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[en] This pilot study was designed to assess whether a synthetic matrix metalloproteinase (MMP) inhibitor has anti-inflammatory properties in mild asthma. Tumor necrosis factor alpha (TNFα) has been shown to be an important cytokine in the pathogenesis of allergic airway inflammatory responses, and its release can be inhibited by MMP inhibitors. Twelve atopic asthmatic subjects received the MMP inhibitor marimastat (5 mg) or placebo, twice daily for 3 weeks, separated by a 6-week washout period in a randomized, double-blind, cross-over manner. All subjects underwent an allergen inhalation provocation test to Dermatophagoides pteronyssinus before and after each study phase. Spirometry, exhaled NO (eNO) levels, differential sputum cell counts, an asthma symptom questionnaire, peak flow, and β2-agonist usage were measured. Nine subjects completed the study, and, when compared with placebo, marimastat reduced bronchial hyper-responsiveness to inhaled allergen in these subjects from an allergen PC20 of 22.2 AU/ml (95%CI 11.7-32.6) to 17.0 AU/ml (95%CI 7.6-26.4, P = 0.02). The marimastat phase showed a nonsignificant fall in sputum inflammatory cells. Marimastat did not modify eNO, FEV1, asthma symptoms, or albuterol usage. In conclusion, airway responsiveness to allergen may be modified by a MMP inhibitor, perhaps via TNFα playing a role in airway inflammation and remodeling
[en] This abstract presents research from two studies investigating urban flood perceptions and mitigative behaviours of private individuals in Canada. The first study, completed in July, 2006, investigated perceptions of overland flooding and sewer backup resulting from extreme rainfall events in Peterborough, Ontario. The second, completed in November, 2007, investigated sewer backup perceptions of homeowners in Edmonton, Alberta and Toronto, Ontario. The research studies sought to explore: Hazard and risk perceptions of individuals affected by overland flooding and sewer backup; Knowledge of mitigative options, and mitigative actions taken by individual residents to reduce the risk of basement flood damage; Attributions of responsibility for urban flood damages; Awareness of municipal actions designed to reduce urban flood risk; Satisfaction with the cost sharing tools of insurance and government relief.
[en] To calculate the wet deposition of aerosol-bound radionuclides on ground and vegetation, the scavenging coefficients must be well known. In case of rainfall there are, however, great differences between some of the experimental results published and theory. In the case of snowfall there is a large scatter in the experimental data published. Too little is known about the snow-out coefficient vs particle diameter as well as precipitation intensity. In the course of investigating snow-out, an outdoor experiment was set up to determine both the overall snow-out and wash-out coefficients (below cloud) of monodisperse test aerosols by natural hydrometeors. The collection efficiency of simple snowflake models was determined in laboratory experiments. The snow-out coefficient was calculated using empirical snowflake size spectra data. In the case of wash-out by rain, the results of the outdoor experiments are compared to results theoretically derived by an earlier study. In the case of snow-out, the results of the outdoor experiments are compared with those calculated from the collection efficiency data. The snow-out coefficients measured outdoors are about five times larger than the wash-out coefficients. (Author)
[en] Predictive models are necessary in order to minimize potential damages in the event of a nuclear or radiological release. For this reason, a novel model for the calculation of both wet and dry deposition from airborne radioactivity is proposed. Full derivation of the model and the estimation of uncertainty are presented, and the validity of the model is evaluated by calculating deposition based on several measured airborne activities in different countries. The results are compared with the corresponding measured deposition activities and the predictive power of the model is found to be good, i.e. calculated depositions being within the limits of measurement uncertainty. Additionally, limitations of the model and possible sources of error in the calculations are discussed. - Highlights: • Novel Semi Empirical Deposition Estimation Model based on probabilistic approach. • Takes into account both dry and wet deposition. • Dry deposition is found to be very susceptible to changes in the particle distribution. • Wet deposition is found to increase to the power of 0.315 of precipitation intensity, instead of increasing linearly.
[en] Field experiments were performed to determine the washout coefficient of iodine vapour scavenged by rain. They consisted in emitting a known amount of stable iodine and sampling the wet deposit in collectors conveniently placed to evaluate the fraction of plume scavenged by rain. It was shown that precautions are to be taken to avoid a superposition of direct deposition of iodine vapour by reaction on collector surfaces (dry deposition) and indirect deposition by rain scavenging (wet deposition). The data obtained (mean value = 8.2 x 10-5 s-1) validate the theoretical values currently used and indicate that, under the conditions of these experiments, iodine uptake by rain droplets is apparently irreversible
[en] The Chernobyl accident demonstrated that localised wet deposition of radioactive aerosols can have major implications for the consequences of a nuclear accident. Traditionally very simple concepts have been used in assessment of this deposition, based on wash-out ratios or very simplified wash-out/rain-out models. These do not allow for the full influence of the dynamical nature of storm systems, and the range of microphysical and chemical processes involved. This paper will illustrate the variability likely to occur, and particular situations which may lead to enhanced hot-spot areas in addition to the variations in the intensity of precipitation. The uncertainties will be illustrated by results from more sophisticated models of storm systems, and the transport of radioactive aerosols through them. Some of the practical implications for real-time consequence assessment and emergency procedures will then be discussed
[en] A model for the determination of drift deposition around natural-draft cooling towers is presented. An application of the model in actual operating conditions indicates the effect of drift rate at the cooling tower outlet and weather conditions on the size and shape of wetted area. (author)