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281.
The field of prenatal screening and diagnosis for fetal anomalies has been marked by a rapid succession of technological advances, including most notably, chromosomal microarray analysis, and next generation sequencing. Despite the diagnostic advantages of these technologies, their incorporation into prenatal testing has created additional challenges of revealing genomic variants of unknown or uncertain significance, and secondary findings. While detailed posttest counseling about uncertain variants is best performed by medical geneticists, many of the screening and diagnostic tests that lead to this information are actually ordered by general maternity health care professionals (HCPs), such as obstetricians, midwives, and family physicians. Maternity HCPs support pregnant women through to the conclusion of their pregnancy and the postpartum period, and thus are close observers of the psychosocial impart of fetal genomic uncertainty on women and their families. While there have been many studies exploring the handling of genomic uncertainty by genetics HCPs, there has been relatively less attention paid to maternity HCPs without speciality training in genetics. This review explores the current literature surrounding nongenetic maternity HCPs' views and experiences of genomic uncertainty and returning uncertain results in the prenatal setting. 相似文献
282.
Bennie W. Good G. Vilcins W.R. Harvey D.A. Clabo Jr. A.L. Lewis 《Environment international》1982,8(1-6)
Two studies evaluating the levels and sources of nitrogen dioxide in approximately 90 employee homes in the Richmond area with continuous sampling during the weeks of August 5, 1980, and February 9, 1981, were performed using samplers in the living room, bedroom, kitchen, and outdoors. Additional data were collected concerning appliance usage, heating/cooling plant, ventilation and cigarette smoking. Results were analyzed using BMDP routines. The largest contributor to NO2 concentration was found to be gas-fired kitchen appliances. The mean kitchen level for homes with gas appliances during the winter study was 188 μg/m3. Excluding participants with gas kitchens, incremental influence due to cigarette smoking was detected. The 7-day, 3-room average level of NO2 in the homes of nonsmokers and smokers without gas-fired appliances was 12 and 15 μg/m3, respectively, in the summer. The corresponding winter values were 19 and 22 μg/m3. Furthermore, the individual levels of NO2 in the homes of smokers were generally below both the adjacent outdoor level and the National Ambient Air Quality Standard limit for annual exposure. 相似文献
283.
In interior western North America, many riparian forests dominated by cottonwood and willow are failing to reproduce downstream
of dams. We tested the hypothesis that establishment is now prevented by absence of the bare, moist substrate formerly provided
by floods and channel movement. Along Boulder Creek, a dammed stream in the Colorado plains, we tested the effects of disturbance
(sod removal), irrigation, and addition of seed on the establishment of seedings of plains cottonwood (Populus deltoides subsp.monilifera) and peachleaf willow (Salix amygdaloides). In unirrigated, undisturbed plots, mean cottonwood density was 0.03 seedlings/m2. Irrigation or disturbance alone produced mean cottonwood densities of 0.39 and 0.75 seedlings/m2. Plots that were both irrigated and disturbed produced a mean cottonwood density of 10.3 seedlings/m2. The effects of irrigation and disturbance on cottonwood establishment were significant (P<0.005); added seed had no significant effect (P=0.78). The few cottonwood seedlings in unirrigated plots were in low positions susceptible to scour by future moderate flows.
We conclude that cottonwood establishment along Boulder Creek is limited by the scarcity of bare, moist sites safe from future
scour. Establishment of peachleaf willow was significantly affected only by disturbance; daily sprinkler irrigation did not
provide sufficient moisture to increase survival of this species. Our results demonstrate the feasibility of restoring plains
cottonwood forests using natural seedfall, even where only widely scattered adult trees are present. Because use of natural
seedfall conserves the genetic makeup of the local population, this method may be preferable to the use of imported cuttings. 相似文献
284.
