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    ABSTRACT: Sugarcane combustion generates fine-grained particulate that has the potential to be a respiratory health hazard because of its grain size and composition. In particular, conversion of amorphous silica to crystalline forms during burning may provide a source of toxic particles. In this study, we investigate and evaluate the toxicity of sugarcane ash and bagasse ash formed from commercial sugarcane burning. Experiments to determine the main physicochemical properties of the particles, known to modulate biological responses, were combined with cellular toxicity assays to gain insight into the potential reactions that could occur at the particle-lung interface following inhalation. The specific surface area of the particles ranged from ∼16 to 90 m(2) g(-1) . The samples did not generate hydroxyl- or carbon-centered radicals in cell-free tests. However, all samples were able to 'scavenge' an external source of hydroxyl radicals, which may be indicative of defects on the particle surfaces that may interfere with cellular processes. The bioavailable iron on the particle surfaces was low (2-3 μmol m(-2) ), indicating a low propensity for iron-catalyzed radical generation. The sample surfaces were all hydrophilic and slightly acidic, which may be due to the presence of oxygenated (functional) groups. The ability to cause oxidative stress and membrane rupture in red blood cells (hemolysis) was found to be low, indicating that the samples are not toxic by the mechanisms tested. Cytotoxicity of sugarcane ash was observed, by measuring lactate dehydrogenase release, after incubation of relatively high concentrations of ash with murine alveolar macrophage cells. All samples induced nitrogen oxide release (although only at very high concentrations) and reactive oxygen species generation (although the bagasse samples were less potent than the sugarcane ash). However, the samples induced significantly lower cytotoxic effects and nitrogen oxide generation when compared with the positive control. © 2012 Wiley Periodicals, Inc. Environ Toxicol, 2012.
    Environmental Toxicology 05/2014; 29(5). DOI:10.1002/tox.21776
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    ABSTRACT: While research now highlights that men who have sex with men (MSM) in places such as South Africa are at particular risk of HIV infection, left relatively unexplored are potential relationships between one of the most pressing social issues affecting peri-urban MSM - namely homophobic stigma - and sexual risk-taking behaviour. Drawing on research from the Ukwazana baseline study of 316 township MSM in Cape Town we examine how homophobic stigma relates to psychosocial factors such as depression and self-efficacy and the risk activity of unprotected anal intercourse (UAI). By deploying cross-sectional association models, we examine a series of relationships between these variables and offer evidence to suggest that HIV prevention programmes aimed at sexual minority groups should be mindful of potentially complex relationships between social stigmas such as homophobia and sexual risk-taking behaviour.
    AIDS Care 12/2013; 26(7). DOI:10.1080/09540121.2013.859652
  • Conservation Biology 09/2013; 27(6). DOI:10.1111/cobi.12141
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    ABSTRACT: Abstract Men who have sex with men (MSM) in South Africa remain at particular risk of HIV infection. The Ukwazana baseline survey is the first to explore this risk in relation to psychological factors associated with unprotected anal intercourse (UAI). A cohort of 316 MSM from township peri-urban Cape Town took part in the survey. The survey found that 55.2% had engaged in UAI over the preceding 6 months. Depression was significantly associated with UAI. Respondents with self-efficacy scores less than two standard deviations above the mean were also more likely to have engaged in UAI. A Sobel test for mediation highlighted that the depression-UAI association was partially mediated by self-efficacy, indicating that most of the effect of depression on UAI was not covarying with self-efficacy. This study, therefore, highlights that both depression and self-efficacy should be considered factors to be addressed in HIV-prevention programmes aimed at peri-urban MSM.
    AIDS Care 02/2013; 25(10). DOI:10.1080/09540121.2013.764383
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    ABSTRACT: This paper presents the results of empirical research on Montserrat, in the British West Indies, undertaken in 2008–2010. It highlights the challenges of managing a crisis that evolved from acute to chronic over a period of fifteen years. In particular, the paper considers the evolution of science and policy over a period of fifteen years in its social and cultural context. It discusses the relationship between different types of evolving knowledges, and the interaction between them. Finally, a reflexive model is introduced to draw attention to some of the challenges of managing the science–policy interface under high uncertainty and high stakes.
