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排序方式: 共有562条查询结果,搜索用时 31 毫秒
191.
Giovannangelo ME Gehring U Nordling E Oldenwening M van Rijswijk K de Wind S Hoek G Heinrich J Bellander T Brunekreef B 《Environment international》2007,33(1):9-16
BACKGROUND: Mold growth is believed to be one causative factor underlying the association between dampness in buildings and increased respiratory morbidity. Measurements of beta(1-->3)-glucans and fungal extracellular polysaccharides (EPS) are used as markers of mold exposure in field studies. Little is known about their levels and determinants in homes. OBJECTIVE: To study levels and determinants of beta(1-->3)-glucan and EPS levels in mattress and living room floor dust in three European countries. METHODS: Mattress and living room floor dust was collected in the homes of 1065 German, Dutch, and Swedish (pre-)school children. All samples were analyzed for beta(1-->3)-glucans and EPS in one central laboratory. Determinants were assessed by questionnaire. RESULTS: Amounts of dust, EPS and beta(1-->3)-glucan levels differed between countries. Amounts of dust, beta(1-->3)-glucan and EPS levels for mattresses were only weakly correlated with those for living room floors. Floor dust beta(1-->3)-glucan loads, EPS loads and EPS concentrations were strongly correlated with the amount of dust sampled, which is largely determined by the type of floor that was sampled (carpeted floors had 5-20 higher amounts of dust). None of the other determinants was consistently and statistically significantly associated with amounts of dust, beta(1-->3)-glucan and EPS concentrations on floors and mattresses. CONCLUSION: Mattress dust and floor dust are two different measures of exposure to the investigated mold components. Living room floor beta(1-->3)-glucan and EPS loads and EPS concentrations are largely determined by the type of floor sampled. Differences between countries can only partly be explained by the determinants studied. 相似文献
192.
Streamflow Depletion Modeling: Methods for an Adaptable and Conjunctive Water Management Decision Support Tool
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Xander Huggins Tom Gleeson Hailey Eckstrand Ben Kerr 《Journal of the American Water Resources Association》2018,54(5):1024-1038
Groundwater pumping depletes streamflow, which can have significant ecological impacts depending on the magnitude of depletion relative to environmental flow needs. Streamflow depletion estimates from groundwater pumping have been quantified using both analytical and numerical methods, but are not routinely compared to environmental flow needs or used in practical water management tools. Decision support tools that incorporate groundwater dynamics are becoming increasingly necessary for water managers as groundwater regulations become more important in environmental policy, particularly concerning the preservation of environmental flow needs. We develop and apply methods for a web‐based decision support tool for conjunctive groundwater and surface water management, demonstrated using a case study watershed in British Columbia, Canada. Open‐source data are analyzed with a combination of spatial algorithms and previously developed analytical models, such that the tool can be applied to other regions. Streamflow depletion estimates are calculated in four regions in the largely undeveloped Bulkley Valley, British Columbia. Our transparent methodology has geographic and data input flexibility which is a significant improvement on currently existing water management tool methods. 相似文献
193.
Various federal regulations require states to evaluate the effectiveness of their vehicle inspection and maintenance (I/M) programs in reducing in-use emissions. One method to evaluate program effectiveness is to compare initial and final program test results of individual vehicles. Unscheduled emissions measurements, from remote sensing measurement or roadside pullover testing, can also be used to provide an independent assessment of program effectiveness. We compared emissions reductions from the Arizona IM240 program measured by program data and a large set of remote sensing measurements. Remote sensing measurements indicate smaller emission reductions from the program than those calculated directly from program test results. We discuss some possible causes of the differences obtained from the two sets of measurements. 相似文献
194.
