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排序方式: 共有294条查询结果,搜索用时 15 毫秒
221.
Professor Jacob A. Canick Ph.D. Leonard H. Kellner Devereux N. Saller Jr Glenn E. Palomaki Roger P. Walker Rapin Osathanondh 《黑龙江环境通报》1995,15(8):739-744
Urinary gonadotropin peptide (UGP; β-core fragment), a major metabolite of human chorionic gonadotropin (hCG), was shown recently to be markedly elevated in Down syndrome pregnancy between 19 and 22 weeks of gestation. To confirm and extend this finding, we obtained maternal urine and matching maternal serum samples from 14 cases of Down syndrome and six other aneuploidies between 17 and 21 weeks of gestation. UGP was measured in all these samples and in 91 singleton control urines. Results were corrected for urinary creatinine level and expressed as multiples of the control median (MOM). hCG levels were assayed in all serum samples from the cases and compared with previously established reference values. The median UGP level in Down syndrome cases was 5.34 MOM (range 2.71–12.57); 88 per cent of the values were above the 95th centile of control levels after modelling. The median maternal serum hCG level for the same cases was 2.20 MOM (range 0.84–3.40); 36 per cent of the values were above the 95th centile. The level of UGP in every case including all other aneuploidies was higher than the comparable maternal serum hCG level. Elevated UGP measurements are strongly associated with fetal Down syndrome during the second trimester and could contribute to improved Down syndrome screening protocols that are more accessible and less expensive than are currently available. 相似文献
222.
Aggrey Ochieng Adimo John Bosco Njoroge Leaven Claessens Leonard S. Wamocho 《Mitigation and Adaptation Strategies for Global Change》2012,17(2):153-171
Climate variability and change mitigation and adaptation policies need to prioritize land users needs at local level because
it is at this level that impact is felt most. In order to address the challenge of socio-economic and unique regional geographical
setting, a customized methodological framework was developed for application in assessment of climate change vulnerability
perception and adaptation options around the East African region. Indicators of climate change and variability most appropriate
for the region were derived from focused discussions involving key informants in various sectors of the economy drawn from
three East African countries. Using these indicators, a structured questionnaire was developed from which surveys and interviews
were done on selected sample of target population of farming communities in the Mt. Kenya region. The key highlights of the
questionnaire were vulnerability and adaptation. Data obtained from respondents was standardized and subjected to multivariate
and ANOVA analysis. Based on principle component analysis (PCA), two main vulnerability categories were identified namely
the social and the bio-physical vulnerability indicators. Analysis of variance using Kruskal-Wallis test showed significant
statistical variation (P ≤ 0.05) in the perceived vulnerability across the spatial distribution of the 198 respondents. Three insights were distinguished
and were discernible by agro-ecological zones. Different vulnerability profiles and adaptive capacity profiles were generated
demonstrating the need for prioritizing adaptation and mitigation efforts at local level. There was a high correlation between
the bio-physical and social factor/livelihood variables that were assessed. 相似文献
223.
This article analyzes the effect of market power in the presence of dynamic and biological externalities. When several countries harvest fish in international waters the evolution of fish population is affected by their joint action, thus generating a biological and a dynamic externality. If there is trade, the market-clearing prices depend on the harvesting and consumption in all countries. Therefore, market-clearing prices also generate an externality. We find a subgame perfect Cournot–Nash equilibrium and study the conditions under which it may be efficient. We also analyze the role of different externalities in generating inefficiency. 相似文献
224.
ALan F. Rees Dimitris Margaritoulis Robert Newman Thomas E. Riggall Paul Tsaros Judith A. Zbinden Brendan J. Godley 《Marine Biology》2013,160(3):519-529
Much is still to be learned about the spatial ecology of foraging marine turtles, especially for juveniles and adult males which have received comparatively little attention. Additionally, there is a paucity of ecological information on growth rates, size and age at maturity, and sex ratios at different life stages; data vital for successful population modelling. Here, we present results of a long-term (2002–2011) study on the movements, residency, growth and sex ratio of loggerhead turtles (Caretta caretta) in Amvrakikos Gulf (39°0′N 21°0′E), Greece, using satellite telemetry (N = 8) and ongoing capture–mark–recapture (CMR; N = 300 individuals). Individuals encountered at sea ranged from large juvenile to adult (46.2–91.5 cm straight carapace length) and demonstrated growth rates within published norms (<2.7 cm yr?1) that slowed with increasing body size. We revealed that an unexpectedly high proportion of animals were male (>44 % of captures above 65 cm straight carapace length), compared to region-wide female-biased hatchling production, indicating sex-biased survival or possible behavioural drivers for likelihood of capture in the region. Satellite tracking confirmed that some turtles establish discrete, protracted periods of residency spanning more than 1 year, whilst others migrated away from the site. These findings are underlined by CMR results with individual capture histories spanning up to 7 years, and only 18 % of individuals being recaptured. 相似文献
225.
Susan Seacrest Robert Kuzelka Rick Leonard 《Journal of the American Water Resources Association》2000,36(2):253-263
ABSTRACT: Global climate change is examined from the perspective of its relevancy and urgency as a public policy issue. Interpreting from literature specific to investigations into public awareness and concern, climate change is seen as a legitimate though less than urgent issue. The literature reveals that the general public holds surprising misconceptions about the processes contributing to climate change, including failure to grasp the fundamental connection to CO2. General ambivalence is also suggested from the results of two surveys conducted by The Groundwater Foundation. They first asked participants in a recent Groundwater Guardian Conference to rate levels of discussion and concern for water resources implications in the participants' communities. A second survey polled national water resource organizations about the extent climate change has been a focus of their educational, investigative, or advocacy efforts. The paper concludes by describing basic barriers to stimulating public response to climate change, which education about the issue should address, and by offering a model to educate and involve citizens based on the Groundwater Guardian program developed by the The Groundwater Foundation. 相似文献
226.
