The records of 708 nonsmoking white adult residents of Washington County, MD, who had participated in two of respiratory symptoms were analyzed to evaluate the effects of exposure at home to two potential sources of indoor air pollution: cigarette smoking by other household members, and use of gas as a cooking fuel. After adjustment for the effects of age, sex, socioeconomic level, occupational exposure to dust, and years of residence in household, the presence of one or more smokers in the household was only suggestively associated with a higher frequency of chronic phlegm and impaired ventilatory function defined as FEV1 < 80% predicted. The use for cooking was associated with a significantly increased frequency of chronic cough and a significantly greater percentage with impaired ventilatory function as measured both by FEV1 < 80% predicted and by FEV1/FVC < 70%. 相似文献
Qualitative samples were taken at 26 stations on the Great Meteor Seamount and in the surrounding deep sea in order to record the meiofauna and to allow first qualitative faunistic investigations. Among the 26 taxa of meiofauna found, nematodes and copepods were the most abundant. Study of the Copepoda Harpacticoida yielded 28 supraspecific taxa, of which 11 have been selected for further investigation at the species level. Of the 56 species determined, 54 are new to science. Two separate faunas can be distinguished: one on the plateau (29 species) and one in the surrounding deep sea (23 species). The number of overlapping species (i.e. recorded in both areas) is rather low (four species). The high number of new species can be taken as a sign of pronounced endemism.An erratum to this article can be found at 相似文献
While a presumed equality between uncertainty and probability is dominant in subsurface hydrology, in other areas of science
and engineering progress in the mathematics of uncertainty is leading the way in providing new types of uncertainty, distinct
from probability. In this paper our focus is on one of these, namely fuzzy set theory and fuzzy logic. We start with an overview
of fuzzy theory introducing terminology, notation, and concepts relevant to our paper. We continue our discussion with an
overview of currently known applications in several areas that include subsurface characterization, groundwater flow and transport
modeling, water resources management and optimization, and groundwater health risk assessment and management. 相似文献
OBJECTIVE: Road safety data are often in the form of counts and usually temporally correlated. The objective of this research is to investigate the distributional assumptions of road safety data in the presence of temporal correlation. METHODS: Using the generalized linear model framework, four distributional assumptions are considered: normal, Poisson, quasi-Poisson and negative binomial, and appropriate models are estimated. Monthly casualty and police enforcement data from Greece for a period of six years (January 1998-December 2003) have been used. The developed models include sinusoidal latent terms to capture the temporal serial correlation of observations. Several statistical goodness-of-fit diagnostic tests have been performed for the results of the estimated models, and the predictive capabilities of the models are investigated. RESULTS: The residuals of the quasi-Poisson and negative binomial models do not show any serial correlation. The signs of the estimated coefficients for all models are consistent and intuitive. In particular, a negative coefficient value for the number of breath alcohol controls indicates that the number of persons killed and seriously injured decreases as the intensity of breath alcohol controls increases. The Poisson model fails to capture the overdispersion in the data, thus underestimating the standard errors of the estimated coefficients. CONCLUSION: The results suggest that the quasi-Poisson and negative binomial outperform the normal and Poisson models in this application. The findings of this research demonstrate a clear link between the intensification of police enforcement and the reduction of traffic accident casualties. In particular, an increase in the number of breath alcohol controls in Greece after 1998 contributed to a reduction in the number of persons killed and seriously injured from traffic accidents. 相似文献
Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are
perceived by the public as the primary indicators of the safely and acceptability of drinking water and are mainly caused by the
presence of two semi-volatile compounds – 2-methyl isoborneol (MIB) and geosmin. A review of these two taste and odor causing
compounds in drinking water is presented. The sources for the formation of these compounds in water are discussed alongwith the
health and regulatory implications. The recent developments in the analysis of MIB/geosmin in water which have allowed for rapid
measurements in the nanogram per liter concentrations are also discussed. This review focuses on the relevant treatment alternatives,
that are described in detail with emphasis on their respective advantages and problems associated with their implementation in a fullscale
facility. Conventional treatment processes in water treatment plants, such as coagulation, sedimentation and chlorination have
been found to be ine ective for removal of MIB/geosmin. Studies have shown powdered activated carbon, ozonation and biofiltration
to be e ective in treatment of these two compounds. Although some of these technologies are more e ective and show more promise
than the others, much work remains to be done to optimize these technologies so that they can be retrofitted or installed with minimal
impact on the overall operation and e ectiveness of the treatment system. 相似文献
Abstract River Nile is one of the longest transboundery rivers and it is shared and used by Burundi, Democratic Republic of Congo, Egypt, Ethiopia, Eritrea, Kenya, Rwanda, Sudan, Tanzania and Uganda. As of today, the Nile is a crucial resource for the economic development of the Nile Basin countries and a vital source of livelihood for 160 million inhabitants as well as 300 million people living in the 10 riparian countries. The Nile Basin Initiative (NBI) is one of the international cooperative river basin management program and regional partnership where all the Nile Basin countries except Eritrea unite to pursue long-term sustainable development, improved land use practices and management. This review therefore focused on the challenges not faced on NBI in terms of integrated use of the river and conducted analysis of strengths, weaknesses, opportunities and threats (SWOT) based on secondary data. The result of the review revealed that for decades, the Nile Basin people have been facing many complex environmental, social, economic and political challenges that have made it difficult for the proper management and sustainability of Nile water. The initiative provides training to develop skills in government ministries, non-governmental organizations and local communities in each country. It is also working to raise awareness of critical environmental issues by strengthening networks of environmental education practitioners; developing curriculum in the education sector. The challenges of NBI include the involvement and funding of World Bank, lack of sufficient staff, procedural and policies conflicts, lack of coordination and linkage with other regional institutions and lack of recognition as river basin organization. Considering the complex nature of the project, it is recommended that the NBI should come up with a strong multi-disciplinary monitoring and evaluation team to follow up all implemented projects. The NBI should carry out participatory land use planning in communities along the river basin. Moreover, livelihood analysis should be carried out especially in communities along the Nile to come up with poverty eradication projects which are socially acceptable, applicable, economically viable and affordable. 相似文献
The presence of recalcitrant contaminants in wastewater is major challenge to decrease pollution and associated health issues. As a consequence, membrane technologies have recently attracted industrial attention, yet a major setback of membrane employment is membrane fouling which leads to frequent discarding of membrane modules. More than 45% of all membrane fouling cases are caused by biofilms that are resistant to antimicrobial agents. Here we review polymeric membranes with antifouling properties, with focus on surface properties, fabrication, characterization, biocatalysis using enzymes and application towards the removal of dyes, phenol, pesticides and fertilizers. Nano-engineered fabrication of polymeric membranes allow to decrease fouling by 80–90%. Immobilized oxidoreductases in polymeric membranes allow 65–98% removal contaminants in wastewater.