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141.
Catherine Marina Pickering Andrew J. Growcock 《Journal of environmental management》2009,90(2):532-540
The Australian Alps, which are of high conservation value, are popular summer bushwalking destinations. Experimental trampling trials using a standardized methodology were conducted to determine the resistance and resilience of the two common vegetation types: tall alpine herbfield and subalpine grasslands. Vegetation parameters were measured in lanes subject to control (no trampling), 30, 100, 200, 500 and 700 passes at five sites prior to trampling, immediately post trampling, 2 weeks, 6 weeks and 1 year post trampling. Vegetation height, cover of graminoids and herbs, as well as net species richness all declined with trampling, while litter cover increased. Thresholds for damage varied between the two communities and among the different vegetation parameters. The resistance indices for the two communities (number of passes resulting in 50% reduction in vegetation cover), however, were similar at around 440–450 passes indicating that these two communities are among the most resistant of the 19 alpine–subalpine communities that have been tested around the world, but only of moderate resistance compared to non-alpine communities. The two communities showed limited recovery with damage still evident 1 year post trampling. This indicates that they have only moderate tolerance to damage due to moderate resistance, but low resilience. 相似文献
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John S. Halow Susan J. Zeek 《Journal of the Air & Waste Management Association (1995)》2013,63(8):676-684
Methods have been developed for calculating the Ringelmann number, opacity, and other optical characteristics of stack plumes from information on particulate properties, concentrations, and system geometry. Such calculations can be used in selecting clean-up equipment to improve stack appearance required to meet Ringelmann number and opacity pollution regulations. Methods were developed for white plumes caused by water drops or crystalline material and for black plumes containing carbon emissions. The Mie theory of light scattering was utilized to calculate plume optical properties which were related to Ringelmann number through psycophysically significant correlations. A computer program was written to perform the Mie theory and related calculations. Graphical methods were developed for plumes with log-probability size distributions composed of water drops, dusts with refractive index of 1.50 or carbon type emissions of refractive index 1.59-0.66i. Agreement of Ringelmann numbers predicted by these techniques and those observed for large stacks is excellent. 相似文献
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Agnès Guichet Stéphane Triau Catherine Lépinard Chantal Esculapavit Florence Biquard Philippe Descamps Férechté Encha-Razavi Dominique Bonneau 《黑龙江环境通报》2004,24(10):828-832
We report an interstitial deletion of chromosome 3q26-q28 in a fetus in which anophthalmia had been detected prenatally. FISH analysis, using BAC clones encompassing the SOX2 locus, showed that SOX2 gene was involved in the chromosomal breakpoint of the deletion. This case confirms that haploinsufficiency for SOX2 plays a crucial role in human eye development and emphasizes the necessity of careful chromosomal analysis, including FISH analysis of the 3q region, in case of prenatal discovery of anophthalmia. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
149.
The U.S. Environmental Protection Agency (EPA) performed a reservoir diagnosis and developed low-cost recommendations to improve drinking water quality for the city of Nizhnii Tagil, Russia. Despite widespread regional pollution, water quality within the drinking water supply source can be summarized as generally good. Sampling and analysis efforts did not reveal appreciable amounts of hazardous chemicals or metals. The major water quality problem stems from an abundance of blue-green algae during the summer months, causing drinking water taste and odor problems and filter clogging at the water treatment plant. City water treatment officials also frequently experience difficulties with maintaining an effective disinfection residual in the distribution system because it spans more than 30 kilometers in length. Regrowth of microorganisms in the distribution system often causes coliform bacteria counts to exceed standards. The implementation of a watershed protection and management program, and the installation of a new disinfection system, to purify drinking water and to reduce bacterial growth in the distribution system should improve drinking water quality for the city residents. 相似文献
150.
Catherine Robb Bevier 《Behavioral ecology and sociobiology》1997,41(5):343-352
Calling activity in frogs is energetically demanding to males because they usually perform at or near their physiological
capacities. Metabolic fuel for muscle contractions during bouts of aerobic calling activity comes from carbohydrates and lipids
that are stored in the trunk muscles. I monitored nightly calling performance in males of seven tropical frog species from
two families, Hylidae and Leptodactylidae, and compared levels of glycogen and lipid in the trunk muscles from males collected
before and after a three-hour period of calling activity. Trunk muscles from late-evening males in five species had up to
63% less glycogen than the trunk muscles from early-evening males; relatively little depletion was observed in two other species.
Overall, glycogen reserves and rates of depletion were highest in species with very high calling rates. It was not possible
to measure changes in the relatively large stores of lipid in the trunk muscles after only 3 h of calling. Nevertheless, intramuscular
lipid stores probably provide a greater percentage of the energy needed for sound production than glycogen stores, and are
largest in species with high calling rates.
Received: 7 January 1997 / Accepted after revision: 20 July 1997 相似文献