Jeffrey L. Hyland Timothy R. Snoots W. Leonard Balthis 《Environmental monitoring and assessment》1998,51(1-2):331-343
A study was conducted to assess the condition of estuaries in the EMAP Carolinian Province (Cape Henry, VA - St. Lucie Inlet, FL). Synoptic measures of sediment contamination, toxicity, and macroinfaunal condition were made at 82 and 86 stations in 1994 and 1995, respectively, in accordance with a probabilistic sampling design. These data were used to estimate percentages of degraded vs. undegraded estuarine area from the perspective of sediment quality. Each year a sizable portion of the province (36% in 1994, 51 % in 1995) showed some evidence of either degraded benthic assemblages, contaminated sediments in excess of bioeffect guidelines, or significant sediment toxicity (based on Ampelisca abdita and Microtox® assays). However, co-occurrences of a degraded benthos and adverse exposure conditions (sediment contamination and/or toxicity) were much less extensive – 17% of the province in 1994 and 25% in 1995. Each year only four sites, representing 5% of the province in 1994 and 8% in 1995, had degraded infauna accompanied by both sediment contamination and toxicity, suggesting that strong contaminant-induced effects on the benthos (based on such combined weight-of-evidence) were limited to a fairly small percentage of estuarine area province-wide. PCBs and pesticides (lindane, dieldrin, DDT and derivatives) were the most dominant contaminants over the two-year period. The broad-scale sampling design of EMAP was not intended to support detailed characterizations of potential pollutant impacts within individual estuaries. Thus, some estuaries classified as undegraded may include additional degraded portions outside the immediate vicinity of randomly sampled sites. Such localized impacts (not accounted for in the above estimates) were detected in this study at additional nonrandom supplemental sites near potential contaminant sources. 相似文献
227.
Fish are commonly used for monitoring the quality of waters receiving pulp mill effluents (PMEs). Isotopic assays of fish tissues have the potential to provide empirical evidence to link an effluent source to exposure. We show in a 45-d factorial laboratory experiment that different exposure pathways lead to isotopic signatures in fish tissue. Rainbow trout (Oncorhynchus mykiss) were exposed to 10% PME in three ways; direct exposure through addition of PME to aquaria, indirect exposure through invertebrate food consumption (Chironomus tentans cultured in 10% PME), and a combination of both exposure pathways. Of the four stable isotopes measured (delta13C, delta15N, delta34S, delta37Cl), delta13C, delta34S, and delta37Cl showed significant differences in exposed animal tissues. Delta37Cl of fish muscle tissue showed consistent differences across trophic levels and revealed contrasting pathways of PME exposure. Contrasting delta 37Cl values in C. tentans due to the presence or absence of 10% PME did not translate into delta37Cl differences in fish. Rather, delta37Cl ratios of fish muscle tissue were specifically related to 10% PME exposure in the aquaria (waterborne exposure pathway). Feasible distributions of 37Cl source contributions for observed mixture ratios confirmed that PME accounted for observed differences in delta37Cl among treatments. Direct uptake of chloride ions across gill surfaces is the most likely pathway for assimilation of PME into fish tissues. Considering the variability of PMEs and receiving environments, use of a multi-isotope approach is recommended for tracing exposure of fish. Use of 37Cl should also be considered in light of its alternative assimilation pathway. 相似文献
228.
Nele Weyens Sarah Croes Lee Newman Robert Carleer 《Environmental pollution (Barking, Essex : 1987)》2010,158(7):2422-2427
The aim of this work was to investigate if engineered endophytes can improve phytoremediation of co-contaminations by organic pollutants and toxic metals. As a model system, yellow lupine was inoculated with the endophyte Burkholderia cepacia VM1468 possessing (a) the pTOM-Bu61 plasmid, coding for constitutive trichloroethylene (TCE) degradation, and (b) the ncc-nre Ni resistance/sequestration system. Plants were exposed to Ni and TCE and (a) Ni and TCE phytotoxicity, (b) TCE degradation and evapotranspiration, and (c) Ni concentrations in the roots and shoots were determined. Inoculation with B. cepacia VM1468 resulted in decreased Ni and TCE phytotoxicity, as measured by 30% increased root biomass and up to 50% decreased activities of enzymes involved in anti-oxidative defence in the roots. In addition, TCE evapotranspiration showed a decreasing trend and a 5 times higher Ni uptake was observed after inoculation. 相似文献
229.
Gas flaring is the burning of crude oil’s associated gas. In Nigeria’s Niger Delta, the flaring process is usually very close
to communities and their farmlands and has been implicated in serious environmental degradation of the region. Studies have
suggested links between gas flaring and health problems in the communities and others have established relationships between
gas flaring and poor agricultural yields. This study explores how the people in the region perceive gas flaring and what their
attitudes are toward it. Ubeji town, a community where gas flaring takes place, was selected as a case study. It was found
that the residents perceive gas flaring as hazardous to health, environment, and general well-being of the community. Most
residents seem to be resigned to the continued presence of gas flaring activities in the community. The study, however, raised
several questions on modeling perception and attitudes toward environmental problems in areas where political tension and
economic adversity are prevalent. 相似文献
230.