    Environmental Science & Policy 01/2013; 39. DOI:10.1016/j.envsci.2013.08.009
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    ABSTRACT: In humid, temperate climates, green algae can make a significant contribution to the deterioration of building stone, both through unsightly staining ('greening') and, possibly, physical and chemical transformations. However, very little is known about the factors that influence the deteriorative impact and spatial distribution of green algal biofilms, hindering attempts to model the influence of climate change on building conservation. To address this problem, we surveyed four sandstone heritage structures in Belfast, UK. Our research had two aims: 1) to investigate the relationships between greening and the deterioration of stone structures and 2) to assess the impacts of environmental factors on the distribution of green biofilms. We applied an array of analytical techniques to measure stone properties indicative of deterioration status (hardness, colour and permeability) and environmental conditions related to algal growth (surface and sub-surface moisture, temperature and surface texture). Our results indicated that stone hardness was highly variable but only weakly related to levels of greening. Stone that had been exposed for many years was, on average, darker and greener than new stone of the same type, but there was no correlation between greening and darkening. Stone permeability was higher on 'old', weathered stone but not consistently related to the incidence of greening. However, there was evidence to suggest that thick algal biofilms were capable of reducing the ingress of moisture. Greening was negatively correlated with point measurements of surface temperature, but not moisture or surface texture. Our findings suggested that greening had little impact on the physical integrity of stone; indeed the influence of algae on moisture regimes in stone may have a broadly bioprotective action. Furthermore, the relationship between moisture levels and greening is not straightforward and is likely to be heavily dependent upon temporal patterns in moisture regimes and other, unmeasured, factors such as nutrient supply.
    Science of The Total Environment 11/2012; 442C:152-164. DOI:10.1016/j.scitotenv.2012.10.050
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    ABSTRACT: Volcanic thermal anomalies measured from space can vary in both size and intensity. These changes are directly related to heat loss from the Earth's surface, a process which is of critical importance to the dynamics of active volcanoes. We use a time series of multispectral thermal infrared images, acquired by the ASTER sensor throughout 2000-2009, to investigate the change in thermal anomalies at Mount Erebus (Antarctica) through time. Differences in the behaviour of low temperature anomalies and high temperature anomalies are observed. The more abundant, seasonally dependent, low temperature anomalies are associated with vaporous volcanic plumes and highlights that caution should be applied when interpreting low temperature anomalies as thermal precursors to eruptive events. The smaller, spatially more consistent, higher temperature anomalies are associated with an actively overturning lava lake and complement previous findings drawn from course resolution time series of the volcano. Measuring the size and intensity of volcanic thermal anomalies through time is possible because of the relatively high spatial and spectral resolution of the ASTER sensor and represents an innovative and useful contribution to volcano monitoring efforts. The methodology developed during this study is likely to facilitate the analysis of volcanic behaviour at other volcanoes as well.