Scott E. Atkinson Donald H. Lewis 《Journal of Environmental Economics and Management》1976,3(4):363-380
This paper utilizes two least-cost emission control strategies and develops rules for structuring and implementing optimal air quality standards. A strategy typical of those currently enforced, based on the State Implementation Plans (SIP's ), is compared to two least-cost strategies: (i) ambient least cost (ALC ), which achieves required air quality at least cost; and (ii) emissions least cost (ELC ), which achieves required emissions reduction at least cost. A demonstration is given of the theoretically derived result that the ALC strategy should be utilized in cost-benefit analyses to determine air quality standards and to generate emissions taxes. Preliminary analysis of the St. Louis area indicated tentative justification for a particulate ambient standard at least as strict as the current Federal primary standard. The efficiency, equity, and administrative costs for implementation of strategies based on the least-cost concept are also examined. 相似文献
285.
Lewis C. Linker Robin Dennis Gary W. Shenk Richard A. Batiuk Jeffrey Grimm Ping Wang 《Journal of the American Water Resources Association》2013,49(5):1025-1041
Application of integrated Chesapeake Bay models of the airshed, watershed, and estuary support air and water nitrogen controls in the Chesapeake. The models include an airshed model of the Mid‐Atlantic region which tracks the estimated atmospheric deposition loads of nitrogen to the watershed, tidal Bay, and adjacent coastal ocean. The three integrated models allow tracking of the transport and fate of nitrogen air emissions, including deposition in the Chesapeake watershed, the subsequent uptake, transformation, and transport to Bay tidal waters, and their ultimate influence on Chesapeake water quality. This article describes the development of the airshed model, its application to scenarios supporting the Chesapeake Total Maximum Daily Load (TMDL), and key findings from the scenarios. Key findings are that the atmospheric deposition loads are among the largest input loads of nitrogen in the watershed, and that the indirect nitrogen deposition loads to the watershed, which are subsequently delivered to the Bay are larger than the direct loads of atmospheric nitrogen deposition to Chesapeake tidal waters. Atmospheric deposition loads of nitrogen deposited in coastal waters, which are exchanged with the Chesapeake, are also estimated. About half the atmospheric deposition loads of nitrogen originate from outside the Chesapeake watershed. For the first time in a TMDL, the loads of atmospheric nitrogen deposition are an explicit part of the TMDL load reductions. 相似文献
286.
This paper aims to contribute to the ongoing debate on the use of resource accounting tools in regional policy-making. The Northern Limits project applied material flow analysis (MFA) and ecological footprinting (EF) to regional policy-making in Northern Ireland over a number of years. The early phase of the research informed the regions first sustainable development strategy which was published in 2006 with key targets relating to the EF and improving the resource efficiency of the economy. Phase II identified the next steps required to address data availability and quality and the use of MFA and EF in providing a measurement and monitoring framework for the strategy and the development of the strategy implementation plan. The use of MFA and EF in sustainable regional policy-making and the monitoring of its implementation is an ongoing process which has raised a number of research issues which can inform the ongoing application and development of these and other resource accounting tools to within Northern Ireland, provide insights for their use in other regions, and help set out the priorities for research to support this important policy area. 相似文献
287.
Radon gas contributes a significant fraction of the natural background radiation dose, and in some areas raised levels are found in buildings. both homes and the workplace. Different UK Action Levels apply to homes and the workplace. because of the diurnal variation of radon. This study reviews the results for a number of hospitals throughout England and Wales. and suggests that the likelihood of finding raised radon levels is similar in the workplace and homes in the same area. Radon measurements and consequent remediation of any raised levels are appropriate in all workplaces in radon Affected Areas with over 5% of houses above the UK domestic Action Level of 200 Bq m(-3). 相似文献
288.
