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91.
One hundred seventy-seven police officers and their spouses from two metropolitan areas completed separate questionnaires regarding stress and coping. Both the police and spouses reported using four coping activities in response to their own stressors: problem focused, emotion focused, religiosity, and rugged individualism. Three potential police strains previously noted in non-empirical literature were given special attention; divorce potential, drinking behavior, and suicide thoughts. 相似文献
92.
Recreational impact was measured on eight beaches in Glen Canyon National Recreation Area and 15 beaches in Grand Canyon National Park using permanently located transects and plots. Recreational impact indices included densities of human trash and charcoal and a measure of sand discoloration due to charcoal. Significant increases in the indices occurred on several Glen Canyon beaches over a seven-month period. Sand discoloration became significantly higher over all Glen Canyon beaches during the same time period. All indices were significantly higher in Glen Canyon than on similar Grand Canyon beaches. These differences are probably due to differences in: (a) level of impacts tolerated by the respective management regimes and, (b) in the number of user days among the two National Park Service administrative units. Management alternatives are presented for reversing the present trends of recreational impact on Glen Canyon beaches. 相似文献
93.
Puneet Srivastava James N. McNair Thomas E. Johnson 《Journal of the American Water Resources Association》2006,42(3):545-563
ABSTRACT: The performance of the Soil and Water Assessment Tool (SWAT) and artificial neural network (ANN) models in simulating hydrologic response was assessed in an agricultural watershed in southeastern Pennsylvania. All of the performance evaluation measures including Nash‐Sutcliffe coefficient of efficiency (E) and coefficient of determination (R2) suggest that the ANN monthly predictions were closer to the observed flows than the monthly predictions from the SWAT model. More specifically, monthly streamflow E and R2 were 0.54 and 0.57, respectively, for the SWAT model calibration period, and 0.71 and 0.75, respectively, for the ANN model training period. For the validation period, these values were ?0.17 and 0.34 for the SWAT and 0.43 and 0.45 for the ANN model. SWAT model performance was affected by snowmelt events during winter months and by the model's inability to adequately simulate base flows. Even though this and other studies using ANN models suggest that these models provide a viable alternative approach for hydrologic and water quality modeling, ANN models in their current form are not spatially distributed watershed modeling systems. However, considering the promising performance of the simple ANN model, this study suggests that the ANN approach warrants further development to explicitly address the spatial distribution of hydrologic/water quality processes within watersheds. 相似文献
94.
Incident reporting systems are playing an increasingly important role in the development and maintenance of safety-critical applications. The perceived success of the FAA's Aviation Safety Reporting System (ASRS) and the FDA's MedWatch has led to the establishment of similar national and international schemes. These enable individuals and groups to report their safety concerns in a confidential or anonymous manner. Unfortunately, many of these systems are becoming victims of their own success. The ASRS and MedWatch have both now received over 500,000 submissions. In consequence, the administrators of incident reporting systems increasingly rely upon software tools to support the administration of their systems. In the past, these systems have relied upon ad hoc applications of conventional database technology. However, there are several reasons why this technology is inadequate for many large-scale reporting schemes. In particular, the problems of query formation often result in poor precision and recall. This, in turn, has profound implications for safety-critical applications. Users may fail to identify similar incidents within national or international collections. These ad hoc approaches also neglect the opportunities provided by recent developments in computer assisted interviewing and in the monitoring of retrieval activities to build models of user behavior. These techniques offer a number of potential benefits. For instance, it is possible to automatically detect potential biases in the way that investigators analyze particular incidents. 相似文献
95.
