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181.
Mrs Janet Vaughan Zehra Ali Sarah Bower Phillip Bennett Tim Chard Gudrun Moore 《黑龙江环境通报》1994,14(8):751-756
Two severely growth-retarded fetuses found to have maternal uniparental disomy (UPD) for chromosome 16 and trisomy 16 placental mosaicism both had an unfavourable outcome. Antenatally, the first case was complicated by an unexplained raised maternal serum alpha-fetoprotein concentration, preterm premature rupture of the membranes, and growth retardation detectable at 21 weeks' gestation, whilst the other had an unexplained raised maternal serum human chorionic gonadotrophin level, a two-vessel cord on ultrasound, and cessation of growth at 25 weeks. At post-mortem, both babies had an imperforate anus. Fetal maternal UPD may explain the poor outcome that occurs in some cases of confined placental mosaicism for chromosome 16 and is also associated with specific fetal abnormalities. 相似文献
182.
A decision inventory approach for improving decision support for climate change impact assessment and adaptation 总被引:1,自引:0,他引:1
Christopher R. Britta G. John Janet Thomas Susan Jordan 《Environmental Science & Policy》2007,10(7-8):610-621
Assessing and adapting to the impacts of climate change requires balancing social, economic, and environmental factors in the context of an ever-expanding range of objectives, uncertainties, and management options. The term decision support describes a diverse class of resources designed to help manage this complexity and assist decision makers in understanding impacts and evaluating management options. Most climate-related decision support resources implicitly assume that decision making is primarily limited by the quantity and quality of available information. However, a wide variety of evidence suggests that institutional, political, and communication processes are also integral to organizational decision making. Decision support resources designed to address these processes are underrepresented in existing tools. These persistent biases in the design and delivery of decision support may undermine efforts to move decision support from research to practice. The development of new approaches to decision support that consider a wider range of relevant issues is limited by the lack of information about the characteristics, context, and alternatives associated with climate-related decisions. We propose a new approach called a decision assessment and decision inventory that will provide systematic information describing the relevant attributes of climate-related decisions. This information can be used to improve the design of decision support resources, as well as to prioritize research and development investments. Application of this approach will help provide more effective decision support based on a balanced foundation of analytical tools, environmental data, and relevant information about decisions and decision makers. 相似文献
183.
Beth E. Waller Casey W. Hoy Janet L. Henderson Ben Stinner Celeste Welty 《Agriculture, ecosystems & environment》1998,70(2-3)
Through interviews and mail surveys, Ohio potato (Solanum tuberosum) growers were surveyed concerning their willingness to adopt three cultural controls being developed for management of the Colorado potato beetle, Leptinotarsa decemlineata (Say), which had become increasingly difficult to control. The principal objective of the research was to obtain a deeper understanding of how farmers make decisions to adopt or not adopt new techniques and how these decisions are related to farmers' educational backgrounds and the way they currently manage their farms. The three cultural management options emphasized ecological approaches to habitat management rather than ecologically disruptive chemical control: (1) using host plants in overwintering sites to slow the spring movement of the beetles to potato fields, (2) using larger potato plants at field borders than in the center of the field as a spring trap crop, and (3) concentrating beetles in relatively small undefoliated areas to be killed with heat in late summer. Most respondents would not adopt these alternative pest management strategies, mainly because they perceived an unsatisfactory trade-off between logistic difficulties and expenses and population suppression they would achieve compared with traditional chemical control measures. Education correlated positively and experience in farming negatively with the willingness to try new pest management techniques. Additionally, growers responding more negatively to questions regarding integrated pest management strategies were more willing to experiment with the alternative techniques, a result attributed to either the survey design or an indication of experience with the more intensive management effort required for integrated pest management. This profile of potential innovators should be used by researchers to establish partnerships with farmers that could assist with both the research and development of new farming techniques and the adoption of successful systems by other farmers. 相似文献
184.
185.
