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排序方式: 共有271条查询结果,搜索用时 31 毫秒
191.
Andjelka Kelic Zachary A. Collier Christopher Brown Walter E. Beyeler Alexander V. Outkin Vanessa N. Vargas Mark A. Ehlen Christopher Judson Ali Zaidi Billy Leung Igor Linkov 《The Environmentalist》2013,33(4):544-560
Increased reliance on the Internet for critical infrastructure and the global nature of supply chains provides an opportunity for adversaries to leverage dependencies and gain access to vital infrastructure. Traditional approaches to assessing risk in the cyber domain, including estimation of impacts, fall short due to uncertainty in how interconnected systems react to cyber attack. This paper describes a method to represent the pathways of disruption propagation, evaluate the macroeconomic impact of cyber threats and aid in selecting among various cybersecurity policies. Based on state of the art agent-based modeling, multicriteria decision analysis, and macroeconomic modeling tools, this framework provides dynamic macroeconomic, demographic and fiscal insights regarding shocks caused by cyber attacks to the regional economy over time. The interlinkage of these models will provide a robust and adaptive system that allows policy makers to evaluate complex issues such as cybersecurity threats and their impacts on the geopolitical, social, environmental, and macroeconomic landscape. 相似文献
192.
Theresa M. Glomb 《组织行为杂志》2013,34(5):698-713
On the basis of justice and exchange theories, the authors propose that employees offset their levels of work–family conflict (WFC) with their levels of pay satisfaction. Results based on two waves of data indicate that pay satisfaction has a negative relationship with WFC after controlling for actual pay and other work‐related and family‐related variables. Analysis of pay satisfaction dimensions reveals that satisfaction with benefits and pay structure are negatively related to WFC, whereas satisfaction with pay level and pay raise are not. Number of dependents and level of education moderate the relationship between pay satisfaction and WFC; specifically, having more dependents and higher education attenuates the relationship between pay satisfaction and WFC. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
193.
Ecological impacts of water-quality problems have developed in the western United States resulting from the disposal of seleniferous
agricultural wastewater in wetland areas. Overt effects of selenium toxicosis occurred at five areas where deformities of
wild aquatic birds were similar to those first observed at Kesterson National Wildlife Refuge in the west-central San Joaquin
Valley of California. These areas are: Tulare Lake Bed Area, California, Middle Green River Basin, Utah, Kendrick Reclamation
Project Area, Wyoming, Sun River Basin, Montana, and Stillwater Wildlife Management Area, Nevada. Potential for ecological
damage is indicated at six more sites in Oregon, Colorado, the Colorado/Kansas border, and South Dakota out of 16 areas in
11 states where biological tissue data were collected. This conclusion is based on the fact that selenium bioaccumulated in
bird livers to median levels that had exceeded or were in the range associated with adverse reproductive effects. Selenium
concentrations in samples of fish and bird eggs support these conclusions at a majority of these areas. Reason for concern
is also given for the lower Colorado River Valley, although this is not exclusively a conclusion from these reconnaissance
data. Biogeochemical conditions and the extent of selenium contamination of water, bottom sediment, and biota from which this
assessment was made are given here. In a companion paper, the biogeochemical pathway postulated for selenium contamination
to take place from natural geologic sources to aquatic wildlife is defined. 相似文献
194.
Removal of batteries from solid waste using trommel separation 总被引:4,自引:0,他引:4
Lau ST Cheung WH Kwong CK Wan CP Choy KK Leung CC Porter JF Hui CW Mc Kay G 《Waste management (New York, N.Y.)》2005,25(10):1004-1012
This paper describes the design and testing of a trommel for separation of batteries from solid waste. A trommel is a cylindrical separation device that rotates and performs size separation. It has also been used in areas such as municipal solid waste (MSW) processing, classifying construction and demolition debris, screening mass-burn incinerator ash and compost processing. A trommel has been designed based on size separation to separate household batteries from solid waste, which can then be used as feedstock for alternative applications of solid waste combustion, particularly where the metal content of the product is also a critical parameter, such as the Co-Co process for integrated cement and power production. This trommel has been tested with batches of university office and restaurant wastes against various factors. The recovery efficiency of batteries increases with decreasing inclination angle of the trommel and decreasing rotational speed. A physical characterization of the university solid waste has been performed with a 20-kg sample of the tested waste. It was found that there is a trend of decreasing recovery of batteries with increasing paper composition, and a trend of increasing recovery of batteries with increasing organic materials composition. 相似文献
195.
196.
The frequency of mosaicism and pseudomosaicism in the prenatal diagnosis of cytogenetic disorders is reported, based on 3000 pregnancies studied in our laboratory. Diagnosis of true mosaicism was only made when an abnomality was detected in two or more independent cultures established from an amniotic fluid sample. On this basis, 0.37 per cent of all cases were diagnosed as true mosaics. 1.07 per cent of all cases had pseudomosaicism involving more than one cell from the same culture with an identical abnormality. 4.13 per cent of cases had a single abnormal cell with an extra chromosome, loss of a sex chromosome (or part of a sex chromosome), or translocation. Details of the outcome and follow-up of cases is given. Particularly problematical were cases where multiple cells from one culture contained an abnormality which could have been clinically significant. A crude estimate of the extent to which true mosaicism might currently be misinterpreted as pseudomosaicism or entirely missed has been made, based on data from the U.S. survey (Hsu and Perlis, in press). It was concluded that even when two, and if necessary a third culture is extensively analysed with an average of 24 cells per culture counted, at least 4.5 per cent of cases of true mosaicism may be completely missed and at least 7 per cent could be misdiagnosed as pseudomosaicism. There is an urgent need for improved laboratory techniques which allow growth of a greater number of cell colonies and therefore a more broadly based analysis. Detailed long term follow-up of prenatally diagnosed mosaics is also essential for assessing the clinical significance of the laboratory findings. 相似文献
197.
