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991.
Prenatal diagnosis of sickle cell diseases has been available for several years, and our laboratory has performed over 1000 prenatal diagnoses. However, currently available techniques are labor-intensive and time-consuming, and thus the diagnosis is delayed, making the mother's decision difficult. We describe a rapid, high-throughput technique based on the ligation assay coupled with automated capillary fluorescence detection. This new approach allows the diagnosis of both Hgb S and Hgb C to be available in a few hours. We have utilized this technique in 30 prenatal diagnoses and found it to be in complete agreement with the standard diagnoses. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
992.
OBJECTIVE: This study aims to determine the potential for improved child occupant protection in side impacts that can be obtained using rigid and semi-rigid anchorage systems and the addition of energy-absorbing padding in the side structures of child restraints. METHODS: This study uses a comprehensive set of simulated side impacts to evaluate the potential for improved side impact protection in forward-facing child restraints. Factors investigated included methods of anchoring the restraint to the vehicle, energy-absorbing materials in the side structure of restraints, and design features of the restraints such as side wing geometry and seat belt routing. RESULTS: The results show clearly that completely rigid lower attachment of restraints offers the potential for great reductions in head injury risk, which anchorage systems employing a combination of a rigid anchorage bar and webbing attached to a child restraint cannot match. The addition of energy absorbing material in the side structure of restraint systems is effective when the head is fully contained within an adequately designed side wing structure. For restraints anchored by seat belts and loop style semi rigid anchorage straps, belt routing has the potential to significantly affect occupant head excursion. CONCLUSIONS: The results suggest that current child restraint standards and consumer testing protocols do not adequately encourage best practice design of child restraints for side impact protection.  相似文献   
993.
Ecotourism and Community Development: Case Studies from Hainan,China   总被引:4,自引:1,他引:3  
The connections between people, parks, and tourism have received significant attention in recent years, recognizing the potential for mutually beneficial relationships. Ecotourism has been promoted and widely adopted as a strategy for funding conservation initiatives, while at the same time contributing to the socioeconomic development of host communities and providing for quality tourism experiences. Parks are among the most common ecotourism destinations. Employing interviews, observations and secondary sources, this study assesses the current status of ecotourism at two protected areas in Hainan, China, where it is being promoted as a strategy for balancing regional economic growth and conservation objectives. Through an evaluation of the existing tourism–park–community relationships, opportunities and constraints are identified. Ecotourism development was found to be at an early stage at both study sites. Socioeconomic benefits for the local communities have been limited and tourism activity has not contributed revenues towards conservation to date. Community residents, nevertheless, generally support conservation and are optimistic that tourism growth will yield benefits. In light of the study findings and the salient literature, planning direction is offered with the intention of enhancing the capacity of ecotourism to generate benefits for both communities and the parks, and thus contribute to the sustainable development of the region more generally. Lessons derived have broad applicability for ecotourism destinations elsewhere.  相似文献   
994.
Knowledge of the balance between nutrient inputs and removals is required for identifying regions that possess an excess or deficit of nutrients. This assessment describes the balance between the agricultural nutrient inputs and removals for nine geographical districts within Arkansas from 1997 to 2001. The total N, P, and K inputs were summed for each district and included inorganic fertilizer and collectable nutrients excreted as poultry, turkey, dairy, and hog manures. Nutrients removed by harvested crops were summed and subtracted from total nutrient inputs to calculate the net nutrient balance. The net balances for N, P, and K were distributed across the hectarage used for row crop, hay, pasture, or combinations of these land uses. Row-crop agriculture predominates in the eastern one-third and animal agriculture predominates in the western two-thirds of Arkansas. Nutrients derived from poultry litter accounted for >92% of the total transportable manure N, P, and K. The three districts in the eastern one-third of Arkansas contained 95% of the row-crop hectarage and had net N and P balances that were near zero or negative. The six districts in the western two-thirds of Arkansas accounted for 89 to 100% of the animal populations, had positive net balances for N and P, and excess P ranged from 1 to 9 kg P ha(-1) when distributed across row-crop, hay, and pasture hectarage. Transport of excess nutrients, primarily in poultry litter, outside of the districts in western Arkansas is needed to achieve a balance between soil inputs and removals of P and N.  相似文献   
995.
As the EU launches its latest 17 billion research programme, which includes significant funding for environmental research, JEM takes a look at the trends in and dynamics of innovation in environmental analysis.  相似文献   
996.