Fire disturbance is a primary agent of change in the mediterranean-climate chaparral shrublands of southern California, USA. However, fire frequency has been steadily increasing in coastal regions due to ignitions at the growing wildland-urban interface. Although chaparral is resilient to a range of fire frequencies, successively short intervals between fires can threaten the persistence of some species, and the effects may differ according to plant functional type. California shrublands support high levels of biological diversity, including many endangered and endemic species. Therefore, it is important to understand the long-term effects of altered fire regimes on these communities. A spatially explicit simulation model of landscape disturbance and succession (LANDIS) was used to predict the effects of frequent fire on the distribution of dominant plant functional types in a study area administered by the National Park Service. Shrubs dependent on fire-cued seed germination were most sensitive to frequent fire and lost substantial cover to other functional types, including drought-deciduous subshrubs that typify coastal sage scrub and nonnative annual grasses. Shrubs that resprout were favored by higher fire frequencies and gained in extent under these treatments. Due to this potential for vegetation change, caution is advised against the widespread use of prescribed fire in the region. 相似文献
186.
Stream ecosystem response to limestone treatment in acid impacted watersheds of the Allegheny Plateau. 总被引:1,自引:0,他引:1
Sarah E McClurg J Todd Petty Patricia M Mazik Janet L Clayton 《Ecological applications》2007,17(4):1087-1104
Restoration programs are expanding worldwide, but assessments of restoration effectiveness are rare. The objectives of our study were to assess current acid-precipitation remediation programs in streams of the Allegheny Plateau ecoregion of West Virginia (USA), identify specific attributes that could and could not be fully restored, and quantify temporal trends in ecosystem recovery. We sampled water chemistry, physical habitat, periphyton biomass, and benthic macroinvertebrate and fish community structure in three stream types: acidic (four streams), naturally circumneutral (eight streams), and acidic streams treated with limestone sand (eight streams). We observed no temporal trends in ecosystem recovery in treated streams despite sampling streams that ranged from 2 to 20 years since initial treatment. Our results indicated that the application of limestone sand to acidic streams was effective in fully recovering some characteristics, such as pH, alkalinity, Ca2+, Ca:H ratios, trout biomass and density, and trout reproductive success. However, recovery of many other characteristics was strongly dependent upon spatial proximity to treatment, and still others were never fully recovered. For example, limestone treatment did not restore dissolved aluminum concentrations, macroinvertebrate taxon richness, and total fish biomass to circumneutral reference conditions. Full recovery may not be occurring because treated streams continue to drain acidic watersheds and remain isolated in a network of acidic streams. We propose a revised stream restoration plan for the Allegheny Plateau that includes restoring stream ecosystems as connected networks rather than isolated reaches and recognizes that full recovery of acidified watersheds may not be possible. 相似文献
187.
Lawrence D. Platt M.D. Greggory R. Devore Janet Horenstein Zdena Pavlova Bruce Kovacs Rena Ellen Falk 《黑龙江环境通报》1987,7(6):407-411
Fetal echocardiography was used to identify a cardiac rhabdomyoma in the second trimester. The combination of this finding with a maternal history of Tuberous Sclerosis allowed the patient and her family to make a more educated decision regarding termination of the pregnancy. Post mortem examination of the fetus confirmed the prenatal findings. This case report demonstrates the importance of ultrasound evaluation of the fetus at risk of recurrence of a genetic syndrome in which one or more anatomical defects might be seen. 相似文献
188.
Strategies for sustainable woodland on contaminated soils 总被引:5,自引:0,他引:5
Dickinson NM 《Chemosphere》2000,41(1-2):259-263
189.
James F. Pankow Richard L. Johnson Janet P. Hewetson John A. Cherry 《Journal of contaminant hydrology》1986,1(1-2)
Contamination has occurred many non-indurated and bedrock systems wherein the groundwater flows almost exclusively through a network of connected, open fractures. The matrix surrounding the fractures often possesses porosity which allows contaminant diffusion into the matrix. If the diffusion rates are fast relative to the fracture groundwater velocity, transport effects may be predicted by considering the system to be an equivalent porous medium (EPM). The rapidity with which fracture/immobile-matrix equilibrium is established will be determined in part by the: fracture aperture (2b); interfracture spacing (2B); porosity in the immobile matrix (θim); and the matrix diffusion coefficient (D′). Two systems which are characterized by very different values of the above parameters have been studied by our laboratories. At Alkali Lake, Oregon, the EPM approach describes contaminant transport well. At Bayview Park, Ontario, the EPM approach is not appropriate. Several features of the two sites are compared to illustrate the different nature of these two sites. These features include: (1) natural characteristics of the groundwater systems; (2) contaminant distributions; (3) observed transport; and (4) computed fracture/immobile-matrix diffusion times. 相似文献
190.