Porta M Grimalt JO Jariod M Ruiz L Marco E López T Malats N Puigdomènech E Zumeta E;PANKRAS II Study Group 《Environment international》2007,33(7):946-954
We aimed to analyse the influence of cholesterol and triglycerides, and of tobacco, coffee and alcohol consumption upon correlations between serum concentrations of organochlorine compounds (OCs) in patients with exocrine pancreatic cancer (EPC). Incident cases of EPC diagnosed in eastern Spain were prospectively identified (N=144). OCs were analysed by high-resolution gas chromatography with electron-capture detection. A strong correlation was observed between hexachlorobenzene (HCB) and beta-hexachlorocyclohexane (beta-HCH) (Spearman's rho=0.758). beta-HCH showed rho>0.4 with p,p'-DDT, p,p'-DDE, PCB138 and PCB153 (all p<0.001). Some correlations among compounds were slightly affected by tobacco, coffee or alcohol consumption. We observed a striking diversity of correlation patterns by strata of cholesterol and triglycerides. Most correlations were higher in the lowest category of triglycerides than in the lowest category of cholesterol. Most coefficients above 0.7 were seen in the lowest category of triglycerides (e.g., OC pairs p,p'-DDT and HCB, p,p'-DDT and beta-HCH, p,p'-DDE and beta-HCH, or HCB and beta-HCH). Correlations among OCs may be stronger when concentrations of triglycerides are low than when they are high. This is compatible with a dilution in the early phases of cancer and with a concentration effect as triglycerides become lower in the advanced phases of the disease. 相似文献
195.
Anna-Maria Vafeiadou Patrick Materatski Helena Adão Marleen De Troch Tom Moens 《Marine Biology》2013,160(9):2517-2523
Stable carbon and nitrogen isotope analysis was used to examine the resources and position of macrobenthos in an estuarine seagrass food web in two sampling moments, during summer and winter. The contribution of each food source to the carbon requirements of consumers was estimated by a mixing model. The used carbon sources were largely seagrass associated, although seagrass tissues were utilized by only few species, and equally contributed to microphytobenthos and suspended particulate organic matter. Based on isotopic data, Lucinidae bivalves have an alternative trophic pathway via symbiosis with chemoautotrophic bacteria. Resource utilization inside and adjacent to seagrass beds did not differ significantly, implying that seagrass-associated inputs extend well beyond the borders of the vegetation patches. 相似文献
196.
Gabriela M. Vélez-Rubio Andrés Estrades Alejandro Fallabrino Jesús Tomás 《Marine Biology》2013,160(11):2797-2811
We present the first study conducted in a wide spatio-temporal scale on marine turtles strandings (N = 1,107) over a 12-year period (1999–2010) in Uruguay. Five species were recorded Chelonia mydas (N = 643; 58.1 %), Caretta caretta (N = 329; 29.7 %), Dermochelys coriacea (N = 131; 11.8 %), Eretmochelys imbricata (N = 3; 0.3 %), and Lepidochelys olivacea (N = 1; 0.1 %). The first three species stranded throughout the Uruguayan coast, but differences in distribution patterns were detected among species. Although occurring year round, stranding records show a clear seasonal pattern with variation in monthly distribution among species, but with a peak of records in austral summer. Strandings provide indirect evidence of threats to marine turtles in Uruguayan and surrounding waters, particularly fisheries and marine debris. Our results demonstrate that Uruguayan coastal waters likely serve as a foraging or development area for at least three endangered marine turtle species in temperate waters. 相似文献
197.
One of the challenges to quantifying the costs and benefits of symbiosis is that symbionts can influence different components of host fitness. To improve understanding of the ecology of inherited symbionts, we developed general theory for a perennial host-hereditary symbiont interaction, in which symbionts can have independent and potentially opposing effects on host regeneration and survival. The model showed that negative effects on one component of fitness may be outweighed by positive effects on another, leading to a net positive impact of symbiosis on population growth. Model predictions depended on the availability of suitable patches, which influenced the relative contributions of survival vs. regeneration to host fitness. We then used experimental symbiont removal to quantify effects of a hereditary, fungal endophyte on a grass host. Endophyte presence strongly reduced host survival but increased regeneration. Application of the model revealed that negative effects on plant survival were overwhelmed by beneficial effects on regeneration, resulting in stable endophyte persistence at 100% frequency, consistent with field observations. Our work demonstrates the utility of a demographic perspective for predicting the dynamics of symbioses and supports the hypothesis that symbionts function as mutualists when host and symbiont fitness are coupled through vertical transmission. 相似文献
198.
