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941.
942.
Andrew D. Dorfmann Jeane Perszyk Patricia Robinson Susan H. Black Joseph D. Schulman 《黑龙江环境通报》1992,12(11):899-902
This paper reports eight cases of non-mosaic, rare, and typically lethal trisomies diagnosed in chorionic villi and not confirmed by amniocentesis. Four cases were 47,XX, + 16; two cases were 47,XX, +2; one was 47,XX, + 12; and one was 47,XY, +7. There have been no known complications in any of these gestations. These eight cases were found in a series of approximately 12 000 samples processed in our laboratory (0.07 per cent). We conclude that (1) rare non-mosaic trisomy not reflecting the fetal condition is an occasional source of diagnostic ambiguity in chorionic villus sampling; and (2) when encountered, a follow-up amniocentesis should be recommended to the patient to confirm or rule out the abnormality. We propose the term ‘confined placental abnormality’ to describe non-mosaic trisomies and other related abnormalities found only in chorionic tissue. 相似文献
943.
H. Brandenburg MD W. De Koning M. G. J. Jahoda Th. Stijnen M. A. J. De Ridder E. S. Sachs J. W. Wladimiroff 《黑龙江环境通报》1992,12(12):1031-1035
One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy. 相似文献
944.
Thuli N. Mdluli Coleen H. Vogel 《Mitigation and Adaptation Strategies for Global Change》2010,15(3):205-222
South Africa faces several development challenges including those linked to climate change. Energy usage in South Africa, for example, is already constrained because of a range of development challenges (the dependence on cheap coal as a heating source; energy availability; access; affordability of alternative energy sources; and a range of health impacts, including air pollution). Notwithstanding calls for a transition to a low carbon economy, there have been few, recent assessments in South Africa of the costs associated with such a transition, particularly the social and economic costs for the poor who use energy in a variety of ways. In this paper we focus on trying to unravel some of the complex energy-use behaviour including understanding what drives consumers in resource-poor areas to choose and use persistently risky energy options. Analysis of qualitative data in two township areas, Doornkop and Kwaguqa, shows that township households, whether electrified or not, continue to burn coal. In both study areas, an estimated 80% of electrified households burn coal for space heating and cooking and also make use of multiple fuel sources for a range of activities. Although the major obstacles preventing people from discontinuing domestic coal combustion are poverty, the ready availability and social acceptability of coal together with other social customs cannot be underrated. This paper therefore highlights some of the persistent challenges associated with sustainable energy transitions in South Africa including implications for improved mitigation and adaptation for the energy sector in wider climate change efforts. 相似文献
945.
Silvia H. Bonilla Rodrigo L. Guarnetti Cecilia M.V.B. Almeida Biagio F. Giannetti 《Journal of Cleaner Production》2010,18(1):83-91
Bamboo presents physical and mechanical characteristics, which turn it an alternative option for product development, replacing native or reforested wood. The sustainability assessment of a Dendrocalamus Giganteus species plantation in Brazil through the emergy methodology evidences a great weight of renewable (30% sej/sej) and human labour contributions (33% sej/sej). These contributions account for the great interface with environment and to the intensive work, respectively. The transformity value of bamboo production is 2.42E + 04 sej/J. The influence human labour has on the total emergy flow and on indicators is evaluated by taking into account different country locations (Brazil, Australia and China). Thus, a different transformity value for labour is assumed for each country. A ranking based on emergy sustainability index (ESI) values shows that bamboo production in China was the first placed, followed by Brazil and Australia (values of 1.18, 0.50 and 0.09, respectively). The insertion of indirect renewability embedded in labour results in the ranking modification, leading to plantation in Brazil in the first place, followed by the Australian and Chinese ones. The relative position of the bamboo systems is visualized in the ternary diagram expressed in terms of emergy. In an attempt to explore the relationship between sustainability and time, a graphic of ESI vs. global productivity is discussed in terms of a prospective evaluation. Indirect support areas of the bamboo production are calculated as a way to evaluate the sustainability-space relationship. 相似文献
946.
A. Carvalho A. Monteiro S. Solman A.I. Miranda C. Borrego 《Environmental Science & Policy》2010,13(6):445-458
Climate change alone may deeply impact air quality levels in the atmosphere because the changes in the meteorological conditions will induce changes on the transport, dispersion and transformation of air pollutants. The aim of this work was to evaluate the impact of climate change on the air quality over Europe and Portugal, using a reference year (year 1990) and a IPCC SRES A2 year (year 2100). The Hadley Centre global atmospheric circulation model (HadAM3P) was used to provide results for these two climatic scenarios, which were then used as synoptic forcing for the MM5-CHIMERE air quality modelling system. In order to assess the contribution of future climate change on O3 and PM concentrations, no changes in regional emissions were assumed and only climate change forcing was considered. The modelling results suggest that the O3 monthly mean levels in the atmosphere may increase almost 50 μg m?3 across Europe in July under the IPCC SRES A2 scenario. In Portugal, this increase may reach 20 μg m?3. The changes of PM10 monthly average values over Europe will depend on the region. The increase in PM10 concentrations during specific months could be explained by the average reduction of the boundary layer height and wind speed. 相似文献
947.
