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271.
Risk decision-making in natural hazards encompasses a plethora of environmental, socio-economic and management-related factors, and benefits greatly from exploring possible patterns and relations among these multivariate factors. Artificial neural networks, capable of general pattern classifications, are potentially well suited for risk decision support in natural hazards. This paper reports an example that assesses the risk patterns or probabilities of house survival from bushfires using artificial neural networks, with a simulation data set based on the empirical study by Wilson and Ferguson (Predicting the probability of house survival during bushfires, Journal of Environmental Management 23 (1986) 259–270). The aim of this study was to re-model and predict the relationship between risk patterns of house survival and a series of independent variables. Various configurations for input and output variables were tested using neural networks. An approach for converting linguistic terms into crisp numbers was used to incorporate linguistic variables into the quantitative neural network analysis. After a series of tests, results show that neural networks are capable of predicting risk patterns under all tested configurations of input and output variables, with a great deal of flexibility. Risk-based mathematical functions, be they linear or non-linear, can be re-modelled using neural networks. Finally, the paper concludes that the artificial neural networks serve as a promising risk decision support tool in natural hazards. 相似文献
272.
273.
Phenotypic Alterations, Evolutionarily Significant Structures, and Rhino Conservation 总被引:1,自引:0,他引:1
To slow the impending loss of wild black ( Diceros bicornis ) and white ( Ceratotherium simum ) rhinos, three African countries have resorted to dehorning, a practice designed to remove the incentive for poachers to kill the hornless animals. The efficacy of this controversial conservation action remains unknown, in part because much uncertainty exists about the functional significance of rhino horns. We assessed the current utility of horns in Namibian black rhinos from phenotypically altered and intact populations in the Namib Desert, and we collated data on mortal fighting among horned females living in Etosha National Park. Infant mortality was 100% when dehorned mothers were sympatric with spotted hyenas ( Crocuta crocuta ). In contrast, infant survival was 100% for both horned mothers living with hyenas and occasional lions ( Panthera leo ) and 100% for dehorned mothers in the absence of dangerous carnivores. These data suggest that female horns can have direct fitness benefits in terms of calf survival. However, because lethal wounding due to fighting may account for up to 33% of the mortality of horned females, dehorning may improve adult survivorship. Our results (1) suggest that, where the aim of conservation programs is to improve population viability through juvenile recruitment, dehorning is unlikely to be a prudent strategy if practiced in areas with dangerous predators, and (2) illustrate the value of experimental approaches to onerous problems in conservation. 相似文献
274.
Carrie Jones Carol Booth Debra Rita Lydia Jazmines Rhonda Spiro Brian McCulloch Christopher McCaskill Lisa G. Shaffer 《黑龙江环境通报》1995,15(9):843-848
We report a case of maternal uniparental disomy of chromosome 10 discovered after chorionic villus sampling (CVS). Direct preparations revealed mosaic trisomy 10, while cultured CVS cells, as well as amniotic fluid cells, showed only a normal 46,XY complement. DNA analysis using microsatellite markers showed both chromosomes 10 to have been inherited from the mother. The pregnancy was complicated by polyhydramnios. A phenotypically normal male infant of appropriate size was delivered by Caesarean section at 41 weeks' gestation. Since only the direct preparations showed trisomy 10, this case illustrates the importance of CVS direct preparations in the detection of pregnancies at risk of uniparental disomy (UPD). Although the increased frequency of confined placental mosaicism (CPM) diagnosed when direct preparations are performed has been viewed negatively, identification of both CPM and UPD may have biological and clinical significance for a pregnancy. Even though only a single case of maternal disomy 10 is reported here, the apparently normal phenotype provides evidence that there are no major imprinted loci on chromosome 10 that affect in utero growth and development. However, other potential effects such as mental retardation will require long-term follow-up of this as well as additional cases. 相似文献
275.
Xiuhua Wang Carol Seaman Myunghee Paik Timothy Chen Arthur Bank Sergio Piomelli M.D. 《黑龙江环境通报》1994,14(9):851-857
Prenatal diagnosis of sickle cell diseases is obtained rapidly and precisely by polymerase chain reaction (PCR) with Ddel restriction analysis and dot-blotting with alllele-specific oligonucleotides (ASO). Prenatal diagnosis of HgbSS and HgbSC was performed in 500 pregnancies, 196 by Southern blot and 304 by PCR. PCR drastically shortened the interval from sampling to reporting, allowing acceptance even of samples with unknown paternal phenotype, and resulted in an overall four-fold increase in diagnoses. In 108 pregnancies, the diagnosis was an affected fetus; 25 were HgbSC: 3 (12 per cent) were terminated; 83 were HgbSS: four ended in miscarriage; 40/79 (51 per cent) were terminated. The gestational age at the time of report to the mother appeared to be a major outcome determinant when the fetal diagnosis was HgbSS. The change-point in the maternal decision was found at 20 weeks of gestation. Before the 20th week, most mothers (64 per cent) chose termination; thereafter, the majority (72 per cent) chose continuation. The odds ratio of termination in earlier relative to later reporting was 4·7. In order to offer a choice to the mothers at risk of delivering a fetus affected by sickle cell disease, the diagnosis should be reported before the 20th week of gestation. 相似文献
276.
