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Tourism can form an important component of a nation's GDP,and Vietnam is among the most visited countries in Southeast Asia.Most studies on personal exposure focus on the general population,or occupational cohorts with exposure to specific pollutants.However,short-term exposure to air pollutants while visiting regions with high levels of air pollution can lead to acute health effects.A personal exposure study was conducted across three cities in Vietnam to estimate exposure to particulate matter(PM_(2.5)) and black carbon for tourists.Measurements were conducted during the wet season in 2014 in Ho Chi Minh City,Da Lat and Nha Trang using portable instrumentation.Average 24-hr PM_(2.5) and BC exposures were estimated as 18.9 ± 9.24 and 3.41 ± 1.33 μg/m~3 and among the three cities,Ho Chi Minh was found to have the highest PM_(2.5) concentrations.Environmental tobacco smoke,commuting and street food stands were found to contribute to highest levels of exposure to PM_(2.5) and BC across all cities.  相似文献   
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The exchanges of phosphorus between the Flax Pond, a tidal Spartina alterniflora marsh on the north shore of Long Island (USA) and Long Island Sound were measured over 18 months. Phosphate was exported from the marsh from May through December and imported during the remainder of the year. Organic phosphorus appears to be accumulated in all seasons, but the yearly phosphorus budget of the marsh is approximately balanced despite the accumulation of about 6 mm of sediment annually.  相似文献   
54.
A dietary requirement for sterols in crustacean larvae was established by the use of isotopic tracer techniques. Larvae of the mud crab Rhithropanopeus harrisii and larvae of the spider crab Libinia emarginata were exposed to acetate-14C or mevalonate-14C. Radioanalysis of the fatty acids of each species indicated sufficient incorporation of acetate for lipid synthesis. No radioactivity was detected in the sterols of animals exposed to either acetate-14C or mevalonate-14C. It was concluded that R. harrisii and L. emarginata larvae are unable to synthesize sterols from acetate or mevalonate and, therefore, require them in their diet.  相似文献   
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Environmental conditions greatly impact the dynamics of host–pathogen relationships, affecting outbreaks and emergence of new diseases. In corals, epizootics have been a main contributor to the decline of reef ecosystems and rising sea surface temperatures associated with climate change are thought to exacerbate virulence of pathogens and/or compromise the immune responses of coral hosts. Among pathogens strategies, protease secretion is a common virulence factor that promotes colonization of the host. As such, protease inhibitors play an invaluable role to the host for protection against pathogen invasion. This study describes changes in activity of proteases secreted by the fungal pathogen, Aspergillus sydowii, and protease inhibitors of Gorgonia ventalina under ambient and elevated temperatures and health conditions (disease and healthy). G. ventalina colonies were collected from Florida Keys, Florida (24° 34.138N, 81° 22.905W) or La Parguera, Puerto Rico (17° 56.091N, 67° 02.577W) in 2007 and 2012, respectively. At elevated temperatures, protease activity was significantly higher than at ambient temperatures in A. sydowii. Temperature stress did not induce a change in protease inhibitor activity, but in healthy G. ventalina colonies, inhibitor activity against proteases was higher than in diseased individuals. Healthy colonies appear capable of resisting proteolytic activity, but diseased individuals are still likely affected by pathogen infections. These data suggest that rising sea surface temperatures due to climate change may increase levels of virulence (protease activity) of A. sydowii, while immunity (protease inhibitor) of G. ventalina may not be affected.  相似文献   
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Managed field margins offer a means of reducing the impact of agricultural monocultures within intensively managed environments. By providing refuge for wild plants and the pollinators associated with them, field margins can also contribute to enhancing the pollination services within the monoculture. However, the effects of the monoculture on pollinator behaviour need to be carefully considered. It is known that pollinators may show density-dependent preferences such as neophobia (an avoidance of unfamiliar items) when different types of flower are available within their environment, and the dominance of monoculture crops within the environment may consequently have adverse effects upon the preferences shown by pollinators living in the field margins within them. In order to examine how pollinator preferences for wild flowers are affected by monocultures, we modelled the effects of density-dependent preferences, flower densities, and the geometry of field margins within a monoculture landscape using numerical simulations. This was done by considering how the placement of pollinator nests within a simple, spatially explicit landscape consisting of fields of monoculture crops separated by margins containing wild flowers affected the ratio of wild and monoculture crops experienced by the pollinator, given that it could only forage within a limited distance from its nest. Increasing field margin width and decreasing monoculture field width both led to an increase in pollinators visiting wild flowers (which levelled off as width increased). The size of the monoculture fields had little additional effect once they had passed an intermediate width. Increasing wild flower density within the margins led to a shift away from preferring monocultures. When wild flowers were at low densities compared to the monoculture, even the addition of small amounts of extra wild flowers had a large effect in shifting foraging preferences away from the monoculture. The distance which pollinators normally forage over only has an effect upon preferences for wild flowers when the travel distance is small. This suggests that careful consideration of margin design might be extremely important for those species which do not travel far. Innate preferences for density-dependence and particular crop types may also have an effect on preference behaviour. We demonstrate that the way in which resources are presented to indigenous pollinators may be extremely important in influencing where they choose to forage within agricultural landscapes. Careful margin design, as well as increasing the density of wild flowers (such as by enhancing the wild seed bank within the margins), may lead to overall improvements in ecosystem function within intensively farmed monocultures.  相似文献   
58.
This paper looks at a recent example of local authority/academiccollaboration over a protracted period of time from the different perspectives of those people who were directly involved in the process as key role players. The arena within which this collaboration took place (Local Agenda 21 policy-making in Manchester) has some particular characteristics of its own which influenced this process, and these are identified alongside some of the theoretical issues which affect the way collaborations of this kind are perceived and (much more rarely) are written about. The perspectivesof the client and of the contractor, as the authors reflect on their experiences in these roles, show that in practice processes of adjustment and of learning were taking place, because both sides for various reasons found that the dynamics of this situation meant that their preconceptions both of each other and of the contractual relationship they had thought they were entering had to be modified as the process unfolded. The paper concludes with both specific observations about this collaboration, and more general and more tentative comments about issues that might be experienced in future collaborations of this kind.  相似文献   
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Journal of Material Cycles and Waste Management - The cementitious and microstructural characteristics of an innovative waste-based eco-cement consisting of ground granulated blast-furnace slag...  相似文献   
60.
Environmental and Ecological Statistics - Recently there has been some renewed interest in skew-normal distribution (SND) because it provides a nice and natural generalization (in terms of...  相似文献   
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