The restoration of surface mining landscapes requires the (re)creation of ecosystems. In Lusatia (eastern Germany), large-scale open-cast lignite mining operations generated spoil dumps widely consisting of acidified, phytotoxic substrates. Amelioration and rehabilitation measures have been developed and applied to these substrates since the 1950s. However, it is still not clear whether these approaches are sustainable. This paper reports on collaborative research work into the ecological potential of forest ecosystem development on typical minesites in the Lusatian lignite district. At first sight, pine stands on minesites along a chronosequence comprising about 35 years did not show differences when compared with stands on non-mined sites of the general region. Furthermore, with some modification, conceptual models for flora and fauna succession in forest stands on non-mined sites seem to be applicable, at least for the early stages of forest ecosystem development. For example, soil organism abundance and activity at minesites had already reached levels typical of non-mined sites after about 20-30 years. In contrast, mine soils are very different from non-mined soils of the test region. Chemically, mine soil development is dominated by processes originating from pyrite oxidation. Geogenic, i.e. lignitic, soil organic carbon was shown to substitute for some functions of pedogenic soil organic matter. Rooting was hampered but not completely impeded in strongly acidified soil compartments. Roots and mycorrhizae are apparently able to make use of the characteristic heterogeneity of young mine soils. Considering these recent results and the knowledge accumulated during more than 30 years of research on minesite rehabilitation internationally, it can be stated that minesite restoration might be used as an ideal case study for forest ecosystem development starting at "point zero" on "terra nova". 相似文献
948.
Climate change and temperature-dependent biogeography: oxygen limitation of thermal tolerance in animals 总被引:2,自引:0,他引:2
Pörtner HO 《Die Naturwissenschaften》2001,88(4):137-146
Recent years have shown a rise in mean global temperatures and a shift in the geographical distribution of ectothermic animals. For a cause and effect analysis the present paper discusses those physiological processes limiting thermal tolerance. The lower heat tolerance in metazoa compared with unicellular eukaryotes and bacteria suggests that a complex systemic rather than molecular process is limiting in metazoa. Whole-animal aerobic scope appears as the first process limited at low and high temperatures, linked to the progressively insufficient capacity of circulation and ventilation. Oxygen levels in body fluids may decrease, reflecting excessive oxygen demand at high temperatures or insufficient aerobic capacity of mitochondria at low temperatures. Aerobic scope falls at temperatures beyond the thermal optimum and vanishes at low or high critical temperatures when transition to an anaerobic mitochondrial metabolism occurs. The adjustment of mitochondrial densities on top of parallel molecular or membrane adjustments appears crucial for maintaining aerobic scope and for shifting thermal tolerance. In conclusion, the capacity of oxygen delivery matches full aerobic scope only within the thermal optimum. At temperatures outside this range, only time-limited survival is supported by residual aerobic scope, then anaerobic metabolism and finally molecular protection by heat shock proteins and antioxidative defence. In a cause and effect hierarchy, the progressive increase in oxygen limitation at extreme temperatures may even enhance oxidative and denaturation stress. As a corollary, capacity limitations at a complex level of organisation, the oxygen delivery system, define thermal tolerance limits before molecular functions become disturbed. 相似文献
949.
Distribution of atrazine in a crop-soil-groundwater system at Baiyangdian Lake area in China 总被引:1,自引:0,他引:1
IntroductionAtrazine(2chloro4ethylamino6isopropylaminostriazine)isoneofthemostwidelyusedselectivepreandpostemergenceherbicidesforthecontrolofbroadleafandgrassyweeds.ThisherbicideisprimarilyusedincorncroppingsysteminNortheastandNorthofChina,andasoftentim… 相似文献
950.
Sathaye J.A. Makundi W.R. Andrasko K. Boer R. Ravindranath N.H. Sudha P. Rao S. Lasco R. Pulhin F. Masera O. Ceron A. Ordonez J. Deying X. Zhang X. Zuomin S. 《Mitigation and Adaptation Strategies for Global Change》2001,6(3-4):185-211
This paper summarizes studies of carbon (C) mitigation potential and costs of about 40 forestry options in seven developing countries. Each study uses the same methodological approach – Comprehensive Mitigation Assessment Process (COMAP) – to estimate the above parameters between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios. Coupled with data on a per ha basis on C sequestration or avoidance, and costs and benefits, it allows the estimation of monetary benefit per Mg C, and the total costs and carbon potential. The results show that about half (3.0 Pg C) the cumulative mitigation potential of 6.2 Petagram (Pg) C between 2000 and 2030 in the seven countries (about 200× 106 Mg C yr-1) could be achieved at a negative cost and the remainder at costs ranging up to $100 Mg C-1. About 5 Pg C could be achieved, at a cost less than $20 per Mg C. Negative cost potential indicates that non-carbon revenue is sufficient to offset direct costs of these options. The achievable potential is likely to be smaller, however, due to market, institutional, and sociocultural barriers that can delay or prevent the implementation of the analyzed options. 相似文献