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- Barnes, David L., et al.
(författare)
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Operation of soil vapor extraction in cold climates
- 2002
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Ingår i: Cold regions engineering. - New York : American Society of Civil Engineers (ASCE). - 784406219 ; , s. 956-967
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Konferensbidrag (refereegranskat)abstract
- Soil Vapor Extraction has proven to be a viable method for reducing the mass of volatile compounds from soils that have been impacted by contamination. The theory, design and use of SVE systems have been fairly well documented, however the use of SVE systems in cold environments such as Alaska has not been adequately investigated to date. This paper examines the use of SVE systems in cold environments. The affect of low soil temperatures on volatile compound removal by SVE is discussed. Methods used to overcome the impact low temperatures have on the operation and effectiveness of SVE systems are examined in detail. Possible low cost strategies such as barometric pumping during winter months are presented as solutions to reducing SVE operating costs in cold regions
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- Hasselquist, Dennis, et al.
(författare)
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Humoral immunocompetence correlates with date of egg-laying and reflects work load in female tree swallows
- 2001
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Ingår i: Behavioral Ecology. - 1045-2249. ; 12:1, s. 93-97
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Tidskriftsartikel (refereegranskat)abstract
- Because quality differences between individuals affect fitness, much research has attempted, with limited success, to relate physiological condition (e.g., body reserves), to differences in life history between individuals. Recently, it has been suggested that immunocompetence may reflect condition, and it thus may mediate variation in individual quality and reproductive performance and, ultimately, fitness. We measured humoral immunocompetence (HIC) by immunizing female tree swallows with a harmless antigen and measured the specific antibody responses in a novel enzyme-linked immunosorbent assay developed for passerine birds. HIC was strongly correlated with egg-laying date, an important determinant of reproductive success in female tree swallows. We also investigated the effect of increased workload on HIC by manipulating female flight costs by clipping flight feathers. Clipped females had lower HIC than nonclipped females. These data suggest that HIC is a measure that may reflect phenotypic quality and also appears to be sensitive to increased workload in female tree swallows.
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- Psiaki, M.L., et al.
(författare)
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A comparison of "direct RF sampling" and "downconvert & sampling" GNSS receiver architectures
- 2003
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Ingår i: ION GPS/GNSS Proceedings. - : Institute of Navigation, The.
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Konferensbidrag (refereegranskat)abstract
- The new direct RF sampling GNSS receiver front concept has been analyzed, experimentally tested, simulated, and compared to a traditional superheterodyne front end that uses mixing to down-convert the signal before sampling. The goal of this study has been to demonstrate that signal power and carrier tracking are not adversely influenced by the use of direct RF sampling. The direct RF sampling strategy that has been examined uses sampling rates that are much lower than the carrier frequency but that are more than twice the information bandwidth. Such a system employs a bandpass filter in front of the analog-todigital converter to avoid sensitivity loss via aliasing of out-of-band noise and interfering signals. This design approach has been evaluated analytically to determine the effects of sample clock jitter, and experimental and simulation results have been used to confirm the analytical results. The experiments have used computer data acquisition systems to record the outputs of direct RF sampling front ends that were connected to roof-top patch antennas. The results indicate that direct RF sampling yields equivalent performance to superheterodyne mixing if sample timing jitter is kept below well defined limits.
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