    Cities on Volcanoes 7, Colima, Mexico; 11/2012
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    ABSTRACT: This study compiled a wide range of modern and historic geospatial datasets to examine ecological and geomorphic change at Diego Garcia Atoll across a 38-year period (1967–2005). This remarkable collection of spatially referenced information offered an opportunity to advance our understanding of the nature and extent of environmental change that has taken place with the construction of the military airbase at Diego Garcia. Changes assessed included movements of the lagoon rim shorelines, changes in the terrestrial vegetation on the lagoon rim and amendments to the bathymetry of the lagoon basin through dredging activities. Data compiled included detailed shoreline and vegetation maps produced as part of the H.M.S. Vidal Indian Ocean Expedition (1967), three Ikonos satellite images acquired in 2005 that collectively covered the complete Atoll area, a ground truthing field dataset collected in the northern section of the lagoon for the purpose of seafloor mapping (2005), observational evidence of shoreline erosion including photographs and descriptions of seawater inundations and bathymetric soundings from five independent surveys of the lagoon floor (1967, 1985, 1987, 1988 and 1997). Results indicated that much of the change along the lagoon rim is associated with the expansion of the inner lagoon shoreline as a result of the construction of the military airbase, with an estimated increase in land area of 3.01 km 2 in this portion of the atoll rim. Comparisons of 69 rim width transects measured from 1967 and 2005 indicated that shorelines are both eroding (26 transects) and accreting (43 transects). Within a total vegetated area of 24 km 2 , OPEN ACCESS Remote Sens. 2012, 4 3445 there was a notable transition from Cocos Woodland to Broadleaf Woodland for a land area of 5.6 km 2 . From the hydrographic surveys, it was estimated that approximately 0.55 km 3 of carbonate sediment material has been removed from the northwest quadrant of the lagoon, particularly in the vicinity of the Main Passage. As no previous record of benthic character exists, a complete benthic habitat map of the atoll was derived through classification of the three IKONOS satellite images. Management implications arising from this overall appraisal of geomorphic and ecological change at Diego Garcia included the need for ongoing monitoring of shoreline change at a representative set of sites around the atoll rim, monitoring of the water flow regime through the northern channels between the open ocean and the lagoon basin and an ongoing mapping campaign to record periodic changes in the character of the benthic surface ecology.
    Remote Sensing 11/2012; 4(11):3444-3461. DOI:10.3390/rs4113444
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    ABSTRACT: Objectives. To investigate whether number of children and, among parents, having a daughter is associated with older people's likelihood of at least weekly face-to-face social contact and later receipt of help if needed. Method. Multivariate analysis of data from Waves 1 and 2 of the English Longitudinal Study of Ageing (ELSA). RESULTS: Older parents in England had higher chances of at least weekly face-to-face social contact than their childless counterparts but larger family size had only a slight additional effect. For parents, having at least one daughter was more important than number of children. Larger family size was positively associated with receipt of help from a child by parents with activities of daily living (ADL) or instrumental activities of daily living (IADL) limitations. Childless women were more likely than mothers to receive help from friends but even so had lower odds of receiving help from any informal source. Contact with a child in 2002 predicted receipt of help 2 years later. Discussion. These results show some advantages for older parents compared with childless individuals in terms of social contact and receipt of help and, among parents, an additional effect of having a daughter. Changes in family size distributions have implications for the support of older people and for planners of formal services.
    The Journals of Gerontology Series B Psychological Sciences and Social Sciences 10/2012; 67(6):742-54. DOI:10.1093/geronb/gbs082
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    ABSTRACT: Building stone provides a habitat for an array of microorganisms, many of which have been demonstrated to have a deleterious effect on the appearance and/or structural integrity of stone masonry. It is essential to understand the composition and structure of stone-dwelling (lithobiontic) microbial communities if successful stone conservation strategies are to be applied, particularly in the face of global environmental change. Ideally, the techniques used to sample such assemblages should be non-destructive due to the sensitive conservation status of many stone buildings. This paper quantitatively assesses the performance of sterile adhesive tape as a non-destructive sampling technique and compares the results of tape sampling with an alternative, destructive, sampling method. We used DNA fingerprinting (TRFLP) to characterise the algal, fungal and bacterial communities living on a stone slab. Our results demonstrate that tape sampling may be used to collect viable quantities of microbial DNA from environmental samples. This technique is ideally suited to the sampling of microbial biofilms, particularly when these communities are dominated by green algae. It provides a good approximation of total community diversity (i.e. the aggregate diversity of epilithic and endolithic communities). Tape sampling is straightforward, rapid and cost effective. When combined with molecular analytical techniques, this sampling method has the potential to make a major contribution to efforts to understand the structure of lithobiontic microbial communities and our ability to predict the response of such communities to future environmental change.
    Journal of microbiological methods 09/2012; 91(3). DOI:10.1016/j.mimet.2012.09.022
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