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21.
Landscape context is an important factor in restoration ecology, but the use of landscape context for site prioritization has not been as fully developed. We used morphological image processing to identify candidate ecological restoration areas based on their proximity to existing natural vegetation. We identified 1,102,720 candidate ecological restoration areas across the continental United States. Candidate ecological restoration areas were concentrated in the Great Plains and eastern United States. We populated the database of candidate ecological restoration areas with 17 attributes related to site content and context, including factors such as soil fertility and roads (site content), and number and area of potentially conjoined vegetated regions (site context) to facilitate its use for site prioritization. We demonstrate the utility of the database in the state of North Carolina, U.S.A. for a restoration objective related to restoration of water quality (mandated by the U.S. Clean Water Act), wetlands, and forest. The database will be made publicly available on the U.S. Environmental Protection Agency's EnviroAtlas website ( http://enviroatlas.epa.gov ) for stakeholders interested in ecological restoration.  相似文献   
22.
The high cost of recombinant enzymes for the production of biofuel from ligno-cellulosic biomass is a crucial factor affecting the economic sustainability of the process. The use of plants as biofactories for the production of the suitable recombinant enzymes might be an alternative to microbial fermentation. In the case of enzyme accumulation in chloroplasts, it is fundamental to focus on the issue of full photosynthetic efficiency of transplastomic plants in the field where they might be exposed to abiotic stress such as high light intensity and high temperature. Xylanases (EC 3.2.1.8), a group of enzymes that hydrolyse linear polysaccharides of beta-1,4-xylan into xylose, find an application in the biofuel industry favouring biomass saccharification along with other cell-wall degrading enzymes. In the present study, we analysed how a high level of accumulation of a thermostable xylanase in tobacco chloroplasts does not impact on photosynthetic performance of transplastomic plants grown outdoors. The recombinant enzyme was found to be stable during plant development, ex planta and after long-term storage.  相似文献   
23.
The future health of ecosystems is arguably as dependent on urban sprawl as it is on human-caused climatic warming. Urban sprawl strongly impacts the urban ecosystems it creates and the natural and agro-ecosystems that it displaces and fragments. Here, we project urban sprawl changes for the next 50 years for the fast-growing Southeast U.S. Previous studies have focused on modeling population density, but the urban extent is arguably as important as population density per se in terms of its ecological and conservation impacts. We develop simulations using the SLEUTH urban growth model that complement population-driven models but focus on spatial pattern and extent. To better capture the reach of low-density suburban development, we extend the capabilities of SLEUTH by incorporating street-network information. Our simulations point to a future in which the extent of urbanization in the Southeast is projected to increase by 101% to 192%. Our results highlight areas where ecosystem fragmentation is likely, and serve as a benchmark to explore the challenging tradeoffs between ecosystem health, economic growth and cultural desires.  相似文献   
24.
What is a healthy ecosystem?   总被引:21,自引:0,他引:21  
Rapid deterioration of the world's major ecosystems has intensified the need for effective environmental monitoring and the development of operational indicators of ecosystem health. Ecosystem health represents a desired endpoint of environmental management, but it requires adaptive, ongoing definition and assessment. We propose that a healthy ecosystem is one that is sustainable – that is, it has the ability to maintain its structure (organization) and function (vigor) over time in the face of external stress (resilience). Various methods to quantify these three ecosystem attributes (vigor, organization, and resilience) are discussed. These attributes are then folded into a comprehensive assessment of ecosystem health. A network analysis based ecosystem health assessment is developed and tested using trophic exchange networks representing several different aquatic ecosystems. Results indicate the potential of such an ecosystem health assessment for evaluating the relative health of similar ecosystems, and quantifying the effects of natural or anthropogenic stress on the health of a particular ecosystem over time.  相似文献   
25.
Purpose: Elevated carbohydrate antigen 125 (CA125) predicts adverse outcome after transcatheter aortic valve implantation (TAVI). While known underlying pathophysiological mechanisms of elevated CA125 include serosal effusions and inflammatory stimuli, clinical determinants associated with elevated CA125 in patients referred for TAVI remain unknown. Therefore, we investigated clinical, laboratory and echocardiographic determinants of elevated CA125 in patients with severe aortic valve stenosis referred for TAVI.

Methods: This study includes 650 patients with severe aortic stenosis referred for TAVI. Baseline CA125 was determined by an immunoassay and dichotomized (elevated versus normal) based on the manufacturer cutoff value (>35?U/mL).

Results: CA125 elevation was present in 28% (181/650). Patients with elevated CA125 had an overall worse clinical profile and were more symptomatic with a higher rate of NYHA class III/IV (80% versus 58%; p?Conclusion: Elevated CA125 levels in patients referred for TAVI summarize a subset of patients with an overall worse clinical profile who are more symptomatic.  相似文献   
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27.
Adventitious roots were observed on 3 wild perennialGlycine species, in short-poddedG. clandestina, G. latifolia and mostG. tabacina (2x, 4x, 6x), while other species lacked adventitious roots. This suggests that the adventitious roots trait is associated with B genome species. Intra- and interspecific F1 hybrids reveal that adventitious roots apparently are inherited recessively. The presence of adventitious roots or short-poddedG. clandestina, coupled with infertility with longer-poddedG. clandestina, and enzymatic and leaflet morphology differences between the twoG. clandestina subgroups, supports segregation of the short-podded form as a separate taxon.  相似文献   
28.
The aim of this study was to examine the relationship between push-time and final race time in skeleton participants during a series of major international competitions to determine the importance of the push phase in skeleton performance. Correlations were computed from the first and second heat split data measured during 24 men and 24 women skeleton competitions. Body mass, height, age, and years of experience of the first 30 men and women athletes of the skeleton, bobsleigh and luge 2003-2004 World Cup ranking were used for the comparison between sliding sports. Moderate but significant correlations (p < 0.05) were found between push-time and final race time in men (r(mean) = 0.48) and women (r(mean) = 0.63). No correlations were found between changes in the individual push-time between the first and second heat with the corresponding changes in final race time. The bobsleigh sliders are heavier than the athletes of the other sliding disciplines. Luge athletes have more experience and are younger than bobsleigh and skeleton sliders. The results of this study suggest that a fast push phase is a prerequisite to success in competition and confirms that the selection of skeleton athletes based on the ability to accelerate to a maximum speed quickly could be valid. However, a good or improved push-time does not ensure a placement in the top finishing positions. On the basis of these results, we suggest that strength and power training is necessary to maintain a short push-time but additional physical training aimed to enhance the push phase might not reflect performance improvements. The recruitment of younger athletes and an increase of youthful competitive activity may be another effective way to reach international competitive results.  相似文献   
29.
A different expression pattern of polyphenol oxidases has been observed during storage in cultivars of potato (Solanum tuberosum L.) featuring different length of dormancy: a short-dormant cultivar showed, at the end of the dormancy, both the highest polyphenol oxidase activity and the largest number of enzyme isoforms. An isoform of polyphenol oxidase isolated at the end of the physiological dormancy from a short-dormant cultivar has been purified to homogeneity by means of column chromatography on phenyl Sepharose and on Superdex 200. The purification factor has been determined equal to 88, and the molecular mass of the purified isoform has been estimated to be 69 and 340 kDa by SDS polyacrylamide gel electrophoresis and gel filtration on Superdex 200, respectively, indicating this PPO isoform as a multimer. The corresponding zymogram features a diffused single band at the cathodic region of the gel and the pI of this polyphenol oxidase has been calculated equal to 6.5.  相似文献   
30.
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