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31.
Five students of a rescue training school cycled at 50 W for 20 min at 20 °C before walking at 5 km/hr up to 30 min in a climatic chamber at 55 °C and 30% relative humidity. 4 different types of clothing ensembles differing in terms of thickness and thermal insulation value were tested on separate days. All subjects completed 28–30 min in light clothing, but quit after 20–27 min in 3 firefighter ensembles due to a rectal temperature of 39 °C or subjective fatigue. No difference in the evolution of mean skin or rectal temperature was seen for the 3 turnout ensembles. Sweat production amounted to about 1000 g in the turnout gears of which less than 20% evaporated. It was concluded that the small differences between the turnout gears in terms of design, thickness and insulation value had no effect on the resulting heat physiological strain for the given experimental conditions.  相似文献   
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The heat transferred through protective clothing under long wave radiation compared to a reference condition without radiant stress was determined in thermal manikin experiments. The influence of clothing insulation and reflectivity, and the interaction with wind and wet underclothing were considered. Garments with different outer materials and colours and additionally an aluminised reflective suit were combined with different number and types of dry and pre-wetted underwear layers. Under radiant stress, whole body heat loss decreased, i.e., heat gain occurred compared to the reference. This heat gain increased with radiation intensity, and decreased with air velocity and clothing insulation. Except for the reflective outer layer that showed only minimal heat gain over the whole range of radiation intensities, the influence of the outer garments’ material and colour was small with dry clothing. Wetting the underclothing for simulating sweat accumulation, however, caused differing effects with higher heat gain in less permeable garments.  相似文献   
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Secondary metabolites from bracken fern (Pteridium aquilinum (L.) Kuhn) are suspected of causing cancer in humans. The main carcinogen is the highly water-soluble norsesquiterpene glucoside ptaquiloside, which may be ingested by humans through food, e.g. via contaminated water, meat or milk. It has been postulated that carcinogens could also be ingested through breathing air containing bracken spores. Ptaquiloside has not previously been identified in bracken spores. The aim of the study was to determine whether ptaquiloside is present in bracken spores, and if so, to estimate its content in a collection of spores from Britain. Ptaquiloside was present in all samples, with a maximum of 29 μg g?1, which is very low compared to other parts of the fern. Considering the low abundance of spores in breathing air under normal conditions, this exposure route is likely to be secondary to milk or drinking water.  相似文献   
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Lichen is a symbiosis between algae and fungi. They have for decades been used as bioindicators for atmospheric deposition of heavy metals, organic compounds and radioactive elements. Especially the species Cladonia alpestris and Cladonia rangiferina are important for the food chain lichen-reindeer-man.The concentration of 129I was determined in lichen samples (Cladonia alpestris) contaminated by fallout from atmospheric nuclear tests explosions and the Chernobyl accident. The samples were collected at Lake Rogen District (62.3°N, 12.4°E) in central Sweden in the periods 1961-1975 and 1987-1998, and analysed with accelerator mass spectrometry (AMS) at CNA (Seville) to study its distribution in different layers. Data on the 137Cs activity measured previously were also included in this study. The 129I concentration ranged from (0.95 ± 0.13) × 108 at g−1 in 1961 in the uppermost layer to (14.2 ± 0.5) × 108 at g−1 in 1987 in deepest layer. The 129I/137Cs atom ratio ranged between 0.12 and 0.27 for lichen samples collected in the period 1961-1975, indicating weapons tests fallout. For lichen samples collected between 1987 and 1998 the behaviour of 137Cs concentrations reflected Chernobyl fallout. The concentrations of the two radionuclides followed each other quite well in the profile, reflecting the same origin for both.From the point of view of the spatial distribution in the lichen, it appears that 129I was predominantly accumulated in the lowest layer, the opposite to 137Cs for which the highest amounts were detected systematically in the topmost layer of lichen. This vertical distribution is important for radioecology because lichen is the initial link in the food chain lichen-reindeer-man, and reindeer only graze the upper parts of lichen carpets.  相似文献   
35.
An international conference on polonium (Po) and radioactive isotopes was held in Seville Spain, 26-28 October 2009 at the Centro Nacional de Aceleradores. It was attended by 138 participants from 38 different countries. The sessions covered all aspects on Po and lead (Pb) such as radiochemistry, terrestrial and marine radioecology, kinetics, sedimentation rates, atmospheric tracers, NORM industries and dose assessment  相似文献   
36.
Regional change under agricultural expansion in the Chaco of Argentina is determined by interactions of rainfall change, infrastructure development, socio-economic actions and values, and the social perceptions of change. Our study focused on adaptation in the socio-environmental system which is the key to understanding opportunities, uncertainties and risk in the context of historical change. Change in land use from extensive grazing through mixed farming and on to industrial-scale soybean production was made possible by a trend of increasing rainfall that reduced the risk of crop failure from drought since the 1970s. Rainfall change coincided with a period in which the Chaco forest was suffering extensive degradation from long-term extractive use. The degradation aided agricultural expansion since the degraded state of the ecosystem justified public policies of deforestation. In parallel to these resource-based processes, public policy changed in the late 70s and 80s toward favoring privatization of state land and exclusion of small producers. This permitted the land concentration needed for industrial-scale production. Technological innovation in both water and land resource management reinforced the process of concentration because small producers rarely have the financial or educational capital to develop or implement emerging technologies. One of the results of the intensification and expansion of agriculture is that soil surface sealing, waterlogging and flood risk are now effective at a landscape scale. To address these risks, private enterprise and government efforts must now come together toward innovative policies in integrated landscape management.  相似文献   
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The study comprised 85 young (25–34 years old) women who underwent genetic amniocentesis, 80 comparable young women who had an ultrasoundscan at the same gestational age and 74 women (35–40 years old) who had amniocentesis. The State-Trait Anxiety Inventory and Visual Analogue Scales concerning anxiety and worry were used on four occasions to evaluate psychological changes during pregnancy. The anxiety level in the younger women decreased after amniocentesis and a further decrease was observed after the results were communicated to them. However, similar changes were seen in the group of younger women after ultrasonography, and there was no difference in anxiety level between the two groups of younger women in the 16th or in the 35th week of pregnancy. Thus, in younger women at low genetic risk amniocentesis was neither anxiety-relieving, nor anxiety-creating. The level of anxiety before amniocentesis was not higher in the older than in the younger women having amniocentesis. However, in the younger women a significant decrease in anxiety was seen as soon as amniocentesis had been performed, while in the older women this decrease was delayed until after the results were known.  相似文献   
40.
Zinc, Cu, Cd, Pb, Ag, Ni, Co, Cr, Fe and Mn concentrations in some tissues of crabeater seal (Lobodon carcinophagus), leopard seal (Hydrurga leptonyx) and Weddell seal (Leptonychotes weddelli) from the Antarctic were determined. Distinct inter-tissue differences in metal concentrations in seals were observed; liver contained maximum levels of Zn, Cu, Ag and Mn, whilst kidney showed the highest levels of Cd, Ni and Co. Muscle was characterized by low concentrations of all the elements analyzed. The metal concentrations in the vertebrates analyzed were compared with those for organisms originating from various aquatic areas. Significant correlations were found between the levels of several of the metals analyzed, e.g. between renal and hepatic concentrations of Zn and Cd. Strong relationships between the hepatic concentrations of some metals were found, e.g. Cd-Zn. These two metals also showed a significant coassociation in their renal concentrations. The slope of the regression line for renal Cd/Zn was about three times higher than the hepatic one and this may reflect a relatively high Cd exposure, probably from specific food (squid and krill) provenance, of the seals analyzed.  相似文献   
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