Mid-ocean ridges are common features of the world’s oceans but there is a lack of understanding as to how their presence affects
overlying pelagic biota. The Mid-Atlantic Ridge (MAR) is a dominant feature of the Atlantic Ocean. Here, we examined data
on euphausiid distribution and abundance arising from several international research programmes and from the continuous plankton
recorder. We used a generalized additive model (GAM) framework to explore spatial patterns of variability in euphausiid distribution
on, and at either side of, the MAR from 60°N to 55°S in conjunction with variability in a suite of biological, physical and
environmental parameters. Euphausiid species abundance peaked in mid-latitudes and was significantly higher on the ridge than
in adjacent waters, but the ridge did not influence numerical abundance significantly. Sea surface temperature (SST) was the
most important single factor influencing both euphausiid numerical abundance and species abundance. Increases in sea surface
height variance, a proxy for mixing, increased the numerical abundance of euphausiids. GAM predictions of variability in species
abundance as a function of SST and depth of the mixed layer were consistent with present theories, which suggest that pelagic
niche availability is related to the thermal structure of the near surface water: more deeply-mixed water contained higher
euphausiid biodiversity. In addition to exposing present distributional patterns, the GAM framework enables responses to potential
future and past environmental variability including temperature change to be explored. 相似文献
199.
Marcel Clusa Carlos Carreras Marta Pascual Stephen J. Gaughran Susanna Piovano Cristina Giacoma Gloria Fernández Yaniv Levy Jesús Tomás Juan Antonio Raga Fulvio Maffucci Sandra Hochscheid Alex Aguilar Luis Cardona 《Marine Biology》2014,161(3):509-519
Loggerhead turtles nesting in the Mediterranean Sea exhibit remarkable genetic structuring. This paper tests the hypothesis that young loggerhead turtles from different rookeries do not distribute homogeneously among the major Mediterranean foraging grounds, due to a complex pattern of surface currents. We extracted long fragments of mitochondrial DNA from 275 stranded or bycaught juvenile turtles from six foraging grounds (Catalano-Balearic Sea, Algerian basin, Tyrrhenian Sea, Adriatic Sea, northern Ionian Sea and southern Levantine Sea). We used a Bayesian mixed-stock analysis to estimate the contributions from rookeries in the Mediterranean, the North-west Atlantic and Cape Verde to the studied foraging grounds. Differences were found in the relative contribution of juvenile turtles of Atlantic and Mediterranean origin to each foraging ground. A decreasing proportion of Atlantic juveniles was detected along the main surface current entering the Mediterranean, with a high prevalence of turtles from eastern Florida in the Algerian basin and lower numbers elsewhere. In regard to the turtles of Mediterranean origin, juveniles from Libya prevailed in central and western Mediterranean foraging grounds other than the Algerian basin. Conversely, the Adriatic Sea was characterised by a large presence of individuals from western Greece, while the southern Levantine Sea was inhabited by a heterogeneous mix of turtles from the eastern Mediterranean rookeries (Turkey, Lebanon and Israel). Overall, the distribution of juveniles may be related to surface circulation patterns in the Mediterranean and suggests that fisheries might have differential effects on each population depending on the overlap degree between foraging and fishing grounds. 相似文献
200.
Carlos Navarro Tomás Pérez-Contreras Jesús M. Avilés Kevin J. McGraw Juan J. Soler 《Behavioral ecology and sociobiology》2010,64(7):1209-1067
Many colourful sexually selected signals in animals are carotenoid-dependent and, because carotenoids function as antiradicals
and immunostimulating molecules, carotenoid-dependent signals may honestly reflect the health state of individuals. Some others
nutrients like vitamin A may also enhance health and colouration, but these have rarely been tested alongside carotenoids
in colourful birds. Here, we examined whether beak colour of the spotless starling (Sturnus unicolor) reflected circulating levels of carotenoids and/or vitamin A (retinol). Spotless starlings are polygynous, sexually dimorphic
birds (i.e. length of chest feathers). The tip of the beaks of male and female spotless starlings is more intensely coloured
at the beginning of the breeding season and becomes dull after mating, which may suggest a sexual function. We found that
females have a more intensely coloured beak and higher plasma carotenoid concentration than males during mating, and, despite
the finding that carotenoid and vitamin A levels were not significantly related; colour intensity was positively correlated
with plasma concentration of carotenoids and vitamin A in both sexes. However, adult beak coloration was not associated with
carotenoid and vitamin A concentrations after nestlings were hatched. Therefore, beak colouration of spotless starlings provides
information about circulating levels of carotenoids and vitamins during the mating season and may potentially function as
a reliable signal of physiological status in the context of sexual selection. 相似文献