Groundwater circulation wells (GCWs) are a quasi‐in‐situ method for remediating groundwater in areas where remediation techniques that limit the water available for municipal, domestic, industrial, or agricultural purposes are inappropriate. The inherently resource‐conservative nature of groundwater circulation wells is also philosophically appealing in today's culture, which is supportive of green technologies. Groundwater circulation wells involve the circulation of groundwater through a dual‐screen well, with treatment occurring between the screens. The wells are specifically designed so that one well screen draws in groundwater and the second returns the groundwater after it has been treated within the well. Historically, the treatment has been performed with specialized equipment proprietary to GCW vendors. Two full‐scale pilot systems at a formerly used Defense Superfund site in Nebraska used best available technologies for treatment components. A multiple‐tray, low‐profile air stripper typically used for pump‐and‐treat remediation systems was successfully adapted for the GCW pilot system located in a trichloroethylene (TCE) hot spot. An ultraviolet water disinfection system was successfully adapted for the GCW pilot system located in a hot spot contaminated with the explosive compound hexhydro‐1,3,5‐trinitro‐1,3,5‐triazine (RDX). The pilot systems showed that GCW technology is competitive with a previously considered pump‐and‐treat alternative for focused extraction, and the regulatory community was supportive of additional GCW applications. A remedial design for the site includes 12 more GCW systems to complete focused remediation requirements. © 2002 Wiley Periodicals, Inc. 相似文献
96.
Demonstrating intrinsic bioremediation requires not only that the right types of evidence be gathered, but also that those data be analyzed at an appropriate level of detail and presented in a manner that clearly illustrates the key trends to the target audience. The goal of this study was to develop one type of multivariate pattern diagram, the pie diagram, for clearly and efficiently presenting data demonstrating the occurrence of reductive dechlorination at sites contaminated by chlorinated ethenes. The pie diagrams were created using normalized ethenes molar concentrations to estimate and illustrate the changes in the concentrations of contaminants and metabolic intermediates that could be attributed to biodegradative processes. Spatial pie‐diagram maps illustrating the normalized chlorinated‐ethenes data were produced using geographic information system (GIS) software. Application of this visualization tool is demonstrated using an example data set and is compared with a conventional x‐y graph of the data. The trends elucidated on the basis of the pie diagrams, coupled with additional site evidence of natural attenuation (e.g., electron donor and acceptor data), are shown to provide a consistent interpretation of the site data. © 2002 Wiley Periodicals, Inc. 相似文献
97.
Peggy A. Johnson Richard D. Hey Eric R. Brown David L. Rosgen 《Journal of the American Water Resources Association》2002,38(1):55-67
ABSTRACT: The number of stream restoration and enhancement projects being implemented is rapidly increasing. At road crossings, a transition must be created from the restored channel through the bridge or culvert opening. Given conflicting design objectives for a naturalized channel and a bridge opening, guidance is needed in the design of the transition. In this paper we describe the use of vanes, cross vanes, and w‐weirs, commonly used in stream restoration and enhancement projects, that may provide an adequate transition at bridges. Laboratory experiments were conducted on vanes and cross vanes to provide a transition for single span bridge abutments and on w‐weirs to provide a transition for double span bridges which have a pier in mid‐channel. The results of the experiments provided design criteria for transitions using each of the three structures. Prior field experience provided guidance on appropriate applications in terms of the stream and bridge characteristics. 相似文献
98.
99.
100.
Regional Representativeness of Swedish Reference Lakes 总被引:1,自引:1,他引:0
Richard K. Johnson 《Environmental management》1999,23(1):115-124
/ Recent focus has been placed on ecoregion delineations for providing an appropriate framework for monitoring and assessment of region-specific attainable water/habitat quality. Using an ecoregion approach to stratify variance, this study was conducted to determine whether earlier (subjectively) selected Swedish reference lakes may be considered as regionally representative reference sites when compared with a randomly selected lake population. Predictive modeling by discriminant function analysis with lakes classified by ecoregion and lake surface area and six physicochemical variables showed that the greater majority of reference lakes may be considered as regionally representative. The highest proportion of lake "misclassifications" occurred in the boreonemoral ecoregion, a relatively diverse ecoregion of southern Sweden. This apparent bias may be in part be due to the criteria used in selecting regional reference lakes. In the earlier selection of reference lakes emphasis was placed on lakes not being adversely affected by land usage or pollutant discharges, consequently forest lakes were often overrepresented and sites in agricultural areas underrepresented in the selected reference sites. As a complement to predictive modeling, PCA ordination showed the placement of reference lakes within the random lake population and indicated where reference sites might be missing along potentially important ecological gradients. KEY WORDS: Regionalization; Ecoregion; Representativeness; Reference; Ordination; Modeling; Temperate lakes 相似文献