A study was carried out in northern Kuwait to investigate vegetation recovery in sandy depressions in the Sabriya oilfield ('Sabriya-IN'), 4 years after it was completely protected from livestock grazing and other anthropogenic activities which have largely depleted the dwarf shrub vegetation. This vegetation was compared with that in seriously overgrazed depressions outside the oilfield ('Sabriya-OUT'), where negative influences persist, and with a sandy site in central Kuwait which has been protected for over 20 years ('Sulaibiya'). There has been a striking recovery of the dwarf shrub vegetation in Sabriya-IN during the 4 years, with cover values of shrubs as high as at Sulaibiya. Rhanterium epapposum has been the main species to benefit from protection. However, the shrubs have not regenerated from seed, but rather from underground stumps that have probably remained in the soil for decades. Cover values of the annual flora at Sabriya-IN were very similar to those at Sulaibiya, and they were significantly higher than at Sabriya-OUT. However, it appears that some species may have disappeared or become extremely rare at Sabriya-IN when compared with Sulaibiya, as Sabriya-IN and Sabriya-OUT are remarkably similar floristically. Despite the impressive regeneration of the dwarf shrub vegetation at Sabriya-IN, which contradicts the view that vegetation recovery is a slow process in desert ecosystems, it is important to consider what the natural vegetation was in this part of the world. It is suggested that the region was once dominated by an open Acacia woodland, in which perennial grasses comprised most of the ground layer, and that the current dwarf shrub vegetation is a response to decades, if not centuries, of moderate to heavy grazing.  相似文献   
997.
Summary Risk-sensitive foraging theory predicts that predators which face starvation if there is a temporary shortfall in their food supply should choose feeding sites on the basis of variation in as well as mean expected reward rate. For a given mean reward rate they should choose high variance feeding sites (be risk-prone) if they are running below energy requirement, but low variance sites (be risk-averse) if they are running above.Common shrews presented with a choice between constant and variable feeding stations were more likely to visit the variable station when they were running below energy requirement and more likely to visit the constant station when they were running above. However, the tendency towards risk-aversion above requirement was greater than that towards risk-proneness below.When all shrews were considered together, the probability of visiting the variable station correlated negatively and continuously with intake relative to requirement.  相似文献   
998.
Differences between inland and coastal aquacultural production systems in Asia are discussed in terms of market orientation, resource allocation and property rights, and scale of operations. The production of shrimp grown in coastal brackish water ponds has featured prominently in aquacultural development programmes in Asia. Emphasis placed on capital-intensive shrimp production for export, however, has distracted attention from the potential of inland freshwater aquaculture to generate employment opportunities for rural people and food production for domestic consumers. The paper concludes with a discussion of an alternative policy direction for promoting aquacultural development on a socially sound basis, recognizing the need to balance equity and human nutrition with profitability and foreign exchange earnings.  相似文献   
999.
If you don't measure it, you can't manage it. Over the past decade, many companies have recognized this need to track environmental performance. Failure to plan metrics systems to fit organizational needs, work flows, and culture has left many companies with costly and ineffective environmental performance measurement systems. This article presents numerous practical steps for designing effective metrics systems which avoid common pitfalls.  相似文献   
1000.
Patch use as an indicator of habitat preference,predation risk,and competition   总被引:34,自引:0,他引:34  
Summary A technique for using patch giving up densities to investigate habitat preferences, predation risk, and interspecific competitive relationships is theoretically analyzed and empirically investigated. Giving up densities, the density of resources within a patch at which an individual ceases foraging, provide considerably more information than simply the amount of resources harvested. The giving up density of a forager, which is behaving optimally, should correspond to a harvest rate that just balances the metabolic costs of foraging, the predation cost of foraging, and the missed opportunity cost of not engaging in alternative activities. In addition, changes in giving up densities in response to climatic factors, predation risk, and missed opportunities can be used to test the model and to examine the consistency of the foragers' behavior. The technique was applied to a community of four Arizonan granivorous rodents (Perognathus amplus, Dipodomys merriami, Ammospermophilus harrisii, and Spermophilus tereticaudus). Aluminum trays filled with 3 grams of millet seeds mixed into 3 liters of sifted soil provided resource patches. The seeds remaining following a night or day of foraging were used to determine the giving up density, and footprints in the sifted sand indicated the identity of the forager. Giving up densities consistently differed in response to forager species, microhabitat (bush versus open), data, and station. The data also provide useful information regarding the relative foraging efficiencies and microhabitat preferences of the coexisting rodent species.  相似文献   
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