Theresa M. Marteau 《黑龙江环境通报》1995,15(13):1215-1226
There are now several well-documented psychological problems associated with prenatal testing programmes. These include poor understanding of tests undergone or declined, anxiety following false positive results, and false reassurance in those receiving negative test results. There is, as yet, little evidence concerning how to provide services to circumvent these. The focus of this review is upon just one of these problems: how best to inform women about prenatal testing and their reproductive options following the diagnosis of a fetal abnormality. Possible methods of improving informed decision-making either about whether to undergo testing or whether to terminate an affected pregnancy are described drawing upon research from antenatal and other health care areas. Future challenges for clinical practice and research in this area concern the range of conditions and predispositions for which prenatal testing with the option of termination should be offered. 相似文献
198.
Ping-Sang Kenneth Leung Nancy J. Sell 《Journal of the American Water Resources Association》1982,18(3):495-502
ABSTRACT: The Lower Fox River, Wisconsin, hosts the densest concentration of paper mills in the US., with 18 located along a 4Gde stretch between Lake Winnebago and Green Bay, Lake Michigan. Some of these companies use only primary, others also secondary, waste treatment techniques. Comparison of the quantities of wastes discharged with the legal limits indicates that all plants discharge only 40-50 percent or less of the allowable suspended solids; most discharge < 50 percent of the allowable BOD. This is equal or better than the performance of paper companies elsewhere in the state. Reductions in pollutant discharges have corresponded to improved water quality, though too much BOD is still discharged to be adequately assimilated by the Fox River. The relatively low current level of discharges means permit levels would have to be drastically cut to make any significant impact on water quality. Only a few companies might be seriously affected by such changes. Flow and temperature related permits would likely be more effective, but more difficult to comply with for the industry. Toxic substances are also a potential problem, particularly chlororganic compounds that can form in situ from the chlorine frequently used for pulp bleaching. 相似文献
199.
Visitor satisfaction has been a consistently stated goal of outdoor recreation management. Recreation resource managers provide
opportunities for the visiting public with the anticipation of satisfying the needs of the visitors. Management efforts are
often evaluated in terms of visitor satisfaction. In the recent decade, a multiple satisfactions approach has been the primary
research paradigm guiding visitor satisfaction research. This paradigm has focused primarily upon behavioral-type dimensions
such as crowding, goal attainment, and resource impacts resulting from behavior. The purpose of this study was to examine
the importance of a setting dimension relative to behavioral-type dimensions for explaining differences in visitor satisfaction.
A sample of 895 river visitors were sent a questionnaire in the mail; 682 were returned for a 76.2% response rate. Regression
analysis indicated the setting dimension was ranked as one of the most important dimensions for explaining differences in
visitor satisfaction. Other dimensions considered included group behavior, perceived crowding, parking, past experience, encounters,
use levels, and time waiting. Implications for management are discussed. 相似文献
200.
Depuration of metals from soft tissues of oysters (Crassostrea gigas) transplanted from a contaminated site to clean sites 总被引:1,自引:0,他引:1
Chan KW Cheung RY Leung SF Wong MH 《Environmental pollution (Barking, Essex : 1987)》1999,105(3):299-310
The present study aimed at studying the transplantation of oysters from a polluted site Lau Fau Shan (existing oyster culture zone) in Deep Bay to two clean sites mariculture zones at Yung Shue O and Kat O. The hydrological data, growth of oyster shell length, mortality and metal contents in whole soft tissue were monitored from February 1993 to February 1994. The high growth phase (increase in shell length) and gametogenesis (decrease in dry weight of whole soft tissue) were noted in winter (with low temperature and high salinity), and slow growth phase and spawning in summer (with high temperature and low salinity). Significant reductions (p<0.05) of Cd, Cr and Pb concentrations (dry wt basis) in soft tissue of transplanted oysters were observed at Kat O by 29, 55 and 29%, respectively, and at Yung Shue O by 34, 44 and 34%, respectively, with respect to the baseline values for the first batch of oysters and the concentrations in samples collected from Lau Fau Shan in the same months. Maximum reductions of total metal burden in whole soft tissue (microg per individual oyster) of the first oyster batch were found for Cd, Cr, Pb and Sb to be 62, 49, 60 and 25%, respectively, at Kat O, and to be 56, 47, 32 and 49%, respectively, at Yung Shue O. For the second batch of oysters transplanted to Yung Shue O in July 1993, significant reductions (p<0.05) of Cd concentration and total burden of Cd by 60 and 21%, respectively, were observed in February 1994. The high accumulated mortality and the significant (p<0.05) lower growth rate of the transplanted oysters illustrated that the best time for transplantation of oysters should be between the end of gametogenesis and the start of spawning (i.e. January and February), and the oysters should not be kept for longer than 3 months at the transplantation sites. 相似文献