Countryside Biogeography of Tropical Butterflies 总被引:7,自引:0,他引:7
277.
William F. O'Brien M.D. Deborah Sternlicht Carol Torres Robert A. Knuppel Raul Montenegro 《黑龙江环境通报》1990,10(3):183-188
The value of determination of maternal serum of alpha-fetoprotein (MSAFP) concentration in i he second trimester is well established. In addition to open neural tube defects, pregnancies associated with elevated second-trimester MSAFP have been shown to be at increased risk for a variety of problems, including low birth weight, preterm delivery, and pregnancy-induced hypertension (PIH). We evaluated the potential usefulness of MSAFP in the early third trimester. MSAFP concentration was determined in over 200 women at the time of glucose screening. Results were analysed with regard to gestational age at sampling, maternal weight, race, diabetes, and presence of twins. MSAFP was twice as high in twin gestation, but not affected by race or the presence of diabetes. In contrast to levels in early gestation, third-trimester MSAFP does not appear to be predictive of preterm delivery, low birth weight, or PIH. 相似文献
278.
Evaluation model for developing,implementing, and assessing conservation education programs: Examples from Belize and Costa Rica 总被引:1,自引:0,他引:1
Susan K. Jacobson 《Environmental management》1991,15(2):143-150
Evaluation of conservation education programs can: (1) provide accountability in demonstrating a program's worth, (2) offer
an opportunity for receiving feedback and improving programs, (3) further our understanding of the process of program development,
and (4) promote conservation education by substantiating claims about its benefits. The Planning-Process-Product systems evaluation
model provides feedback needed for making decisions about the development, implementation, and outcome of a program. Planning
evaluation was useful in assessing the needs, goals, opportunities, and constraints of a number of programs in Costa Rica
and Belize, such as a forestry education project and a zoo outreach program. It provided a basis for making planning decisions
incorporating specific objectives, such as the reforestation of a region or a change in knowledge and attitudes in program
participants. Process evaluation provided a Costa Rican sustainable development program with feedback during its implementation
and enabled it to modify and improve its newsletter for local farmers and its ecology classes for school children. Product
evaluation assessed project accomplishments, such as the $700,000 raised by the Children's Rainforest group and the 20 miles
of riparian land under conservation management as part of the Belize Community Baboon Sanctuary project. Outcomes are compared
with the programs original monetary or land management objectives to determine the success of the programs and to provide
feedback for improvement. 相似文献
279.
Carol A. Ferguson 《Journal of the American Water Resources Association》1989,25(6):1199-1204
ABSTRACT: Given limited available data and the present state of knowledge on the social aspects of irrigation, there is a need to develop new quantitative methods to measure water management performance in large-scale systems. A qualitative response framework is adapted to formulate a dynamic logit model of weekly field water adequacy and quantify indirectly farmer water utilization. Model parameters are estimated in a weighted least-squares regression using four seasons of data from a Philippine canal system. Estimated coefficients and independent model forecasts indicate greater effective use of rainfall than irrigation in sustaining high levels of water adequacy during the rainy season. Irrigation utilization is two times higher in the dry season, while system location has a much smaller but still significant impact. Utilization rates for both rain and irrigation showed considerable responsiveness to the prevailing scarcity of water. The qualitative response approach is well suited to the aggregated data available for large-scale systems, and allows advances in modeling dynamic water management behavior. Formal evaluation of the model will require further empirical applications. 相似文献
280.
Carol J. Miller Manoj Mishra 《Journal of the American Water Resources Association》1989,25(3):551-556
ABSTRACT: The existence and importance of macro-pores to the containment efficiency of cover clay liners at waste landfills is documented. Macro-pores exist as voids, or cracks, and act to increase the volume and rate of leakage through cover liners. Existing numerical models used to simulate flow through clay liners are shown to neglect the macro-pore aspect of the problem. Current theories of macro-pore flow developed from related areas of research are presented, and applications to the landfill liner problem are considered. 相似文献