repressing transcription initiation. Optimal repression requires MelR binding to a site that overlaps the melR transcription start point and to upstream sites. In this work, we have investigated the different determinants needed for optimal repression and their spatial requirements. We show that repression requires a complex involving four DNA-bound MelR molecules, and that the global CRP regulator plays little or no role

    Screening for Meares-Irlen sensitivity in adults: can assessment methods predict changes in reading speed?

    Get PDF
    Two methods of assessing candidates for coloured overlays were compared with the aim of determining which method had the most practical utility. A total of 58 adults were assessed as potential candidates for coloured overlays, using two methods; a questionnaire, which identified self-reported previous symptoms, and a measure of perceptual distortions immediately prior to testing. Participants were classified as normal, Meares-Irlen sensitive, and borderline sensitive. Reading speed was measured with and without coloured overlays, using the Wilkins Rate of Reading Test and the change in speed was calculated. Participants classified as normal did not show any significant benefit from reading with an overlay. In contrast, a significant reading advantage was found for the borderline and Meares-Irlen participants. Current symptom rating was found to be a significant predictor of the change in reading speed, however the previous symptom rating was not found to be a reliable predictor. These data indicate that the assessment of perceptual distortions immediately prior to measuring colour preference and reading speed is the most meaningful method of assessing pattern glare and determining the utility of coloured overlays

    Food meanings in HIV and AIDS caregiving trajectories: Ritual, optimism and anguish among caregivers in Lesotho

    Get PDF
    The article describes the caregiving responsibility to provide food for chronically ill family members and the meanings attached to food and eating when ill created stress for family caregivers. The results come from a qualitative phenomenological study using in-depth interviews with 21 family caregivers of chronically ill HIV and AIDS patients in one district in Lesotho. Analysis of the interview data showed that the caregivers attached profound meanings to food and feeding care recipients. Their perceptions about food as part of family life and caring, the role of food and eating in curbing disease progression, the link between food and medical efficacy and the link between food and life led to ritualised behaviour around food, and moments of optimism and anguish in caregiving. Patientsā€™ behaviour in relation to food was in most instances inconsistent with the caregiversā€™ goals, thus leading this aspect of caregiving to induce stress. Services intended to support home-based caregivers and patients could contribute to the reduction of stress associated with food through suitably tailored food assistance and professional support to caregivers to enhance their competences and understanding of the dynamics of food intake as AIDS progressed

    Personality dimensions of people who suffer from visual stress

    Get PDF
    Personality dimensions of participants who suffer from visual stress were compared with those of normal participants using the Eysenck Personality Inventory. Extraversion-Introversion scores showed no significant differences between the participants who suffered visual stress and those who were classified as normal. By contrast, significant differences were found between the normal participants and those with visual stress in respect of Neuroticism-Stability. These differences accord with Eysenck's personality theory which states that those who score highly on the neuroticism scale do so because they have a neurological system with a low threshold such that their neurological system is easily activated by external stimuli. The findings also relate directly to the theory of visual stress proposed by Wilkins which postulates that visual stress results from an excess of neural activity. The data may indicate that the excess activity is likely to be localised at particular neurological regions or neural processes

    Improved membranes for the extraction of heavy metals

    Full text link
    This work presents a series of experimental tests on new practical approaches in membrane design to improve extraction capacity and rate. We chose an extraction system involving Aliquat 336 as the extractant and Cd(II) as the metal ion to be extracted to demonstrate these new approaches. The core element in the new membrane assembly was the extractant loaded sintered glass filter. This membrane assembly provided a large interface area between the extractant and the aqueous solution containing metal ions. By recycling the aqueous solution through the membrane assembly, the extraction rate was significantly improved. The membrane assembly also offered good extraction capacity
    • ā€¦
    corecore