Input-output modeling and multiplier analysis are used to assess Taiwan's five petrochemical industries, based upon their economic contribution and potential impacts on energy consumption and CO2 emission. In addition, a consolidated index system was developed for evaluating energy and economic efficiencies as well as targets for CO2 reduction. Results indicate that petrochemical materials (PM) make a major contribution to economic development, with lesser contributions from plastic materials (PL) and artificial fibres (AF). PM has the highest energy multiplier while PL has the largest induced potential for energy consumption. Plastic and rubber products (PP, RP) are relatively insignificant energy consumers. AF has the highest CO2 multiplier, and its induced potential for CO2 emission is the most significant. The consolidated index shows that the upstream petrochemical industries perform rather poorly in an integrated view of economic, energy, and CO2 emission, and should be seen as the primary targets for CO2 reduction. Investment of the petrochemical industries in Taiwan should be adjusted to improve energy efficiency, economic bases, and lower CO2 emissions. 相似文献
289.
William T. Mason Jr. Philip A. Lewis Cornelius I. Weber 《Environmental monitoring and assessment》1983,3(1):29-44
Evaluation of analytical methods employed for wet weight (live or preserved samples) of benthic macroinvertebrates reveals that centrifugation at 140 x gravity for one minute yields constant biomass estimates. Less relative centrifugal force increases chance of incomplete removal of body moisture and results in weighing error, while greater force may rupture fragile macroinvertebrates, such as mayflies. Duration of specimen exposure in ethanol, formalin, and formol (formaling-ethanol combinations) causes significant body weight loss with within 48 hr formalin and formol cause less body weight loss than ethanol. However, as all preservatives tested cause body weight loss, preservation time of samples collected for comparative purposes should be treated uniformly. Dry weight estimates of macroinvertebrates are not significantly affected by kind of preservative or duration of exposure. Constant dry weights are attained by oven drying at 103 °C at a minimum of four hours or vacuum oven drying (15 inches of mercury pressure) at 103 °C for a minimum of one hour. Although requiring more time in preparation than oven drying and inalterably changing specimen body shape, freeze drying (10 microns pressure, -55 °C, 24 hr) provides constant dry weights and is advantageous for long term sample storage by minimizing curatorial attention. Constant ash-free dry weights of macroinvertebrate samples are attained by igniting samples at 500–550 °C for a minimum of one hour with slow cooling to room temperature in desiccators before weighing. 相似文献
290.
Disturbance and recovery of large floodplain rivers 总被引:7,自引:0,他引:7
Richard E. Sparks Peter B. Bayley Steven L. Kohler Lewis L. Osborne 《Environmental management》1990,14(5):699-709
Disturbance in a river-floodplain system is defined as an unpredictable event that disrupts structure or function at the ecosystem,
community, or population level. Disturbance can result in species replacements or losses, or shifts of ecosystems from one
persistent condition to another. A disturbance can be a discrete event or a graded change in a controlling factor that eventually
exceeds a critical threshold.
The annual flood is the major driving variable that facilitates lateral exchanges of nutrients, organic matter, and organisms.
The annual flood is not normally considered a disturbance unless its timing or magnitude is “atypical.” The record flood of
1973 had little effect on the biota at a long-term study site on the Mississippi River, but the absence of a flood during
the 1976–1977 Midwestern drought caused short- and long-term changes. Body burdens of contaminants increased temporarily in
key species, because of increased concentration resulting from reduced dilution. Reduced runoff and sediment input improved
light penetration and increased the depth at which aquatic macrophytes could grow. Developing plant beds exerted a high degree
of biotic control and were able to persist, despite the resumption of normal floods and turbidity in subsequent years.
In contrast to the discrete event that disturbed the Mississippi River, a major confluent, the Illinois River, has been degraded
by a gradual increase in sediment input and sediment resuspension. From 1958 to 1961 formerly productive backwaters and lakes
along a 320-km reach of the Illinois River changed from clear, vegetated areas to turbid, barren basins. The change to a system
largely controlled by abiotic factors was rapid and the degraded condition persists.
Traditional approaches to experimental design are poorly suited for detecting control mechanisms and for determining the critical
thresholds in large river-floodplains. Large river-floodplain systems cannot be manipulated or sampled as easily as small
streams, and greater use should be made of man-made or natural disturbances and environmental restoration as opportunistic
experiments to measure thresholds and monitor the recovery process.
Coauthors are listed in alphabetical order. 相似文献